JP5328955B2 - How to retransmit digital broadcast signals - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for digitally retransmitting a satellite digital broadcast signal via a cable television broadcast network whose transmission capacity is smaller than that of the signal only by replacing an NIT. <P>SOLUTION: The transport streams of satellite bands 1 and 2 of satellite digital broadcast, where the band per transmission channel is 40 Mbps (Fig.2 (a)) are respectively divided into the streams of two CATV bands (Fig.2 (b)), so that a program unit and the band (29 Mbps) per transmission channel of CATV broadcast are satisfied. In this case, the respective divided CATV bands 1-4 are added with EPG 1 and 2 accessory to the signals of the satellite bands 1 and 2, as they are, with merely the necessary NIT information being replaced. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a method for retransmitting a digital broadcast signal, and more specifically, a method for digitally retransmitting a satellite digital broadcast signal via a cable television broadcasting network having a transmission capacity smaller than that of the signal, The present invention relates to a channel selection method performed by a receiver that receives a signal retransmitted by the method.

  As is well known, following the communication satellite (CS), digital television broadcasting by the broadcasting satellite (BS) has started, and the field of wireless broadcasting is shifting to digital multi-channel. On the other hand, in the cable television (CATV) system which is a cable broadcast, from the viewpoint of increasing the number of channels to be provided and securing subscribers, in addition to digitizing itself, it is conventional to collectively receive and retransmit these wireless broadcasts. More.

  As a method for digitally retransmitting a digital broadcast signal by CATV, there is a method using a transmodulation method. In this transmodulation system, the band per transmission channel of digital broadcasting is required to be equal to or less than the band per transmission channel of CATV. Therefore, a BS digital broadcast signal with a maximum bandwidth per transmission channel of 28.259 Mbps and a CS digital broadcast signal with a bandwidth of 29.162 Mbps are CATV with a bandwidth per transmission channel of 29.162 Mbps. Re-transmission can be performed. Regarding the BS digital broadcasting transmodulation system, “Japan Cable Television Broadcasting Multiplexer”, “Cable Japan Television Television Broadcasting Multiplexing Device”, “Japan Cable Television Technology Association Standard JCSPEC-001” It is defined in the 1.0 version “BS digital broadcasting transmodulation operation specification”.

  By the way, plans are being made to launch CS at 110 degrees east longitude, the same as BS, so that the newly started BS digital broadcast signal and CS digital broadcast signal can be received by the same equipment. However, CS digital broadcasting (hereinafter referred to as 110-degree CS digital broadcasting) performed using this new satellite is scheduled to be operated in a band of 39.1275 Mbps per transmission channel. For this reason, the above-described transmodulation method cannot be used for digital retransmission of the 110-degree CS digital broadcast signal by CATV.

Therefore, as a method for digitally retransmitting the 110-degree CS digital broadcast signal by CATV, a method using a remultiplexing (remax) method can be considered. FIG. 10 is a diagram for explaining the concept of the re-multiplexing method. FIG. 11 is a diagram illustrating an example of a configuration of a remultiplexing system that can be used to perform this remultiplexing method. FIG. 12 is a diagram illustrating an example of a detailed configuration of the CS receiver and the multiplexing device of FIG.
As shown in FIG. 10 and FIG. 11, this remultiplexing system uses a 110-degree CS digital broadcast signal in a band of 39.1275 Mbps per transmission channel (hereinafter referred to as a satellite band) as the number of broadcast programs (streams). Each program is received by a plurality of corresponding CS receivers. Then, re-multiplexing is performed so that each extracted program fits in a band of 29.162 Mbps per CATV transmission channel (hereinafter referred to as CATV band).

JP 2000-350180 A Japanese Patent Laid-Open No. 2000-174813

Japan CATV Technology Association Standard JCTEA STD-002-2.0 “Digital Cable Television Broadcast Multiplexer” Nippon Cable Lab Specification JCL SPEC-001 1.0 “BS Digital Broadcasting Transmodulation Operation Specification” Japan CATV Technology Association Standard JCTEA STD-003-1.1 “Digital Cable Television Broadcasting Program Sequence Information Structure and Identifier Operation Standards”

  However, in this remultiplexing system, a plurality of dedicated CS receivers must be prepared according to the number of programs, and the entire system becomes expensive. Furthermore, in order to re-multiplex programs in different satellite bands into one CATV band, it becomes necessary to operate an electronic program guide (EPG) provided along with the program for each satellite band. That is, the EPG transmitted in each band needs to include detailed information regarding programs in the same band (note that detailed information or simple information may be used for programs in other bands).

  There are the following three methods for operating this EPG. First, the first method is a method using a simplified EPG. The simple EPG replaces the NIT by storing simple program information in a network information table (NIT) having physical information on the transmission path without using service information (SI information) attached to the program. It is feasible. The NIT has a smaller amount of information (about several KB) than the SI information, has a low update frequency (at most several times / day), and is static information, so it does not particularly require real-time processing to generate the NIT. . For this reason, the replacement of NIT can be realized with a simpler configuration than the reconstruction of SI information. However, with the simple EPG alone, functions at the receiver provided by the 110-degree CS digital broadcast EPG, that is, display of a program schedule table, program content guidance, recording, etc. cannot be realized. Therefore, in this method, there arises a problem that a service is different between a case where a broadcast is directly received by a satellite wave and a case where a broadcast is received via CATV. This problem becomes a life-and-death problem in acquiring subscribers for the CATV provider side whose service content is limited. The simplified EPG is defined in “Japan CATV Technology Association Standard JCTEA STD-003-1.1“ Digital Cable Television Broadcast Program Arrangement Information and Identifier Operation Standard ””.

  The second method is a method using a conversion table described in JP 2000-350180 A. However, this method has a problem that it does not comply with the JCTEA standard because SI information that is not consistent with the actual program configuration is transmitted. In addition, since a completely new process is added to the analysis of the EPG, there is a problem that it becomes difficult to share the CATV receiver program and the direct wave receiver program corresponding to this method. In the 110-degree CS digital broadcasting, it is necessary to correspond to an advanced service performed by EPG / data broadcasting or the like, and the program of the receiver becomes complicated. Therefore, it is not realistic to develop dedicated software for a CATV receiver.

  The third method is a method of reconfiguring SI information. If the SI information is reconfigured, an EPG function equivalent to direct wave reception can be realized by CATV reception in accordance with the JCTEA standard or the like. However, reconstruction of SI information of 110-degree CS digital broadcasting is difficult for the following reasons. First, since the number of channels is large and the program schedule can be referred and reserved for about two weeks ahead, the amount of data is very large. In addition, the SI information is frequently updated every time the program starts and ends, every time a future program schedule is changed, and the like. In addition, the EPG reservation function allows VTR reservation recording control, and enables recording in the changed time frame even when the program time frame is changed due to program extension or the like. This is a function that can be realized by the receiver to control the VTR by referring to the SI information as needed. Therefore, in order to perform recording correctly with the CATV receiver, when SI information is updated, it is necessary to reconfigure and transmit in real time. Even if real-time processing is performed, there is a possibility that the time required for reconfiguration, the timing of the transmission cycle, etc. may not be in time. Furthermore, since the SI information needs to be transmitted with the period changed according to its importance, the reconstructed SI information is also complicated and large-scale. As described above, in order to extract only SI information related to a program being retransmitted from all SI information in real time, and to reconfigure and transmit it, the processing time is not enough. In addition, since a device for reconfiguring SI information requires a large amount of memory and a complicated processing circuit, the equipment of the center station of CATV becomes large and expensive. Therefore, the method for reconfiguring SI information is not practically feasible.

  Therefore, an object of the present invention is to perform digital broadcast signal conversion by simply replacing the NIT without performing complicated modification of SI information or reconfiguration of programs for the normal channel selection operation of the receiver. Another object of the present invention is to provide a digital broadcast signal retransmitting method capable of digitally retransmitting via a cable television broadcasting network having a transmission capacity smaller than that of the signal. Another object of the present invention is to realize a function equivalent to that of a direct wave receiver at a low cost even in a CATV receiver while complying with a standard such as MPEG / JCTEA, and to make both receiver programs common. It is an object of the present invention to provide a digital broadcast signal retransmitting method capable of achieving the above.

  The present invention relates to a transmission apparatus used as a relay apparatus that receives a signal from a transmission channel for satellite digital broadcasting, converts the signal into a signal for CATV (cable television) broadcasting, and retransmits the signal to the transmission channel for CATV. A communication system comprising a plurality of receiving devices for receiving transmitted signals, wherein the transmitting device receives and demodulates TS (transport stream) from a plurality of transmission channels of satellite digital broadcasting. For each transmission channel, streams constituting a plurality of programs included in the demodulated TS are grouped in units of programs so as to be within the transmission capacity per one transmission channel of CATV broadcasting, and the demodulated TS is At least SI information (program information) and PSI information (program identification information) included are added to each of the divided groups to separate them. TS dividing means for generating a plurality of streams, each divided stream, a program included in the divided stream, a TS number for identifying the TS in which the divided stream is included, and a transmission channel of CATV broadcasting for transmitting the divided stream NIT replacement means for generating information associating with identifying information as retransmission credit NIT (program tuning information), and replacing the generated retransmission credit NIT with NIT information in the PSI information included in each divided stream , A modulation means for digitally modulating each divided stream into a signal for CATV broadcasting, and a sending means for mixing each digitally modulated divided stream and sending it to a CATV broadcast transmission channel. Receive and demodulate a modulated split stream from a broadcast transmission channel Whether the divided stream including the selected program and the divided stream including the currently received program are the same by using the SI information included in the demodulated divided stream and providing the electronic program guide function Control means for switching the reception to the CATV transmission channel to which the divided stream including the selected program is transmitted is determined based on the retransmission credit NIT included in the demodulated divided stream. With. The present invention is also directed to methods for signal conversion, retransmission and reception used in such communication systems.

  As described above, according to the present invention, a satellite digital broadcast signal is divided into TS for each transmission channel into a CATV broadcast transmission channel band signal. Accordingly, it is possible to digitally retransmit a satellite digital broadcast signal having a large transmission capacity via a cable television broadcasting network having a small transmission capacity, simply by changing information for program selection. Also, since SI information is not reconstructed, a device compliant with standards such as MPEG / JCTEA can be realized. Furthermore, in the CATV receiver, it is possible to realize a function exactly the same as that of the direct wave receiver at a low cost.

  Also, the retransmission method of the present invention can be easily applied to 110-degree CS digital broadcasting or the like simply by replacing the NIT having physical information related to the transmission path in correspondence with the divided program.

  In addition, the CATV receiver can realize functions equivalent to those of the direct wave receiver at low cost, and can share both receiver programs (software).

It is a block diagram which shows the structure of the re-transmission apparatus using the re-transmission method of the digital broadcast signal which concerns on one Embodiment of this invention. It is a figure explaining the concept of the retransmission method of the digital broadcast signal which concerns on one Embodiment of this invention. It is a block diagram which shows an example of a detailed structure of TS division | segmentation part 12 and 22 of FIG. It is a block diagram which shows an example of the receiver which can apply the retransmission method of this invention. 5 is a flowchart showing an example of a basic process of a channel selection operation performed by the receiver of FIG. It is a figure explaining the concept of the structure method of CAIT NIT. It is a block diagram which shows an example of the other receiver which can apply the retransmission method of this invention. It is a block diagram which shows the other structure of the retransmission apparatus using the retransmission method of the digital broadcast signal which concerns on one Embodiment of this invention. It is a figure explaining the concept of the retransmission method of the digital broadcast signal which concerns on one Embodiment of this invention. It is a figure explaining the concept of the conventional remultiplexing system. It is a figure which shows an example of the structure of the remultiplex system which can be taken in order to perform the remultiplex system of FIG. It is a figure which shows an example of a detailed structure of CS receiver and multiplexing apparatus of FIG.

  Hereinafter, as an example, a case where a 110-degree CS digital broadcast signal having a band per transmission channel of 39.1275 Mbps is digitally retransmitted by CATV having a band per transmission channel of 29.162 Mbps will be described. The digital broadcast signal retransmission method of the invention will be described. In the present embodiment, a digital broadcast signal (FIG. 2A) composed of a satellite band 1 signal including programs 1 to 3 and a satellite band 2 signal including programs 4 to 6 is converted into four CATV bands 1 to 1. A case where re-transmission is performed using a digital CATV signal (FIG. 4B) using 4 is described.

FIG. 1 is a block diagram illustrating a configuration of an apparatus using a digital broadcast signal retransmission method according to an embodiment of the present invention. 1, the retransmission apparatus of the present invention includes QPSK demodulation units 11 and 21, TS division units 12 and 22, QAM modulation units 13 and 14, QAM modulation units 23 and 24, and a system control unit 15. . As shown in FIG. 1, the retransmission apparatus configures a QPSK demodulator, a TS divider, and two QAM modulators for each satellite band of a received digital broadcast signal. In this example, each TS division unit has a configuration including two QAM modulation units to divide one satellite band into two CATV bands, but the number of components depends on the number of divisions in the TS division unit. Determined.
FIG. 2 is a diagram illustrating the concept of a digital broadcast signal retransmission method according to an embodiment of the present invention.

  Of the digital broadcast signals input via the antenna, the signal in the satellite band 1 is input to the QPSK demodulator 11. Then, the QPSK demodulator 11 demodulates the signal of the satellite band 1 subjected to QPSK modulation, and extracts a TS (transport stream) including the programs 1 to 3. On the other hand, among the digital broadcast signals input via the antenna, the signal in the satellite band 2 is input to the QPSK demodulator 21. Then, the QPSK demodulator 21 demodulates the signal in the satellite band 2 subjected to QPSK modulation, and extracts a TS including the programs 4 to 6. The QPSK demodulation units 11 and 21 perform QPSK demodulation in response to the 110-degree CS digital broadcast signal. However, in the case of a digital broadcast signal that has been modulated by another method, Demodulation according to the method is performed.

  The TS dividing unit 12 divides the TS of the satellite band 1 including the extracted programs 1 to 3 into two divided streams so as to satisfy the band per program and one transmission channel (29.162 Mbps). (FIG. 2 (b)). Here, the TS dividing unit 12 stores EPG1 accompanying the signal of the satellite band 1 as it is in two divided streams. Further, the TS dividing unit 22 converts the TS of the satellite band 2 including the extracted programs 4 to 6 into two divided streams so as to satisfy the band per program and one transmission channel (29.162 Mbps). Divide (FIG. 2B). Here, the TS dividing unit 22 stores the EPG2 attached to the signal of the satellite band 2 as it is in the two divided streams. Note that the method of TS division is not limited to that shown in FIG.

  Here, a detailed configuration of the TS dividing units 12 and 22 will be described. FIG. 3 is a block diagram illustrating an example of a detailed configuration of the TS dividing units 12 and 22. In FIG. 3, the TS dividing units 12 and 22 include a PSI analyzing unit 31, a PID filtering unit 32, a NIT changing unit 33, and a rate converting unit 34 for each transmission channel.

  First, as a premise, in a digital broadcasting TS, streams of information, video / audio, and the like are packetized and multiplexed. Each information and stream can be identified by a packet ID (PID) attached to the packet. Information and streams multiplexed in one TS include SI information for transmitting program information, program identification information (PSI information) necessary for selecting a desired program, and video / There are streams of audio and additional data. When the total of the streams of information, video / audio, etc. is less than the transmission channel bandwidth, a packet called a NULL packet is used for padding. The PSI information includes a network information table (NIT), a program association table (PAT), a program map table (PMT), and the like. NIT indicates physical information regarding a transmission path and an identification number of a program. PAT indicates the NIT PID (PID = 0x0010 in 110-degree CS digital broadcasting) and the PMT PID of the program included in the TS. The PMT indicates the PID of a stream such as video / audio / additional data constituting each program.

  The PSI analysis unit 31 extracts PSI information from the input TS, and acquires the PMT of each program and the PID of a stream such as video / audio constituting the program. Then, the PSI analysis unit 31 determines the PIDs to be passed by each PID filtering unit 32 according to the program allocation to each divided stream. In 110-degree CS digital broadcasting, PIDs of streams that do not belong to programs such as SI information, PAT, and NIT are allocated in the range of 0x0000 to 0x002F. Therefore, PIDs in this range are passed by both PID filtering units 32. . Based on the determination of the PSI analysis unit 31, the PID filtering unit 32 replaces each packet other than the PID to be passed with a NULL packet. When the NIT replacement unit 33 detects a packet transmitting the NIT, the NIT replacement unit 33 replaces the packet with the NIT packet for CATV. Each of the speed conversion units 34 deletes the NULL packet to adjust the transmission speed of the divided stream to the CATV band, and performs PCR (Program Clock Reference) correction. This PCR is time information added to the TS in order to keep pace with the system clock used by the receiver to measure the reproduction timing of video / audio. In the speed conversion unit 34, due to the deletion of the NULL packet, the delay time jitter that the arrival time of the PCR packet at the receiver differs for each packet occurs. For this reason, it is necessary to perform PCR correction to prevent the receiver system clock from being disturbed by delay time jitter. As a PCR correction method, the method described in Japanese Patent Application Laid-Open No. 2000-174813 can be used.

  By such processing of the TS dividing units 12 and 22, as shown in FIG. 2, it is possible to create four CATV band 1 to 4 TSs from two satellite band 1 and 2 TSs. In the example of FIG. 2, the PMT and stream of program 1 are re-sent to the split stream of CATV band 1, and the PMT and stream of program 2 and program 3 are re-sent to the split stream of CATV band 2. Also, PAT1 and SI information 1 are retransmitted to both divided streams. The NIT for satellite broadcasting is replaced with the NIT for CATV broadcasting and is transmitted in both divided streams. In FIG. 3, the NIT reassignment unit 33 is provided between the PID filtering unit 32 and the speed conversion unit 34, and thus is necessary for each transmission channel. However, the NIT information to be reassigned is divided and transmitted. If the channels are the same, only one may be provided in the preceding stage of the PID filtering unit 32.

  The QAM modulators 13 and 14 digitally modulate the two divided streams output from the TS divider 12 into 64-value QAM, respectively. On the other hand, the QAM modulators 23 and 24 digitally modulate the two divided streams output from the TS divider 22 into 64-value QAM, respectively. Here, each QAM modulator 13, 14, 23, and 24 has been described with reference to the case where the input signal is digitally modulated to 64-value QAM, but this modulation scheme is determined according to the transmission scheme of the digital CATV system. It will be. Each of the divided streams after digital modulation is mixed by a mixing unit (not shown) and sent to the CATV transmission path. The system control unit 15 controls the entire retransmission apparatus.

  Next, an apparatus for receiving a digital CATV signal transmitted by the above-described retransmission method will be described with reference to FIGS. FIG. 4 is a block diagram showing an example of the configuration of a receiver to which the retransmission method of the present invention can be applied. FIG. 5 is a flowchart showing an example of the basic process of the channel selection operation performed by the receiver. 4, the receiver includes a QAM demodulator 41, a TS decoder 42, an AV decoder 43, and a controller 44. The QAM demodulator 41 receives a digital CATV signal transmitted via a CATV transmission path, performs QAM demodulation, and extracts a divided stream. The TS decoder 42 decodes the extracted divided stream to obtain a program signal. The AV decoder 43 decodes the video / audio of the decoded program signal. The control unit 44 controls the entire receiver.

  As described above, in the present invention, in the retransmission apparatus, the TS of the input digital broadcast signal is divided into two and retransmitted, but only the NIT is replaced without reconfiguring the EPG itself. Do. For this reason, the following characteristic channel selection operation is performed in the receiver. The channel selection operation shown in FIG. 5 starts when the identification number of the program to be selected is input by the user from the displayed EPG screen or directly by pressing a button on the remote controller. When the program identification number is input, the receiver first receives the NIT of the currently selected transmission channel (step S51). Note that the NIT may be received in advance and stored in the memory, and the stored NIT may be read. In this way, step S51 can be omitted. Next, the receiver searches the received NIT information, and the selected program is (1) the currently selected divided stream (the own TS's own divided stream), and (2) the current selected channel. Exists in any of the other divided streams of the same TS as the divided stream that has been selected (other divided streams of the own TS) or (3) a divided stream (other TS) of a band different from that of the currently selected divided stream Is determined (steps S52 and S53). Information necessary for determining whether the stream is the self-divided stream or the other divided stream is written in the NIT in advance at the time of TS division and transmitted to the receiver.

  If it is determined in steps S52 and S53 that the selected program is in the own divided stream of the own TS ((1) above), the receiver receives the PAT and receives the PMT PID of the selected program. And the PMT of the program is received (steps S55 and S56). Then, the receiver obtains the PID of the video / audio stream constituting the program from the PMT, and separates and decodes each stream (step S57). On the other hand, if it is determined in steps S52 and S53 that the selected program is in another divided stream of the own TS (above (2)) and if it is determined that it is in another TS (above (3)), reception Using the NIT information, the machine moves the channel selection channel to the channel through which the divided stream including the program is transmitted (step S54). Then, the receiver receives the PAT of the moved transmission channel, obtains the PMT PID of the selected program, and receives the PMT of the program (steps S55 and S56). Then, the receiver obtains the PID of the video / audio stream constituting the program from the PMT, and separates and decodes each stream (step S57). As described above, by providing a step for determining whether the stream is the self-split stream or the other split stream during the channel selection operation, it is not necessary to change the TS identifier, and the software on the receiver side can be changed less.

  Finally, a method for configuring the CATV NIT will be described. Conceptually, the physical information of the transmission path given by the NIT is transmitted in a structure as shown in FIG. FIG. 6A shows the satellite NIT and shows that a network is constituted by two TSs (TS1 and TS2). A network is defined for a collection of TSs in the same distribution system. In 110-degree CS digital broadcasting, a network is defined for digital broadcasting by a CS satellite launched at a position of 110 degrees east longitude. . In CATV, there are cases where a single network is formed by all TSs sent to a transmission line to which a receiver is connected, or a plurality of networks are defined for each headend facility. The frequency information of the band in which each TS is transmitted is described in the NIT as a satellite distribution system descriptor (cable distribution system descriptor in the case of CATV), and the program identifier included in the TS is described as a service list descriptor. . FIG. 6A shows that TS 1 is transmitted in satellite band 1 and includes program 1, program 2, and program 3. In addition, TS2 is transmitted in the satellite band 2 and includes program 4, program 5, and program 6. Each TS is provided with a 16-bit identifier called a transport stream identifier and an original network identifier, and the TS can be uniquely identified in the network by a total of 32 bits. When retransmitting a digital broadcast signal without reorganizing SI information as in the present invention, the value of this identifier must not be changed in order to maintain consistency with SI information.

  FIG. 6B shows an example of a CATV NIT configuration method (first method). In the first method, the NIT is configured with the divided streams as independent TSs. Here, it is necessary to add the same transport stream identifier and original network identifier to each divided stream as before the division. For this reason, in order to make it possible to uniquely identify the TS, the divided streams that constitute the same TS before the division cannot be accommodated in the same network. Therefore, two networks (CATV-1 and CATV-2) are defined on the CATV side for re-transmission, and each segment stream is assigned to each network so as not to include the segment streams that constitute the same TS before the segmentation. Accommodate. In this case, in step S53 for determining whether or not the selected program shown in FIG. 5 is present in the own divided stream, the newly selected program is changed to the own network (the network in which the currently selected program exists). It can be determined whether it exists in the same network.

  FIG. 6C is a diagram showing another example of a CATV NIT configuration method (second method). In this second method, the cable distribution system descriptor is expanded to store frequency information and the like of two channels. In this case, in step S53 shown in FIG. 5, it is necessary to transmit information on which of the two channels each program is included by separately defining a descriptor to be transmitted by NIT.

  As described above, in the digital broadcast signal retransmission method according to an embodiment of the present invention, the satellite digital broadcast signal is divided into the transmission channel band signals of the CATV broadcast for each transmission channel and the TS. Accordingly, it is possible to digitally retransmit a satellite digital broadcast signal having a large transmission capacity via a cable television broadcasting network having a small transmission capacity, simply by changing NIT information. Also, since SI information is not reconstructed, a device compliant with standards such as MPEG / JCTEA can be realized. In addition, the CATV receiver can realize functions equivalent to those of the direct wave receiver at a low cost, and can share both receiver programs.

  In the above embodiment, a case has been described in which the TS dividing units 12 and 22 divide the satellite band TS into two divided streams so as to satisfy the band for each program and one transmission channel. It is not necessary to divide the TS. However, in this case, since one program is retransmitted across two divided streams, the receiver side needs to be configured to individually receive and synthesize two divided streams. Therefore, the receiver corresponding to this case has a configuration including two QAM demodulating units and a TS synthesizing unit as shown in FIG. 7, for example, and becomes expensive as compared with the above-described receiver.

  In the above embodiment, since the TS dividing units 12 and 22 divide the satellite band TS into two divided streams so as to satisfy the band for each program and one transmission channel, as shown in FIG. Thus, a useless band in which the program is not transmitted is generated (the portion indicated by a blank in the figure). Therefore, a configuration shown in FIG. 8 is conceivable as a retransmission apparatus according to another embodiment of the present invention. The multiple TS multiplexing unit 71 in FIG. 8 multiplexes divided stream programs including useless bands in the TS dividing units 12 and 22 to generate a new CATV band. Thereby, the CATV band can be effectively used as shown in FIG.

11, 21 QPSK demodulation unit 12, 22 TS division unit 13, 14, 23, 24 QAM modulation unit 15 System control unit 31 PSI analysis unit 32 PID filtering unit 33 NIT replacement unit 34 Speed conversion unit 41 QAM demodulation unit 42 TS decoder 43 AV decoder 44 controller

Claims (2)

A transmission device used as a relay device that receives a signal from a satellite digital broadcast transmission channel, converts the signal into a CATV (cable television) broadcast signal, and retransmits the signal to the CATV transmission channel, and the retransmitted signal A communication system comprising a plurality of receiving devices for receiving
The transmitter is
Demodulation means for receiving and demodulating TS (transport stream) from a plurality of transmission channels of satellite digital broadcasting;
Streams constituting a plurality of programs included in the demodulated TS for each transmission channel are grouped in units of programs so as to be within the transmission capacity per transmission channel of CATV broadcasting, and the demodulated TS TS dividing means for generating a plurality of divided streams by adding at least SI information (program information) and PSI information (program identification information) included in
Information that associates each divided stream, a program included in the divided stream, a TS number that identifies the TS in which the divided stream is included, and information that identifies a transmission channel of a CATV broadcast that transmits the divided stream. NIT replacement means for generating retransmission credit NIT (program channel selection information) and replacing the generated retransmission credit NIT with the NIT information in the PSI information included in each of the divided streams;
Modulation means for digitally modulating each of the divided streams into a CATV broadcast signal;
Sending means for mixing each of the digitally modulated divided streams and sending them to a CATV broadcast transmission channel;
The divided stream and the other divided stream included in the same TS are sent to different CATV broadcast transmission channels, respectively.
The receiving device is:
Demodulating means for receiving and demodulating the modulated divided stream from a transmission channel of CATV broadcasting;
Using the SI information included in the demodulated divided stream, providing an electronic program guide function, whether the divided stream including the selected program and the divided stream including the currently received program are the same Is determined based on the retransmission credit NIT included in the demodulated divided stream, and if they are not the same, the reception is switched to the transmission channel for CATV from which the divided stream including the selected program is transmitted. Control means,
The communication system, wherein a transmission capacity per one transmission channel is 29.162 Mbps. A transmission device used as a relay device that receives a signal from a satellite digital broadcast transmission channel, converts the signal into a CATV (cable television) broadcast signal, and retransmits the signal to the CATV transmission channel, and the retransmitted signal A method for retransmission and reception used in a communication system comprising a plurality of receiving devices for receiving
The transmitter is
A demodulation step of receiving and demodulating a TS (transport stream) from a plurality of transmission channels of satellite digital broadcasting;
Streams constituting a plurality of programs included in the demodulated TS for each transmission channel are grouped in units of programs so as to be within the transmission capacity per transmission channel of CATV broadcasting, and the demodulated TS A TS dividing step for adding a plurality of divided streams by adding at least SI information (program information) and PSI information (program specifying information) included in
Information that associates each divided stream, a program included in the divided stream, a TS number that identifies the TS in which the divided stream is included, and information that identifies a transmission channel of a CATV broadcast that transmits the divided stream. NIT replacement step of generating as retransmission credit NIT (program channel selection information) and replacing the generated retransmission credit NIT with the NIT information in the PSI information included in each of the divided streams;
A modulation step of digitally modulating each of the divided streams into a CATV broadcast signal;
Performing a retransmission step including a step of mixing each of the digitally modulated divided streams and sending them to a transmission channel of CATV broadcasting,
The divided stream and the other divided stream included in the same TS are sent to different CATV broadcast transmission channels, respectively.
The receiving device is:
A demodulation step of receiving and demodulating the modulated divided stream from a transmission channel of CATV broadcasting;
Using the SI information included in the demodulated divided stream, providing an electronic program guide function, whether the divided stream including the selected program and the divided stream including the currently received program are the same Is determined based on the retransmission credit NIT included in the demodulated divided stream, and if they are not the same, the reception is switched to the transmission channel for CATV from which the divided stream including the selected program is transmitted. And a receiving step including a control step,
The method for retransmission and reception, wherein the transmission capacity per transmission channel is 29.162 Mbps.

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