Cable television both-way system

A two-way cable television system is designed to generate and collect statistics on cable television networking (100). E.g. Data regarding the monitored television channels in the remote terminals (120, 315) may be generated in each remote terminal (120, 315) and then collected by the system organizer (310). The system organizer (310) divides one or more forward / Srem recording times into one or more remote terminals (120, 315). indicating the future moment at which the terminal (120, 315) is to record tracking statistics. The remote terminals (120, 315) store one or more recording times in memory (503) and when the recording time coincides with real time. the terminals (120, 315) store monitoring statistics in the memory (503). Then, in response to the selection signal from the system organizer (310). the terminals (120, 315) send the previously recorded tracking statistics together with the time code corresponding to the time the statistics were recorded back to the system organizer (310) and the system organizer (310) processes this information. In one embodiment, tracking statistics are generated from status information within each remote terminal (120, 315). In another embodiment, tracking statistics are generated from user input (440) to each of the remote terminals (120, 315). In one embodiment, there are several collection sections in each of the remote terminals for receiving and maintaining the wolf than one recording time at a time. In another embodiment, the system organizer (310) transmits recording times and selection signals f for each individual section independently of the other collection sections and at different times.

than other collection sections.

8^1-32.

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Field of technology

The invention relates generally to a method and apparatus for generating and obtaining tracking statistics from a plurality of remote terminals in a cable television system, and more particularly to a method and apparatus for remotely programming remote terminals for monitoring and recording tracking statistics at certain times and transmitting such data to a system. organizer in time for them to be collected and processed.

BACKGROUND OF THE INVENTION The development of cable television systems has reached a state where the possibility of information flow in both directions is not only desirable but is practically required by the need to provide new services. E.g. in the implementation of the impulse payment service for monitoring, when the subscriber can arbitrarily choose what he wants to look at and expect to pay for it, at least one data channel similar to a telephone transmission channel or RF channel in the / opposite / direction is required, i.e. from the television subscriber to the terminal in order to report usage data. Other uses of the return path include energy meter reading, alarm services, subscriber selection and voting, collection of statistics from subscribers on tracking, and buying from home. While not every cable television operator provides the possibility of transmissions in both directions, the manufacturers of cable television equipment have sought to ensure transmission in the opposite direction from the subscriber to the terminal. Virtually all manufacturers provide a so-called split or bidirectional system, which has a whole spectrum of frequencies for transmission in the opposite direction, which contains at least the band from 5 to 30 MHz. This band includes cable television channels T7 / 5.75 - 11.75 MHz /, T8 / 11 ^ 75 - 17.75 MHz /, T9 / 17.75 - 23.75 MHz / and T10 / 23.75 - 29, 75 MHz /. These 2-channel channels, each of which has a TV signal bandwidth, can be used, for example, for video conferencing. Whether the terminal operator uses a "subdivision", "medium division" or "upper division" system for bidirectional transmission, all three types of the split transmission system typically include a 5-30 ΙΉζ reverse transmission.

The concept of IPPV impulse pay-per-view is well known, but we will describe it briefly here for completeness. In essence, it is a sales method in which a paying cable subscriber can individually purchase a particular program. Furthermore, this purchase can only be made on the basis of an impulse '' interaction with the terminal in the subscriber's apartment. Although it is not required that the items being purchased are in progress, the system is required to allow the purchase of items that are on the agenda. The purchase must be made in such a way that it does not cause any obvious delay in the subscriber's ability to watch the program immediately / ie. immediate satisfaction.

Although there are several ways to implement this method of sale, all of these methods have common requirements. Some part of the system must decide whether or not to allow the sale and subsequent monitoring of the program. If tracking is enabled, the sale of that particular item must be recorded and reported to what is commonly known as a billing system, so that the program vendor eventually gets paid for the transaction.

In order to report the sale of an event, the so-called save and sell technique is used. In this method of storage and handover, the terminal assumes that if the subscriber is given the IPPV option in advance, then the sale of the item is allowed. When the subscriber takes the necessary steps to purchase the item, the terminal will allow tracking of the item /e.g. by decoding the video signal on a particular channel / and recording information or data related to the purchase of the item. The record is usually stored in a secure, non-volatile memory because it represents a payment to the program vendor.

Obviously, the seller's billing system must from time to time receive stored sales data from all subscriber terminals in order to get paid. To achieve this, the system control computer (hereinafter referred to as the system organizer) periodically requests the terminals to send IPPV sales data, which are stored in memory.

When the system organizer receives data © from the terminal, it confirms their receipt to the terminal / see Citts ad. U.S. Patent No. 4,536,078, and the data is erased from the memory to make room for additional

- 3 sales. The system organizer passes this data to the billing system and thus the IPPV purchase cycle is completed.

Closely related to the concept of impulse payment from monitoring is the requirement to collect statistical data on monitoring from remote subscriber terminals. Such viewing statistics may include: which channels the sbonent watches on his TV, whether the TV is on or off, the volume level of the TV, the brightness level of the TV std. It can also provide information on the number of television viewers, their age, gender, etc. It is highly desirable for cable operators to know which television channels I am watching at each remote terminal so that they can determine the success of the television programs available to subscribers.

When this viewing information is gathered, cable operators will be better able to plan future programs based on the real habits and interests of their subscribers. Potential cable advertisers can also decide on the markets where they should broadcast their commercial messages. However, the above list of types of tracking statistics is not exhaustive, as other types of information related to subscribers' habits can be collected by remote terminals.

Cable companies have also recently been asked by administrations to provide emergency and / or basic services to certain individuals or to provide certain programs, such as broadcasts from government negotiations. Such requests are accompanied by the need to measure their success by measuring the tracking habits of the individuals concerned.

There are several ways to collect viewing statistics on cable TV. However, the implementation of all these methods is subject to serious limitations. A particular limitation suffered by all of these methods is the inability to quickly and efficiently transmit the required tracking statistics from each remote terminal to the system organizer at the end station.

One way to collect such viewing statistics is for each subscriber to be manually asked which television channels he or she is watching. This can be done by phone, mail / letter / or in person. The obvious disadvantage of this method is that tracking information cannot be collected in time and that the reliability of the subscribers' memory,

- 4 for channels they watched some time ago may be limited.

Another method used to collect tracking statistics is to generate these tracking statistics at each remote terminal in response to commands from the system organizer at the end station. Tracking statistics are usually stored in a memory located in each remote terminal and then transmitted by pre-existing telephone lines to the system organizer. Although this method represents an improved system for the reliable and timely transmission of channel monitoring information, it nevertheless has several shortcomings. First, because existing telephone lines are used for transmission, these lines are not available for normal home use during the transmission. Second, special additional equipment needs to be used to connect both the remote terminal and the terminal to the telephone line, which increases the acquisition and maintenance costs of the system. Thirdly, because lines are used which are not intended for this purpose alone, it is necessary to take into account the considerably long additional time during which the respective transmission connection is established, which significantly reduces the efficiency for data throughput.

As a result, there is still a need in the prior art to find a method and apparatus in a cable television system for the rapid and efficient generation and collection of tracking statistics from remote terminals.

The essence of the invention

The present invention relates to a method and apparatus for collecting tracking statistics associated with remote terminals in a two-way cable television system. In particular, the invention relates to programming remote terminals to record channel tracking information in the future and for these remote terminals to later return this information in the opposite direction to the system organizer as soon as this information is recorded.

One of the aims of the invention is that the use of the implementation of RF reverse data transmission from subscribers does not require substantial changes in the billing system. Furthermore, RF data transmission from subscribers should operate independently of telephone data transmission; ie they had

- 5 would work together, side by side. The equipment for RF reverse transmission of data from subscribers should be compatible with all terminal equipment used for direct or forward transmission. Knowledge of system equipment and terms can be obtained from this overview: The system organizer is the basic control computer of the cable television system. The system organizer receives input commands from both the operator and the billing computer. It generates the relevant control transactions, which are transmitted via the control transmitter by a forward cable path to the terminals. It receives feedback from a multi-frequency receiver and processor (here called an IPPV processor) and passes the feedback to a billing computer.

Control transmitters are devices for converting standard RS-232 serial data from the system organizer to a modulated RF signal for cable transmission to IPPV terminals or modules. In a known cable system available from the inventors, the control transmitter may be an addressable ATX transmitter or control unit and a terminal encoder or a combination of both. For the purposes of the present invention, the control transmitter is primarily a pass-through device and is described for completeness only.

Bidirectional amplifier These line amplifiers and auxiliary amplifiers amplify and transmit a certain part of the RF spectrum in the forward direction and another part of the RF spectrum in the reverse direction. This allows two-way transmissions over a single coaxial cable. Bidirectional amplifiers are also pass-through devices and are described for completeness only.

A terminal is a device that forms the interface between a cable system and a subscriber and his television set. Among other functions, the terminals perform tuning, down-conversion and decoding of video signals from the cable on an optional basis. They accept both total / global / and addressed control transactions / ie. transactions routed brd to all or only individual terminals / from the control transmitter to set up and control the services they provide. In addition, the terminal can be equipped with an internal RF ignition module or with an interface for an additional external feedback module.⁺so that either the terminal or the external module can have a reliable steam _Dfor storing data on purchased items or other data for retransmission.

Furthermore, either the tertiary or the associated module includes a frequency switching data return transmitter according to the invention. Such a terminal, either equipped or associated with an IPPV module, will hereinafter be referred to as STT. An IPPV module is a module associated with a terminal if the terminal does not include an internal frequency-switched RF data return path transmitter.

The IPPV processor is primarily a frequency-switched RF data receiver for the feedback data transmitters of IPPV terminals or modules. At the same time, it detects data from modulated RF signals from up to four / or more / different return data channels. It then filters redundant messages, groups the data into packets, and forwards the packets over the standard RS-232 data line to the system organizer. At least one IPPV processor is required for each cable terminal.

The overall object of the present invention is that the collection of monitoring statistics works reliably and has high data throughput, integrity and security. In terms of details, the invention is designed to meet four specific performance objectives:

1. The collection of monitoring statistics must use a data throughput plan, in which case the maximum amount of data from the terminals must be returned within a predetermined period of time in order to monitor regularly what the subscribers are monitoring.

2. The time allocated to the collection of surveillance statistics must be long enough to obtain a reliable statistical sample of the viewing population.

3. The time for monitoring statistics to be collected from each terminal must be precisely defined to guarantee a true state of the art at a number of terminals, which is transmitted to the system organizer.

4. Types and formats of statistics · Tracking suitable for generation and collection must be flexible.

According to the invention, there is provided a method with an apparatus for generating and collecting tracking statistics from a plurality of remote terminals, and the method and apparatus meet the four objectives set forth above. viewing statistics may correspond to different types of data according to the types of viewers watching the TVs connected to the remote terminals or according to the data relating to

- 7 to the state of the remote terminal itself.

Each remote terminal has at least one free collection section consisting of a memory location for storing recording time, a memory location for storing monitoring statistics and a memory location for storing a time code for recording recording time, information about monitoring statistics and other time-related information. , in which the monitoring statistics were generated. In the proposed embodiment, the television channel to be watched is the one whose s⁺the tracking statistics are for collection, and thus the above memory location for storing tracking statistics will correspond to the memory location for recording the channel. However, the memory location for recording viewing statistics may just as well be the memory location for storing the volume, the location for storing the power on and off indication status of the remote terminal, or any other designation corresponding to the data relating to viewers watching the TV / data viewer profile / or the state of the TV itself / TV status data /.

The recording time consists of information sent in the direction from the system organizer to each terminal, which relates to some future time at which each terminal is to store the status of certain monitoring statistics. The recording time is stored in a memory location for storing the recording time, and when the recording time is equal to normal real time, the status of the remote terminal corresponding to the particular type of monitoring statistics being recorded is stored in the memory location for storing statistical data. The tracking and time code representing the current time are stored in a memory location for storing the time code. E.g. in the proposed arrangement, where the channel is currently being collected, the monitored channel is stored in a memory location for storing monitoring statistics (in this case it is referred to as a channel storage location) and the time code is stored in a memory location for storing the time code when the recording time equals the current real time.

When tracking statistics, such as the channel and time code in the proposed embodiment, have been stored in the appropriate storage locations in the remote terminal, the contents of these storage locations are sent back to the system organizer either automatically or in response to

- 8 call signal. The system organizer determines which particular section is sent back by comparing the returned time code with a list of recording times sent directly to each terminal.

In this way, the system organizer is able to verify which collection section has been sent back by each terminal and can collect statistical data for the entire number of terminals.

According to the invention, there is also provided a method for generating and collecting tracking statistics, which comprises the above-described steps and additional steps. As already described, the recording time is stored in a memory location for storing the recording time, and once the recording time is equal to the current real time, the corresponding tracking statistics and time code are stored in the channel storage location and the time code storage location. . However, unlike the situation where the organizer sends all recording times for different collection sections in a straight line at once, the invention allows the system organizer to send the recording time in a direct direction at any time for any collection section. Thus, it is possible that while the system organizer programs one collection section to record a channel sometime in the future, it may simultaneously receive tracking statistics and time code from another collection section, transmitted from the same or another terminal.

These and other features of the present invention will be readily apparent to those skilled in the art from the following detailed description when read and viewed in the drawings.

Overview of figures in the drawings

Giant. 1 is a general block diagram illustrating a cable television distribution network with bidirectional amplifiers and splitters that allow the connection of remote terminals containing RF transmitters for reverse data transmission to a terminal equipped with a frequency-switched data receiver. Giant. 2 is a block diagram of the system showing several parts of the system of FIG. 1 including the billing system, the system organizer, the data return RF receiver, and the terminal and its associated data return module. Giant. 1 is a block diagram of a typical terminal, with the terminal shown including a command receiver;

- 9 addressed out of band. Giant. 4 is a block diagram of an IPPV module for the terminal of FIG. 3, the module comprising either a portion of the terminal or connected to the terminal by a suitable bus system. FIG. 5 is a timing diagram of a data return sequence from a frequency switching RF transmitter of FIG. 4. FIG. 6 is a block diagram of an IPPV processor (receiver) shown in the system diagram of FIG. 2. FIG. 7-11 are block diagrams of several groups of parts of the IPPV processor of FIG. 6; Fig. 7 shows an input module, Fig. 8 shows a frequency synthesizer, Figs.

9A-C show an RF receiver, FIG. 10 shows a signal strength analyzer, and FIG. 11 shows a control unit assembly. Fig. 12 is a timeline diagram of the IPPV data transfer sequence. Fig. 13 is a diagram showing individual storage locations associated with each collection section within the terminal. Fig. 14 is a timing chart showing recording times sent to remote terminals and the resulting time codes returned to the system organizer. No fig. 15 is a timing diagram showing the programming and acquisition sequences for each of the four pairs of memory locations in the terminal. Giant. 16 is a diagram showing a pattern of a response packet with program and tracking statistics transmitted from an IPPV processor to a system organizer; includes the content of the response with program statistics and tracking, as indicated in Fig. 17. 17 is a diagram showing the contents of a program and tracking statistics response transmitted in the reverse direction from an IPPV module located at the terminal. Giant. 18 is a diagram of the instruction on the recording time of the monitoring statistics transmitted in the direct direction from the system organizer to the terminal.

Examples of embodiments of the invention

Giant. 1 shows a typical cable television distribution network 100 for distributing cable television signals to subscribers and for receiving feedback messages from subscriber terminals 120. The cable television network 100 connects the terminal 110 to a series of televisions 130 via cable television terminals 120. The cable television network 100 is connected in a tree configuration with branches 148 and 150 using splitters 143. Sometimes jumper switches are used in place of splitters 143 to switch transmission between the terminal and subscribers to only one branch of the return input to splitter 143. One of the objects of the invention is to obviate the need for jumper switches previously used to increase data throughput from subscriber to terminal. . In the forward direction, a number of subscribers typically receive the same signal transmitted from terminal 110, typically a broadband cable television signal. In future systems with increased pair width, such as fiber optic systems, it is unlikely that different subscribers would be able to receive different signals intended only for them, the scope of drive being restricted only by telephone companies. The distribution amplifiers 142 are also regularly distributed in the cable network 100 to amplify the θ repetition of the transmitted signal. Transmission from the subscriber terminal 110 to the cable television terminal 120 is sensitive to interference entering along the main, line 141, branches 148, 147, 146, 145 and port 144.

However, far more serious interference enters the transmission from the subscriber to the end station 110.

The frequency-switched reverse RF transmitter 200 may be within or associated with the cable terminal 120 and allows communication with the terminal 110 by transmitting messages back over the cable television network. The terminal 110 includes a frequency-switched RF receiver 300 for receiving messages transmitted by the RF reverse data transmitter 200 at the cable television terminal 120 or the associated module, located at any point in the number of subscribers. Other subscribers equipped with IPPV or other services requiring data return may be equipped with telephone transmitters for transmissions to the telephone processor (not indicated) at the terminal.

Many cable television networks are so-called split systems, equipped for two-way transmission, ie transmission from the terminal to the subscriber and from the subscriber to the terminal. In these cable television networks, amplifiers 142 are equipped for bidirectional transmission, including reverse amplification. Cable companies have so far avoided the use of two-way transmission in a cable television network, partly because the return transmission from the subscriber to the terminal is significantly more sensitive to interfering noise. Reverse transmission is more sensitive to interfering noise because the cable network has the shape of a tree configuration, allowing propagation and amplification

- 11 interfering noise from all points of the cable TV network in the reverse direction.^mo can be marked^xit as a funnel phenomenon. Nap *. the interfering noise 160 and 161 on the terminal 144 and the branch 154 will combine the interfering noise 162 in the splitter 143 connected to the receiver 144 and the branch 154. As the signals propagate towards the terminal 110, the noise will combine with the noise on the branches 153 , 152, 151, 150 and on all other lines in the entire cable television network. In the reverse direction, it may become difficult to distinguish the transmitted data signal at terminal 110 from the noise induced in the branches of the cable television network.

Interfering noise can include impulse noise, in-phase distortion, external signal intrusion, and amplifier nonlinearity. Examples of sources of interfering noise may be lightning 10, radio 11 and distribution network 12. Cable television networks may contain old and poorly grounded and connected cable shields and the like, which allows noise to enter anywhere in the cable television network. Aging distributors 143 or old non-linear distribution amplifiers 142 can also cause interfering noise. Because interfering noise from each individual branch of the cable television network affects the reverse transmission, while direct transmission is affected only by interfering noise along a single line /e.g. branches 141, 148, 147, 146, 145 and connections 144 /, the cable television return network requires costly maintenance as it ages more often than the forward network. The invention makes it possible to transmit return signals over an imperfect cable television network, where the reverse transmission has hitherto been difficult without costly regular maintenance of the cable television network. The invention enables the two-way transmission of messages over cable television networks even at a higher level of interference than has hitherto been possible. The amount of noise that occurs in a typical cable television network of different frequencies is described in U.S. Pat. No. 07 / 562,675, issued as of Aug 3, 19090, entitled RF Return Method for Cable Television, which is incorporated herein by reference.

Fig. 2 is an overall solution of an IPPV system according to the invention. The system includes accounting computer J05, which records and maintains records for each subscriber in the system. Records typically contain information such as the subscriber's name, address and telephone number, the tyr equipment that the subscriber has and which paid services the subscriber may use. According to the invention, the records may contain information relating to age, sex, marital status, income, credit, etc. subscribers that can be used in conjunction with an identification code that a subscriber enters at a remote terminal before watching a particular television program. This information can be useful to cable operators or advertisers as it will help them effectively market their television programs.

The cable operator typically has its own billing computer, leases this equipment from a company that specializes in this type of equipment, or shares time on a machine that belongs to the billing company.

The billing computer 305 is connected to the system organizer 310. The system organizer controls the operation of the cable system. The system organizer 310 is typically a personal computer, such as an HP 1000 A400 Micro 24 Computer or an HP 1000 A400 Micro 14 Computer, which has a program memory for storing algorithms. The system organizer may advantageously include a System Organizer IV or V or a Subscriber Organizer V, which may be obtained from an agent of this application. The system organizer 310 maintains a list of all addressable terminals in the cable system as well as the services that each terminal is authorized to receive. System Organizer 3 IQ also determines and maintains the parameters selected by the operator for each system. These parameters may include the frequencies associated with each cable channel in the system, which channels are being coded, the security measures of the system and the system time. In addition, the system organizer is responsible for authorizing and disallowing pay-per-view programs.

The system organizer 310 also stores IPPV information. The system organizer resident program reads the IPPV transactions selected from the cable system terminal. Transactions are stored in the system organizer's database until they are retrieved by accounting computer 305. System organizer 310 controls the transmission of IPPV sales feedback by sending data requests to cable system terminals.

As indicated in Figure 2, the commands generated by the system organizer can be transmitted to the terminals in one of two ways. In the first method, the addressable ATX transmitter 314 transmits commands from the system organizer 310 (or via the terminal control unit 312) on a dedicated channel (e.g. 104.2 MHz / in a format understandable to addressable terminals. In the second method, the commands are transmitted using a so-called "system" in the band where the novels are incorporated into the video by the action of the encoder 313. The in-band system is described in co-pending application no. No. 188,481, incorporated herein by reference. Other methods can be used for both addressed or global data transmission from the end station to the subscriber's terminal, and the present invention is not to be construed as limited in this regard. E.g. data transmission by acoustic frequencies, spread spectrum or other means of transmission over the same cable or an equivalent group of alternatives may be used on a switched or private telephone line or on a distribution line.

Subscribers to the cable system may be equipped with terminals 315. FIG. 2 shows three terminals, of which two (315a, 315b) are associated with an in-band system and one (315c) is associated with an out-of-band system. E.g. terminals 315a and 315b may be Scientific Atlanta Model 3570 and 8590, while terminals 315c may include Scientific Atlanta Model 8580. Terminal "t" allows the subscriber to tune and decode services required by the cable system operator. Each terminal contains a digital identifier as a numeric address, which allows the operator to send commands directly to each terminal. These commands are called addressed commands. The terminals are also able to receive global commands, processed by all terminals in the cable system. Subscribers who are entitled to purchase programs via pay-per-view pulses are equipped with terminals with built-in pulse modules. In summary, the impulse module allows the subscriber to authorize his terminal to receive the program on the basis of payment for monitoring, storage of data associated with the purchase of the program and transmission of stored data to the cable network operator. As indicated in FIG. 2, the stored data may be transmitted back to the operator by the telephone pulse module using the public switched telephone network 317 via the telephone processor 321 or via the RF pulse module using the RF callback 319 via the IPFV processor 322. The HF feedback will be described in more detail below. The telephone processor 321 and the IPPV processor 322 are connected to the system organizer 310 by a suitable interface such as RS-232.

The accounting counter 305 sends a transaction to the system organizer 310, which identifies whether the terminal in the system uses RF call 319 or the telephone network 317. The system organizer 310 then enters the transaction into the terminal 315 to initiate and configure it. E.g. the frequencies to be used for RF transmission and the calibration procedures described below must be entered into the ν 'pulse module. These frequencies can be inserted into the module during production or they can be inserted there by a global transaction from the system organizer 310. Another option is to enter these frequencies by an addressed command.

When the system organizer inserts a configuration transaction into a terminal, additional transactions can be entered to set the real time for each terminal. As we will show below, in the present invention, the terminal uses an internal clock for real time, and in order to maintain a high degree of accuracy, periodic settings from the system organizer can be used.

Giant. 4 shows a block diagram of a conventional addressable terminal of the known solution, namely the Scientific Atlanta 8580. According to the principles of one embodiment of the invention, the terminal is a through-going device and does not form part of the invention. With its output, the first microprocessor 400 only transmits all commands received by the addressable data receiver 430 to the second microprocessor 504 in the associated IPPV feedback module indicated in FIG. 4 via the data bus 490. 7 in an alternative embodiment, the functions of the second microprocessor 504 of the module of FIG.

The basic building blocks of the out-of-band addressable terminal are the converter and tuner 410 for receiving and converting the incoming signal from the cable. The data receiver 450 receives the converted out-of-band 104.2 MHz signal or other suitable data carrier frequency from the converter and tuner 410. The output of the converted TV signal is decoded as required by decoder 420. The decoded channel is converted up to channel 3 or 4 for TV, tape recording video or other subscriber's device / not indicated /.

Associated with the first microprocessor 400 is a non-volatile first memory £ 470. timing logic 480, user input 440

- 15 with keypad, infrared or other remote control receiver 450 for receiving the remote control input and display 460. The display shows, for example, the number of the tuned channel or the time of day.

According to the invention, the described terminal model 8580 is only a through-going device. Each of the 8570, 8590, and other third-party terminals normally includes a control processor such as the first microprocessor 400, which must always have inputs and outputs or connectors for exchanging data with the module as shown in FIG. 4 or for controlling the element of FIG. 4, if this module does not contain a microprocessor. The second memory 502 of FIG. 4 is a nonvolatile memory that simply replenishes the capacity of the first memory 470. The first microprocessor 400 has access to it.

For home purchase, energy management, meter reading, burglary alarm and other services in addition to the IPPV service, the terminal must contain appropriate interfaces for entry and exit to various devices in the subscriber's household / none of which is indicated in Fig. 3 /.

Fig. 4 shows a group diagram of an IPPV module according to the invention. The IPPV module is a BPSK microprocessor transmitter used to transmit information in the reverse direction of cable television networks from the subscriber's site to the terminal. The second microprocessor 504 communicates with the first microprocessor 400 of the terminal and receives information which it stores in the third memory 503 (for later transmission) or transmission instructions. During the transmit cycle, the second microprocessor 504 turns on the power to the frequency synthesis circuits, programs the appropriate transmit frequency, turns on the power amplifier, sets a predetermined gain level at the modulator, and transmits the required information.

The second microprocessor 504 is the brain of the module, as it determines when to transmit (according to the instructions transmitted from the terminal, discussed below), determines and sets the frequency and power level, and encodes the data stored in the third memory 503 for transmission. In order to ensure a prompt and efficient return d8t, this data is preferably pre-formatted when stored in the third memory 503. Upon completion of the transfer, the second microprocessor 504 also turns off the RF circuits, thereby reducing the line output of the module and reducing the overall power consumption. The third memory 5-03 stores order data (pre-formatted for transmission), safety information, transmission frequencies and power levels, and module identification information.^mthe third memory 503 also stores viewing statistics which correspond to how certain subscribers watch the television in question, or to the state of the television itself, as will be described in more detail below.

The phase-locked loop 505, the low-pass filter 505 and the voltage-controlled oscillator 507 synthesize the frequency to be used for transmission. The frequency is synthesized from a 4 MHz crystal clock 501, which is also controlled by a second microprocessor 504. This arrangement reduces the number of components required to perform the synthesis and also eliminates the problems that could arise when using a dual clock of the same frequency.

The phase lock loop 505 of the module receives serial data from the second microprocessor 504 to set its registers to a certain frequency. The phase-locked loop 505 compares the sampled signal from the voltage controlled oscillator 507 with the signal derived from the clock.^q01 4 MHz to determine if the generated frequency is higher or lower than the programmed frequency of the synthesizer with polarity representing the high or low generated frequency. The low pass probe 506 performs mathematical integration of this signal and generates a dc voltage to control the output frequency of the voltage controlled oscillator 507. The output of the oscillator 507 is fed to the modulator 508 and also back to the phase lock loop 505. so it can be sampled again and the transmission is repeated after. throughout the broadcast.

The data filter 510 is a bandpass filter that prevents the RF energy of the transmitted digital information from being modulated on the RF carrier. Thus, the data filter 510 acts as a limiter of the modulation energy and the modulated signal within certain limits.

The modulator 508 receives the input of the filtered data from the second microprocessor 504 and the RF carrier from the voltage controlled oscillator 507 and modulates the phase of the carrier in proportion to the data signals. The modulator also uses a DC bias generated by a digital-to-analog converter to control the overall gain of the modulated signal. The converter is controlled directly by the second microprocessor 504. The modulator 508 is described in more detail below in connection with FIG. 6.

For modulation feedback data, three modulation solutions have been considered in the present invention: Binary frequency shift keying / PSK /, binary phase shift keying / 3PSK / and direct spread spectrum sequence.

- 17 / DSSS / with BPSK modulation. The solution was considered too complex and unnecessary, as saving bandwidth is not a critical requirement.

Of these three, BPSK has the greatest resistance to broadband noise, DSSS has the greatest resistance to discrete frequency interference, and FSK is the simplest to implement. On the other hand, BPSK and FSK have little resistance to signal interference at the same frequency, but the receiver for DSSS is quite complex and has a wide noise band. The DSSS transmitter also requires a very complex filter to prevent interference with both the forward and reverse video signal. In addition, FSK receivers suffer / in this case / from the capture phenomenon, which is a problem in this situation.

The system of the invention provides some of the best features of all. The system uses BPSK signaling on four different frequencies. This solution can be called BPSK with frequency selection / or FDBPSK /. In this way, the noise band of the receiver is very narrow, the inherent properties of BPSK are used in noise suppression and, with the appropriate choice of frequencies, discrete frequency interference is avoided. However, although BPSK modulation has been used in the present invention for the above reasons, other modulation methods may be used, and the invention is not limited thereto. A complete description of BPSK modulation is provided in U.S. Pat.

Power amplifier 509 amplifies the resulting signal from modulator £ 08 to the desired output level of the module. The gain of the amplifier is at a fixed level, with the signal from the anti-crosstalk control 513 controlling the on and off of the power amplifier 509.

The crosstalk control 517 is a circuit that allows the second microprocessor 504 to control the state of the power amplifier 509. In the event of a failure of the second microprocessor 504, the crosstalk control 513 turns off the power amplifier 509 after a predetermined time or after several consecutive transmissions. This prevents the module from sending messages longer than designed or more frequently than intended, regardless of the state of the microprocessor. Terminals that chatter or scream are unmanaged and generate intrusive messages that can block the entire system when enabled. The anti-listening circuit prevents

- 18 chatter by turning off the data transmitter after a predetermined time, which is longer than the longest message would need. Anti-hearing control is described in co-pending U.S. Patent No. 4,692,919, which is incorporated herein by reference.

The pooling filter 511 is a two-part filter: a bandpass filter 515 for 12-19 MHz for suppressing the harmonic energy of the module transmitter and a high pass filter 516 for 54,870 MHz for cable television signals that pass through to the terminal undisturbed.

The design considerations associated with the solution of the IPPV module for the so-called internal systems are not particularly suitable for the solution of the so-called external systems. Internal systems include, for example, in-band and out-of-band addressable terminals such as Scientific Atlanta 8570 terminals,

8580 and 8590. External * conditions assume the relocation of the terminal device from the subscriber object. Such external systems include, for example, the prohibition and restraint technique. As a result, there is, for example, at least a domestic, if not connection, cable separation between the cable television terminal and the subscriber's device, which is not particularly suitable for data transmission. On the other hand, some subscriber equipment is needed for IPPV, home shopping and two-way services that cannot be implemented with a conventional television set.

Due⁺It would be difficult to implement the module of Fig. 4, which assumes a bus or other transmission path between the terminal and the module, with conventional house cables or connections without any special transmission solution. The invention therefore relates to those principles of the terminal and module solution which can be extended from the internal terminal solution to the IPPV module solution for subscriber units in the so-called external prohibition and hold system.

We will now describe the operation of the various parts previously described in connection with the features of the invention.

As previously stated, in order for each terminal 315 to be able to pass the purchase purchase information back to the system organizer 310, it must have a reverse transmission path (unlike the forward path used to transmit control information from the system organizer 310 to the terminal 315). As mentioned, it intends to use the IPPV RF system in cable networks that have the ability to divide return channels. These cable systems have amplifiers that allow

The propagation of channels T7,? 8, T9 and T10 (approximately 0-30 MHz) in the reverse direction, i.e. to the end station.

The invention provides an IPPV module according to Figure 4, which uses portions of channel T8 for transmissions from terminals or an IPPV module to a data receiver with frequency switching at the terminal via an selectable series of modulated channels and data carriers. The use of channels T7, T9 and T10 for video conferencing or other transmissions is not adversely affected by data transmissions, which are generally limited to the band of channel T8.

The use of return channels in the cable network as a data transmission network for subscriber terminal information suffers from two fundamental shortcomings: the high noise and disruptive reverse transmission environment, as discussed in detail earlier, and the lack of a concurrency mechanism by which data can compete with network access. Both problems arise from the topology of the system, which is an inverted tree, as not indicated in Figure 1.

In terms of interference, tree branches can act as a large antenna network. Faulty shielding and broken or loose cable system connections allow RF interference to enter the system, as previously described. Because the amplifiers are set to a total gain of one, in-band interference and noise are regenerated in each of the amplifiers. In addition, in the reverse direction, interference and noise from individual branches are combined in each node of the network. As a result, all the interference and noise that has penetrated the entire cable system is finally added up at the terminal where the IPPV RF data receiver is located. To minimize these problems associated with the use of cable TV return channels for data transmission, a number of four channels were selected from a range of 23 data channels at 100 kHz in the T8 TV channel band for use in this RF IPPV system, based primarily on data throughput considerations. As will be described below, the invention is not to be construed as limited to four channels, but may use more than four channels. The probability of receiving messages increases with each additional channel used, but the cost of additional transmitters and receivers becomes prohibitive.

The 6 MHz video return channel can be divided into 60 transmission channels of 100 kHz each, of which 23 are used in the current implementation. Four of the twenty-three channels are selected according to the frequency of noise and interference.

- 20 Both transmitters and receivers are frequency variable. The frequencies used for the reverse transmissions can be automatically programmed by the system organizer computers to avoid channels that contain noise or major interference. These frequencies can be changed as often as necessary to adapt to time-varying interference.

Each transmitter will sequentially transmit its data at a rate of preferably 20 kbps on each of the four frequencies. Four RF receivers (one tuned to each channel) are used in the terminal. This arrangement provides redundancy for each message. The probability of an error caused by interference on the same frequency is now the product of four probabilities that interference is present on all four channels at the time this channel is used by the transmitter. The height is a high ratio of transmission and successful reception.

Note that this method may provide better parameters than spread spectrum systems because the sequential transmission arrangement provides both time and frequency variability.

In a typical feedback system, four video channels are available: T7, T8, T9 and T10. Usually the lowest channel T7 has the most noise with the highest channel T10 the least noise. This would lead to the conclusion that the T10 would be the best. However, other aspects must be taken into account when selecting frequencies, which are described in detail in U.S. Pat. No. 07 / 562,675, issued Aug. 3, 1990, entitled RF Return Mode for Cable Television, which is incorporated herein by reference.

At^xactivities of the IPPV system, it is generally desirable to be able to request a message with feedback data, ie to select terminals equipped with IPPV modules according to several different criteria. The following list summarizes the most useful cases for requesting feedback from certain groups of terminals:

1. Unconditionally, ie all terminals must report.

2. All terminals containing IPPV data for one or more programs.

3. All terminals containing IPPV data for a specific meeting.

4. Certain terminals individually, regardless of program data.

Furthermore, as mentioned earlier, it is very important, even in the first case of unconditional data request, that all terminals be able to return data in a period of less than 24 hours. It

- 21 should be possible with a number of terminals of thousands or even several hundred thousand, leading to a throughput requirement of around 25,000 IPPV data responses per hour.

Each of the reverse narrowband data channels can transmit only one message at a time. This means that when two or more terminals anywhere in a given cable system send messages that overlap in time, the transmissions will interfere and all data affected by the collision is likely to be lost. Therefore, in three of these cases, some procedure is required to control access to the medium to prevent several terminals from trying to use the reverse data channel at the same time.

However, all these cases could be dealt with as a series of individual data requests / as in the fourth case /. However, this is not compatible with the throughput requirement due to the system delay of the messages associated with a typical request-response message sequence. It is much more efficient to send a single group request for data to a relatively large group of terminals, which then return the data according to a scheduled procedure or media access protocol. This protocol must ensure a high success rate of reporting, ie. without collisions.

Unfortunately, known media access protocols, such as those used in local area networks and which rely on bearer sensing mechanisms to prevent collisions, are unsuitable for use in a cable system. The topology of the inverted cable system tree adds the transmitted signals from the individual branches and propagates them towards the terminal. Terminals located in different branches, each of which is isolated by a node amplifier or other device, cannot detect the presence of an actively transmitting terminal in another branch.

Another access protocol, time interleaving, also suffers from time fluctuations in the worst case message. This forces the time slot for each terminal to be unbearably long, which reduces throughput.

All these circumstances have led to the development of a medium access protocol that provides acceptably high throughput with a calculated collision tolerance. The method uses the predicted statistical probability of collisions / and, conversely, the successful passage of messages / behind

- 22 assuming a controlled evenly distributed frequency of terminal attempts to transmit feedback data.

Quite simply, according to this method, the system organizer sends data requests to manageable large subgroups of the total number of terminals. / These subgroups are independent of the four election cases mentioned earlier./ Each subgroup or simply group has a defined time period in which to return data. Within this period, each terminal independently selects a programmed number of pseudo-random moments to start the reverse data transmission. When using relatively large subgroups, return attempts are statistically evenly distributed within the period. Furthermore, because the mean frequency of attempts is predetermined and the mean length of the feedback messages is known, the resulting probability for at least one successful feedback data message for any terminal can be predicted.

Although this statistical concept is the basis of the data return method, a number of longer key elements are needed to make the process operational. We can summarize them as follows:

1. The optimal frequency of trials that gives the best effective throughput throughput is determined.

2. The total number of terminals at the cable system terminal is divided into manageable subgroups of known scope. The size and number of subgroups as well as the data return period can be determined for a given optimal number of trials.

3. A data return plan is needed that provides a structure for how the system organizer will request feedback from each group.

4. The set of rules controls how the terminals in the groups respond to data return requests and to acknowledge data within the return data sequence.

Fig. Β shows in more detail the group diagram of the IPPV processor according to Figs. 1 and 3. The return RF signal from the terminals is transmitted in the VHP channel T8. The transmitted carrier can be set with a resolution of 100 kHz in the frequency band 11.8 to 17.7 MHz, which provides a choice of a maximum of 50, preferably 23 different data channels with a bandwidth of 100 kHz. Modulated carrier z⁺terminal or module

- 23 contains 3PSK 20 kbps information in the Mller code. the signals from the entire set of terminals in the system are combined and returned to the IPPV process located in the terminal. The function of the IPPV processor is to receive feedback input signals, demodulate information and pass the decoded message to the system organizer.

While only the reverse data transmission from the terminal is described in detail, the processor according to the invention can also be used to monitor the status of bidirectional amplifiers with other elements of a cable television distribution device equipped with data transmitters. The IPPV processor can also receive signals transmitted from 32RT and other test devices connected at any point on the cable network.

Still referring to Fig. 6, the reverse RF signal is typically received at a single carrier level of + 12 dBmV. The IPPV processor is designed to operate in a single carrier level of +2 to +22 dBmV. Often more than one carrier is received and the total received power will be proportionally higher than + 12 dBmV. If they are on different frequencies, the IPPV processor can simultaneously receive, demodulate and decode the Four Modulated Carriers; only non-redundant decoded messages are sent from the IPPV processor control module via the RS-232 serial interface to the system organizer.

The first element of the IPPV processor to be described is the so-called input module 800. The RF return signal from the terminal is fed from the input cable to the connector of the input model 800, which most preferably contains separate units. The input module 800 offers the input signal a nominal termination impedance of 75 Q. This unit consists of a bandpass filter, a preamplifier, and a splitter circuit that divides the incoming RF signal into four RF receiver modules A through D. The bandpass filter passes the T8 band with negligible attenuation and distortion when suppressing signals outside us. The preamplifier compensates for filter losses and power splitting losses. RF signals are fed from the RF connectors of the input module to four RF receivers. The input module has a gain of approximately 1 dB, so the signal fed to the RF receivers 810 to 813 has a level of approximately +13 dBmV. All internal coaxial connections of the IPPV processor, with the exception of the input RF signal, are terminated with a nominal impedance of 50 Q. Input module 800

- 24 does not have a direct connection to the 840 control module. All other IPPV processor receiver and synthesizer blocks are connected to the 840 control module.

The second main building block of an IPPV processor is the receiver. There are four blocks A and? In the IPPV processor. The receivers 810 - 813 know. These are functionally equivalent units, three of which supply 50 Q terminations at the signal strength analyzer output, so these units are interchangeable. The fourth receiver Aanal D / is indicated with a coaxial connection to the signal strength analyzer block 830. The RF receiver converts the signal coming from the input module using the output of the frequency synthesizers as a local oscillator (on the higher side). The output frequency of the synthesizers may be between 22.5 and 28.4 MHz and is preferably between 26.2 and 28.4 MHz, which corresponds to an input frequency range of 11.8 to 17.7 MHz or preferably 15.5 to 17.7 MHz. MHz. The intermediate frequency signal is at a medium frequency of 10.7 MHz. Ceramic IF filters, tuned to 10.7 MHz, suppress adjacent channels and other mixer products and pass the desired signal. The narrowband IF signal is detected by a circuit that provides a rough estimate of the signal strength. The output is the DC voltage RSSI, proportional to the level of the received RF signal. This voltage is fed to the control module together with other signals of the connecting wiring of the RF receivers. The RSSI information indicates the terminal's feedback signal level as received by the IPPV processor. This information is available to the system organizer.

The RSSI for a particular terminal indicates which terminals need a new calibration. To this end, the system organizer maintains a list of too high and too low RSSI data about the terminals, so that it is possible to include the addresses of these terminals for recalibration. This new calibration is not periodic, but is performed on a higher priority basis, ie with equivalent priority with new terminals requesting calibration for the first time. Time unit RSSI data tables can also be used to determine rise or fall characteristics for all 23 channels through which messages can be sent from a particular terminal. The rise or fall characteristics are then entered into the terminal so that the terminal can determine the appropriate transmission levels for all Category One and Category Two channels based on the optimal results for the calibration channel.

- 25 The main function of the RF receiver is to demodulate the BPSK 10.7 MHz IF signal. The signal is demodulated using a double balanced mixer. The unmodulated data sequence is filtered and synchronized. This detected 20 kbps Miller code data is fed to the control module. The HSST voltage derivation and BPSK demodulation functions are performed by all four RF receivers. A narrowband filtered intermediate frequency signal of 10.7 MHz - at a level of approximately +13 d3mV is introduced from the RF receiver D into the block of the signal analyzer.

The signal strength analyzer 830 is associated with the function of the RF receiver. The function of the signal strength analyzer block is to detect the level of the 10.7 MHz IF signal coming from the RF receiver selected for calibration purposes. This RF receiver output is not subject to automatic AGO gain control; as a result, any change in the RF input level to the IPPV processor will result in a level change between the 10.7 MHz frequency signal at the input of the signal strength analyzer. When the RF feedback system is calibrated, the signal strength analyzer and detection of a 10.7 MHz IF signal gives the control module 830 an indication of which terminal or IPPV module the output level corresponds to the received signal level + 12 dBmV. The control module 840, on the other hand, will inform the system organizer via the RS-232 interface. Until the next calibration cycle (described in more detail below), the system organizer will instruct the terminal to use the level of the transmitted signal reported by the control module.

The 10.7 MHz + 13 dBmV IF signal at the signal strength analyzer terminates at 50 Q. The two isolation amplifiers have a gain of approximately 30 dB for the IF frequency. The amplified intermediate frequency signal is peak detected by the diode circuit. The second diode circuit has a similar dc bias voltage. The outputs of both diode circuits add up for temperature compensation according to the known technique. The output accurately reflects the level of the IF signal, as the DC components of both diodes are compensated. This detected signal is filtered and further amplified. The final DC output signal, proportional to the level of the IF signal, is fed to the control module.

The frequency anynthesizer controlled by the generator system organizer is a frequency for demodulating incoming data carriers. The frequency synthesizer is a local oscillator for converting a single kmi ·

- 26 turns, taking place in the RF receiver. The single frequency synthesizer block contains four separate units, i.e., synthesizers 820 to 823. The control module 840 provides frequency tuning information via serial data commands. The four frequency synthesizer units 820 to 823 are referred to as frequency synthesizers A, B, C and I), which correspond to the RF receivers 810 to 813.

There is a total of 60 frequencies in the bandwidth of the T8 channel, which can be set by the control module 840; however, according to the invention it is used only

23. The output frequency range is preferably 25.1 to 28.4 MHz and is converted down to the upper part of the T5 band, i.e. 14.4 to 17.7 MHz. The frequency resolution is 100 kHz. The output signal is at a typical level of +17 dBm.

Each frequency synthesizer unit includes an oscillator, a frequency divider, a phase locked PLL loop, an integrated circuit 10, and an active loop filter. These parts together form a phase-locked loop. The output frequency of the oscillator is phase and frequency coherent with a free-running 4 MHz crystal oscillator. The phase-locked loop ensures that the synthesizer output is spectrally clear and frequency accurate. The output of the oscillator excites the anti-stroke amplifier. An anti-tact solution is used to obtain the required level of +17 dBm local oscillator.

The group diagram of the input module is shown in Fig. 7. The input and power division module consists of a band preselector filter 900, preamplifier 910, containing e.g. MHW1134 and a divider circuit 930 for powering four RF receiver modules. The gain of all modules, including transformer 920, is indicated.

Referring to Fig. 8, the arrangement of the IPPV processor frequency synthesizer will now be described in more detail. The frequency synthesizer assembly includes four subgroups on the printed circuit boards, as indicated in Figure 8. Each subgroup is set to a specific frequency by the IPPV processor control module 840. The range of frequency synthesizers is preferably between 26.2 and 28.4 MHz, but may be up to 22.5 to 28.4 MHz. The tuning resolution is 100 kHz. Each of the four subgroups of frequency synthesizers can be set to any of 60 channels in the 22.5 to 28.4 MHz range. The RF output of a subset of frequency synthesizers is a local oscillator signal for one of the four RF receivers in the IPPV processor. The local oscillator is on the higher side, so

- The 27 RF band from 15.5 MHz to 17.7 MHz is converted down to the receiver's 10.7 MHz intermediate frequency. Νε Fig. 8 is a group diagram of a frequency synthesizer subgroup. There are again four such subgroups in the synthesizer assembly.

The 1000 MHz fundamental frequency crystal 1000 is connected to a high gain feedback amplifier 1001. The amplifier is part of a large integration element with a phase-locked loop, preferably of the Motorola MC145158 type. The 4 MHz output signal is fed inside the element to a counter 1002 operating as a 1:40 frequency divider. The counter output is a reference frequency of 100 kHz, which is fed inside the element to a phase and frequency detector 1003.

The phase and frequency detector 1003 compares two output signals (reference 100 kHz and variable 100 kHz) and generates error pulses when both inputs are not at the same frequency and phase. These pulses are tuned by the oscillator so that a variable signal of frequency 100 kHz is forced to have the same frequency and phase as the reference signal 100 kHz. When this happens, the output of the frequency synthesizer will be at the correct frequency. Differential error signals from the phase and frequency detector 1003 are fed from the element to the loop filter 1004 and associated components. This filter 1004 filters the error signals and converts them to an unbalanced tuning voltage which controls the oscillator 1005. The oscillator 1005 includes a transistor Q1 and associated components. Oscillator 1005 is designed so that the input tuning voltage corresponds to output frequencies in the desired output range of 22.5 to 28.4 MHz, or more preferably 26.2 to 28.4 MHz. The output of the oscillator is fed to a isolating amplifier Q2 1006. This amplifier 1006 provides a relatively high impedance and separates the oscillator from the double divider 1005 and the power amplifier Q3, Q4 1009. The separated oscillator output signal is fed to the double divider 1008 where the frequency is divided by either ten or eleven. The programmed double divider 1008 together with the dividers A and N 1007 form a total divider with the ratio Nt = 10xN + A. Counters N and A are programmed by the processor control module 840 - IPPV by serial commands as Pout = Ntx0.1 MHz. E.g. the control module sets Nt to 250 for an output frequency of 25.0 MHz. Nt can be set by the control module to any of 60 values ​​between 225 and 284, but preferably between 251 and 284. The function of the double divider control line is to determine when the divider will divide by ten and when by eleven.

- 28 Isolating amplifier Q2 1006 also excites power amplifier Q3, Q4 1009 »Potentiometer setting is used / not indicated / so that the output signal level is about + 17 d3m. A low-pass filter 1010 is connected behind the power amplifier, which attenuates mainly the second and third harmonics of the synthesizer's output signal. The + 17 dBm output of the frequency synthesizer is fed to the associated RF amplifier of the IPPV processor.

The group diagram of the RF receiver module is shown in Fig. 9A - C.

There are four separate RF receiver modules. Referring first to Fig. 9A, each of the RF receivers includes a mixer 1101 for converting input signals to an intermediate frequency of 10.7 MHz. Top injection is used. The IF signal passes through ceramic filters 1104 and 1105 to suppress adjacent channel signals and distortion products.

The IF signal then passes through an amplifier 1106 and a level detector 1115. The detector circuit derives a rough determination of the HSSI signal strength. The circuit of the level detector 1115 is formed in a known manner, for example, from an NB604AN element. The HSSI output is an analog voltage that is sent to the control module 840 for digital conversion and sent to the system organizer.

The IF signal further passes through the directional coupler 1108. The tapped output is fed to an external output for use by the SSA signal strength analyzer module. The intermediate frequency signal is then further amplified and fed to the demodulator.

According to Fig. 9B, the demodulator preferably consists of a frequency doubler 1125 and an injection synchronized carrier recovery oscillator 113Q. According to Fig. 90, data detection is achieved by a modem filter, a clock regeneration circuit and a sampling circuit. The output of the demodulator is digital data.

Referring now to Fig. 10, a signal strength analyzer is indicated which receives a signal indicating signal strength from RF receivers. The signal strength analyzer module is used to obtain an accurate measurement of the transmitted data performance. The RF signal to be measured is fed from the intermediate frequency of one of the RF receiver modules, eg channel D. The signal strength analyzer module consists of a preamplifier

1200 30 dB, level detector 1201 and isolating stage 1202. The output is an analog voltage which is sent to the control module of the TPPV processor for conversion to digital form and transmission to the system organizer. Before entering the differential amplifier 1205, two diodes are used to achieve thermal compensation, i.e., the thermal compensation diode 1204 compensates the diode of the level detector 1201.

Referring now to Fig. 11, a control module is shown which controls ^xIPPV processor activity. Nedul sets up the synthesizers, monitors the signal strength, decodes the received messages from the RF receivers, checks the validity of the messages and forwards the messages to the system organizer. The control module contains a user interface / keyboard and display / for diagnostics, error reporting and configuration without switching.

According to FIG. 11, the control module board consists of six function blocks: control microprocessor 1500, memory subsystem, receiver interface containing type 8097 processors and RAM with two inputs / outputs for each receiver, system organizer interface and front panel interface.

The control microprocessor 1500 used in the control module is Intel 80188. It is a 16-bit processor with 2 direct memory access channels, 4 interrupt levels, 3 timers, 13 decoded address ranges and an 8-bit external interface.

The memory subsystem consists of dynamic RAM 1380 256 K for messages and variable storage, non-volatile RAM 1370 2 K for parameters and sockets for 128 K memory EPROM 1360 for program storage.

Two 256 K elements are used in the dynamic RAM. These are used, for example, to store group statistics, valid received messages, calibration results and others for system terminals, as a result of which these memories must have adequate capacity to store data packets. When messages are transmitted to the system organizer, the tables for storing messages from the terminals are reset. Normal instruction selections from the EPROM should be sufficient to regenerate the contents of the dynamic RAM. If there are more than 15 fis between the two EPROM accesses, the DMA controller will read from the EPROM. The LCS memory of microprocessor 80188 is used to access dynamic memory

FRAME. After resetting, the LCS memory must be programmed to the active memory area. After the initial setting of the DMA control unit, regeneration takes place without software influence.

There are two sockets for EPROM 1360 program memory

- 30 for up to 128 K program memory. These sleeves can be used for any EPROM elements between 2764 and 27512. One sleeve is used for UCS access and the other for MCS3. After resetting, the UGS will be active in the memory range from FFBFO to FFFFF / hexadecimal /. MCS3 must be reprogrammed to the active area.

One 2 K EEPROM memory element is available as a non-volatile steam £ 1370 to store configuration information. Two copies of the configuration information are stored in the EEPROM. 3 each copy stores a checksum as a means of verifying the correctness of the copy. If one copy is damaged, eg by a power failure during the recording operation, the other, correct copy will be used to repair the damaged copy. The programmer must be careful not to enter the EPROM for 10 ms after recording the syllable on the chip. No recovery delay is required after the read cycle. The chip is accessed from the MCSO. The MCSO must be programmed to the active area.

Each channel of RF receivers has its own contact processor 1310 1340 implemented by Intel 8097. Contact processors 1310 - 1340 decode and format Miller code data from RF receiver modules, monitor signal strength level from individual receivers and also from SSA signal strength analyzer module and control frequency RF synthesizer modules.

Each of the contact processors 1310 - 1340 has its associated RAM 1311 - 1341 1 K syllables with two inputs / outputs. These memories are used to pass data and commands between the contact processors and the control microprocessor 1300. The memory includes a mechanism for bidirectional interrupts. The software can define any suitable protocol for memory usage and interrupts. EPROM memories 1312 - 1342 are available for storing programs for contact processors 131Q to 1340. LEDs 1313 - 1343 are also available as receiver status indicators, as we will explain below.

A common T7ART 8250 serial element is used to implement a 1350 serial interface to the system organizer. One of the interrupts of the microprocessor 1300 is connected to the interface 1350, so that the serial interface can be controlled by the interrupt. The 8250 can operate at frequencies up to 38.4 kBd.

Modem signals (RT3, DTR, etc.) are available for the challenge-response method. The multiplexer in the system organizer can sig these

- 31 bells to use or ignore, as desired. The receiver has a data terminal configuration similar to a known telephone processor board.

The front panel includes a keyboard 860, a liquid crystal display 850, and a block of 1390 light emitting diodes. The keyboard 860 preferably includes sixteen decimal keys 0 to 9 and function keys such as help, next page, next line, input, reset, and menu. The keypad and display allow configuration without switching, indication of significant errors and local access to built-in test and diagnostic routines. The area of ​​1390 LEDs provides an indication of various states, as we will explain below.

The liquid crystal display, which has four lines of twenty characters, is accessible via two registers. The pitch angle can be changed by pressing the keyboard, as will be described later. The data for the display is inserted into one output and the sampling commands into the other output. Display sampling is relatively slow / 1 ms /.

When the key is pressed, an interrupt of the control microprocessor 1300 is generated. The coded key data is identified by reading a four-bit register. When accessing this register, the interrupt is reset. The keypad logic includes a contact bounce circuit that prevents further interruption until the end of the delay.

The control module 840 also provides power to the IPPV processor. The control module switches on the power supply of the elements as required. Each of the cables that connects this board to the RF receiver or synthesizer contains four + 12 V lines, 3 + 12 V lines, 3 + 5 V lines, and six ground wires as needed.

There are 12 LEDs on the front of the IPPV processor to monitor the status. Eight LEDs, two for each RF receiver 1313 - 1343, indicate the status of the four RF receivers. There is also a block 1390 of light emitting diodes containing four light emitting diodes. Two LEDs monitor the operation of the serial input / output. One LED indicates the status of the isolating amplifier, the fourth LED indicates the status of the power supply. These four diodes are shown as a block of 1390 LEDs, connected to the bus system via asynchronous flip-flops.

- 32 When data is being received on a channel, the upper LED on that channel flashes green. The lower LED on each channel will be green when the channel is active and red when the channel is off. Entering the wrong frequency into the system organizer or front panel will cause the channel to shut down. Normally, all channels should be active.

In the unlikely event that one of the receivers fails the Diagnostic Test, the upper LED of this channel will be solid red and the lower LED will flash red.

Two LEDs, labeled TXD and RXD, indicate serial input / output activity connecting the IPPV processor to the system organizer. If data is being transferred from the processor to the system organizer, the TXD will flash. Conversely, if the processor is receiving data from the system organizer, RXD will flash.

The LED labeled Buffer indicates the state of the buffer between the IPPV processor and the system organizer. If the LED is off, there is no data in the buffer for the system organizer. If the LED is green, it is steaming! less than. half full. If steaming! fills more than halfway, the LED does not turn solid green to flashing green. When steaming! when full, the LED turns flashing red. Under normal circumstances, balancing would be steam! it should never be completely full.

The LED labeled Power will turn green when the power is turned on. When the power is turned on, this LED will briefly turn red, then turn green. If the IPPV processor ever returned to a non-fusible state, this LED would briefly turn red while the processor restarted itself.

The calibration program in the system organizer together with the IPPV processor are responsible for calibrating the transmitters of the IPPV modules associated with the terminals. The calibration procedure ensures that the data transferred from the terminal reaches the processor at the appropriate level. Automatic and periodic calibration of all terminals in the system further eliminates any requirements for automatic gain control in the IPPV processor. The calibration control unit controls the flow of commands to the IPPV module during the calibration sequence and determines its calibration status based on the responses it receives from the module. Driver a

- 33 procedures are fully Entered in the combined application US Ord. No. 07 / 562,675, issued Aug. 3, 1990, uninvited, RF retransmission method for cable television, which is incorporated herein by reference.

The present invention allows each terminal to generate and collect system monitoring statistics at predetermined times. The generated and collected viewing statistics may contain various data that may be determined by the terminal, such as viewer profile data or TV status data. Viewer profile data includes information such as who watches certain television programs at home, that person's age, that person's gender, etc. Television status data includes information such as which television program is being watched, the volume of the channel being watched, the brightness of the television channel, etc. In one embodiment of the invention, a television channel watching one or more subscribers is certain surveillance information that is generated and collected . The procedure for generating and collecting this type of monitoring statistics will be discussed in detail below. The equipment and methods for generating and collecting other types of monitoring statistics will, of course, be very similar to those described in this embodiment.

Let us now look at Fig. 13; it indicates the different memory locations contained in each terminal. Each terminal has several collection sections, which consist of a PTSL memory location for the recording time, a memory location CSL for the channel designation (memory location for monitoring statistics) and a TCSL memory location for the time code. in this embodiment, the system organizer generates a global transaction that defines four recording times in which the IPPV module should record the channel to which the terminal is tuned. The recording times are stored in the memory locations HTSL ^ to stsl₄ for the recording time at each terminal; these memory locations usually consist of the memory locations of the non-volatile third memory (NVM 507 in Fig. 4), but they can also be memory locations in the random access memory. Recording times can have any suitable period, such as day, week, two weeks, etc.

To illustrate, we will assume that the system organizer instructs the IPPV module to record the channel tuned to the terminal on Sunday at 7:00 PM, Tuesday at 9:00 AM, on Thursday at 8:00 AM

- 34 in the evening and on Thursday at 10.00 in the evening and repeating every week. As explained above, these four recording times are stored in four memory locations oro time recording / 3TSIq. to PT0L4 / preferably in the non-volatile third memory 503. The real time clock, derived from the 4 MHz crystal clock (Fig. 4), maintains a normal real time for each IPPV module. To maintain accuracy and consistency, these clocks can be periodically updated by the system organizer in a direct transaction.

The second microprocessor 504 periodically compares the different recording times stored in the third memory 503 with the real time value, and when they match, the IPPV module records in the GSL memory location a channel designation corresponding to the recording time, the channel just tuned by the terminal. As shown in FIG. 4, the channel memory location is located in the third memory 503 and is stored by the second microprocessor 504. Microprocessor 504 receives monitored channel information over data bus 490 from first microprocessor 400 / FIG. 3 / terminal. The first microprocessor 400 receives information about the currently monitored channel from the first memory 470.

As mentioned earlier, these statistics and monitoring are included in the statistical responses about the programs and monitoring, transmitted in the opposite direction to the system organizer. E.g. this reply contains information relating to the number of syllables in the message, the type of message, the digital address of the terminal, the recording times and channels tuned by the terminal and their recording times, and any dates of purchase. However, the content of this answer is not limited to this data; the response may also, in another embodiment, include data representing other viewing statistics relating to certain viewers watching television programs, or data corresponding to the state of the television itself.

In the proposed embodiment, the recording time transmitted to the terminals is composed of a multi-bit value that unambiguously determines one or more specific future times at which the required tracking data is to be recorded. The number of unambiguous times that can be defined in this case can be given by the following formula:

Number of unique times = 2 ^, where b is equal to the number of bits used. E.g. when the recording time consisted of a 16-bit quantity that unambiguously specifies an interval of one minute, 2 ^ 6 or 65,535 different one-minute intervals can be displayed. Because an hour has 60 minutes and a day has 24 hours, this resolution can theoretically resume any one-minute interval in a time period of 45 days /65.536/60/24 = 45.5 ../. It is equally possible to use a larger or smaller number of bits, which gives a higher or lower resolution /e.g. up to one second or a shorter or longer time interval. When the recording time has been sent to all terminals, it is stored in the RTSL gateway location for the recording time associated with a particular collection section that is addressed. Then, when the recording time stored on a certain collection section coincides with the current real time of the clock located in the terminal, the channel name being monitored is stored in the channel storage location CSL for this collection section and the time code corresponding to the current time. , is stored in the corresponding memory location for the time code. As it is possible that the terminal and the corresponding TV set are not currently in operation, it is possible to take measures to record the status of the terminal switch as well. According to the terminal diagram of the terminal in Fig. 3, the power supply comprises an auxiliary AC socket into which the television can be switched on. Then, when the viewer turns off the terminal with the external keyboard, this socket turns off and the TV also turns off. The first microprocessor 400 checks whether this socket is switched on or off, and this status information can be stored in a memory location for the channel together or in the location of the observed channel.

As described earlier, they may be at the time of the recording. equal to the value of the real-time clock, stored different types of tracking statistics. For convenience, the types of data that can be monitored and recorded at a remote terminal can be divided into two categories: Viewer profile data can include data such as the identification of the viewer watching the television program, the viewer's age and gender. Returning to FIG. 3, which shows a user V3tup 440 in the form of a keyboard through which a terminal user can enter commands and data. This keyboard can be used by the viewer to record their identity before or during the television program. This data can then be stored together with other statistical data in the third memory 503 or in another memory, or it can be included in_/ responses sent back to the system organizer and compared with viewer profile data to determine the specific type of viewers watching different television programs.

In addition to the data entered by the TV viewer via the keypad, a unique remote terminal identification code assigned to the various remote terminals may be included as tracking statistics in the response sent back to allow comparison with subscriber profile data stored by the system organizer. Subscriber profile data relating to a particular remote terminal, as opposed to an individual viewer, can be used to determine a household image in relation to viewing rather than an individual viewer. In order to gather this information, it would not be necessary for an individual viewer to enter their identity through the terminal terminal, because the identification code of that remote terminal would already be stored in a particular remote terminal.

TV status data can include data such as which TV channel is being watched, whether the TV is on or off, TV sound level, TV brightness, etc. This information can be directly accessed by the IPPV module and terminal and can be stored together with other TV statistics. tracking in the third memory 503 or other memory and sent back to the system organizer along with any viewer profile data as previously stated.

When the recording time has elapsed and the channel and time code have been recorded, the system organizer may issue either a global or addressed command to select the terminal (s) to send the contents of one of its channel and time code locations back to the system organizer. At this point, each terminal sends a response, which will contain tracking statistics (in the proposed embodiment, it will be tracking channel data) and time code data, to the system organizer for processing. We will describe the content and format of this answer in more detail later.

The time code is stored in the terminal's memory and sent to the system organizer to ensure that the system organizer is able to distinguish which channel it is receiving information about. Each of the different collection sections will be reprogrammed and data will be selected from it for different recording times, and it is therefore necessary to be able to assign the tracking information sent back from each terminal to a specific point in time at which it was generated.

- 37 Eg. if the terminal is unable to send its channel monitoring information for the collection section before that particular section is reprogrammed to another Recording Time, the returned time code will serve as an indication that the observed channel information was generated for an earlier programming and collection cycle. This can be done because the system organizer is able to track the recording times associated with each section and compare this information with the returned time code.

Like the recording time, the time code is a multibit quantity that uniquely identifies a specific point in time within a specified time period. 7 of the proposed embodiment, the time code consists of 03 bits and has a resolution of one hour intervals. In this case, if the formula given above is used, 2θ or 256 different one-hour intervals can be displayed. Because the day has 24 hours, this corresponds to about ten days / 256/24 = 10.6 ../. Similarly, in another embodiment, the time code may have a higher or lower resolution within a longer or shorter time period.

Referring now to Fig. 14, there is a timing diagram showing recording times sent to the terminals and the resulting time codes returned to the system organizer in the proposed embodiment we have just described. In the proposed embodiment, the resolution of the recording times is ΡΤη_ to RT4 in minutes, while the resolution of the Time Codes TC is_n etc. is in hours. In the proposed embodiment, four sections A to D are also implemented for recording information about the monitored channels, no more often than four times per hour.

In this embodiment, the resolution of the Time Code is one hour, and the hour in which the^xfree section programmed. It is assumed that two consecutive recording times of any particular free section will never fall within the same hour, and therefore the resolution of one hour for the time code is sufficient to sufficiently identify the tracking information that is being returned. In other words, distinctiveness^xThe time code is not tied not to the resolution of the Recording Time, but only to the number of collection sections used and how often these sections are used (in this case once an hour). Because the system controller monitors the Sas for which a particular section has been programmed, there can be no ambiguity as to which recording time the collected monitoring information relates, because no collection section is used more than once an hour. Also, because the number of time code bits is kept to a minimum, the time required to transmit the time code back to the system organizer is minimized, thereby reducing the likelihood of collisions between transmissions from gentle terminals.

Assume, for example, according to FIG. 14, that the recording times RT1, RT₂, RT1 and RT4 correspond to 7.10, 7.25, 7.35 and 7.50, respectively, which all fall within the same one-hour period of 7.00 to 8.00. When the recording time equals the real time clock time, at each terminal, the channel being watched is stored in the memory location for the signal and the current time, in clock increments it is stored in the memory location for the time code. In this example, the contents of the time code memory location would correspond to a one-hour period from 7.00 to 8.00. Later, when each terminal returns the contents of these memory locations to the system organizer, the system organizer determines that the returned information relates to recording times ranging from 7.00 to 8.00 as opposed to earlier recording times programmed in earlier programming and collection cycles.

The time period that the 8-bit time code can display does not fully cover the period that can be displayed by the 16-bit recording time described earlier, but a period of ten days is considered sufficient to allow everyone; IPPV modules return their tracking statistics to the system organizer. The number of bits and the resolution of the recording time and the time code, as described, should not be construed as limiting the invention, but merely as an example of an arrangement that shows a convenient and practical mode of operation.

Giant. 15 shows a sample timing diagram for programming each IPPV module with a recording time and subsequent collection of channel monitoring information in the proposed embodiment. As can be seen from this diagram, each section can be used individually, independently of the others. In other words, while the system organizer transmits the recording time to the IPPV module from one section, it can collect from another section the channel and time code information stored there earlier. In order to fully understand this way of moving from one section to another,

- 39 we present a detailed discussion of Fig. 15

At the beginning, at the start at time RT1, it can be assumed that the collecting section A has previously been programmed by the system organizer for the recording time RT1. In addition, at time RT1, the organizer programs sections B and G to record times R2 and RT2, and from the collection section D, the system organizer is currently selecting data.

At time RT1, the system organizer issues a global or addressed selection signal that instructs one or more terminal codes / s to begin retransmitting the contents of its channel GSLs and timecode memories TC3L, which correspond to collection area A. Each the terminal then tries to send tracking information from this collection section A to the system organizer for a specified time. In the proposed embodiment, the programming and collection periods are roughly evenly distributed in a one-hour cycle during which each collection section is used. If each section is programmed and selected less than once an hour, then the collection period may be reasonably longer. However, the maximum length of time for collection can be placed arbitrarily in one time cycle (one hour), as this length of time should be sufficient to obtain a reasonable frequency of responses from most terminals. Therefore, as indicated in the diagram as / RT5 - RTy // 2, the collection time allocated to each section only needs to be less than the time of one cycle or / roughly / half the time between the first recording time and the time of the next recording.

As time progresses, the period for collecting from section D ends immediately before RT2. sends the recording time RT4 to all terminals, which is stored in the memory location RTSL for the recording time (see Fig. 13) for this section in all terminals.

At time RT2, the programming period for collection section B ends and the system organizer sends a global or addressed selection signal to one or more terminals to start the malting statistics collection period for this section. Then each terminal, addressed by the selection signal, behind^xdo not send your discount information for section B / content of 3 memory locations for the channel and time back to the system organizer, bass period reserved

- 40 Dec.⁺The collection period is the same as described above for collection section A. During this time, as can be seen from Fig. 15, collection sections A, S and 3 are in their respective programming or collection states and their operation. is independent of each other.

3ezprostredn^x before the time RT'3, the collection period for section A ends and the system organizer starts reprogramming this section with the new recording time / RT5 /. At this point in time, all the terminals that responded to the collection sample already had enough time to send their tracking statistics back to the system organizer. As in the case of the acquisition selection signal described previously, the system organizer can program the terminals either globally or addressed. When the collection section is reprogrammed for a new recording time, the existing information stored in the channel and time code memory locations is reset to prevent the same data from being retransmitted to the system organizer.

At time RT3, the programming period for collection section C ends and the system organizer sends a selection signal directly to one or more terminals to start the collection period for this section. The length of time allocated for this collection period is the same as the length of time previously described for collection sections A and B.

Immediately before the RT4 time, the collection period for section B ends and the system organizer reprograms this section with the recording time ΗΤγ. Finally, at time R.T5, the collection period for collection section D ends and the system organizer sends a selection signal to one or more terminals, as described above for the other sections. Each terminal then begins transmitting the contents of its channel memory locations and time code back to the system organizer. At this point, the complete cycle of all collection sections is completed and the process begins again.

This way of moving from one section to another has a number of significant advantages over programming all sections and subsequent collection from all sections. If all sections are programmed before the corresponding sales information has been collected, the length of time available for collection has been reduced for those sections whose recording time is closer to the end of the programming and collection cycle. Dill. when four sections are used and the recording times for each of the sections are 7.10, 7.14, 7.40 and 7.50, the later sections have only a minimum collection time before the next programming cycle begins. If the next programming cycle

- 41 start at 8.00, IPPV modules will only have 10 minutes to send channel information back^xt to the system organizer before this section will be reprogrammed.

Restrictions on how all sections are programmed with subsequent acquisition include a situation where there is too little time to reprogram certain sections after the previous acquisition period. E.g. in the example above, if the initial programming period starts at 7.00 s and then continues after hours, there may be little time to program all four sections before the first recording time expires. Therefore, the total time required to program all four sections may take 30 minutes, which may exceed the first two recording times. It is possible that some or both of these recording times will elapse before this section is programmed, which would miss the critical time for recording the watched channel.

As already described, Fig. 15 graphically illustrates a step-through programming and collection method that removes the limitations discussed. By arranging the time periods during which each section is alternately programmed and selected, the time for each operation can be evenly distributed for all four sections. Instead of being limited to alternating programming and then collecting from all sections at once, each operation can only be performed on one collection section ηβ at a time, while the other section is in the middle of another operation.

E.g. again with reference to Fig. 15, at time RT₄ the system organizer sends a selection command to one or more terminals to start the collection period for section D. Meanwhile, the collection of section A is in the second half of its programming period, section B is at the beginning of its programming period and section C is in the middle of its collection period. Therefore, the system organizer needs to perform a section selection operation of section D and is not burdened with operations on the other three sections, which could cause the previously mentioned timing problems. The system organizer never performs an operation on more than one section at a time, which leads to an even distribution of time requirements during the programming and collection periods of all sections.

In an alternative embodiment, the system organizer could enter an addressed tracking statistics transaction with only one subscriber who has agreed to allow monitoring of his tracking habits. In yet another embodiment, the system organizer could insert the addressed tracking statistics transaction only into a certain group of terminals.

Recording time programming instructions, transmitted from the system body⁺to one or more addressed terminals in the proposed configuration is indicated in Figure 18. In the proposed configuration, the recording time instruction contains 96 bits, divided into 24 4-bit half-syllables in these 32-bit words. The first 4 half-syllables (from the left) contain the values ​​1, 5, 0 and 0, and the 9th, 10th and 12th half-syllables contain the values ​​6, 5 and 0. The values ​​of these half-syllables uniquely identify the instruction as a recording time programming instruction. The rest of the half-syllables contain values ​​corresponding to the programmed collection sections and the corresponding recording times associated with these collection sections.

As follows from the attached legend in Fig. 18, the programming instruction contains two types of data: Record sets, denoted TxO to Tx3 / where x is the designation of the collection section A to D / and the ACT mask of the reception time. The recording time for each collection section consists of 4 half-syllables or 16 bits. The receive time mask contains one half syllable or 4 bits. The diagram in the figure shows that the recording time for section A,

TAO - TA3, occupies: 5th, 6th, 7th and 8th half-syllable from the left, recording time for section B, TBO - TB3, occupies 13th, 14th, 15th and 16th half-syllable, recording time for section C, TCO - TC3, occupies · 17th, 18th, 19th and 20th half-syllables and recording time for section D, TDO - TD3, occupies 21st, 22nd, 23rd and 24th half-syllables.

The description of Fig. 18 also shows that the recording time bits are transmitted with the highest bits first. That is, e.g., TAO contains bits 12 to 15, TA1 contains bits 8 to 11, etc. For the receive time mask, the lowest valid bit / ACTq / corresponds to the collecting section A, while the highest valid bit / ACTj / corresponds to the collecting section D.

In one embodiment of the present invention, more than one collection section is programmed with a recording time in the same transaction. In another embodiment, especially with the previously described transition programming method? only one collection section is programmed in any given transaction. The structure of said instruction time programming instruction allows to obtain any of these possibilities using the same instruction format. This is achieved by using an ACT mask.

As we explained earlier, the ACT time mask contains

- 43 one half syllable or 4 bits of data. Each bit corresponds to one of the four collection sections in the proposed configuration. If the value of a certain hit is 1, then it is interpreted by the terminal as an indication that the combined recording time is a valid recording time and that the terminal should record the monitored channel at the appropriate time. On the other hand, if the value of a certain bit is 0, this means for the terminal that the combined recording time is rather blind and does not mean that the next^xThis section will record the channel.

E.g. let's assume that the system organizer wishes to instruct all terminals to record the monitored channel at 8.00 and 8.15. In this case, the system organizer could transmit the recording time of 8.00 and 8.15 in TAO-TA3 and T30-TB3.

The contents of TCO-TC3 and TDO-TD3 would not be used, but would still be included to keep the length of the programming instruction constant. The value of the AGT reception time mask would be set accordingly, so that the terminal would know which sections are being programmed. In this case, the system organizer would set the bits ACTq and ACT1 to 1 and ACT2 and ACT-j to 0. In this way, the terminals would know which of the bus sections are to be programmed.

It is important to note that each of the recording time points TAO TA3 to TDO-TD3 can be used independently of each other. In the example shown, sections 3 and D could be programmed as easily as sections A and B. In this case, the respective recording time points corresponding to sections B and D, T30-TB3 and TDO-TD3 would be filled with recording times and mask bits for sections B and D, ACTj and ACTj? would be set to 1 to indicate that these two recording times are valid. Accordingly, the mask bits for sections A and C, ACTq and ACTg, would be set to 0 to indicate that these two sections do not contain valid recording times. The values ​​entered at the TAO-TA3 and TCO TC3 recording time locations can be set to any value, as these locations are used only as an instruction pad. In this way it is possible to program any number of recording times in any combination of collection sections with one instruction.

Giant. 5 shows a timing diagram of a typical data return sequence.

As mentioned earlier, the total number of terminals is divided into manageable subgroups of approximately the same extent. We will simply call them groups. The time each group can return data is called the group period (or simply period). During the IPPV data selection, the system organizer gradually sends data requests from the cable system station to all groups. One complete sequence of data returns from v ^ e- ^ b skuDin is called a cycle. Finally, the sequence of two or more cycles that make up a complete / typical day / data return sequence is called a zone. When a terminal sends its data during a given zone and receives an acknowledgment, that terminal will not retry during that zone. Each group data return request sent by the system organizer contains the group number ε instant cycle and zone numbers.

There are two types of autoresponders: global and addressed. Global auto-responses can be further divided into cyclical and continuous. For cyclic auto-responses, the user defines the time interval in which the IPPV modules respond. In a continuous automatic response, the system defines the time interval as 24 hours.

Referring to Figure 5, the time interval for both cyclic and continuous auto-response is called the zone. Each zone is assigned a number so that the IPPV module can determine if it has already responded during a particular zone. Each zone is divided into a series of cycles. The cycle is defined as the time required for the entire number of terminals to attempt a response. Each cycle is assigned a single number (within the zone) so that the IPPV module can determine if it has already responded during its cycle. Due to RF collisions, not all IPPV modules can reach the RF receiver. To increase the probability that a certain IPPV module will reach the RF receiver, it is possible to define a minimum number of cycles in the zone. This minimum number of cycles in a zone can be changed.

Each cycle is divided into groups. The group is part of the total number of IPPV modules in the system. Each IPPV module is assigned to a specific group and is assigned a group number. The group number can be assigned to the IPPV module by an external source / user-defined / or it can be derived from a numeric address using a shift value, as will be described in more detail below. No matter how the split group number is removed, the IPPV module will respond to the global auto-response during its group time. Each IPPV module is further assigned a variable number of attempts. The number of attempts indicates the number of times a given IPPV module will attempt to respond during its group time.

The algorithm according to the invention is first described in general terms and then in more detail.

The response algorithm of the invention is based on an effort to guarantee a constant number of response attempts. This constant is called the response rate and is measured in IPPV modules per second. the frequency of responses can be changed. The number of IPPV modules must be limited to ensure a constant response rate. We will call this constant the maximum number of modules in a group. This maximum number of modules in a group can be changed. Based on the maximum number of modules in a group, the number of groups in a cycle can be calculated as follows:

Number of groups = -^C.^EJŽ2yf Number nogulflmaximal number in the group

In a system where group numbers are derived automatically from a numeric address, as shown below, the number of groups is rounded to the nearest power of 2.

The average number of IPPV modules in a group can be calculated as follows:

Wed *. number of modules =.^C-^E.^lknvý ^poget number of groups

We will use this number to calculate the length of the group in seconds:

Group length = -^with· ^ Group response rate

The cycle length in seconds can then be calculated as follows:

Cycle length = group length x number of groups

The number of cycles in a zone can be calculated as follows:

Number of cycles - ^end^ zone time - start time of the cycle length

If the calculated number of cycles is less than the minimum allowed number of cycles, the number of cycles is set to the minimum. The minimum zone length can then be calculated as follows:

Minimum zone length = number of cycles x cycle length This number is matched by the zone length specified by the user in the case of cyclic auto-responses to determine if the given zone length is large enough.

The indicated values ​​are calculated at the beginning of the automatic response sequence. The system assigns a new zone number and an initial cycle number. The automated response control sequence is then ready for SDRust.

- 46 The system starts with the first group in the cycle of this zone and continues until the calculated number of groups in the cycle is reached. The cycle number is then incremented and a check is made to see if the total number of cycles in this zone has been exceeded / ie. The end of the zone has already been reached.

In the negative case, the group number is reset and the sequence continues.

While the IPPV module group responds, the system receives the data and enters it into its database. After successful storage of data from any PPPV module in the database, a confirmation is sent to the IPPV module.

Part of the data passed from the IPPV module to the system is a checksum of all data in this case. This checksum is a confirmation code and is sent back to the IPPV module in a confirmation message. When the acknowledgment code matches the one originally sent with the case data, the data is dropped from the IPPV module's memory. If the IPPV module does not receive an acknowledgment message from the system during the current cycle, the IPPV module will respond again during the next cycle of the current zone. When the IPPV module receives an acknowledgment message during an ongoing cycle, it will not respond until the next zone. A confirmation code is sent to all modules that responded, regardless of whether data was sent with the data. This will reduce the number of collisions in each subsequent cycle in the zone.

Addressed auto-reply or dialing is designed to select IPPV data from a specific IPPV module. The information sent to the IPPV module is the same as in the global auto-response with the following exceptions: The numeric address of the selected IPPV module is included, the zone number is set to zero and the rest of the information / group, cycle, offset value, etc./ is set so that the IPPV module responds as quickly as possible, even if it has no sales report.

In the contemplated embodiment, the group size is between 2500 and 5000 terminals. Terminals are added to existing groups until all groups have 5,000 terminals each. When. have all groups of 5000 terminals, the number of groups doubles, so that all groups have 2500 terminals again. To illustrate, assume that the total number of P initially contains 3500 terminals in a single group. As more terminals are added to the total number P, the total number is compared to the upper limit of 5000. When the number reaches 5000 terminals, the number of groups doubles from one to two. This creates two groups, each with 2,500 terminals. When they are added

- 47 terminals more terminals, the number of terminals in both groups is growing. When both groups contain 5,000 terminals each, the number of groups is again doubled to a total of four groups, each containing 2,500 terminals.

Empirically, it was determined that the optimal frequency of attempts for the considered IPPV feedback system is 50,000 attempts / hour. To keep this frequency of attempts constant, the non-diode of the group must change as more terminals are added to the system. In a given embodiment of the invention, both the frequency of attempts are kept constant, the period of one group, i.e. the time in which each of the terminals in the group must try to send its data, must increase from 3 to 6 minutes.

These principles can be illustrated by a simple algorithm. This algorithm can be used when groups are created automatically using the bits of the digital address of the terminals. Assume that at the beginning the number of groups is 1 and the total number of terminals is N, then

1 / if G &lt;2 or P / G&gt; 5000 G = 2 x G

2 / S = P / G

3 / Τ = K x S, where S is the number of terminals in one group, T is equal to the period of the group and K is a constant chosen to maintain a constant frequency of trials, which in the given example is equal to 3 min./2500 terminals.

The group of which a particular terminal is a member is determined using a certain number of bits in the terminal address. E.g. if the number of groups is eight, the last three bits of the terminal address are used. If the number of groups is sixteen, the last four bits of the terminal address are used.

At the beginning of the group period, the system organizer commits the transaction to the IPPV processor, indicating that a new group period has begun. The system organizer sends a global command to the terminals, indicating the beginning of a new group period and which group number has been selected. The terminals contain a pseudo-random number generator. This pseudo-random generator^xnumbers generates a number of start times, corresponding to the number of attempts and the number of reverse frequencies. E.g. if it has three attempts and the return path uses * four frequencies.

* ^w v / idě let

- 48 pseudo-random generator generates twelve random numbers. These random numbers are divided into the entire period of the group.

Messages from terminals to the terminal do not overlap.

However, in a given embodiment, rather than generating random numbers that do not overlap within a given group period, the module will wait until the transmission is completed before starting the second transmission, if it were to start before the first message ends. It will be apparent to one skilled in the art that a sgdu of non-overlapping random numbers can be generated and used to determine transmission time, and the invention should not be limited in this regard.

One method of how terminals return data is one in which all terminals send the data at some point during a predetermined callback period. However, this method can result in overloading of the reverse amplifiers and generation of undesirable phenomena in the forward path if all terminals try to transmit at the same time. Therefore, it is advantageous to divide the whole number into a number of groups. However, it is possible to use a group equal to the number of terminals

The terminals are divided into groups in one of two ways.

In cases where it is important that individual terminals belong to a certain group /e.g. when bridging / is required, each terminal can be assigned to a certain group using an assignment transaction addressed to the group. The cable operator may wish to assign the terminals to certain groups based on the frequency of purchases or other factors associated with a particular group or subgroup of the total. There may be other reasons why cable operators assign a given number of members to a given group and the invention should not be limited in this respect.

In this case, the number of groups is selectable in the range of 2 to 255. The group size also does not have to be the same, and the group period can be set individually to allow different group sizes. Since it is an object of the invention to eliminate bridging switching, it is desirable that the group assignment is not predetermined by the switching bridging network.

In the more general case, individual assignment to groups is not required. All terminals are controlled by a global transaction to use the lowest bits of the unique numeric identification / address / terminal as group numbers. The number of groups in this case is always given

- 49 by the power of 2/2, 4, 8, 16, etc./. Because the lower address bits of the terminals are very evenly distributed in a large number of units, the number of terminals in all groups is practically the same and equal to the total number of terminals divided by the number of groups. The actual number of groups is determined by two factors.

The first factor is the optimal frequency R that the terminals attempt^-! send messages to the IPPV processor regardless of the number of retries. The second factor is the appropriate minimum callback period Pmin. Then the total number of terminals can be divided into a maximum of 2ⁿ manageable groups by choosing the largest value n, for which the number of terminals κ n —R x Pmxn applies

2ⁿ

Power 2, ie n, determined by this equation then indicates the number of lower bits that the terminal must use to determine the group of which it is a Member. E.g. if we specify n = 4, then there are a total of 16 groups and each of the terminals uses the lowest 4 bits.¹ your address as a group number.

The optimal number of R terminal attempts used in the upper equation is expressed simply as the mean number of terminals per unit time. However, each terminal has an adjustable number of retries, so the actual frequency of message attempts is equal to the number of terminals in the group times the number of transmissions each unit makes, divided by the length of the group period. During the data return period, the average frequency and length of the message transmissions made determines the message density and thus also the collision probability for any given transmission. If we assume that the average transmission length is relatively fixed, then the frequency with which the terminals try to send back data is the main influence determining the probability of collision and, conversely, the throughput of messages.

A low frequency of message attempts results in a low probability of collision, while a higher frequency of message attempts leads to a correspondingly higher probability of collision for any administration. However, a high percentage of success at low rates (or a low percentage of success at high rates) can result in low overall throughput. Therefore, the measure of the true success rate is the probability of success for any message times the frequency of terminal attempts. E.g. when 1000 terminals try to return data within a one-minute period and the probability that any message will be affected by a collision is 20%, then the actual success rate will be

1000 terminal x / 100 - 20 /% / min. = 800 terminals / min.

A numerically high success rate of terminals is not the final measure of IPPV throughput unless it results in almost 100% success. Because the data is a profit for the cable operator, all terminals must return the data stored in it. An approximation of 100% success may require two or more periods in the statistical approach to return data. To continue with the example, assume that the group has the specified success rate during the first data return cycle. 800 terminals / min. throughput may be most desirable, but it is not acceptable to leave 20% of the group without sending a message. During the next return data cycle, 800 successful terminals should receive confirmation of the received data. As mentioned above, terminals that receive an acknowledgment that exactly matches the data stored in secure memory will not respond again until the beginning of the new zone. Therefore, only 200 terminals that failed in the first cycle will attempt to return data. The result is a much lower probability of a collision during the second cycle. To illustrate, we will assume that the probability that a message will be affected by a collision is 1%. During this one-minute period, 200 x / 100 - l /% = 198 terminals will be successful. The combination of the two cycles will be the effective percentage of success:

/ 800 + 199 / terminals / 2 min. or 499 terminals / min.

This frequency is achieved with almost 100% of the message terminals and is therefore a very good measure of the throughput of a real system. The optimal frequency of trials is thus defined as the frequency of trials that provides essentially 100% effective success for a given number of terminals in the shortest time interval.

The invention used a simulation method based on the IPPV data return system model to determine the optimal frequency of trials. However, it should be noted that while the choice of the optimal frequency of attempts affects the performance of the system, it is not critical to the function of the invention.

The description and calculations above assume that data return is achieved to return IPPV case data from IPPV modules. However, the RF return system of the invention can be used widely in systems

- 51 in which a board of remote units or terminals attempts to transfer the stored data to a central location. Burglar alarm requirements, power management, home shopping and other services are generally an adjunct to the IPPV service. However, some efficiency gains can be achieved by combining the reverse data of these additional services with IPPV transactions, although for different transactions, especially with real-time requirements such as two-way voice / telephone / transmission, it may be appropriate to use differently addressed or global calls. and answers.

For a number of reasons, such as signal-to-noise ratio and neighboring channel interference requirements, it is necessary that the output level of the IPPV transmitter's carrier data for the return channel be set close to optimum. Furthermore, for low installation costs, easy maintenance, repeatability and reliability, it is highly desirable that the output level setting be as automatic as possible. The method of automatic calibration of the transmitter level is described in detail in the associated Pat. US application no. No. 07 / 562,675 of 3. August 1990 - entitled RF Return Method for Cable Television, which is incorporated herein by reference.

A complete description of the procedures and equipment for transmissions between the IPPV processor and the system organizer and between the terminal and the IPPV module is contained in U.S. Pat. No. 07 / 562,675 of August 3, 1990 entitled RF Return Transmission Method for Cable Television, c⁺erou is listed here as a link.

The IPPV method transmits data using I &amp; ller data encoding. Killer coding, also known as ZD modulation, transmits 1 as a signal transition in the middle of a bit interval. 0 has no transition unless followed by another 0; in this case, a transition occurs at the end of the bit interval. The use of Miller coding in the present invention is described in detail in co-pending U.S. application Ser. No. 07 / 562,675, issued Aug. 3, 1990, entitled "RF Return Method for Cable Television," which is incorporated herein by reference.

The sequence of data transfer between the IPPV module and the IPPV processor. Each time data is transferred, the IPPV module performs the following sequence:

A. It starts switching the transmission data line at 10 kHz. This does not beat the data filter.

S. Sets the gain to the minimum.

0. Switches on the switched voltage + 5 V to the RF circuits.

- 52 f * z / r- · * · f ry

D. Delays to about 1 ms to stabilize + 5V.

2. Does not set the correct phase-locked loop frequency / from NVTI memory /

7. It delays by about 20 ms to catch the phase lock

G. Keying circuit against crosstalk liability

H. Delays by about 1 ms to stabilize the final output point

I. Drives to the correct gain / read from NVM memory /

J. Sends data.

When the transfer is complete, the IPPV module performs the following sequence:

A. Generates a Liller code error in the transmitted data to end the transmission / for the receiver /.

B. Reduces gain to minimum.

C. Keying circuit against crosstalk liability.

D. Delays by about 1 ms to prevent frequency slippage.

Ξ. Switches off the switched voltage + 5 V.

These sequences are indicated in detail in Figures 15-8 using the following definitions:

Switching voltage + 5 V to the phase-locked loop, data input

Delay for capturing the phase-locked loop

Data filter charging time

Keying of the anti-crosstalk circuit until the start of the gain tON ^ LK tCHG * AB tRD topp

Reinforcement approach

Gain download

From withdrawal gain to switch off + 5 V

The data transfer sequence in said step J can be further decomposed into its components. Fig. 16 is a graphical representation of a sample response packet with program and tracking statistics according to the proposed arrangement. The complete packet in this figure represents a typical packet transmitted from the IPPV processor to the system organizer. The content of this packet includes a response with program and viewing statistics received from the terminal with additional header and conclusion information attached. We will now describe the components of the packet sample:

According to Fig. 16, the column on the far left, labeled Byte / syllable / corresponding number (s) / syllables for each location in the packet. The bars column, labeled Oescription, contains the Letter

- 53 individual places. The third column, labeled Value, contains a range of eigenvalues ​​in either hexadecimal (labeled h) or decimal / unlabeled / format, for each individual location. Finally, the last column, labeled Comments Comment / contains additional descriptive notes regarding the custom values ​​for each individual site. In addition, the various components of the response packet are intended to graphically illustrate when a particular part was added.

The first group of parts marked on the left, labeled RF-IPPV Processor Originated and corresponding to syllables 0 to 17, contains headers generated by the IPPV processor regarding the type of data contained in the packet. This header adds the IPPV processor to the connected terminal responses. Starting with the first part for syllables 1 and 2, the description indicates the type of answer. As can be seen from the Value column, the value of this space is 0 for the program and watch statistics response packet. For other types of responses, such as calibration and frequency selection, this value will be different.

The next part contains syllables 2 and 3 and corresponds to the state of the receiver. The value of this location corresponds to the state of the IPPV processor receiver.

In the proposed arrangement, only 4 bits of this two-syllable part are used. Bit 0 Indicates on state, bit 1 indicates setting request, bit 2 indicates local block and bit 3 indicates error state.

Syllables 4 to 7 contain the hemlessing count corresponding to the number of messages to be sent from the IPPV processor to the system organizer. In the present invention, the term message refers to a response with program and tracking statistics, but as explained previously, it may also refer to other types of messages that the IPPV processor sends to the system organizer. The number of messages that can be sent to the system organizer at one time is limited, and therefore the value of this section indicates the total number of messages waiting to be sent, including messages / replies / immediate packets. In the proposed arrangement, the value of this part may be in the range of 0 to 65,535.

Syllables 8 to 11 contain a Uniouo Kessage Uount (number of separate messages), which indicates the number of single or non-duplicated fields received by the IPPV processor from a plurality of terminals. As previously explained, given the somewhat noisy return environment of the physical cable network, each of the terminals transmits a program-responsive response and monitoring several times at different frequencies. o Necessarily leads to redundancy of responses received by the IPPV processor, which eliminates duplicate messages. Therefore, in these syllables, the system organizer is given an indication of the number of single messages received so far. In the proposed arrangement, the value of this part can be in the range of 0 to 65,535.

Moving on to the next section in this group, syllables 12 and 13 contain the Packet Count, which corresponds to the number of messages / replies / in the program and watch statistics packet. In the proposed arrangement, the value of this part can be in the range 0 to 25? ·

Finally, syllables 14 to 17 correspond to packet length. This value indicates the total number of syllables in the packet and can range from 0 to 65,535 in the proposed configuration.

Another group of response and tracking statistics response packet portions is designated RF-STT Originated and contains a portion of the packet that relates to information collected from one or more terminals. Most of this information was taken literally from the tracking statistics information sent from the terminal to the IPPV processor, which is graphically indicated in Figure 17. The content of this response reflects the content of the response sent back by the terminal, and thus the elements of this response will be discussed below in connection with both Figures 20 and 21.

The response with program and monitoring statistics transmitted from the terminal to the IPPV processor contains 4 syllables of initialization information.

As shown in Fig. 17, syllables 1 to 3 contain an introductory group indicating that the following syllables to be transmitted contain a response with program and viewing statistics. The introductory group consists of a sequence of three syllables equal to AA / hexadecimal /. After sending these three syllables, the Start of message / SOM / equal to AB / hexadecimal / is sent. The remaining syllables of the message are then sent, as we will add later.

Syllables 1 and 2, see Figure 16, correspond to a Level Rating value, which indicates the power level of the response received by the IPPV processor from the terminal. Because this measurement is performed by the IPPV processor, it is the only component of this part of the packet that is not transmitted by the terminal, but instead added by the IPPV processor during transmission to the system organizer. This value is then used in the system organizer to trigger a terminal output level recalibration if required. In the proposed arrangement, the value of this component may be in the range 0 to 2, where 0 indicates too high a level, 1 indicates a satisfactory level and 2 indicates too low a level. Recalibration is performed if the level is too high or too low.

The syllables 2 and 3, indicated in Fig. 16 Reply Length, correspond to the length of the next message in the syllables in addition to the previous level size value. In the original response sent back from the terminal, indicated in Fig. 17, this element is placed in the syllable 5. In the proposed arrangement, the value of this component may range from 0 to 255.

The next component of the answer contains syllables 4 and 5 marked in Fig. 16 Message Type ”. In the original response transmitted from the terminal, as indicated in Fig. 17, this element is located in syllable 6. The value of this component indicates whether the terminal operates in or out of band, as described earlier. This value is sent from the terminal to the IPPV processor. If the value of this component is 4, then it indicates out-of-band activity, if it is 14 / hexadecimal /, it indicates in-band activity.

The syllables 6 to 13 correspond in Fig. 16 to the address of the terminal. In the original response transmitted from the terminal, as indicated in FIG.

17, this element is located in syllables 7 to 10. Each terminal is assigned a unique address, which is returned to the IPPV processor with a response with program and tracking statistics, and this identifier is passed to the system organizer.

The next section of the response with program and monitoring statistics, shown in Figs. 16 by syllables 14 to 29, contains the actual monitoring statistics, which were transferred from the terminal back to the IPPV processor. the element is located in syllables 11 to 18. In the proposed arrangement according to Figs. 16 and 21, four tracking sections A to D are used and each has the ability to report back the monitored channel and the tracking time.

The figure shows the watched channel with the data View Channel n / watched channel n / and the time when the channel was watched with the data Time Code n / time code n /, where n is the designation of the section A to D * For the component of the watched channel range 0 - 128 and 255,

- 56 where 0 means that no channel was watched, 1 - 128 indicates the watched channel and 255 means that this section has already been reported. The time code value must be in the range 0 - 255, where this value corresponds to a time with lower resolution than the recording time originally programmed for this section.

In an embodiment of the invention using the programming and collection transition method from different collection sections, as described previously, only one section is transmitted back to the IPPV processor at one time, so that all values ​​of the individual View Channel ns will be 255 except the section in question. will be 0 / no channel has been watched / or between 1 and 128 for a specific channel number.

The remaining 4 syllables in this section, ie syllables 30 - 33 marked in Fig. 16 as Security Nibble and Auth Channel Checksum and AUTH and EVENT in Fig. 17, correspond to special security and authorization information transmitted by the IPPV processor to the system organizer to ensure system integrity and to ensure that only those channels allowed for monitoring by the terminal are actually monitored.

The next section of the program and monitoring statistics packet contains information about the information sent back from the terminal to the IPPV processor. The invention is primarily directed to the retransmission of tracking statistics, but since this overall system can also be used to monitor events at each of the terminals, this part of the packet is included for completeness. As can be seen in Figures 16 and 21, it is possible to monitor and report more than one event in a single packet, with each event occupying 10 syllables. In Fig. 16, event 1 occupies syllables 0 to 9, and other events reported within the packet occupy additional blocks after ·. 10 syllables. In the original response transmitted from the terminal to the IPPV processor, each event represents 5 syllables, with the first event being indicated by syllables 21 to 25.

The next section of the packet, marked in Fig. 16 Peply Checksum (LSB first) and in Fig. 17 CHECK, corresponds to the additional checksum generated by the terminal and used as a Dro error detection means. Two syllables in the previous response are used for the checksum, returned in the packet and sent with the packet. The checksum is generated by adding each transmitted: character to the lowest valid checksum hit. The result then turns one hit to the left. The checksum is initially set to 0. Every character other than the checksum is included in the checksum.

The next section of the packet, labeled Packet Checksum, corresponds to an additional checksum generated by the IPPV processor and used as a means of error detection. This checksum is generated exactly as described above, except that all the characters of the total transmitted packet are added, not just the terminal response.

Finally, a CR / carriage return / character is transmitted from the IPPV processor to the system organizer to indicate the end of the packet. At this point, the system organizer checks all checksums to verify that no errors occurred during the transfer. If errors are detected, a retry command is sent to the IPPV processor and the entire transmission sequence is retried.

We have described a preferred embodiment of the invention. Other embodiments of the invention will be apparent to those skilled in the art. The invention is not limited to the embodiments described herein, but is limited only by the appended claims.

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