JP4029504B2 - Information transmitting apparatus and information transmitting method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an information transmission apparatus and an information transmission method for redistributing a digital satellite broadcast signal via a cable television network, for example.
[0002]
[Prior art]
Conventionally, for example, a digital broadcast broadcast on an arbitrary network such as a cable TV operator receiving a digital multi-channel broadcast program supplied via a satellite and distributing it to each home using its own network A program is distributed on another network.
[0003]
In a modulation conversion retransmission system that retransmits a digital multi-channel service provided in a satellite network using a modulation conversion method in a cable network (cable television facility or hearing facility), a digital multi-channel broadcast by a satellite operator is transmitted via a cable. It is received at the operation equipment of the station and the hearing facility, returned to the transport stream (TS) state, converted again to the RF frequency of the cable television by the cable modulation method, and retransmitted to the cable network. Digital multi-channel service is realized in the company.
[0004]
In this case, it is a part of information related to channel selection called program specification information (PSI: Program Specific Information) multiplexed in the TS, and mainly network information (NIT: Network Since the Information Table is different for satellites and cables, it must be replaced with network information for cables. Further, the NIT includes information related to a program (service ID) included in a transmitted channel in addition to physical information such as frequency information. A set top box (in-home receiving apparatus) connected to the transmission line of the cable television is configured to detect the NIT and receive a predetermined program based on program information included therein.
[0005]
In order to normally display programs and services on the set top box, the above service ID remains the same when all satellite programs are serviced during re-transmission, but only specific transponders are re-transmitted. The service ID of the address included in the transponder that is not retransmitted must be deleted from the NIT.
[0006]
[Problems to be solved by the invention]
By the way, when a digital broadcast program broadcast on an arbitrary network is distributed on another network, the contents described in the NIT of the digital broadcast data corresponding to each network have an important meaning as described above. Therefore, if there is an error in the correspondence between the physical information of each network and the service information to be transmitted, an appropriate distribution service cannot be performed.
[0007]
Therefore, the cable service provider cannot cope with the change of the NIT unless the satellite provider knows the time for changing the NIT of the digital broadcast data.
[0008]
In addition, the NIT of digital broadcast data is normally changed periodically. However, if the NIT is changed at a timing different from normal for some reason, there is a possibility that the NIT change cannot be immediately handled. is there.
[0009]
In the NIT, a version number indicating the update status is described. When the contents of the NIT are changed, the value of this version number is increased by one. In the current operation of digital satellite broadcasting, the version is updated once a day regardless of whether or not the contents of the NIT are changed.
[0010]
In the re-transmission into the cable network, the content of the re-transmission is of course changed, but even if there is no change, there is a possibility that the NIT content will change such as a change in the satellite program structure. Therefore, it is necessary to rewrite the NIT in accordance with the satellite system change time.
[0011]
In order to perform NIT rewrite processing in accordance with the satellite NIT change time, it is necessary to perform automatic operation processing using an administrator or a timer or the like. It becomes.
[0012]
In the case of retransmitting services from a plurality of satellites, the processing for responding to the change in NIT is further complicated.
[0013]
In addition, when there is basically no administrator as in the case of a hearing facility, it becomes difficult to perform processing for responding to changes in the NIT.
[0014]
Accordingly, an object of the present invention is to provide an information transmission apparatus and an information transmission method capable of automatically performing a process corresponding to a change in NIT of digital broadcast data in view of such a conventional problem. There is.
[0015]
[Means for Solving the Problems]
An information transmitting apparatus according to the present invention includes a receiving unit that receives a digital satellite broadcast signal, a demodulating unit that demodulates a signal received by the receiving unit, and a network information extraction unit that extracts network information of the signal demodulated by the demodulating unit. And network information extracted by the network information extracting means, and when the version information is updated, the network information extracted by the network information extracting means is retransmitted to the network. Network information converting means for converting to suitable network information, and network information for replacing the network information of the signal demodulated by the demodulating means with the cable information, using the network information converted by the network information converting means as cable information. Replacement hand When, characterized in that it comprises a modulation means for network information modulates the signal that has been replaced in the information for transmission cable by being demodulated by the demodulation means the network information replacement means.
[0016]
In the information transmitting apparatus according to the present invention, the network information converting means sequentially stores, for example, the version information included in the network information extracted by the network information extracting means, and the previously stored version information and the version information stored this time are stored. By comparing, it is detected that the version information has been updated.
[0017]
The information transmission method according to the present invention includes a reception step for receiving a digital satellite broadcast signal, a demodulation step for demodulating the signal received at the reception step, and a network for extracting network information of the signal demodulated at the demodulation step. When the version information included in the network information extracted in the information extraction step and the network information extraction step is updated, the network information extracted in the network information extraction step is changed to network information suitable for the network. Network information conversion step for conversion, network information converted in the network information conversion step as network information, and network information for replacing the network information of the signal demodulated in the demodulation step with the information for cable And conversion step, the network information in the network information replacement step is demodulated in the demodulation step is characterized in that it comprises a modulation step of modulating a signal that has been replaced with the information for the transmission cable.
[0018]
In the information transmission method according to the present invention, in the network information conversion step, for example, version information included in the network information extracted in the network information extraction step is sequentially stored, and the previously stored version information and this time are stored. By comparing the version information, it is detected that the version information has been updated.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is applied to, for example, a cable transmission system configured as shown in FIG.
[0020]
In this specification, the term “system” means an overall apparatus constituted by a plurality of apparatuses and means.
[0021]
In this cable transmission system, a cable TV station 3 receives a digital broadcast signal or the like transmitted from a satellite broadcast service provider 1 via a communication satellite 2, and a viewer's home is transmitted from the cable TV station 3 via a cable TV network 4. 5 to the receiver 6.
[0022]
In this cable transmission system, the transmission unit 11 of the satellite broadcast service provider 1 scrambles the MPEG-compressed program information supplied from the program supply provider to provide electronic program guide information (EPG: Electoric Program Guide). Are multiplexed together with service information such as viewer management information and transmitted to the communication satellite 2 as a linearly polarized CS wave. In addition, the viewer management unit 12 issues an IC card 60 to the viewer. The key management unit 13 of the viewer management unit 12 manages a viewable program corresponding to the IC card 60. Furthermore, the viewing information processing unit 14 calculates a viewing fee based on the viewing information notified from the receiver 6 of the viewer's house 5 and notifies the customer management unit 35 of the cable television station 3.
[0023]
The cable television station 3 receives a CS wave transmitted from the communication satellite 2 by a CS antenna 31, receives a television broadcast radio wave using an analog wave by a terrestrial antenna 32, and transmits from a broadcasting satellite (not shown). Received satellite broadcast radio waves (hereinafter referred to as “BS waves”) are received by the BS antenna 33, and the distribution unit 34 mixes the input CS waves and analog broadcast waves (terrestrial and BS waves). The mixed wave is distributed to the receiver 6 of the viewer's house 5 via the cable television network 4. Further, the customer management unit 35 charges the viewer for a viewing fee based on the viewing fee information from the viewing information processing unit 14 of the center station 1.
[0024]
Then, the receiver 6 of the viewer's house 5 extracts predetermined program information from the input mixed wave and outputs it to the television receiver 7. The television receiver 7 displays the input program information.
[0025]
Here, the digital broadcast signal transmitted from the communication satellite 2 will be described. In this embodiment, the digital broadcasting signal corresponds to a DVB (Digital Video Broadcasting) system. FIG. 2B shows the frame structure of digital broadcast data in the DVB system. One frame is composed of eight MPEG2 transport packets (see FIG. 2A). In this case, the synchronization byte (= 47H) in the packet is used, and the synchronization byte is inverted (= B8H) once in 8 packets to obtain frame synchronization. An error correction code according to Reed-Solomon (204, 188) is added to each MPEG2 transport packet (MPEG2TS packet). The digital broadcast data shown in (B) of FIG. 2 is modulated by QPSK (Quadrature Phase Shift Keying), and then converted into the SHF band to be a digital broadcast signal transmitted from the communication satellite 2.
[0026]
FIG. 3 shows the packet structure of an MPEG2 transport packet, and the first 4 bytes of 188 bytes form a packet header. A packet identifier (PID: Packet Identification) indicating the attribute of the individual stream (data string) of the packet is arranged in the packet header. As is well known, a PES (Packetized Elementary Stream) packet whose packet structure is shown in FIG. 4 is subdivided and arranged in the payload (data portion) of the MPEG2 transport packet, and is further defined in the MPEG2 system. Program Association Table (PAT), Program Map Table (PMT), Network Information Table (NIT) as Program Specific Information (PSI) ) Etc. are also arranged in section format.
[0027]
Here, PSI is information necessary for realizing a simple channel selection operation and program selection. PAT indicates the PID of the PMT that transmits the information of the packets constituting the program for each program number (16 bits), and FIG. 5 shows the table structure of the PAT. As the PID of the PAT itself, PID = “0x0000” is fixedly assigned.
[0028]
The main contents will be described. The table ID indicates the type of table, and is “0x00” (hexadecimal notation) in the PAT. TS ID identifies a stream (multiplexed encoded data), and corresponds to a transponder in the case of a satellite. The version number is added every time the contents of the table are updated. The current next indicator is used for identification when the old and new versions are transmitted simultaneously. The program number identifies each channel. The network PID indicates the PID of the NIT when the program number is “0x0000”. The program map PID indicates the PID of the PMT.
[0029]
The PMT indicates, for each program number, the PID of a packet in which a stream of video, audio, additional data, etc. constituting the program is transmitted. The PID of the PMT itself is specified by the PAT as described above. FIG. 6 shows a table structure of the PMT. The main contents not overlapping with PAT will be described. The table ID indicates the type of table and is “0x02” in the PMT. The PCR PID indicates the PID of a packet including a clock (PCR: Program Clock Reference) serving as a reference for decoding. The stream type indicates the type of signal transmitted in the stream, such as video, audio, and additional data.
[0030]
The NIT indicates physical information on the transmission path, that is, in the satellite, the orbit of the satellite, the polarization, the frequency for each transponder, and the like. The PID of the NIT itself is specified by the PAT as described above. FIG. 7 shows the NIT table structure. Main contents not overlapping with PAT and PMT will be described. The table ID indicates the type of the table. The network is “0x40” and the other networks are “0x41”. The network ID identifies the network. In the case of a satellite, it corresponds to an individual satellite.
[0031]
When the satellite digital multi-channel broadcast signal is retransmitted on the cable television by the modulation conversion method, the NIT is rewritten. Here, a descriptor that is included in the NIT and needs to be rewritten will be described.
[0032]
First, the satellite delivery system descriptor in the satellite NIT will be described. This descriptor is used as the first descriptor repeated according to the TS (Transport Stream) descriptor length, and is paired with the TS ID.
[0033]
FIG. 8 shows the structure of the satellite delivery system descriptor. The descriptor tag is defined by DVB and indicates the type of descriptor. In this descriptor, “0x43” is set. The frequency indicates a transmission frequency for each stream (here, transponder). The orbit / west longitude / east longitude flag / polarization indicates the orbit and polarization of the satellite. The modulation / symbol rate / inner error correction coding rate indicates a specification related to the transmission method.
[0034]
At the time of re-transmission at the cable television station, the satellite delivery system descriptor is replaced with a cable delivery descriptor as shown in FIG. In the descriptor, it is “0x44”. The frequency indicates a transmission frequency for each physical channel in the cable television to be retransmitted. The modulation / symbol rate / inner error correction coding rate indicates a specification related to the transmission method. This descriptor has the same total length for the satellite and the cable and can be simply replaced.
[0035]
Next, the service list descriptor will be described. This descriptor is used as the second and subsequent descriptors that are repeated according to the TS descriptor length, and indicates the ID of the service (channel) multiplexed in the stream (here, transponder). That is, a plurality of service list descriptors are attached to one TSID.
[0036]
FIG. 10 shows the structure of the service list descriptor. The descriptor tag is defined by DVB and indicates the type of descriptor. In this descriptor, “0x41” is set. The service ID identifies a service. Usually, the service matches the channel that the viewer selects. The service type indicates the contents of the service such as video, audio, and data.
[0037]
At the time of re-transmission at a cable TV station, if the program for all transponders from the satellite is serviced within the cable, the information of this descriptor remains as it is, but it is re-transmitted when only the signal of a specific transponder is serviced The service ID of the program included in the transponder not to be deleted is deleted. In this case, dummy data is added to the information that has been deleted and reduced, so that the total length of the service list descriptor is the same as that of the satellite system, and can be simply replaced.
[0038]
The MPEG2 system stipulates that the transmission of the PSI table is segmented in a format called section. For example, the NIT is sectioned every 4 kbytes, and each section is configured in the format shown in FIG. NITs divided into a plurality of sections are related by section numbers. The total number of sections is described as the last section number in the table, and a series of NIT data until the section number matches the last section number.
[0039]
Next, a specific configuration example of the distribution unit 34 of the cable television station 3 in the cable transmission system shown in FIG. 1 will be described with reference to FIG.
[0040]
In the distribution unit 34 having the configuration shown in FIG. 11, the signal distributor 41 converts the CS waves input via the CS antenna 31 into modulation conversion devices 42-1 to 42-N (N is a channel included in the CS waves). Number). The channel described above is a single propagation wave including a plurality of programs multiplexed by one transponder, unlike a channel (broadcast station) in an analog broadcast wave. FIG. 12 shows an example of the state of the CS wave before being input to the signal distributor 41. That is, the CS wave H polarization includes TS1, TS3, and TS5, and the CS wave V polarization includes TS2, TS4, and TS6.
[0041]
The modulation conversion device 42 converts the input TS into a signal (QAM signal) for one channel of cable television and outputs the signal to the signal mixer 45.
[0042]
The terrestrial retransmitting device 43 RF-converts the analog broadcast wave received via the terrestrial receiving antenna 32 and outputs it to the signal mixer 45. The satellite signal retransmitting device 44 receives the BS received by the BS antenna 33. The wave is RF converted and output to the signal mixer 45.
[0043]
FIG. 13 shows a specific configuration example of the modulation conversion device 42. In the modulation conversion device 42 configured as shown in FIG. 13, the QPSK demodulation circuit 421 performs QPSK demodulation on the input CS wave and outputs it to the error correction circuit 422. The error correction circuit 422 performs error correction on the input signal and outputs the error-corrected TS to the network information (NIT: Network Information Table) conversion circuit 423.
[0044]
The NIT conversion circuit 423 is NIT for CS wave (information common to all channels of CS wave and shows information of a program included in the channel (propagation wave). When receiving a desired program in the receiver Is replaced with NIT for cable television and output to the QAM modulation circuit 424.
[0045]
The QAM modulation circuit 424 QAM modulates the input signal and outputs it to the frequency conversion circuit 425. The frequency conversion circuit 425 converts the frequency of the input signal into a predetermined value and outputs it to the signal mixer 45.
[0046]
The signal mixer 45 mixes the signals input from the modulation conversion devices 42-1 to 42-N, the terrestrial re-transmission device 43, and the satellite signal re-transmission device 44, as shown in FIG. Output to 46. The amplifier 46 amplifies the input mixed wave and supplies it to the receiver 6 via the cable television network 4.
[0047]
A specific configuration example of the NIT conversion circuit 423 will be described with reference to FIGS.
[0048]
As shown in FIG. 15, the NIT conversion circuit 423 includes a NIT extraction unit 440 and a NIT reinsertion unit 450 controlled by the control device 431 via the interface 432, and error correction sequentially output from the error correction circuit 422. The completed TS is supplied to the NIT extraction unit 440 and the NIT reinsertion unit 450.
[0049]
The NIT extraction unit 440 includes a NIT detection circuit 441 to which the TS is supplied, and a memory 442 that temporarily stores the NIT detected from the TS by the NIT detection circuit 441.
[0050]
As shown in FIG. 16, a specific configuration example of the NIT extraction unit 440 includes a NIT / PID filter 444 controlled by the control unit 443 and a detection performed by the NIT / PID filter 444. NIT packet output circuit 445 for outputting the NIT to the memory 442, a version number extraction circuit 446 for extracting a version number included in the NIT detected by the NIT / PID filter 444, and this version number extraction circuit A comparison circuit 448 to which the version number extracted by 446 is supplied directly and via the delay circuit 447 and an OR gate circuit 449 for supplying a comparison output from the comparison circuit 448 to the control unit 443 are provided. The control unit 443 of the NIT detection circuit 441 is supplied with a logic “H” detection start signal start from the control device 431 via the OR gate circuit 449. The comparison circuit 448 in the NIT detection circuit 441 uses the version number extracted by the previous version number extraction circuit 446 sequentially supplied via the delay circuit 447 for the version number extracted by the version number extraction circuit 446. When the version number does not match, that is, the version number is updated, the NIT extraction request signal is output as the comparison output of logic “H”. Is supplied to the control unit 443 through the OR gate circuit 449. Further, the memory 442 includes a first-in first-out (FIFO) memory, and writing and reading of data are controlled by the control device 431 via the interface 432.
[0051]
Here, when a service is provided by a plurality of satellites, the TS has a NITa related to the TS and a plurality of NITOs related to the TS transmitted by other satellites. It can be identified by ID. In the NIT extraction unit 440, the NIT detection circuit 441 performs NIT detection for both NITa and NITo, and writes them in the FIFO memory 442 in the order of detection. Writing to the FIFO memory 442 is performed using a write clock write_clk synchronized with TS, and detection of NIT by the NIT detection circuit 441 and writing processing to the FIFO memory 442 are performed in real time. .
[0052]
The NIT extraction unit 440 performs NIT extraction processing according to the procedure shown in the flowchart of FIG.
[0053]
That is, the NIT extraction unit 440 outputs the logic “H” detection start signal start from the control device 431 or the logic “H” comparison output from the comparison circuit 448, that is, the NIT extraction request signal from the OR gate circuit 449. The NIT extraction operation state is entered when the control unit 443 accepts the NID via, and the NIT detection operation is performed for each TS packet by referring to PID (= “0x0010”).
[0054]
The control unit 443 loads the TS packet into the NIT / PID filter 444 (step S1), determines the PIT of the NIT (step S2), and when the PIT of the NIT is detected, determines whether or not it is the head data of the NIT. If it is determined (step S3) that the table ID is included in the packet in which the PID of NIT is detected, the table ID (own network “0x40”, other network ” 0x41 ″) (step S4), the NIT detected by the NIT / PID filter 444 is output from the NIT packet output circuit 445, and after the start of detection, from the head data of the first received table (That is, the table ID) is written into the FIFO memory 442 (steps S5 and S ).
[0055]
Further, the control unit 443 determines whether or not both the NITa of its own network and the NITo of the other network have been extracted (step S7). If the extraction has not ended, the process returns to step S1. The NIT extraction process is repeated for every 188 bytes of the TS packet (step S8).
[0056]
Then, the control unit 443 detects all the NITs of both the NITa of the own network and the NITo of the other network, writes them to the FIFO memory 442, notifies the control device of the end of extraction, and ends a series of detection operations. . After the writing is completed, the NIT data is held in the FIFO as shown in FIG.
[0057]
The NIT reinsertion unit 450 includes a memory unit 451 to which cable NIT data is sent from the control device 431 via the interface 432, as shown in FIG. The NIT replacement circuit 452 to which the TS is supplied stores the NIT data for the cable in the memory unit 451, and the NIT of the TS sent from the satellite system is converted into the NIT data for the cable by the NIT replacement circuit 452. Replace sequentially.
[0058]
The memory unit 451 has two FIFO memories 453 to which cable NIT data is sent from the control device 431 via the interface 432, and two pieces of cable NIT data are extracted from the FIFO memory 453 and stored. SRAMs 454A and 454B and an address counter 455 for generating the addresses of the SRAMs 454A and 454B. The memory unit 451 is controlled by the control device 431 to write and read data to and from the FIFO memory 453 via the interface 432, and is sent from the control device 431 via the interface 432. The cable NIT data is held in the FIFO memory 453, the cable NIT data is extracted from the FIFO memory 453, stored in the SRAM 454A or SRAM 454B, and the TS NIT is transferred from the satellite system to the NIT replacement circuit 452. Each time it is repeatedly sent, cable NIT data is sent from the SRAM 454A or SRAM 454B to the NIT replacement circuit 452.
[0059]
The NIT replacement circuit 452 includes a NIT packet detection circuit 456 to which the TS is supplied, a control unit 457 to which a detection output of the NIT packet detection circuit 456 is supplied, and a RAM switching circuit that is controlled by the control unit 457. 458 and a NIT switching circuit 459 that is switched and controlled by the detection output of the NIT packet detection circuit 456.
[0060]
The two SRAMs 454A and 454B of the memory unit 451 in the NIT reinsertion unit 450 are controlled by the control unit 457 of the NIT replacement circuit 452 to control data writing and reading each time the NIT is rewritten. Used alternately. That is, the controller 457 of the NIT replacement circuit 452 keeps the other SRAM 454B in an output-off state while outputting the data written in one SRAM 454A to the NIT replacement circuit 452, for example. The cable NIT data is written to the SRAM 454B via the FIFO memory 454A. When the writing of the latest cable NIT data to the SRAM 454B is completed, the output of the SRAM 454B is turned on so that the NIT data can be output to the NIT replacement circuit 452, and the output of the SRAM 454A is turned off. And wait until the next rewrite. The rewrite processing of NIT data transferred from the FIFO memory 453 to the SRAMs 454A and 454B is performed in real time with a clock synchronized with the TS.
[0061]
Here, the NIT data for the cable is written in the FIFO memory 453 via the interface 432 by the control device 431 in the order of NITa of the own network and NITo of the other network. Thereby, NITa of the own network and NITo of the other network are stored in the FIFO memory 453 as shown in FIG.
[0062]
When the control unit 457 receives the transfer start signal start from the control device 431, the NIT replacement circuit 452 transfers NIT data from the FIFO memory 453 to the SRAM 454A or the SRAM 454B. The transfer operation starts from NITa of the own network, and after writing all the data of NITa to the SRAM, the data of NITo of another network is written to a storage location different from the storage location of NITa of the SRAM. An example of writing NIT data to the SRAMs 454A and 454B is shown in FIG.
[0063]
In this NIT replacement circuit 452, NIT data transfer processing from the FIFO memory 453 to the SRAMs 454A and 454B is performed according to the procedure shown in the flowchart of FIG.
[0064]
That is, in the NIT replacement circuit 452, the control unit 457 controls the RAM switching circuit 458 to select one SRAM 454A corresponding to the TS packet (step S11), and the NIT packet detection circuit. It is determined whether or not the NIT packet detected by 456 is the NITa packet of its own network (step S12). If it is the NITa packet, the controller 457 is allowed to write to the memory unit 451 and the address counter 455 is set. Start (step S13), an address is generated by the address counter 455 (step S14), and the NITa data of its own network is transferred from the FIFO memory 453 to the other SRAM 454B and written (step S15).
[0065]
When the writing of the NITa data of the own network to the SRAM 454B is completed (step S16), or when the NIT packet detected by the NIT packet detection circuit 456 in the step S12 is not the NITa packet of the own network, the NIT It is determined whether or not the NIT packet detected by the packet detection circuit 456 is a NITo packet of another network (step S17). If it is not a NITo packet, the process returns to step S11, and the NIT packet detection circuit 456 determines the network of its own network. It waits for the detection of the NITa packet or the NITo packet of another network, and when it is a NITo packet, it gives the controller 457 permission to write to the memory unit 451 and addresses it. The counter 455 is started (step S18), the address is generated by the address counter 455 (step S19), and the NITo data of the other network is written into the SRAM 454B (step S20).
[0066]
When the writing of the NITo data for one packet of the other network to the SRAM 454B is completed (step S21), it is determined whether or not the processing has been completed for all the data of the NITo packet (step S22), and the processing for all the data of the NITo packet is performed. When the process is not completed, the process returns to step S11. When the processes for both the data of the NITa packet and the NITo packet are completed, the control unit is notified of the end, and the RAM switching circuit 458 is controlled to select the other SRAM 454B. (Step S23), the NIT data transfer process from the FIFO memory 453 to the SRAM 454B is terminated.
[0067]
In this way, the SRAM 454B storing the newly rewritten NIT data is put into a use state, and the SRAM 454A used so far is put into a standby state for the next NIT rewrite.
[0068]
Further, the NIT replacement circuit 452 performs transmission processing of NIT data from the FIFO memory 453 to the other SRAM 454B as described above, and transmits from the satellite system using the NIT data stored in one SRAM 454A. The replacement process for replacing the TS NIT with the cable NIT data is performed according to the procedure shown in the flowchart of FIG.
[0069]
That is, the NIT replacement circuit 452 determines whether or not the NIT packet detected by the NIT packet detection circuit 456 is the NITa packet of its own network (step S31). The address counter 455 is started (step S32), the address is generated by the address counter 455 (step S33), the NITa data of its own network is read from the SRAM 454A, and the NIT switching is performed via the RAM switching circuit 458. This is supplied to the circuit 457 (step S34).
[0070]
The NIT switching circuit 457 is switched from the error correction circuit 422 side to the RAM switching circuit 458 side during the NIT data period by the detection output from the NIT packet detection circuit 456. As a result, the contents of the TS NIT data sent from the satellite system are replaced with the cable NITa data (step S35).
[0071]
When reading of the NITa data of the own network from the SRAM 454A is completed (step S36), or when the NIT packet detected by the NIT packet detection circuit 456 in step 1 is not the NITa packet of the own network, the NIT It is determined whether or not the NIT packet detected by the packet detection circuit 456 is a NITo packet of another network (step S37). If it is not a NITo packet, the process returns to step S1 and the NIT packet detection circuit 456 returns to the network of its own network. The system waits for the detection of the NITa packet or the NITo packet of another network, and when the packet is a NITo packet, the read permission from the memory unit 451 is issued and the address counter 455 is used. (Step S38), an address is generated by the address counter 455 (step S39), and the NITo data of the other network is read from the SRAM 454A (step S40).
[0072]
When the reading of the NITo data of the other network from the SRAM 454A is completed (step S41), the process returns to step S31, and the NITA packet detection circuit 456 detects the NITa packet of the next own network or the NITo packet of the other network. Wait.
[0073]
In the NIT conversion circuit 423 configured as described above, the satellite NIT data taken into the FIFO memory 442 by the NIT extraction unit 440 is sent to the control device 431 via the interface 432. The control device 431 generates NIT suitable for cable transmission from the satellite NIT by software processing. Then, the NIT data converted for the cable is supplied from the control device 431 to the FIFO memory 453 of the NIT replacement unit 450 via the interface 432. In NIT replacement unit 450 in this embodiment, data is written in FIFO memory 453 in the order of NITa and NITo.
[0074]
The NIT conversion circuit 423 having such a configuration performs NIT processing according to the procedure shown in the flowchart of FIG.
[0075]
That is, first, the version number is changed (step S51), and the network ID is changed if necessary (step S52).
[0076]
Then, the processing loop of the TS from the satellite network is entered (step S53), and it is determined whether or not the stream (transponder in this case) from the satellite network is a transponder to be retransmitted to the cable network (step S54). If it is a transponder to be retransmitted, it is confirmed that it is a service list descriptor (Service_list_descriptor) (step S55), and it is determined whether or not it is a retransmission service (step S56).
[0077]
If it is not a retransmission service, the service ID and service type are deleted. That is, the information (service ID) and service type of the program that does not provide a service in the stream being retransmitted are deleted (step S57).
[0078]
When it is a retransmission service, or after deleting the service ID and service type, check the descriptor length (step S58), change the service list descriptor (Service_list_descriptor) length, and insert the stuffing descriptor (Stuff_descriptor) Then, the satellite delivery descriptor (Sattelite_delivery_descriptor) is replaced with the cable delivery descriptor (Cable_delivery_descriptor) (step S60).
[0079]
As described above, in the NIT rewriting process, for example, when a stream from the satellite network (here, transponder) is retransmitted to the cable network, at least the satellite delivery descriptor (Sattelite_delivery_descriptor) is replaced with the cable delivery descriptor (Cable_delivery_descriptor). Thus, the frequency information is matched. This is the minimum processing necessary to enable the receiving operation in the cable receiver. In addition, the information about the stream (in this case, the transponder) that is not retransmitted to the cable network and the information (service ID) of the non-serviced program in the stream that is being retransmitted are deleted, and the data reduced by dummy data or the like is made up. Furthermore, the NIT version number, the bit error index, and the like are matched with respect to the data length such as section length and descriptor length in the NIT as necessary.
[0080]
The dummy data needs to be negotiated so as not to cause a malfunction in the receiver. For example, a stuffing table ID, a stuffing descriptor tag, etc. are determined and determined as transmitter specifications, and when such a table ID or descriptor tag is transmitted, it is ignored on the receiver side. What should I do?
[0081]
If it is not a transponder to be retransmitted, the service list descriptor (Service_list_descriptor) and the satellite delivery descriptor (Sattelite_delivery_descriptor) are replaced with a stuffing descriptor (Stuff_descriptor) (step S61).
[0082]
Each time the process for the transponder to be retransmitted (steps S55 to S60) or the process for the transponder not to be retransmitted (step S61) is performed, the loop length of the TS is confirmed, the process returns to step S53, and the processes of steps S53 to S62 are performed. Is repeated over the loop length of the TS (step S62), after which the CRC 32 is replaced (step S63), and the NIT rewriting process is terminated.
[0083]
Similarly, network information related to other networks can be rewritten. For example, when services are provided by two satellites, if only one of the services is retransmitted in the cable network, the NITo section of the other network is converted to dummy data using the stuffing table ID. The NITa of both satellite networks is rewritten according to the service status in the cable network, and at the same time, the NITo is rewritten in conformity with the NITa.
[0084]
Next, a specific configuration example of the receiver 6 in the cable transmission system shown in FIG. 1 will be described with reference to FIG.
[0085]
In the receiver 6 having the configuration shown in FIG. 25, the reception tuner 62 of the cable front end unit 61 extracts a TS including a predetermined program from the mixed wave and outputs it to the QAM demodulation circuit 63. The QAM demodulating circuit 63 performs QAM demodulation on the input TS and outputs it to the error correction circuit 64. The error correction circuit 64 corrects the error information of the input TS and outputs it to the transport unit 65. The descrambler 66 of the transport unit 65 decodes (descrambles) the scramble applied to the TS using the descrambling information recorded on the IC card 60 issued by the satellite broadcasting service provider 1. Output to the multiplexer 67.
[0086]
The demultiplexer 67 extracts predetermined program information from the TS in which a plurality of program information is multiplexed and supplies the extracted program information to the MPEG decoding unit 68. The MPEG decoding unit 68 decompresses the input program information to generate a video signal and an audio signal, and outputs them to the television receiver 7.
[0087]
The host processor 69 controls the entire receiver 6 based on the viewer's channel selection operation, and records the received pay program information (program viewing information) on the IC card 60. Further, the host processor 69 reads the descrambling information recorded on the IC card 60 and supplies it to the descrambler 66. Further, the host processor 69 controls the communication unit 70 to notify the viewing information processing unit 14 of the satellite broadcast service provider 1 of the program viewing information recorded on the IC card 60 periodically via the public telephone line. .
[0088]
Next, information distribution processing by the distribution unit 34 in the cable television station 3 will be described with reference to the flowchart of FIG.
[0089]
In step S <b> 71, the CS antenna 31 receives a CS wave via the communication satellite 2 and outputs it to the distribution unit 34. The terrestrial antenna 32 receives an analog broadcast wave and outputs it to the distribution unit 34. The BS antenna 33 receives a BS wave via a broadcasting satellite and outputs it to the distribution unit 34.
[0090]
In step S72, the signal distributor 41 distributes the CS wave to the modulation conversion devices 42-1 to 42-N. The terrestrial re-sending device 43 performs RF conversion on the input analog broadcast wave and outputs it to the signal mixer 45. The satellite signal retransmitting device 44 converts the input BS wave into RF and outputs it to the signal mixer 45.
[0091]
In step S <b> 73, the QPSK demodulation circuit 421 of the modulation conversion device 42 performs QPSK demodulation on the input CS wave, and outputs it to the error correction circuit 422.
[0092]
In step S74, the error correction circuit 422 performs error correction on the input signal and outputs the error-corrected TS to the NIT conversion circuit 423.
[0093]
In step S75, the NIT conversion circuit 423 replaces the CS wave NIT with the cable television NIT and outputs the NIT for the cable television to the QAM modulation circuit 424.
[0094]
In step S76, the QAM modulation circuit 424 QAM modulates the input signal and outputs the result to the frequency conversion circuit 425.
[0095]
In step S 77, the frequency conversion circuit 425 converts the frequency of the input signal into a predetermined value that can be transmitted in the cable television network 4, and outputs the converted value to the signal mixer 45.
[0096]
In step S78, the signal mixer 45 mixes the signals input from the modulation conversion devices 42-1 to 42-N, the terrestrial retransmitting device 43, and the satellite signal retransmitting device 44, and outputs them to the amplifier 46. .
[0097]
In step S <b> 79, the amplifier 46 amplifies the input mixed wave and distributes it to the receiver 6 via the cable television network 4.
[0098]
Next, the program reception process of the receiver 6 will be described with reference to the flowchart of FIG.
[0099]
In step S <b> 81, the reception tuner 62 of the cable front end unit 61 extracts TS including the program (program included in the CS wave) selected by the viewer from the mixed wave, and outputs it to the QAM demodulation circuit 63.
[0100]
In step S <b> 82, the QAM demodulation circuit 63 performs QAM demodulation on the input TS and outputs it to the error correction circuit 64.
[0101]
In step S <b> 83, the error correction circuit 64 corrects the error information of the input TS and outputs it to the transport unit 65.
[0102]
In step S84, the descrambler 66 of the transport unit 65 decodes the scramble applied to the TS using the descramble information recorded on the IC card 60 issued by the satellite broadcasting service provider 1, Output to the multiplexer 67.
[0103]
In step S85, the demultiplexer 67 demultiplexes the TS, extracts information on the program selected by the viewer, and supplies the extracted information to the MPEG decoding unit 68.
[0104]
In step S 86, the MPEG decoding unit 68 decompresses the input program information to generate a video signal and an audio signal, and outputs them to the television receiver 7. The television receiver 7 reproduces the input video signal and audio signal.
[0105]
In step S87, when the received program is a pay (pay per view) program, the host processor 69 records the information (program viewing information) on the IC card 60. The communication unit 70 periodically notifies the customer management unit 35 of the program viewing information recorded on the IC card 60 via the public telephone line and the viewing information processing unit 14.
[0107]
That is, in the cable transmission system having such a configuration, the cable television station 3 receives a digital broadcast signal or the like transmitted via the communication satellite 2, and the viewer's house 5 is transmitted from the cable television station 3 via the cable television network 4. Network signal of the signal demodulated by the NIT conversion circuit 423 with respect to the signal obtained by QPSK demodulating the TS of the digital satellite broadcast signal by the QPSK demodulation circuit 421 in the modulation conversion device 42 of the cable television station 3. Is replaced with cable network information, and is retransmitted from the QAM modulation circuit 424 to the cable television network 4 via the frequency conversion circuit 425. The NIT conversion circuit 423 detects that the version information included in the network information extracted from the demodulated signal has been updated, and converts the network information into network information for a cable that is compatible with the network for retransmitting. By doing so, the network information of the demodulated signal can be replaced with the network information for the cable.
[0108]
Here, the control device is an on-board microcomputer, and by incorporating software so that certain processing is possible, all conversion processes from extraction to rewriting and reinsertion can be performed automatically. Thus, for example, rewriting processing of network information can be automatically performed in an apartment consonance hearing device or the like.
[0109]
Further, by using a microcomputer or a DSP capable of high-speed processing, functions equivalent to the hardware configuration in the above-described embodiment can be realized by software.
[0110]
【The invention's effect】
As described above, according to the present invention, the digital satellite broadcast signal is demodulated, the version information included in the network information extracted from the demodulated signal is detected, and the network information is retransmitted. By converting the network information of the demodulated signal into the network information for the cable suitable for the network, and replacing the network information of the demodulated signal with the network information for the cable, the processing corresponding to the NIT change of the digital broadcast data is automatically performed. Can do.
[0111]
That is, according to the present invention, even if the satellite operator does not know the time to change the NIT, the version information included in the network information from the satellite system is monitored constantly or at an appropriate time interval, and the version of the satellite system is monitored. When information is updated, network information can be automatically rewritten in accordance with changes in the satellite system, without the need for a resident administrator or timer, and so on. Can be avoided. Further, even in a hearing facility that basically has no manager, processing for responding to changes in NIT can be performed.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing a configuration of a cable transmission system to which the present invention is applied.
FIG. 2 is a diagram illustrating a frame structure of an MPEG2 transport packet and a DVB system.
FIG. 3 is a diagram illustrating a packet structure of an MPEG2 transport packet.
FIG. 4 is a diagram illustrating a packet structure of a PES packet.
FIG. 5 is a diagram showing a table structure of a program association table (PAT).
FIG. 6 is a diagram showing a table structure of a program map table (PMT).
FIG. 7 is a diagram showing a table structure of a network information table (NIT).
FIG. 8 is a diagram showing a structure of a satellite delivery system descriptor in the NIT.
FIG. 9 is a diagram showing a structure of a CATV delivery system descriptor in the NIT.
FIG. 10 is a diagram illustrating a structure of a service list descriptor in the NIT.
FIG. 11 is a block diagram illustrating a configuration example of a distribution unit of a cable television station in the cable transmission system.
FIG. 12 is a diagram illustrating linear polarization of a CS wave.
FIG. 13 is a block diagram illustrating a configuration example of a modulation conversion apparatus in the distribution unit.
FIG. 14 is a diagram illustrating mixed waves.
FIG. 15 is a block diagram illustrating a configuration example of a NIT conversion circuit in the modulation conversion apparatus.
FIG. 16 is a block diagram illustrating a configuration example of a NIT extraction unit in the NIT conversion circuit.
FIG. 17 is a flowchart illustrating NIT extraction processing by the NIT extraction unit.
FIG. 18 is a diagram illustrating an example of writing to a FIFO memory in the NIT extraction unit.
FIG. 19 is a block diagram illustrating a configuration example of a NIT replacement unit in the NIT conversion circuit.
FIG. 20 is a diagram illustrating an example of writing to a FIFO memory in the NIT replacement unit.
FIG. 21 is a diagram showing an example of writing to SRAM in the NIT replacement unit.
FIG. 22 is a flowchart illustrating data transfer processing from the FIFO memory to the SRAM in the NIT replacement unit.
FIG. 23 is a flowchart for explaining NIT replacement processing by the NIT replacement circuit in the NIT replacement unit;
FIG. 24 is a flowchart illustrating NIT replacement processing in the NIT replacement unit.
FIG. 25 is a block diagram illustrating a configuration example of a receiver in the cable transmission system.
FIG. 26 is a flowchart illustrating information distribution processing by the distribution unit.
FIG. 27 is a flowchart for explaining program reception processing by the receiver.
[Explanation of symbols]
1 satellite broadcasting service provider, 2 communication satellite, 3 cable TV station, 4 cable TV network, 6 receiver, 7 television receiver, 11 transmission unit, 12 viewer management unit, 13 key management unit, 14 viewing information processing unit , 34 Distribution unit, 35 Customer management unit, 41 Signal distributor, 42 Modulation conversion device, 45 Signal mixer, 421 QPSK demodulation circuit, 422 Error correction circuit, 423 NIT conversion circuit, 424 QAM modulation circuit, 425 Frequency conversion circuit, 431 control unit, 432 interface, 440 NIT extraction unit, 441 NIT detection circuit, 442, 451 memory, 443 control unit, 444 NIT / PID filter, 445 NIT packet output circuit, 446 version number extraction circuit, 447 delay circuit, 448 comparison Circuit, 449 OR gate circuit, 450 NIT reinsertion unit, 52NIT replacement circuit

Claims (4)

Receiving means for receiving a digital satellite broadcast signal;
Demodulation means for demodulating the signal received by the receiving means;
Network information extraction means for extracting network information of the signal demodulated by the demodulation means;
A network suitable for a network that monitors version information included in network information extracted by the network information extracting means and retransmits the network information extracted by the network information extracting means when the version information is updated Network information conversion means for converting information,
Network information converted by the network information converting means as cable information, network information replacing means for replacing the network information of the signal demodulated by the demodulating means with the cable information,
An information transmitting apparatus comprising: modulation means for modulating a signal demodulated by the demodulating means and network information replaced by information for cable transmission by the network information replacing means. The network information conversion means sequentially stores the version information included in the network information extracted by the network information extraction means, and the version information is updated by comparing the previously stored version information with the version information stored this time. The information transmitting apparatus according to claim 1, wherein the information transmitting apparatus detects the above. A receiving step for receiving a digital satellite broadcast signal;
A demodulation step for demodulating the signal received in the reception step;
A network information extraction step for extracting network information of the signal demodulated in the demodulation step;
Network information conversion for converting the network information extracted in the network information extraction step into network information suitable for the network to be retransmitted when the version information included in the network information extracted in the network information extraction step is updated Steps,
Network information converted in the network information conversion step as cable information, network information replacement step for replacing the network information of the signal demodulated in the demodulation step with the cable information,
A modulation step of modulating a signal demodulated in the demodulation step and the network information replaced in the network information replacement step with information for cable transmission. In the network information conversion step, the version information included in the network information extracted in the network information extraction step is sequentially stored, and the version information stored last time is compared with the version information stored this time, thereby 4. The information transmission method according to claim 3, wherein the update is detected.

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