JP4325052B2 - Sending network information - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a network information transmission method when a satellite digital service signal is converted into a digital service signal for cable transmission by a modulation conversion method in a local area and retransmitted to a cable network.
[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 TV 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 state of Transport Stream (TS), converted to the RF frequency of the cable TV again 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 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. In this case, the service ID of the program included in the transponder that is not retransmitted must be deleted from the NIT.
[0006]
Since the digital broadcast receiver selects a program based on this NIT, if there is a service ID of a program that does not exist on the transmission path, it may cause a malfunction due to searching for a program that does not exist.
[0007]
[Problems to be solved by the invention]
In this way, when a satellite program is retransmitted to the cable network by the modulation conversion retransmitting method, basically, the stream other than the NIT information is not touched. Is difficult to insert, and different networks cannot be associated.
[0008]
In addition, in order to process information related to services in the local area, all PSI / SI information in the stream is replaced, and enormous capital investment and operation costs are required.
[0009]
In addition, since the operation of the receiver is performed based on network information, the reception operation may be complicated in a system that does not have local network information as other network information.
[0010]
Furthermore, since SI information such as electronic program guide information (EPG: Electoric Program Guide) is different for each network, a system that does not distinguish different networks by network identifiers may cause malfunction in the reception operation at the receiver. .
[0011]
Accordingly, an object of the present invention is to eliminate the problem of inconvenience for both the network operator and the receiver who perform the re-transmission service in this way, and to transmit the satellite digital service signal in the local area by cable conversion using the modulation conversion method. It is an object of the present invention to provide a network information transmission method that makes it possible to add a new network based on a program structure in a local area when it is converted into a digital service signal for use and re-transmitted to a cable network.
[0012]
[Means for Solving the Problems]
The network information transmission method according to the present invention is a method for converting satellite-based digital service signals into digital service signals for cable transmission by a modulation conversion method in a local area and retransmitting them to the cable network. At the time of creation, a stuffing table that secures a capacity for inserting local network information as other network information in the local area is transmitted, and the local network information based on the program configuration in the local area is used as other network information in the satellite transport stream. It is inserted and sent out to a cable network.
[0013]
Further, the network information transmission method according to the present invention converts a satellite digital service signal into a digital multi-channel service signal for cable transmission by a modulation conversion method in a local area, and retransmits it to the cable network. Some of the programs in the transport stream are deleted, and instead of the deleted program network information, local network information based on the program structure in the local area is inserted into the satellite transport stream as other network information and transmitted. It is characterized by doing.
[0014]
The network information transmission method according to the present invention is a method of converting a digital service signal of a plurality of satellite systems into a digital multi-channel service signal for cable transmission by a modulation conversion method in a local area and retransmitting it to a cable network. Instead of a part of satellite network information that is not retransmitted, local network information based on the program structure in the local area is inserted into the satellite transport stream as other network information and transmitted.
[0015]
The network information transmission method according to the present invention is a method of converting a digital service signal of a plurality of satellite systems into a digital multi-channel service signal for cable transmission by a modulation conversion method in a local area and retransmitting it to a cable network. The local network information based on the program structure in the local area is intermittently replaced with other network information included in the satellite-based transport stream and transmitted.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0017]
The network information transmission method according to the present invention is applied to, for example, an information transmission system configured as shown in FIG.
[0018]
In this information transmission system, a cable television station 3 receives a digital broadcast signal or the like transmitted from a center station 1 operated by a plurality of cable operators via a communication satellite 2, and the cable television station 3 transmits a cable television network 4. Is distributed to the receiver 6 of the viewer's house 5 via
[0019]
In this information transmission system, the transmission section 11 of the center station 1 scrambles the MPEG-compressed program information supplied from the program supplier, and provides electronic program guide information (EPG: Electoric Program Guide) and viewers. It is multiplexed with service information such as 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.
[0020]
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.
[0021]
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.
[0022]
In this information transmission system, one of the following three methods is adopted in order to be able to insert information NItro related to other networks added in the local area into the TS retransmitted by the modulation conversion method.
[0023]
In the first method, an area of other network information NItro is secured in the TS in advance at the time of transmission in the satellite system.
[0024]
In the second method, the portion of the NIT area that has been stuffed due to a decrease in retransmission information is allocated to the area of the other network information NItro.
[0025]
In the third method, when the NITo area is secured in the TS from the satellite system, the original NITo rewritten for cable transmission using this area and the NITo which is local information are alternately transmitted. To do.
[0026]
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 FIG. 2B is modulated by QPSK (Quadrature Phase Shift Keying), and then frequency-converted to the SHF band to become a digital broadcast signal transmitted from the communication satellite 20.
[0027]
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 an attribute of an individual stream (data string) of the packet is arranged in the packet header. In the payload (data part) of the MPEG2 transport packet, a PES (Packetized Elementary Stream) packet whose packet configuration is shown in FIG. 4 is subdivided and arranged, and program specification information defined in the MPEG2 system is further provided. Tables such as Program Association Table (PAT), Program Map Table (PMT), and Network Information Table (NIT) as (PSI: Program Specific Informetion) Types are also arranged by section format.
[0028]
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 = “0 × 0000” is fixedly assigned.
[0029]
The main contents will be described. The table ID indicates the type of the table and is “0 × 00” (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 “0 × 0000”. The program map PID indicates the PID of the PMT.
[0030]
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 “0 × 02” 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.
[0031]
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 “0 × 40” and the other networks are “0 × 41”. The network ID identifies the network. In the case of a satellite, it corresponds to an individual satellite.
[0032]
When the 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.
[0033]
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.
[0034]
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, “0 × 43” is obtained. 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.
[0035]
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 “0 × 44”. 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.
[0036]
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.
[0037]
FIG. 10 shows the structure of the service list descriptor. The descriptor tag is defined by DVB and indicates the type of descriptor. This descriptor is “0 × 41”. 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.
[0038]
At the time of re-transmission at the 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. 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.
[0039]
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.
[0040]
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.
[0041]
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 341. That is, it is shown that TS waves, TS3, and TS5 are included in the H polarization of the CS wave, and TS2, TS4, and TS6 are included in the V polarization of the CS wave.
[0042]
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 43.
[0043]
The terrestrial retransmitting device 44 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 45 receives the BS received by the BS antenna 33. The wave is RF-converted (modulation conversion from the FM signal to the AM signal is performed by analog processing) and output to the signal mixer 45 as a retransmitted wave to the cable television.
[0044]
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) conversion circuit 423.
[0045]
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.
[0046]
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.
[0047]
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.
[0048]
A specific configuration example of the NIT conversion circuit 423 will be described with reference to FIGS.
[0049]
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.
[0050]
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.
[0051]
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. The NIT packet output circuit 445 outputs the NIT to the memory 442. The memory 442 includes a first-in first-out (FIFO) memory, and data writing and reading are controlled by the control device 431 via the interface 432.
[0052]
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. .
[0053]
The NIT extraction unit 440 performs NIT extraction processing according to the procedure shown in the flowchart of FIG.
[0054]
That is, the NIT extraction unit 440 enters an operation state when the control unit 443 receives the detection start signal start from the control device 431, and refers to the PID (= “0 × 0010”) for each NIT packet. Detection operation is performed.
[0055]
The control unit 443 loads the TS packet into the NIT / PID filter 44 (step S1), determines the PIT of the NIT (step S2), and when the PIT of the NIT is detected, determines whether it is the head data of the NIT. If it is determined (step S3) and the packet in which the PID of NIT is detected includes a table ID, the table ID (own network “0 × 40”, others) The network “0 × 41”) is referred to (step S4), the NIT detected by the NIT / PID filter 444 is output from the NIT packet output circuit 445, and the table received first after the detection is started. Are written into the FIFO memory 442 from the top data (ie, table ID) (steps S5 and S6).
[0056]
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 each 188-byte TS packet (step S8).
[0057]
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.
[0058]
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.
[0059]
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 the 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.
[0060]
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.
[0061]
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.
[0062]
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.
[0063]
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.
[0064]
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.
[0065]
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 permitted 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).
[0066]
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).
[0067]
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.
[0068]
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.
[0069]
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.
[0070]
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. It supplies to the circuit 457 (step S34).
[0071]
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).
[0072]
When reading of the NITa data of the local 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 local 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 S31, and the NIT packet detection circuit 456 returns to 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 the NITo packet, it gives permission to read from the memory unit 451 and at the same time the address counter 45 5 is started (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 and supplied to the NIT switching circuit 457 via the RAM switching circuit 458 (step S40). ).
[0073]
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 content of the TS NIT data sent from the satellite system is replaced with the cable NITo data (step S41).
[0074]
When the reading of the NITo data of the other network from the SRAM 454A is completed (step S42), 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.
[0075]
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 the NIT replacement unit 450 in this embodiment, data is written to the FIFO memory 453 in the order of NITa and NITo.
[0076]
The NIT conversion circuit 423 having such a configuration performs NIT processing according to the procedure shown in the flowchart of FIG.
[0077]
That is, first, the version number is changed (step S51), and the network ID is changed if necessary (step S52).
[0078]
Then, the processing loop for 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).
[0079]
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).
[0080]
If it is not a retransmission service, the service ID and service type are deleted. That is, information (service ID) and service type of a program that does not provide a service in the stream that is being retransmitted are deleted (step S57).
[0081]
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).
[0082]
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 that is not retransmitted to the cable network (here, the transponder) and the information about the program that does not perform the service (service ID) in the stream that is being retransmitted are deleted to make up for the data that has been reduced by dummy data or the like. 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.
[0083]
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 by the receiver. What should I do?
[0084]
If the transponder is not to be retransmitted, the service list descriptor (Service_list_descriptor) and the satellite delivery descriptor (Sattelite_delivery_descriptor) are replaced with the stuffing descriptor (Stuff_descriptor) (step S61).
[0085]
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 S3 to S12 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.
[0086]
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.
[0087]
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.
[0088]
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.
[0089]
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 RF-converts the input BS wave (modulation conversion from FM signal to AM signal is performed by analog processing) and outputs it to the signal mixer 45 as a retransmitted wave to the cable television.
[0090]
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.
[0091]
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.
[0092]
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.
[0093]
In step S76, the QAM modulation circuit 424 QAM modulates the input signal and outputs the result to the frequency conversion circuit 425.
[0094]
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.
[0095]
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. .
[0096]
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.
[0097]
Here, in this information transmission system, description will be given on the first to third methods adopted in order to allow information NItro related to other networks added in the local area to be inserted into the TS retransmitted by the modulation conversion method. To do.
[0098]
First, in the first method, an area is secured in which the network information NItro added in the local area such as the cable television station 3 can be inserted into the TS when the satellite side multiplexes the program data and other PSI / SI. Therefore, as shown in FIG. 26, a stuffing table having a table ID “0 × 72” is transmitted with NIT PID (= “0 × 0010”).
[0099]
Then, the cable television station 3 uses this area to insert the network information NIRo added in the local area when the rewrite NIT is reinserted by the modulation conversion device 42. At this time, the table ID “0 × 72” is changed to a table ID “0 × 41” indicating information NItro of another network.
[0100]
Next, in the second method, as shown in FIG. 27, data related to information not to be transmitted at the time of re-sending in the cable system is deleted from the NIT, so that the vacant area is information NItro of other networks in the local area. Used as an insertion area for This second method cannot be used when all satellite services are retransmitted to the cable network.
[0101]
Furthermore, the third method is effective when a service is provided by a plurality of satellites. That is, when the service is performed by a plurality of satellites as described above, the TS includes the NITa related to the TS and the NITo related to the TS transmitted by other satellites, and these are identified by the table ID. can do. NIT is specified to be retransmitted within a certain period, but when it is retransmitted twice or more within this period, at the time of rewriting, as shown in FIG. The network information NItro can be inserted by replacing the NIT data area with the local network information NItro. For example, when the retransmission cycle of NITa is defined as once per second and the retransmission cycle of NITo is defined as once every 5 seconds, retransmission is performed at a frequency of once per second in operation. The local network information NItro is inserted by replacing at least one of the NITo sent five times within 5 seconds with the NItro.
[0102]
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.
[0103]
In the receiver 6 having the configuration shown in FIG. 29, the reception tuner 62 of the cable front end unit 61 extracts a TS including a predetermined program from the mixed wave and outputs the TS 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 center station 1, and sends it to the demultiplexer 67. Output.
[0104]
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.
[0105]
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 71 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. .
[0106]
Next, the network switching operation in the receiver 6 will be described.
[0107]
Here, a description will be given of a network switching operation in the case of receiving a signal retransmitted from a plurality of satellites by the cable television station 3 by a modulation conversion method.
[0108]
The host processor 69 of the receiver 6 stores the latest network information NITa in the memory, and based on this, controls the reception tuner 62 of the cable front end unit 61 to select a channel in the network. The presence of another network is performed by recognizing the table ID “0 × 41”, and it is possible to know which network the other network belongs to by recognizing the network ID.
[0109]
When there is a network switching request, the host processor 69 takes in NITo and performs a receiving operation so that the switching destination TS can be received based on this information.
[0110]
Then, the host processor 69 of the receiver 6 that has obtained the TS to be switched to fetches the network information NITa from the TS into the memory, thereby enabling the channel selection operation within the network. For example, when a service is provided by two networks, the TS of the first network includes information NITa1 of the local network and information NITo2 of the other network, and the TS of the second network includes the local network. Network information NITa2 and other network information NITo1 are included, and the host processor 69 of the receiver 6 stores the network information NITa1 and NITo2 or the network information NITa2 and NITo1 in a memory. When switching from the first network to the second network, information for switching to the second network is obtained based on the information NITo2 of the other network. Normally, the other network information NITo does not include all the information of other networks and only a part of the information is written. Therefore, after switching to the second network by the information of NITo2, the memory storage is performed. It is possible to select a channel for all the services in the second network based on the information of NITa2 being used.
[0111]
Here, as a specific example of the network switching operation in the receiver 6, a case where the network ID = "01" is switched to the network ID = "02" will be described.
[0112]
As shown in FIG. 30, in the network stream having the network ID = “01”, the own network information NITa relating to the network ID = “01” and the other network information NITo relating to the network ID = “02” are transmitted. In the network stream having the network ID = “02”, the own network information NITa related to the network ID = “02” and other network information NITo related to the network ID = “01” are transmitted.
[0113]
When switching from the network ID = “01” to the network ID = “02”, the host processor 69 of the receiver 6 is initially related to NITa (network information related to the network ID = “01”) and NITo (network ID = “02”). Network information) is stored in a memory, and a program is selected within the network based on frequency information and program information in NITa. Here, NITo includes frequency information and program information in the network with the network ID = “02”, but it is sufficient to have the minimum information necessary for switching the network. In the example shown in FIG. 30, as part of the information in the network with the network ID = “02”, CH. 3 and only the program information (SID = "05") included in the stream.
[0114]
When there is a network switching request, the host processor 69, in this example, uses the CH .. based on the information in the other network information NITo stored in the memory. 3 is received and the program information relating to SID = "05" is displayed on the screen. The host processor 69 is connected to the CH. 3 is received, the local network information NITa relating to the network having the network ID = “02” and the network information NITo relating to the network ID = “01” are acquired from the stream of this network, and stored in the memory.
[0115]
Also, the same operation can be performed when a third network is added in the local area.
[0116]
In this case, as shown in FIG. 31, the TS of the first network having the network ID = “01” includes the other network information NITo2 and the network ID = “03” regarding the local network information NITa and the network ID = “02”. The other network information NITo3 related to "is sent, and the TS of the second network having the network ID =" 02 "has the other network information NITo and the network ID =""related to the information NITa of the own network and the network ID =" 01 ". Other network information NITo relating to 03 ”is transmitted, and the TS of the third network having the network ID =“ 03 ”is transmitted to the network information NITo relating to its own network and the network ID =“ 01 ”. Other network information NITo is delivered about the work ID = "02".
[0117]
For example, when switching from the first network to the third network, initially, the host processor 69 of the receiver 6 relates to NITa1 (network information related to network ID = “01”) and NITo2 (network ID = “02”). Network information) and NITo3 (network information related to network ID = “03”) are stored in the memory, and the program is selected in the first network based on the frequency information and program information in NITa. . Here, each NITo includes frequency information and program information in each network with network ID = “02” and network ID = “03”, but can have the minimum information necessary for switching the network. That's fine. In the example shown in FIG. 31, one NITo is a part of the information in the network with the network ID = “02”. 3 and only the program information (SID = “05”) included in the stream, and the other NITo has the CH as part of the information in the network with the network ID = “03”. . 5 and only the program information (SID = "09") included in the stream.
[0118]
When switching from the first network to the third network, NITo3 is used. The second network and the third network can be distinguished from each other by a table ID “0 × 41” indicating another network and a network ID in the table. The operation after detecting NITo3 is the same as when switching from the first network to the second network.
[0119]
That is, when there is a network switching request, the host processor 69 selects the requested network information (in this example, other network information related to network ID = “03”) from the two other network information stored in the memory. Based on the information in the other network information related to this network ID = “03”, in this example, CH. 5 is received, and program information relating to SID = "09" is displayed on the screen. The host processor 69 is connected to the CH. 5, the local network information NITa relating to the network having the network ID = “03” and the other network information NITo relating to the network ID = “01” and the other network relating to the network ID = “02” from the stream of the third network. Information NITo is acquired and stored in memory.
[0120]
Next, the program reception process of the receiver 5 will be described with reference to the flowchart of FIG.
[0121]
In step S <b> 81, the reception tuner 52 of the cable front end unit 61 extracts a QAM signal including the program (program included in the CS wave) selected by the viewer from the mixed wave and outputs the QAM signal to the QAM demodulation circuit 63.
[0122]
In step S <b> 82, the QAM demodulation circuit 63 performs QAM demodulation on the input QAM signal and outputs it to the error correction circuit 64.
[0123]
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.
[0124]
In step S84, the descrambler 66 of the transport unit 65 decodes the scramble applied to the TS using the descrambling information recorded in the IC card 60 issued by the center station 1, and sends it to the demultiplexer 67. Output.
[0125]
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.
[0126]
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.
[0127]
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.
[0128]
When the viewer selects a program transmitted by terrestrial or BS waves, the program information is not multiplexed and is not received by digital CATV / STB.
[0129]
【The invention's effect】
As described above, according to the network information transmission method according to the present invention, the satellite system digital service signal is converted into the digital service signal for cable transmission by the modulation conversion method in the local area and retransmitted to the cable network. When creating program information in the satellite system, a stuffing table that secures a capacity for inserting local network information as other network information in the local area is transmitted, and local network information based on the program configuration in the local area is transmitted in the satellite system. Since it is inserted into the stream as other network information and sent to the cable network, the satellite digital service signal is converted into a digital service signal for cable transmission by a modulation conversion method in the local area. When re-transmitted in Le network, it is possible to add a new network by the program configuration in a local area.
[0130]
Further, according to the network information sending method according to the present invention, in the local area, the satellite-based digital service signal is converted into a digital multi-channel service signal for cable transmission by the modulation conversion method and re-sent to the cable network. Some programs in the satellite transport stream are deleted, and the local network information based on the program structure in the local area is inserted into the satellite transport stream as other network information in place of the deleted program network information. Therefore, when a satellite digital service signal is converted into a digital service signal for cable transmission by a modulation conversion method in the local area and re-sent to the cable network, a new network based on the program structure in the local area is transmitted. It is possible to add a network.
[0131]
Also, according to the network information transmission method of the present invention, a plurality of satellite digital service signals are converted into a digital multi-channel service signal for cable transmission by a modulation conversion method in a local area and retransmitted to the cable network. In this case, the local network information based on the program structure in the local area is inserted into the satellite transport stream as other network information and transmitted instead of a part of the satellite network information that is not retransmitted. When a digital service signal of the system is converted into a digital service signal for cable transmission by a modulation conversion method and re-transmitted to the cable network, a new network having a program configuration in the local area can be added.
[0132]
Furthermore, according to the network information transmission method of the present invention, a digital service signal of a plurality of satellite systems is converted into a digital multi-channel service signal for cable transmission by a modulation conversion method in a local area and retransmitted to the cable network. In this case, the local network information based on the program structure in the local area is intermittently replaced with other network information contained in the satellite transport stream, and the satellite digital service signal is transmitted by cable using the modulation conversion method in the local area. When the digital service signal is converted into a digital service signal and re-transmitted to the cable network, a new network having a program structure in the local area can be added.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing a configuration of an information 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 information 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 flowchart for explaining information distribution processing by the distribution unit;
FIG. 26 is a diagram illustrating a state of network information in the first scheme employed in order to be able to insert information on another network added in the local area into a TS retransmitted by the modulation conversion scheme.
FIG. 27 is a diagram showing a state of network information in a second scheme adopted in order to be able to insert information on another network added in the local area into a TS retransmitted by the modulation conversion scheme.
FIG. 28 is a diagram illustrating a state of network information in a third scheme employed in order to be able to insert information on another network added in the local area into a TS retransmitted by the modulation conversion scheme.
FIG. 29 is a block diagram illustrating a configuration example of a receiver in the information transmission system.
FIG. 30 is a diagram showing a specific example of the network switching operation from the first network to the second network by the receiver.
FIG. 31 is a diagram showing a specific example of a network switching operation from the first network to the third network by the receiver.
FIG. 32 is a flowchart for explaining program reception processing by the receiver.
[Explanation of symbols]
1 center station, 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, 35 customer Management unit, 41 signal distributor, 42 modulation conversion device, 45 signal mixer, 60 IC card, 61 cable front end unit, 62 reception tuner, 63 QAM demodulation circuit, 64 error correction circuit, 65 transport unit, 66 descrambler , 67 Demultiplexer, 68 MPEG decoding unit, 69 Host processor, 70 Communication unit, 421 QPSK demodulation circuit, 422 Error correction circuit, 423 NIT conversion circuit, 424 QAM modulation circuit, 425 Frequency conversion circuit

Claims (4)

In the local area, the satellite system digital service signal is converted into a digital service signal for cable transmission by the modulation conversion method and re-sent to the cable network.
When creating program information in the satellite system, send out a stuffing table that secures the capacity to insert local network information as other network information in the local area,
A network information transmission method, wherein local network information based on a program structure in a local area is inserted as other network information into a satellite-based transport stream and transmitted to a cable network. In the local area, the satellite system digital service signal is converted into a digital multi-channel service signal for cable transmission by the modulation conversion method and re-sent to the cable network.
Some programs in the satellite transport stream are deleted, and the local network information based on the program structure in the local area is inserted into the satellite transport stream as other network information in place of the deleted program network information. Network information transmission method, characterized by: When converting digital service signals of multiple satellite systems into digital multi-channel service signals for cable transmission using a modulation conversion method in the local area and retransmitting them to the cable network,
Instead of a part of satellite network information that is not retransmitted, local network information based on the program structure in the local area is inserted into the satellite transport stream as other network information and transmitted. Delivery method. When converting digital service signals of multiple satellite systems into digital multi-channel service signals for cable transmission using a modulation conversion method in the local area and retransmitting them to the cable network,
A network information transmission method, wherein local network information based on a program structure in a local area is intermittently replaced with other network information included in a satellite-based transport stream.

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