Audience response system and data transfer protocol

The invention relates to a method and apparatus for polling user responses to a base unit entered into individual remote response units. The invention is particularly suitable for obtaining individual answers from listeners to a question asked of them. The invention is applicable as an educational aid for determining the comprehension of pupils in a class and as a commercial means of conducting audience voting and the like. The invention can be used even for remote orders in restaurants, goods trading and the like.

There has long been a need to get immediate feedback from listeners on a question asked to them. For example, at a lecture, the lecturer may wish to ask the audience a question to monitor the level of understanding. If the class's response indicates a high level of understanding, the speaker may proceed with a new material. If the understanding is too low, a repeat may be displayed. In another application, a marketing plan may include the presentation of various options to a test audience and include an immediate audience vote to determine particular preferences for various packaging designs, logos, advertisements, and the like.

There are two basic types of response systems: wired, in which the remote units are connected by conductors to a base unit, and wireless. While the wired systems provide more circuit design options to allow quicker collection of responses, permanent installation of the leads in a particular space is often not possible and involves high installation costs. The wireless system, on the other hand, is flexible in terms of use on different occasions and is freely movable. However, the fact that wireless systems communicate via transmit signals limits the options of a system design. As a result, the response speed is compromised, which results in conventional wireless answering systems collecting the responses or Responses are too slow, especially if the system contains a large number of remote response units, such as 250. In addition, the number of functions in a wireless system is limited.

U.S. Patent 5,093,786 discloses a remote wireless answering system in which a base unit transmits address words to remote response units. Each response unit identifies an address word associated with that particular response unit and transmits a response entered by the user to the base unit in response to the identification of its address word. The base unit determines that a valid word is received from the responder and sends a confirmation message. The remote response unit assumes a first mode or status upon receipt of a response by a user. The remote response unit continues to transmit a data message when it receives its own address word until the central control unit transmits an acknowledgment message to the transmitting responder. Upon receipt of the confirmation message, the remote response unit changes to a second idle status or mode. While such a system is reliable and fast, it still has disadvantages. To quickly and reliably transmit address words from the base unit to the response units, as well as response data from the response units to the base unit, two communication channels operating at different frequencies are used so that the communication from the base unit to the remote response units concurrently with the communication from the remote response units with the base unit. However, separate communication channels require increased bandwidth and are not available in all cities. Also, the data format in my patent is rigid and does not use more than one response from the user. Therefore, it is limited to a yes / no answer and multiple choice questions.

DE 43 21 801 discloses a device for wireless connection of responses from multiple users. Query signals are sent to response units to elicit a response from the units into which the user has entered a particular code or number. In this way, the base station can determine the number of responses by measuring the power of the response signals received after the transmission of each of the request signals. There is no disclosure of a basic data packet consisting of several characters, at least a part of which concerns different response units.

It would be desirable to be able to operate a wireless remote response system with a large number of remote response units with a single communication channel in a fast and reliable manner. In addition, it is desirable to provide multiple capabilities in a wireless remote response system. For example, it would be desirable to provide a user such as a student with an indication of whether a given answer is correct or false. In addition, it is desirable to also provide a microphone in a remote response unit to allow a user to request audio communication with the instructor, with the actual control of the audio channel remaining in the hands of the instructor. It would also be desirable to provide a more interactive system that can deliver complex messages on an individual basis to students according to the accuracy of their answers. It would also be desirable to collect study responses that have a multiple character length instead of single character answers. It would also be desirable to effectively download large blocks of text and other computer code from a central processing unit to the remote response units.

Accordingly, it is an object of the present invention to provide a wireless remote response system that has significantly improved flexibility and functionality over conventional systems.

The present invention provides a remote wireless response system for collecting responses from multiple users to a base unit entered by the users into a plurality of remote response units, each user being provided with a response unit. The base unit transmits a base data packet over a wireless communication link to the plurality of remote response units that decode the base packet and load a portion of the decoded base packet into a memory at each response unit. Each response unit examines the characters loaded in the memory and determines each character in the portion of the decoded base packet concerning the particular response unit. Each remote response unit then processes each character belonging to that particular responder. This may include, but is not limited to, assembling and transmitting a response data packet over a wireless communication link from that particular response unit to the base unit. The response data packet contains each response entered by the user.

In accordance with another aspect of the invention, the portion of the decoded base packet loaded into the memory of each remote response unit includes a plurality of characters each relating to a different response unit. The plurality of characters may include acknowledgment to indicate that a valid response has previously been received from the particular responder. The multiple characters may also contain an error-free character or Contains corrective characters indicating whether a previously received response hits a correct answer in a response key. The particular responder may respond to the corrective sign in several ways. It can only be an ad to the. Users submit that a correct or incorrect answer has been received. Alternatively, the portion of the decoded base data packet loaded into the memory of each remote response unit may include a plurality of characters globally pertaining to all the response units or a group. In this way, a particular response unit displays a first message contained in the global characters in response to a predetermined value of the correction character concerning that particular response unit, and displays a second message included in the global characters. in response to another value of the correction sign relating to that particular response unit.

According to another aspect of the invention, the remote response units may be advantageously divided into groups, and the portion of the decoded base data packet loaded into the memory of each remote response unit may include a determination of a group of response units pertaining to the individual characters. The decoded base data packet may further include a designation which group of remote response units is to transmit a response data packet in response to the determined base data packet transmission. In this way, a group of response units may receive individually tailored messages in the same basic data packet requesting another group of response units to transmit their response data packets. The portion of the encoded base data packet loaded into the memory of each remote response unit may further include a plurality of characters globally pertaining to all the response units. These global characters can be stored in memory at each responder unit for any desired purpose, for example, as the opcode for the microcomputers processing each responder. In this way, the operation code and other data for the remote response units can be downloaded from the base unit without requiring physical access to the remote response units to exchange ROM devices or the like.

According to another aspect of the invention, the basic data packet may include a determination of a desired response length from the response units. Each response unit responds to this determination by assembling its response data packet to include the desired number of characters specified to provide the desired response length. In this way, the response units are capable of responding to responses that consist of more than one character, yet the total interview time is no longer than necessary to retrieve all responses. In addition to assembling a response data packet including each response entered by the user, the remote response unit may assemble a null data packet transmitted in response to a base data packet transmission even if a user has not entered a response. This allows the base unit to perform an examination of all response units to ensure that all response units can respond without the need for a response.

According to another aspect of the invention, the basic data packets and response data packets are encoded and decoded according to a single technique. The values ​​of each bit are encoded as a time interval over at least one cycle of a periodic waveform in which the time period is varied either between successive rising edges or between successive falling edges of the periodic waveform. Thus, the time between rising edges or falling edges of successive waveforms of a transmitted signal can be varied to encode each value of each bit. The decoding is performed by measuring the time intervals between the rising edges or between the falling edges of successive waveforms. In a preferred form, it is determined whether each measured time interval falls within one of at least two different non-overlapping time periods to determine a value of each bit. If a measured time interval does not fall within one of the precise ranges, it is ignored and the entire data packet is ignored. In this way, the data transfer is extremely reliable since each decoded bit is only accepted if its measured time interval fits precisely within a given range. Since the data is encoded using a variable time interval, the time duration of the encoded packet varies as a function of the value of the respective bits making up the packet. In order to avoid the need to provide a sufficient time window to accommodate the worst case possibility in which the bits making up the packet have the longest period coding, the content of each packet before encoding is thereupon checks to see if the majority of the largest length bits are encoded. If so, the bits are inverted so that they are encoded according to a shorter length, and an indication that the inversion is asserted with the transmitted data packet to ensure correct decoding at the receiving unit.

The method and system of the invention are defined in independent claims 1 and 24. Some preferred features are given in the dependent claims.

The method may include determining whether each measured time interval falls within one of at least two distinct non-overlapping time ranges to decode a value of each bit.

A transmission is preferably ignored if at least one measured time interval does not fall within one of the time ranges.

Preferably, this characteristic is a number of characters forming the response data packet, the data response packet length being controlled by the basic data packet.

The basic data packet preferably contains a determination of a characteristic of the basic data packet. In this case, the characteristic of the basic data packet may be a number of characters constituting the basic data packet.

Alternatively, the method includes a single identification for each of the response units and determining each of the response units in a response interval following the basic data packet as a function of the characteristic of the basic data packet and the single identification of that response unit.

Preferably, the remote response units are divided into a plurality of groups, wherein the basic data packet includes a determination of a group of response units that respond to the basic data packet.

The transmission of a response data packet preferably includes the transmission of a null response data packet when a user has not entered a response.

These and other objects, advantages and features of the invention will become apparent from the following description with reference to the drawings.

Fig. 1 is a block diagram of a wireless remote response system according to the invention;

Fig. 2 is a block diagram of a system controller and a remote response unit;

Fig. 3 illustrates a coding scheme according to the invention;

Fig. 4 illustrates a decoding scheme according to the invention;

Fig. 5 illustrates the structure of a basic data packet;

Fig. 6 illustrates the structure of a response data packet;

Fig. 7 is a flowchart of the system controller;

Fig. 8 is a flowchart of a remote response unit;

Fig. 9 is a flow chart of the transfer data function of the system controller;

Fig. 10 is a flow chart of the reception data function of the system controller;

Fig. 11 is a flow chart of the transmission data function of the remote control units;

Fig. 12 is a flow chart of the reception data function of the remote control units;

FIG. 13 is a block diagram of a transceiver useful in the present invention; and FIG

Fig. 14 is a flowchart of a method of efficiently transmitting large blocks of data to the remote response units.

With reference to the drawings and the illustrated embodiments, a remote wireless response system 20 includes an instructor base station or base unit 22 and a plurality of remote response units 24 (FIG. 1). The base 22 includes a system controller 26 having a transmit and receive antenna 28 that forms a wireless communication link with the transmit and receive antennas 30 of each remote response unit 24. The base unit 22 further includes a personal computer 32 with which an instructor may issue commands to the system controller 26 via a wired connection channel, such as a serial channel 34. The personal computer 32 may include operating software that does not form part of the present invention for comparing the responses received from the remote response units 24 with a response key, for counting correct responses of each student and performing statistical analyzes, etc. The base unit 22 may also be connected via telephone lines or the like to a central control area (not shown), which in turn may communicate with a plurality of base units 22. This allows the instructor to be located at a geographical distance from the classroom or test room, and communicates with the room in which each base unit 2 is located at least via his voice and data connection.

Each remote response unit 24 includes an input device such as a keyboard 36 to receive user responses and a display 38 for displaying responses input to the keyboard 36 as well as information transmitted by the base unit 22 in a manner described below. In the illustrated example, the remote response units 24 and the system controller 26 have substantially the same hardware architecture (Figure 2). The system controller 26 includes a first microprocessor or microcomputer that receives serial communication over the channel 34 from the computer 32. The microcomputer 40 exchanges the data signals via a bus 39 which extends to an RF transceiver 42. A power management circuit 44, under the control of the microcomputer 40, activates the transmission circuitry of the RF transceivers 42 over a line 43 only when it is time to transmit a data packet. A keyboard 36 and an LED or LCD display 38 represent the respective input and output functions for the microcomputer.

Similarly, the remote response unit 24 includes a microcomputer 40 'having an input-output connection via a bus 39' to an RF transceiver 42 'which transmits and receives signals via an antenna 30. A power management circuit 44 'activates the transmission circuitry of the RF transceiver 42' over a line 43 'only if transmission is to occur. A keyboard 36 'and a display 38' represent the input / output functions for the microcomputer 40 '. Each unit 24 includes a microphone 46 which is connected to an audio transmitter 47a, which in turn is connected to an audio receiver 47b in the system controller 26 through an audio communication link formed by the antenna 48a, 48b. This allows voice communication from a user of the responder with the instructor. When the instructor is away from the system controller 26, the audio connection uses a telephone line, shown at 49. The audio communication link is open to the system controller 26 and the responder 24 by activating the transmitter 47a and the receiver 47b under the control of the microcomputers 40, 40 'only in response to an instruction of the instructor.

In the illustrated embodiment, the microcomputers 40, 40 'are each an 8-bit microprocessor distributed by Microchip Technology under model number PIC 17C42 and having a 2K byte internal ROM for control program storage, an internal 256 byte read and write memory and 128 bytes of external electrically erasable ROM. In a first preferred embodiment, the RF transceivers 42, 42 'are frequency-modulated, surface acoustic wave resonator devices that can transmit and receive at a mean band frequency of 418 MHz. The receiving circuit includes a bandpass intermediate frequency stage and a phase locked loop detector. Such a transceiver is commercially available from Radiometrix Ltd., United Kingdom, under model number BIM-418-F.

In a second preferred embodiment, the RAF transceiver 42, 42 'operates at a frequency in the 902 to 928 MHz band (Figure 13). The transceiver 42, 42 'includes a receive section consisting of an RF amplifier 200 and a mixer 202 which is provided with a 904.3 MHz signal from a local oscillator 210 to provide an average frequency signal (IF) of 10.7 MHz , The IF signal is amplified by the IF amplifier 204 and applied to a detector and data splitter 206 which produces data signals compatible with a microprocessor 208. The microprocessor 208 is connected by data lines "39, 39 'to the respective microcomputer 40, 40'. The transceiver 42, 42 'also includes a transmission section that includes a local oscillator 210 modulated by a data output of the microprocessor 208 and a current amplifier 212 whose output is connected to the antenna 28, 30. The local oscillator 201 is stabilized by a phase-locked loop frequency synthesizer 214 which contains a reference signal of 6.3 MHz from a frequency reference 216. The current amplifier 212 is turned on and off by a solid state power switch 220 which is actuated by a solid state switch 218 under the control of the power management circuits 44, 44 'through lines 43, 43'. All circuit components that make up the transceiver 42, 42 'are available from numerous commercial sources.

The keyboard 36, 36 'of the illustrated embodiment is a commercially available 10-finger membrane switch panel marketed by Spektra Symbol Company of Salt Lake City, Utah. It should be understood that the input device 36 is not limited to a keyboard, but may also be a voice recognizer, a digitizer pad, an alphanumeric keyboard, or other devices capable of receiving input from a user. In the illustrated embodiment, the display 38, 38 'is a commercially available 24-character 2-line display. Such a display is marketed by Optrex Company of Japan under model number DMC 24227. The FM communication link between the base unit 22 and the remote response units 24 is a half-duplex channel in which a basic data packet 50 is transmitted from the system controller 26 to all remote response units 24, and the response data packets 52 are sent from each keypad 24 one at a time within the time slot System controller 26 assigned to each remote response unit is transmitted. As will be more apparent from the following discussion, the basic data packet and the response data packet 52 have the same basic structure.

The basic data packet 50 and the response data packet 52 each contain a preamble 54, 54 ', which consists of nine bytes of 55 hex, which identifies the transmission as a data packet (Figures 5 and 6). The content of the preamble is sufficiently determined to preclude false detection of various EMI sources. The preamble 54, 54 'is followed by a sync byte 56, 56', which provides a time stamp to allow the receiving units to be coordinated in their response intervals. The remainder of each data packet 50, 52 consists of a HEADER 58, 58 ', a MESSAGE 60, 60' and a CHECKSUM 62, 62 '. HEADER 58 may include a one-byte response character field 59 that identifies which of 5 groups of remote response units 24 should transmit a response data packet in response to that basic data packet. For large groups of response units, for example 250 units, it is convenient to subdivide the units into groups of, for example, 50 units. This gives the system flexibility in using different numbers of response units by eliminating the response intervals for phantom response units. The response character field 58 'contains a null character to identify the data packet as a response data packet 52.

HEADER or packet header 58 may additionally include a response length byte 72 informing the remote response units of the number of characters to include the MESSAGE field 60 '. This allows the transmission of responses longer than a single character under the control of the base unit. HEADER 58 may additionally include a base packet length field to instruct the remote response units about the number of characters in the base data packet 50. This allows the transmission of messages of various lengths globally to all the response units in a global MESSAGE field 76. MESSAGE field 60 contains a group of characters 64, 66, 68 and 70 that pertain individually to the particular response units. The data in the MESSAGE field is structured such that each remote response unit is able to identify which character or characters belong to that entity. However, the entire contents of MESSAGE 60 are received by all remote responses and loaded into their memory. Each individual remote response unit examines the character storage or storage locations associated with the particular unit and responds to the value of the character at the particular storage location.

The MESSAGE field 60 contains a data structure of the acknowledgment byte array 64 which indicates to each remote response unit to which each byte belongs whether the previous data response packet transmitted by that entity is validly received at the system controller 26. A field of correct / incorrect flag bits or flag bits is identified each remote response unit whether the response entered in the previous response data packet by the user was correct or incorrect. The value of the correct / incorrect flag bit is set by the computer 32 by comparing the received responses with a correct response key. The MESSAGE field 60 also includes Mike control bits 68. Each Mike control bit 68 may be set by the instructor 62 via the computer 32 in response to a user requesting audio communication with the instructor by entering a defined answer into the keyboard 36 , Each Mike control bit 68 is associated with a particular remote response unit in a group of remote response units and, if set, is processed by the microcomputer 40 '. In response to a Mike control bit, the microcomputer 40 'actuates the audio transmitter 47 for that particular remote response unit for one-way audio communication from the remote unit user with the instructor via the audio receiver 47b in the system controller 26 and a transmitter to the host location over a telephone line 49 to allow.

The MESSAGE field 60 also contains a group identity byte 70, which can take a value between 1 and 5. The group identity byte determines which of the groups of remote response units 24 is affected by the MESSAGE field 60. The values ​​of the group identity byte 70 and the MESSAGE field 60 may advantageously be set to a group other than the response byte 59 in the HEADER 58. For example, the base data packet 50 may set the MESSAGE group identity byte 70 on the first group (Group 1) and the response byte 58 on a subsequent group (Group 2), thereby confirming the group previously answered by transmitting a response data packet during a subsequent transmission can to turn off the transceiver for the remote response unit that has previously transmitted a response data packet that has been validly received by the base unit.

The MESSAGE field 60 may additionally include a global MESSAGE field 76 containing characters globally pertaining to all remote response units 24 or a group thereof. One application of the global MESSAGE field 76 is to download the opcode for each microcomputer 40 '. This avoids the need for hardware modifications to upgrade the operation software of each remote response unit 24. Another application for the global MESSAGE field is the conjunction with the correct / incorrect flag bits 66. Two or more messages may be included in the global MESSAGE field 76, with the microcomputers 40 'being programmed to use one of the To read messages on the display 38 when the correct / incorrect flag bit 66 has a predetermined value, and to read another message if the flag bit has a different value. In this way, the student can be informed in more detail about incorrect answers. In the illustrated embodiment, the global MESSAGE field 76 has a capacity of 200 characters. Longer code strings may be downloaded at each microcomputer 40 through a series of transmissions.

CHECKSUM 62, 62 'provides an error detection byte at the end of each basic data packet or response data packet. This byte is set to the value of the least significant byte of the sum of all bytes in the respective data packet to ensure that valid reception of the packet is effected, as known to those skilled in the art.

The response data packet 52 contains the response message or keystrokes in the message field 60 '. In one embodiment, the response of the message field 60 'is a single character that produces a single keystroke entered with the keyboard 36. Alternatively, the response in the message field 60 'may have a multi-character length, with the number of characters fixed or determined by the response length byte 72. This allows the system controller 26 to control the length of the response from the response data packet 52. The microcomputer 40 'of each remote response unit 24 responds to the value set in the response length byte 72 by assembling the response data packet 52 with the desired number of characters indicated by the response length byte 72. In this way, responses consisting of multi-character words can be collected by the remote response system 20.

In a further alternative embodiment, the microcomputer 40 configures the response data packet 52 including a null input in the message field 60 'if the user has not entered a response with the keyboard 36. When such a null response data packet is used, each response unit 24 transmits a response data packet in response to each basic data packet transmitted from the base unit, regardless of whether a user has input a response or not. In this way, a base unit may perform an examination of each remote unit to determine if the remote unit is within a non-interfering communication area of ​​the base unit.

Each remote response unit 24 is assigned a unique identification number or address. Each remote response unit can also be assigned to one of the several groups, which in the illustrated example are designated as groups 1 to 5. The identification number or group number is included in a response unit memory. When receiving and decoding a basic data packet 50, each remote response unit determines by calculation the sync byte or the time interval following Synchronization byte 56, if you want to respond. This calculation is based on the position occupying the identification number for this remote response unit in its group, as well as the value of the base data packet length byte 74 and the response length byte 72. If no base data packet length byte or response length byte is used, a default value is used.

As mentioned above, the base data packet 50 and the response data packet 52 are assembled at the respective system controller 26 and the remote response unit 24 and frequency modulated at the RF transceiver 42, 42 '. The received FM transmission is received, frequency reduced and detected by the RF transceiver 42, 42 'of the receiving unit. The detected signal has an analog waveform with peaks and valleys that substantially coincide with the transmitted data packet. The analog signal generated by the detector is further processed by a data slicer (not shown) which produces a waveform having better defined rising and falling points and an amplitude sufficient for processing by the microprocessor 40, 40 '. suitable is. The microprocessor 40, 40 'performs the final step in the decoding process by responding to the rising edges of the data stream from the RF transceiver 42, 42' to the 0-value bits and the 1-value bits in a manner identify, which will now be described.

Each bit of the basic data packet and the response data packet is encoded and decoded as follows. A 0-bit 80 consists of a whole cycle of a square wave measured from a rising edge 82 to the subsequent rising edge 82 (Figure 3). Alternatively, the waveform cycle could be measured from the falling edge 84 to the next falling edge (not shown). The advantage of this coding technique is that the interval between rising edges or, alternatively, between falling edges of a transmitted data pulse is exceptionally constant, while the interval between a rising edge 82 and a trailing falling edge 84 is quite inconsistent and subject to environmental effects such as signal strength and temperature , The length L & sub0; the 0-bit is encoded at a predetermined time interval by the microprocessor 40, 40 ', which toggles an output of a particular repetition rate to produce the 0-bits. A 1-bit 86 is defined from its leading edge 88 to the leading edge 88 of the subsequent waveform. The waveform cycle has a time interval L & sub1; which is much smaller than the interval L & sub0; for the 0-bit 80. This is accomplished by generating the 1-bit by the microprocessor 40, 40 ', which toggles its outputs at its predetermined frequency, which is higher than that used to generate the 0-bit 80. It is understood that the above description is arbitrary whether the 0-bit or the 1-bit is encoded with a longer waveform, the 1-bit having a length L & sub0; and a 0 bit having a length L & sub1; can be encoded. It is also within the scope of the invention that one bit could be encoded for multiple complete waveforms of the square wave. The duration of an interval L & sub0 ;, L & sub1; however, starts and ends at the leading edges or, alternatively, the trailing edges of each waveform. In the illustrated example, L & sub0; 185 microseconds and L & sub1; is 90 microseconds.

Since the data is encoded using a variable time interval, the encoded packet varies in duration as a function of the value of the respective bits 81 forming the packet (Figure 3). In order to avoid having to provide a sufficiently large worst-case window, the data 81 is checked prior to encoding to determine if the majority of the bits, in this case 0, correspond to the largest length would be coded. In the illustration of Fig. 3, the required duration for transmission of the data 81 would be excessively long if the 0-bit with the largest length were encoded. As a result, the data 81 is converted to 81 ', thereby mainly consisting of 1-bits coded with a shorter time length. In this way, the length interval required to transmit the data 81 is never longer than would be required to transmit a data word consisting of 50% of its bits encoded according to the longest duration.

A bit decoding technique 90 is shown in FIG. The microcomputer 40, 40 'includes an internal counter that counts the intervals between the rising edges of the bit-sliced ​​data stream D coming from the RF transceiver 42, 42'. The length of the interval defined by the microcomputer count is then compared to two separate, non-overlapping areas. A number must fall within one of the ranges to be decoded as a valid bit. A bit number 92 is below the limit of one of the intervals, and a bit number of 94 is larger than the limit of the same area. Thus, numbers 92 and 94 would be considered invalid if they did not fall in the other non-overlapping area, in which case the number would be decoded as the opposite bit. A number 96 falling in one of the areas is decoded as a bit defined by this area. Since a bit number must be larger than the minimum of a range and smaller than the maximum of a range to be decoded as a valid bit and the ranges do not overlap, the possibility of erroneous decoding of one bit is very small. Any bit that is mistakenly decoded would probably be eliminated by the CHECKSUM calculation performed on the CHECKSUM byte 62. If the receiving module can not decode any of the bits or if the CHECKSUM calculation is invalid, the entire received data packet is discarded and the receiving unit will not act on that data packet. However, the nature of the remote response system 20 is such that, after leaving out of transmission, the receiving unit is fully capable of responding to a subsequent data packet. Should a remote response unit be. If the base unit is positioned in such a way that communication between the two units is repeatedly unsuccessful, the remote response unit must be repositioned relative to the base unit to be useful. According to the present invention, since the remote response unit may be programmed to transmit a response data packet with a 0MESSAGE 60 'when a user has not entered a response, the base unit may inform the instructor that the particular remote response unit is out of order or otherwise inactive.

The system controller 26 includes a control program 100 (FIG. 7). The control program 100 is initialized at 102 by powering up the controller 26. A routine 104 checks whether the personal computer 32 has formulated tasks at 106 and responds to each formulated task. The program 100 transmits 108 a basic data packet 150 to all remote response units 24. The program then forms a time delay 110 of the final duration so that the remote response units 24 can form their responses. At the beginning of an interval 1 at 112, the system controller 26 receives a response data packet from the first keyboard designated for response, decodes the response data packet, and passes the decoded data to the base personal computer 32 at 114. The program then proceeds to the next interval at 116 and receives, decodes and forwards the response data packet from the next keyboard at 118 to the personal computer 32. After all intervals have been checked, control returns to the routine 104 to determine if a new task is being requested by the computer 32. The software in the instructor's computer 32 may formulate a task for the system controller 26 to repeatedly transmit basic data packets until valid answers are received from all remote response units, or for a certain number of cycles or a particular length of time. Thereby, the routine defined by the steps 108 to 118 can be repeatedly executed among the instructions.

A control program 120 is repeatedly executed at each remote response unit (FIG. 8). The program is initialized at 122 by booting the unit and waits at 124 to receive a basic data packet from the system controller 26. When the basic data packet is received, the remote response unit checks the characters in the HEADER field 58 to determine if that particular remote response unit is in the group designated by the group designator 59 to respond at 126. The particular remote response unit also checks the MESSAGE Field 60 and checks from the group identity byte 70 whether the content of the MESSAGE field concerns the group of which this particular response unit is a member. Each response unit within the group determined by the group identity byte 70 examines the acknowledgment bit field 64, the correct / incorrect FLAG bit 66, and the Mike control bit 68 associated with the particular unit within the group, and responds to the values ​​for those particular bits are set. If the acknowledgment bit field 64 is set for that particular unit, the system controller 26 has legitimately received the previous response data packet sent by the particular responder. If the correct / incorrect flag bit 66 is set to correct, the microprocessor 40 'may light a "correct indicator" or "incorrect indicator" (not shown) or provide a particular indication on the display 38. In a preferred embodiment, a correct indication may be made by lighting only the uppermost horizontal segment of a seven-segment display of the display 38, and the incorrect display could illuminate the lowermost horizontal segment of the display 38, or vice versa. Alternatively, the microcomputer 40 'may respond to a value of the correct / incorrect flag bit by displaying a portion of a global MESSAGE field 76 associated with the correct answer, or other portion of the global MESSAGE field 76 associated with a incorrect answer. If the mike control bit 68 is set for the particular remote response unit, the microcomputer 40 'responds by operating the audio transmitter 47a to enable one way audio communication between the user's microphone 46' and the instructor. The remote response unit 24 also responds to the response length byte 72 and the basic data packet length byte 74 to set the appropriate interval timing, as described above. If the installation task 126 is complete, an interval timer runs at 128 and the controller waits at 130 for the appropriate interval for that particular response unit to transmit. A response data packet is transmitted at 132 during the appropriate interval.

The routine for this system controller 26 for setting and transmitting a basic data packet 108 is also shown in FIG. The control program 100 initiates a transfer by the system controller 26 by taking over each task required by the personal computer 32 at 104. The transmission part of the RF transceiver 42 is actuated at 134. The preamble 54 is transmitted at 136 to all remote response units 24 to stabilize the data transmitted from the RF transceiver 42, RF transceiver 42 'and each remote response unit. The data can be stabilized because the sensing portion of the RF Trunk Receiver has a finite stabilizing time interval. The sync byte 56, HEADER packet 58, MESSAGE packet 58, and CHECKSUM 62 are transmitted at 138. The transmission is then turned off at 140 and an interval timer is started at 142. The interval timer matches the response data packets from the remote response units 24 with each particular response unit, decodes the packets, and makes the information available to the personal computer 32.

The system controller 26 receives keyboard data under control of the program 100 by repeatedly transmitting the base packet and monitoring subsequent intervals for the response data packets from the response units (108, 110, 112, 116) (Figure 10). The receiving response data packets are decoded and the data is passed to the computer 32 (114, 118). After the entire group of remote response units has transmitted 24 response data packets, the system control device 26 compiles the confirmation bit field 64 at 144 with a validity test made of each received response data packet.

To transmit the response data packets, each remote response unit 24 includes a basic data packet from the system controller, at 124, via the RF link between the antenna 28 and the antenna 30 (Figure 11). The microcomputer 40 'decodes the received data and determines at 126 whether that remote response unit is in the group designated by the response byte 59 to transmit a reply and in the group designated by the group identity byte 70 as belonging to the MESSAGE Field 60 is identified. If so, the characters in MESSAGE 60 associated with the particular remote response unit are extracted at 126. If the remote response unit is in the group designated by response byte 59 to transmit a response, microcomputer 40 'starts an interval timer and waits for the interval determined at 126 associated with the particular response unit for response. When the interval arrives, the microcomputer 40 'turns on the RF transceiver 42' at 148 to stabilize its transmission part and transmits the preamble 54 'to stabilize the data in the transceiver 42 of the system controller 26 at 150. The remote response unit 24 then transmits the sync byte 56 ', HEADER 58', MESSAGE character 60 'and CHECKSUM 62' to the system controller.

Each remote response unit 24 receives the data packet from the system controller via the RF link at 126 (FIG. 12). If all bits are decoded without rejection, CHECKSUM is verified for the entire base data packet at 164 to accept or reject the transmission. The timer acknowledgment and mode information is taken at 126 when the responder is in the group designated by the group identity byte 70. It is then determined at 166 whether the confirmation bit associated with the particular remote response unit in the confirmation bit field 64 is set. If so, the transceiver 42 'for this keyboard is turned off at 168. If it is determined at 166 that the confirmation bit for the particular remote response unit is not set and the remote response unit is in the group designated by response byte 59 to transmit a response, microcomputer 40 'starts the interval timer at 128 and waits for it calculated transmission interval at 130. The remote response unit 24 transmits the response data packet at 132. If the remote response unit is not in the group designated by response byte 59 to transmit a response, microcomputer 44 'awaits its response byte 59 and then transmits a response data packet.

A method 170 for transmitting a large block of data to all remote response units in a time-effective manner is illustrated in FIG. The method 170 is initiated by the personal computer connected to the system controller 26 and dividing the large block of data to be transmitted in a multiple packet data stream at 172. The multiple packet data stream is routed to the system controller 26 at 174 and transmitted in its entirety to all remote units at 176. Each remote response unit 24 decodes the multiple packet data stream and determines if each packet was received exactly. A bit map is formed in each remote response unit 24 of the bits indicating which packets were received exactly. The system controller 26 at 178 transmits a central data packet 50 to all remote response units 24 that is formatted according to the request of the bitmap reports from all remote response units. A bitmap master is formulated at 180 in the system controller 26 from the response data packets 52 encoded with the bitmaps of the various remote response units. The system controller examines the master bitmap at 182 and sends all packets corresponding to the packets that were not exactly received even by a remote response unit, as reflected in the master bitmap. The bitmaps of the individual remote response units are collected at 184 to reflect the additional exactly received data packets in the same manner as before. The master bitmap is updated at 186 and it is determined at 188 whether the number of repetitions set to obtain a 100% accurate packet data transmission is reached, if not, another cycle 182, 184, 186 repeating the sending of missing packets, the bitmaps are updated at each remote response unit, and the master bitmap is updated. When a 100% accurate transmission is achieved or the retry limit at 188 is reached, a message is sent to the base personal computer at 190. The instructor may require that additional retries be attempted, or he may issue verbal instructions to the users if one or more remote response units have not fully received the multiple packet data to move to another location to retry the process.

The advantage of method 170 is that the amount of time required to energize transceivers 42 'of all remote response units 24 after all data packets are transmitted is avoided. This time interval can be significant as it is multiplied by each keyboard. By subdividing the very extensive transmission of the data into multiple data packets, only the data packets that were not received exactly by all the units are repeated. This avoids the need to repeat all very large data transfers when one or more remote response units have not received the entire transmission exactly.

Thus, the present invention provides a wireless remote response system that has excellent noise immunity and a tolerance for variations in the timing of the transmitted signals while ensuring virtually error-free operation. The system has excellent flexibility that enables the transmission of message data from the base unit to the remote response units in the same basic data packet that synchronizes the transmission of the response data packets from the remote response units. Different groups of response units, which are divided into groups to accommodate a large number of response units on a single RF connection, may advantageously be determined by a basic data packet:

(a) transmitting a response data packet and

(b) processing the message data.

The message data receives the acknowledge bits for validly received responses to cause the acknowledged response units to stop the transmission. Correctness signs and characters for inserting a microphone can additionally be transmitted in the message data and processed by the remote response units. In addition, the invention enables the download of a large array of characters globally to all remote response units in an efficient manner. This allows z. For example, the user can view large feedback messages in response to a correct or incorrect response, as well as downloading the opcode for each remote response device and downloading the code for other purposes. In addition, the ability of the base unit to instruct the remote response units over the length of the intended responses of each of the remote response units and the ability of the remote response units to respond to such a determination by structuring an appropriate response data packet enables gathering responses that are more complex than one single character.

Changes and modifications of the described embodiments are within the scope of the principles of the invention, which is only limited by the scope of the appended claims.