System and method for routing data messages through a cable transmission system

ES 2 176 740 T3

DESCRIPTION

System and procedure for routing data messages through a cable transmission system.

Scope of the invention

The present invention deals with data communication and, more specifically, with data communication over cable television networks (CATV).

Background of the invention

Cable television systems are well known. Normally, these systems are composed of a header with one or more trunk lines that extend from there, each of the trunk lines having a plurality of power lines that extend from there to a subscriber area, which is located connected each subscriber through a branch line in the power or service line. If the distances between the headend and the subscriber areas are considerable, distribution nodes may be placed to intervene to replenish the strength and quality of the signal that is being provided to the subscribers. Distribution nodes act simply as small headends and exist to guarantee the quality of the distributed signal in large CATV networks. Each distribution node may, however, be coupled to a plurality of service sites through power lines. Each service site may have one or more service lines extending from there to couple a plurality of subscribers to the service site. In this network, a transmission signal is provided through the trunk lines to the distribution nodes or the service nodes. This amplified signal is then provided to power lines extending from the distribution node or the service node to provide the signal to the service sites. If the distance between a distribution node and the service site is so great that it impairs the strength of the signal to an unusable level, another distribution node may come in between the service site and the first distribution node to re-amplify the force. Of the signal. Amplification takes place along the trunk, power and service lines to the degree necessary to maintain the transmission signal at a suitable level before it is provided to the subscriber equipment. Taps located at each subscriber site bring the transmission signal to the subscriber site.

The transmission signal from the headend may include entertainment signals and data signals. Entertainment signals may be received as broadcast signals received via satellite from a broadcast signal creation location. At the headend, each broadcasting signal is placed on its own channel within the spectrum of the trunk, power and service lines used in the CATV system. The spectrum of the lines that are coupled together to the CATV system is the frequency range admitted by the communication conduits used by the lines. In a typical CATV system, this spectrum is divided into a transmission section and a return section. The return section of the spectrum could be used to admit data transmissions, telemetry and / or control information that returns from the subscriber sites to the headend. Data transmissions from subscribers typically include status information relating to subscriber equipment, which could be used by headend components to determine the status of the cable system or subscriber equipment. The splitting procedures for the most common spectrum types are called subdivision, middle splitting, and high splitting. The subdivision refers to a lower section of the spectrum that is smaller than the transmit spectrum available for the return spectrum. The middle division refers to the fact that one half of the spectrum is located in the transmission section and the other half in the return section. The high divide refers to an upper section of the spectrum smaller than the return spectrum, which is used for the transmit spectrum.

At the headend, each broadcasting signal is assigned to a channel of the transmission spectrum. In a subdivision system, the first channel of the transmission spectrum begins, for example, at 55 MHz. The width of the channel varies according to the standard used in the system. In the United States, most CATV systems use the National Television Systems Commission (NTSC) standard that assigns 6 MHz to each channel. In Europe, the standard Phase Alteration Line (PAL) is used, which assigns 8 MHz to each channel. The frequency of a broadcast signal could be increased or decreased to place the broadcast signal in one of the channels of the transmitting section of the transmitting signal spectrum provided by the headend. The data signals in the headend could also be placed in a channel of the transmitting signal for distribution through the network. By convention, display devices, such as televisions or the like at subscriber sites, use broadcast signals to create audio and video, while data devices, such as cable modems or other smart devices, convert the broadcast signals. data signals for the use of computers or the like.

The trunk, power and service lines of many CATV systems are coaxial cables. Because the signals carried by coaxial cables are electrical, these systems are susceptible to electrical and electromagnetic noise from natural phenomena or other electrical or electromagnetic sources. In an effort to improve the clarity of signals carried by a CATV system, the coaxial cables used for trunk and feeder lines are being replaced by fiber-optic cables. Since fiber optic cable carries light signals, the signals are less susceptible to electrical or electromagnetic noise from other sources. In addition, optical fiber cables carry signals over longer distances without a loss of signal strength compared to coaxial cable. Without em2

However, the cost of replacing coaxial cable with fiber optic cable has prevented many companies from converting their service lines to fiber optic cable. CATV systems that have both fiber optic power and trunk lines alongside coaxial service lines are conventionally called Hybrid Fiber Cable (HFC) systems. In HFC systems, the service sites where the light signal from a fiber optic cable is converted into an electrical signal for a coaxial service line are called fiber nodes.

The known CATV systems have limitations to support data communication in the return spectrum of a system. In a typical subdivision CATV system, the return spectrum is in the range of approximately 5 to 42MHz. This leaves, at best, approximately six (6) channels for data communication back to the headend using the NTSC standard and approximately four (4) using the PAL standard. However, not all of these channels are equally desirable for data communication. Some of the channels in this range are more susceptible to noise degradation than other channels. As a result, there are very few good channels for data communication in a subdivision system, which is probably the type of system most commonly used in the United States. Also, standards are under development, which could define channel widths for the forward and return spectrum different from those of the already established NTSC and PAL standards.

Even if all channels in the subdivision interval were available for data communication use, other limitations would arise as the number of subscribers in the system increased. Assigning subscribers coupled to a service line to available channels in a return spectrum could place a reasonable number of subscribers on each channel. However, at the service site or fiber node, all service lines are typically merged so that all subscribers coupled to the service site or fiber node are assigned to the same available channels in the return spectrum. cable connecting the service site to the distribution node. At the distribution node, the data messages from each service site or fiber node coupled to the distribution node are merged into the same spectrum from a trunk or power line. This fusion of data messages from the lower levels of the network in the return spectrum of a single cable continued to the headend. In an effort to avoid consuming all the capacity of the channel that is being shared by a group of subscribers, a time frequency or multiplexer scheme could be used. While this procedure assigns a fraction of time or frequency band to a subscriber's channel, the time or spectrum available for messages decreases as the number of subscribers decreases. For example, if a fiber node has four lines extending from there and each line has 125 clients, the 500 clients attached to a fiber node or service site are placed on six channels or less. At the distribution node coupled to the fiber node, there could be, for example, three other fiber nodes coupled as well. As a result, 2000 subscribers are now fighting for space for data messages on the same six channels. In a large metropolitan area where the number of subscribers could be 200,000 or more, there would be about 30,000 subscribers or more per channel. As a result, message traffic within a channel could become congested and the overall performance of the message system degraded. In the same way, the response time of messages increases significantly when each subscriber has to compete for space in a channel with a large number of other subscribers within the return spectrum of the system.

A way would be needed to allocate the available return spectrum in a CATV system to subscribers across the network without the need for all subscribers to compete for the same channels within the return spectrum of a cable. WO-A-9217010 describes a method for automated frequency selection in a bidirectional cable television system. The system has a tree-shaped structure formed by a header, a plurality of dividers, which form the branch nodes of the tree, and a plurality of CATV terminals, which form the leaves of the tree. The return messages are transmitted from the CATV terminals to the headend. These return messages include basic billing messages and other messages used to transfer data to a central location.

Summary of the invention

The above limitations of the known CATV systems are overcome by a system and a procedure carried out in accordance with the principles of the present invention. The system of the present invention includes a headend for creating transmission signals having broadcast and data signals, a plurality of service sites, each service site being coupled to the headend by a transmission cable and a return cable, providing the transmission cable to each of the service sites the transmission signal to the service site, extending a plurality of service lines from each of the service sites to couple a plurality of subscribers to the service sites and provide the transmission signal to the subscribers and a parallel spectrum router (SPR) in each of the service lines, each SPR being coupled to one of the service lines extending from the service site; the SPR receives data messages from subscribers in the return spectrum of the service lines; The SPR routes data messages from one service line to another service line coupled to the SPR, which corresponds to a destination address of the received messages, and places the received data messages on the return wire for transmission. to the header in response to the destination address in a data message that does not correspond to one of the service lines

ES 2 176 740 T3 coupled to the SPR, so that data messages from one service site are isolated from data messages from other service sites via the return wire.

The system of the invention could also include a plurality of distribution nodes that are coupled between the headend and the service site. More than one service site could be attached to each distribution node; however, each service site has its own transmission line and return line to couple the service site to the distribution node. At the distribution node, one SPR is provided for each return line and each SPR is coupled to the transmission line for each fiber node. In response to a data message that has a destination address that corresponds to one of the service sites attached to a distribution node, an SPR sends the data message to the SPR of the distribution node that is attached to that distribution site. service. In the case of data messages that have a destination address that does not correspond to a service site coupled to a distribution node, the SPR sends the data message to the return wire coupled to the headend SPR or to the next largest distribution node. The return cable for each of the routers within a distribution node is coupled to the corresponding router at the headend or the next larger distribution node. The data messages that an SPR receives from another SPR at the distribution node are provided to a transmission cable coupled to the next lower level of the network. In this way, data messages from one service site are kept isolated from data messages from other service sites until a data message is coupled to a transmission cable at a lower network layer in either a distribution node or in the header.

This scheme for isolating data messages from a service site as they are routed upward through the network to the headend or distribution node, where a message could be attached to a single-level transmission cable. Lower, applies to systems where the transmission and return lines are coaxial cable or fiber optic cable conductors. Preferably, the SPRs at the service sites also include a frequency stacker, so that data messages from each service line could be provided over a separate channel of the return cable. For example, if three service lines are coupled to a service site, the frequency stacker could place all data messages from a first service line on a first channel of the return cable, data messages from the second service line on a second data channel and data messages from the third service line on a third data channel. The corresponding frequency destacker at the next higher level of the network places the data messages on separate data channels of a common return spectrum for the SPR to convert and process at that level. By separating data messages from each service line into a single return wire, isolation of data messages for one service line is possible.

Most preferably, the SPRs of the present invention include a switch for routing the data messages based on a destination address of the data messages. Each switch is an intelligent device that has programmed logic that could be stored in memory or stable wiring. To route a message, the switch compares the destination address of a data message with the addresses stored in a switch address table. If the destination address corresponds to an address in the table, the switch routes the data messages to the corresponding peer at the destination address. If the address is not found in the table, the SPR receives a data message from a switch on the same network level and forwards the data message on a transmission line coupled to the next lower network level. Preferably, the SPR compares a source address in data messages sent by the peer switches with a table of channel addresses. The data message is then sent to the input of a frequency stacker corresponding to the switch that corresponds to the data channel of the source address. In this way, the separation and isolation of the data messages in the transmission cables of the network could also be achieved.

In the headend (or even in the distribution node), destination addresses that do not correspond to an address in the address table of a switch preferably correspond to destination addresses of other networks. Preferably, the headend or distribution node of the present invention is provided with a gateway device that couples to the other networks and routes data messages to other networks, including the Internet. The headend further preferably includes an advertisement server which could be used to superimpose sections of the broadcast and data signals on the transmission signal before it is delivered to the network.

The present invention could be used in CATV systems where the transmission cables, return cables and service lines are all either optical fiber cables or coaxial cables. In HFC systems, the invention is preferably practiced with an SPR having a sender / receiver group for each coaxial service line at a service site and a fiber optic transmitter and a coaxial fiber optic receiver to couple the SPR. from the service site to the return cable and the transmission cable to the next higher level, although other implementations were within the scope of the invention. If the service lines are also fiber optic cables, an SPR could be used at a subscriber site to route broadcast signals for the display devices and data signals for the data devices. Each switch of an SPR at the subscriber's site could return data messages over one cable.

ES 2 176 740 T3 return, a conductor of fiber optic cable not used by other subscriber sites coupled to the service line. In this way, subscriber data messages could be isolated from each other. Also, a subscriber site SPR could include a frequency stacker that places data messages from different data devices at the subscriber site on data channels of a return cable.

These and other objects and advantages of the present invention may be better understood by reviewing the detailed specification below in conjunction with the drawings. Brief description of the drawings

Fig. 1 is a block diagram of a CATV system using the invented routing procedure of the present invention;

Fig. 2A is a block diagram of an alternative embodiment of the spectrum parallel router used at the service site shown in Fig. 1;

FIG. 2B is a block diagram of an alternative embodiment of the parallel spectrum router when implemented in a distribution head or headend of the system shown by FIG. 1;

Fig. 3 is a block diagram of a preferred embodiment of the spectrum parallel router used at the service site shown by Fig. 1; Y

FIG. 4 is a block diagram of a preferred embodiment of the parallel spectrum router when implemented in a distribution head or headend of the system shown by FIG. 1.

Detailed description of the invention

A system made in accordance with the principles of the present invention is shown in Fig. 1. That system 10 includes a headend 12, a plurality of distribution nodes 14 and a plurality of service sites 16. Each service site 16 is coupled to one or more service lines 18 to which a plurality of subscribers are coupled through of leads 20. To couple each service site 16 to a corresponding distribution node 14 is a transmission cable 28 and a reception cable 30. These cables and service lines 18 could all be fiber optic cables or coaxial cables. In an HFC system, the transmission cables 28 and the reception cables 30 are fiber optic cables while the service lines 18 are coaxial cables. In this type of system, the service site 16 is generally known as a fiber node. The term "fiber node" is commonly used to describe a component in which signals carried by fiber optic cables from a higher level are converted into electrical signals for coaxial cables. As used herein, the term service site includes a fiber node. Each service site connected to a distribution node has its own transmission and reception cable to couple the service site to the distribution node. Headend 12 is coupled to each distribution node 14 through transmission cables 28 and reception cables 30.

As shown in Fig. 1, the header 12 is the highest level of the CATV system and is called level 1. The distribution nodes 14 are called level 2 and the service sites, level 3. Fig. 1 is merely illustrative of a system that incorporates the principles of the present invention and additional levels of distribution nodes 14 could be provided between the headend 12 and the service sites 16, as is known. Header 12 of Fig. 1 creates a transmission signal having broadcast and data signals stacked in the transmission spectrum of transmission cables 28 and service lines 18, as is known. Preferably, the headend 12 includes a transmit wire / receive wire pair for each service site 18 in the network. An alternative embodiment that supports isolation of data messages across single return wires could be to use just one transmission wire 28 to couple a distribution node to headend 12.

An alternative embodiment of the fiber node is shown in Fig. 2A. Each service line 18 is coupled to a sender-receiver group 40 which in turn is coupled to a router or switch 42. The router or switch, as used in this patent, refers to an intelligent data communication device. The intelligence could be either hard-wired logic or it could be programmed logic that has been stored in stable memory, such as PROM or ROM. Known switches of this type include Layer 3 Ethernet switches, 802.5 token ring switches, or FDDI or ATM switches and routers. The switch 42 is programmed to identify the destination address and the source address within a data message. The techniques for identifying these addresses within a message are well known in the art. Switch 42 also includes an address table that identifies the addresses of all subscribers attached to a service site 18. By comparing a destination address with addresses in a switch's address table, switch 42 determines whether the message It is to be en route to a sender / receiver group 40 within the service site 18. The switch 42 also includes a plurality of outputs, a number of which correspond to the number of service lines coupled to the switch 42 through transmitter / receiver groups 40. These outputs are coupled through bridges 44 and high frequency stackers. 48 to a 50 transmitter. Each sender / receiver group 40 is further coupled to a receiver 52 that receives the transmission signal from cable 28 and provides the transmission signal to the transmission sender / receiver group through service lines 18.

Each emitter / receiver group 40 includes a bridge 58, a translator 60, a low bandwidth receiver 62, a high frequency transmitter or diplexer filter 64, and couplers 68. The components of the emitter / receiver group 40 for

ES 2 176 740 T3 coupling to both fiber optic cables and coaxial cables is well known in the art. Translator 60 has its input coupled to a low frequency receiver 62 through a coupler 68 and its output is coupled through a pair of couplers 68 to a high frequency transmitter / filter 64. This arrangement allows data messages received in the low frequency return spectrum of a subdivision spectrum system to be increased in frequency by one channel within the transmission spectrum of the transmission signal used for the data messages. This signal is then provided to a high frequency transmitter / filter 68 for transmission to a lower service line 18. In this way, the data equipment at a subscriber site could verify that the message has been received at the filter node and calculate the duration and other communication parameters thereafter. Bridge 58 converts digital data received from a switch 42 into analog data on a frequency that corresponds to the data channel of a sender / receiver group in the transmit signal and further converts analog data messages received from a receiver 62 into data. to distribute them to a switch 42. As discussed above, switch 42 maintains address tables that identify destination addresses that are coupled to a service site 16 through each of the sender / receiver groups 40. Using these address tables, switch 42 could identify the destination address of a data message when it corresponds to each of the sender / receiver groups within the service site 16. Should this occur, the switch 42 provides the digital data to the bridge 58 of the corresponding sender / receiver group 40 so that the message could be sent downstream on the service line 18 to the subscriber identified by the destination address of the data message. If the destination address does not correspond to one of the addresses in the address table, the switch 42 provides the data message to the corresponding output in the sender / receiver group 40 that sends the message and the corresponding bridge 44 coupled to that The output provides an analog signal, preferably, to a frequency stacker 48. Alternatively, the stacker 48 could be eliminated and all data signals could be placed on the same channel or frequency of the return spectrum of the receiver cable 30 by a transmitter 50. In yet another alternative embodiment, the transmitter 50 could place data messages coming from each emitter / receiver group 40 on different channels within the spectrum of the receiver cable 30. However, the data messages from each sender / receiver group 40 are preferably placed on their own spectrum within the entire spectrum supported by a receiver cable 30. In this way, the subscriber groups could be placed on different channels within the receiver. spectrum of receiver cable 30 used by emitter / receiver group 40. This operating procedure provides the greatest isolation of data messages as they travel upstream through the network 10.

An alternative embodiment of the distribution node 14 or header 12 that operates in conjunction with the alternative embodiment of the service site 16 is shown in FIG. 2B. At a distribution node 14, a receiver 52 is provided for each next lower level fiber node or distribution node coupled to the distribution node. The receiver 52 provides analog signals from the spectrum, used for data messages on the receiver cable 30. Using the service site embodiment 16 that stacks a spectrum for each of the sender / receiver groups, the node distribution 14 has its corresponding frequency de-stacker 70 that places the return spectrum of each emitter / receiver group 40 in a common interval of the spectrum. This signal is then provided to translator 60 and bridge 58 that correspond to the dropped frequency channel of the sender / receiver group. The frequency of the translator ups the analog signal to a frequency that corresponds to a data message channel of the transmission signal and provides the data message to a transmitter 50. In this way, the data message is returned to the service line 18 that created the data message so that the subscriber's equipment could verify the reception of the message in the distribution node and modify the duration of the communication and other parameters. . Bridge 58 converts the data message to digital format so that distribution node switch 42 could determine if the destination address corresponds to another distribution node or service site from the next lower level coupled to the distribution node. If so, the data message is routed through line 86 to another switch on the distribution node that corresponds to the destination address of the data message. The message was sent through one of the bridges 58, so that it could be placed in the data message channel of the distribution signal that is being sent to the corresponding distribution node or service site. If switch 42 does not identify the destination address as an address belonging to a distribution node or service site coupled to the distribution node, the data message is provided through an output that corresponds to the channel of the sender / receiver group to a bridge 44 that converts the data message into an analog signal that is provided to transmitter 50. The transmitter 50 could include a frequency stacker 48 to stack the spectra of the emitter / receiver groups processed by the switch 42 or, as explained above, all data messages could be included in a single spectrum of the receiver cable 30 that extends up to the next higher level of the network.

The structure of header 12 in the alternative embodiment is identical to that shown in Fig. 2B, except that receiver 52 and transmitter 50 are not provided which extend to the next higher level of the network. Instead, devices that provide broadcast signals and data signals from external sources are provided as a signal.

ES 2 176 740 T3 that is coupled to each transmitter 50 for transmission to the next lower level of the network. Likewise, each switch 42 in the headend 12 is also coupled via a line 86 to the other switches in the headend and to the gateway 74 to couple to other networks, including the Internet. Any destination address that is not recognized by a switch 42 in the headend 12 as belonging to the CATV network 10 is provided to a gateway 74 for distribution to a destination in another corresponding network.

As can be seen in Figures 2A and B and established from the above description, the service site 16, the distribution nodes 14 and the header 12 as they are put into practice according to the alternative embodiment of the present The invention provides isolation for data messages received from each service line at a service site, as a monym, to the point where the data messages are coupled to a transmission signal. When frequency stackers and unstackers are used to stack spectra for data message transmissions from a lower level to a higher level and unstack the spectra at the next higher level, the isolation of the data messages for each level could also be maintained. sender / receiver group. In this embodiment, the equipment at a subscriber site controls the data message channels of the transmission signal and, once it recognizes the destination address as its own address, it retrieves the data messages from the transmission signal. .

Preferably, a parallel spectrum router is used to route data message traffic in system 10. The preferred parallel spectrum router ("SPR") 80, as implemented at a service site 16, is shown in Fig. 3. The SPR 80 includes a router or switch 42 that is coupled to a plurality of sender / receiver groups 40. The signal lines that connect to sender / receiver groups 40 and switch 42 are bi-directional. Also coupled to switch 42 is a receiver 52 and a transmitter 50. In a fiber optic or HFC system, receiver 52 and transmitter 50 are fiber optic receivers and transmitters, respectively. Receiver 52 includes a frequency destacker 70 that provides data signals from one channel within the channel transmission signal on separate outputs. Preferably, each of these data channels corresponds to the return spectrum used for each service line provided by a service site. Preferably, this includes all or a section of the 37 MHz spectrum in the 5-42 MHz range of a subdivision system. The transmission signal received by receiver 52 is provided to a notch filter 54 to provide broadcast signals in the transmission spectrum to coupler 86. Coupler 86 provides the transmit signal to each sender / receiver group 40 in SPR 80. Each data channel is provided to a corresponding bridge 44 which in turn is coupled to a switch 42. Also coupled to a bridge 44 is finds an input from frequency stacker 48 that corresponds to the same data channel for a sender / receiver group 40 within the spectrum of return wire 30 coupled to a transmitter 50. Bridges 44 are controlled through a switch 42 to receive data messages on a data channel from a receiver 52 or to provide data messages on a data channel to their corresponding input on a frequency stacker 48 for the transmitter. fifty. Switch 42 could be any type of smart switching device that uses address information from a data message to route data messages to their corresponding locations. This type of switch could be a Layer 3 Ethernet switch, a token ring switch, an ATM switch, FDDI or the like. Similarly, bridges 58 are intelligent devices that control the data messages they receive from lower devices on the network and examine the source addresses of the messages. The source addresses are appended to a source address table so that bridges 58 can determine whether a data message was created on a lower level network device attached to the bridge. The remaining components of the SPR in Fig. 3 they are well known to those skilled in the art.

For more details, the sender / receiver groups 40 include a bridge 48, a translator 60, a low-bandwidth receiver 62, a high-frequency transmitter 64, and couplers 68. The high-frequency transmitter or diplexer filter 64 receives the signals. broadcasting from a coupler 86 and data messages from a switch 42 and a bridge 58 on the message channel corresponding to a sender / receiver group 40. The resulting transmission signal is provided by a transmitter 64 to a service line 18 for distribution to subscribers attached to the service line. The data messages created by subscribers in the return spectrum of the service line 18 are received by low frequency receivers 62 and provided through a coupler 68 and a bridge 58 to a switch 42. These messages are also provided to a translator 60 which reroutes them through a coupler pair to the high frequency transmitter 64 for transmission to the lower service line.

18. This return transmission of the message serves (1) to allow a destination address that identifies a subscriber on the service line that created the data message to receive the data message and (2) to provide the sending subscriber with a copy of the data message. message so that the sender's equipment can calculate the duration and other communication parameters of the network. The return signal is also provided through coupler 68 to bridge 58. Bridge 58 converts data messages received by receiver 52 in the return spectrum into digital data messages that are provided to switch 42 for routing.

Switch 42 determines whether the destination address of each data message received from a sender / receiver group 40 corresponds

ES 2 176 740 T3 with another sender / receiver group at the service site. If so, switch 42 routes the data message to bridge 58 of the appropriate sender / receiver group for transmission down to the corresponding service line 18. If the data message does not correspond to any of the sender / receiver groups at the service site, switch 42 sends the data message to bridge 44 that corresponds to the data channel of the sender / receiver group that sent the message to the switch 42. Each sender / receiver group 40 has its corresponding data channel, so that data messages from each sender / receiver group can be separated from data messages from other sender / receiver groups. Bridge 44 converts the digital data messages to an analog signal in the return spectrum of service line 18 and provides the analog signal to the corresponding data channel input on frequency stacker 48. The 5-42 MHz bands for some of the data channels of the sender / receiver groups are frequencies boosted to a suitable range of the spectrum available on the receiver cable 30 and provided to the fiber optic transmitter 50 for transmission to a radio node. layout or header.

A preferred SPR for the distribution head or headend is shown in Fig. 4. The transmission cable 28 to the service site 16 is supplied by a transmitter 50 having an associated frequency stacker 48. The signal output by the transmitter 50 directed to the next lower level of the network is a transmission signal that includes the broadcast signals received through the fiber receiver 52 coupled to the headend 12 for the reception of a transmission signal. . As described above, the transmit signal is provided to the notch filter 84 which provides the broadcast signals 86 to the coupler and transmitter 50 of each SPR of the distribution node.

As explained above, the receivers 52 also include a frequency de-stacker 70 that provides the data channels from the transmission signal corresponding to the sender / receiver group of a service site. Each data channel is provided to a bridge 58 that converts the analog signals in the data channels into digital data messages that are provided to a switch 42. The coupler 68 that provides the data channels for each bridge 58 also provides the data channels to a corresponding translator 60 for distribution to its corresponding data channel input in the frequency stacker 48. Once again, it is provided again. a copy of the data message from the distribution node to the subscriber's site for the determination of network parameters and the like.

The switch 42 includes a connection to the switches of the other SPRs that the distribution node contains. If switch 42 does not determine that a data message is for another SPR of the distribution node, the data message is provided through one of the bridges 58 that corresponds to the data channel on which the message was received. The data channel could be selected by comparing a source address with a table of source addresses / data channels. The data channel of the table that corresponds to the source address of the message identifies the bridge 44 that corresponds to the data channel of the sender / receiver group that sent the message. Bridge 58 converts the message to an analog signal and provides the signal to the corresponding input of frequency stacker 48 for transmission to the headend or next higher distribution node. If switch 42 determines that the data message corresponds to a distribution node SPR, switch 42 routes the message across line 86 to the corresponding SPR. In response to the reception of these data messages, the switch 42 of an SPR provides the data message through a bridge 58 towards the input of the frequency stacker 48 of the data channel that corresponds to the sender / receiver group for the transmission. to the destination subscriber. The transmitter 50 then transmits the data message on the data channel to the service site or distribution node coupled to the transmitter.

At the headend, one SPR with a receiver 52 and a transmitter 50 is provided to each SPR located in a distribution node coupled to the headend. The head-end SPRs are coupled in the manner explained above with respect to the distribution node SPRs. Also, the headend 12 could be coupled via line 86 to a gateway 200 that couples the headend 12 to other networks, including the Internet. In this embodiment, a switch in a headend SPR could determine whether a data message does not correspond to any destination address for a subscriber within a network. In that case, switch 42 provides the data message to a gateway 200 which in turn summarizes the data message into a suitable message protocol for routing through another network. Similarly, the gateway 200 could receive data messages from another network and recognize the destination address as belonging to a subscriber of network 10. This data message is directed to the SPR of the headend that determines the destination address coupled. to the SPR. The message is then directed through the network of the distribution node / service site to the corresponding subscriber. An advertisement insert server 90 is preferably provided at the header 10 to insert advertisements and other information, which could be provided from remote sources, into the broadcast signals. Therefore, the SPR of the present invention allows content to be superimposed within the broadcast signals created at the headend before they are delivered over the network.

Preferably, the SPRs of the present invention are used in an HFC network. Most preferably, the SPRs of this network at the fiber node are coupled to subscribers through coaxial service lines and coupled to the next higher level of the network through fiber optic cables. Each of the higher levels of the network is also coupled to one another through networks of

ES 2 176 740 T3 optical fiber. In this way, the reliability and clarity obtained through fiber optic cables could be used without the capital cost of replacing coaxial service lines. In such a system, the transmitters and emitters / receivers at each end of a transmitting and receiving cable are fiber optic transmitters and receivers. Because a transmitter and a router of an SPR coupled to a fiber optic cable could each use a single conductor of the cable, the present invention could be implemented in the system without the need for additional cables. The present invention could also be implemented in a system in which all the transmission and reception cables are coaxial cables as well as the service lines. In this type of system, the receiving cable of each of the SPRs has to be a separate coaxial cable and the transmission cable of each SPR in the preferred embodiment of the invention has to also be a coaxial cable. Although expensive to provide the additional coaxial cables, this type of system provides even isolated data channels for return spectrum communications, which improves the data message traffic problems of present systems.

Another extension of the present invention is to use fiber optic cables for service lines.

18. In this type of system, SPRs could also be included at each subscriber site. The switch address tables at the subscriber's site SPR could be used to direct data messages to cable modems or other data processing equipment in the home, while broadcast signals are directed to display devices, televisions or similar. Therefore, the SPR of the present invention could be used in systems with all coaxial cables, in systems with all fiber-optic cables, or in hybrid systems of coaxial and fiber-optic cables. The present invention could also be used in mid-split and high-split systems to isolate data messages up to the headend, down to service sites, or in both directions.

To build a system in accordance with the principles of the present invention, the existing distribution nodes and service sites of a CATV system are provided with SPR to route data traffic through the network. Specifically, in all fiber nodes, each service line is coupled to an SPR installed at the service sites. From there, the SPR collects the data messages from the subscribers on the service lines and either places them en route to the service line coupled to the service sites that correspond to the destination address or transmits the messages from data that is not directed to a subscriber attached to the service sites at the next higher level of the network. Data messages are placed on the data channel corresponding to a sender / receiver group that receives a message and transmits it to the next higher level of the network. In a distribution node, the amount of SPR provided at the node corresponds to the number of service sites attached to the node. Each of the switches of the SPRs in the node connects to the switches of the other SPRs of the node, so that the switches could route data messages to the service site that corresponds to the destination address of a subscriber coupled to a service site that is connected to the distribution node. For each SPR of a distribution node, messages that do not have a destination address that corresponds to a service site coupled to the distribution node are sent to a transmitter for transmission to the next level of the network. The transmitters of each SPR of the distribution node have a corresponding SPR and receiver in the next layer of the network.

At the headend, the switch of each SPR is coupled to the switches of the other SPRs, so that the switches could provide data messages that have destination addresses that correspond to headend coupled service sites through the SPRs. from the header. If any switch in the headend could not determine whether a destination address of a message is associated with any of the SPRs in the headend, it would provide the message to a gateway for distribution over another network. Likewise, the headend is preferably provided with an ad insertion server which could be used to insert information superimposed on the broadcast signals as they are distributed across the network. Also, a processor could be provided at the headend having its own unique destination address, so that data messages can be received through a processor from subscribers. In this way, the CATV system operator could communicate with individual subscribers.

Because SPRs are of modular construction, the organization of distribution nodes, headends, and service sites is relatively easy to implement. Also, the system of the present invention allows subscribers to communicate with other subscribers through the network or with other sites through the Internet or other networks without having to dispute with all subscribers of the network during the time of the message in the return spectrum of the same network communication cables. Accordingly, communication over the network is more reliable and faster than in previously known systems.

Although the present invention has been illustrated by a description of the preferred and alternative embodiments and although the procedures of the preferred and alternative embodiments have been described in detail, it is not the applicants' intention to restrict or in any event , limit the scope of the appended claims for this purpose. Additional advantages and modifications will be readily identifiable to those skilled in the art.