JPH11355224A - System and method for distributing information - Google Patents

Abstract

PROBLEM TO BE SOLVED: To distribute a program to be broadcast by digital satellite broadcasting to plural cable television networks at a low cost by converting a digital multi-channel service signal distributed from a center station through a satellite line for cable transmission and distributing the signal to plural pieces of reception terminal equipments. SOLUTION: In this information distribution system, a center station 1 distributes the digital multi-channel service signal through the satellite line. Plural cable television stations 31 -3n receive the digital multi-channel service signal transmitted from the center station 1 through the satellite line and the received digital multi-channel service signal is converted to a digital multi-channel service signal for cable transmission by a modulation/conversion means and sent to respective own cable television networks 41 -4n . Plural pieces of reception terminal equipment 511 -5nm receive the digital multi-channel service signal distributed from the cable television stations 31 -3n through the cable television networks 41 -4n .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information distribution system and an information distribution method for digital multi-channel service signals via a satellite line and a cable network.

[0002]

2. Description of the Related Art In recent years, so-called cable television has begun to spread as a multi-channel medium even in areas other than remote areas and difficult-to-view areas. FIG. 30 shows an example of a cable television receiver. The data receiving unit 71 extracts a receiver control signal from a cable television signal transmitted from a cable television station and supplies the signal to the host processor 72.
Note that this cable television signal is an analog signal.
The host processor 72 controls the entire receiver based on a receiver control signal and a channel selection operation by a viewer. The receiving tuner 73 extracts the signal of the program selected by the viewer from the cable TV signal and outputs the signal to the descrambler 74. The descrambler 74 descrambles the program signal using the synchronization signal supplied from the AM detection circuit 77 and outputs the descrambled signal to the video detection circuit 75 and the AM detection circuit 77. The video detection circuit 75 extracts and demodulates the video signal from the program signal, and outputs the remainder of the program signal to the FM detection circuit 76. F
The M detection circuit 76 demodulates the audio signal.

As described above, in a cable television, information (a video signal, an audio signal, and a control signal) is
It is transmitted as an analog signal. Therefore, it is impossible to compress and multiplex information.
The number of channels (programs) that can be supplied in cable television is about 60 channels.

[0004] By the way, in digital multi-channel satellite broadcasting (for example, PerfecTV (trademark)) which is now spreading, broadcasting of more than 100 channels is realized.
As market needs, it is desired that cable televisions have more channels.

[0005] In order to further increase the number of channels in a cable television, it is conceivable that a cable television station compresses and multiplexes a video by digitizing all signals. It is difficult to realize in view of capital investment of cable TV stations, running costs, and the like. Therefore, a method is conceivable in which, for example, digital multi-channel satellite broadcasting such as PerfecTV is redistributed to a cable television network to realize more multi-channels in cable television.

Here, a digital multi-channel satellite broadcasting system will be described with reference to FIG. The transmitting unit 111 of the satellite broadcasting service provider 101 scrambles the MPEG-compressed program information supplied from the program provider to provide electronic program guide information (EPG: Electoric Progra
m Guide) and service information such as viewer management information, and transmits the resultant signal to the communication satellite 102 as a linearly polarized CS wave. This CS wave is received by the CS antenna 181 via the communication satellite 102 and supplied to the receiver 182. The receiver 182 extracts predetermined program information from the CS wave and outputs it to the television receiver 106. The viewer management unit 112 issues the IC card 160 to the viewer. The key management unit 113 of the viewer management unit 112 manages a viewable program corresponding to the IC card 160. The viewing information processing unit 114 calculates a viewing fee based on the viewing information notified from the receiver 182, and notifies the customer management unit 115. The customer management unit 115 charges a viewing fee to the viewer.

FIG. 32 shows a detailed configuration of the receiver 182. The reception tuner 192 of the satellite front end unit 191 extracts a transport stream (TS: Transport Stream) including a predetermined program from the CS wave, and performs QPSK.
The signal is output to the demodulation circuit 193. QPS
The K demodulation circuit 193 performs QPSK demodulation on the input TS and outputs it to the error correction circuit 194. Error correction circuit 194
Corrects the error information of the input TS and outputs it to the transport unit 155. The descrambler 156 of the transport unit 155 converts the TS scrambled by the transmitting unit 111 of the satellite broadcast service provider 101 into
IC card 1 issued by satellite broadcasting service provider 101
Decryption using descrambling information recorded in 60
(Descramble) and output to the demultiplexer 157.

[0008] The demultiplexer 157 stores multiplexed program specification information (PSI: Program Specific Infor- mation).
) based on the information of a given program
It is supplied to the decoder unit 158. MPEG decoder section 15
8 MPEG expands the input program, generates a video signal and an audio signal, and outputs the video signal and the audio signal to the television receiver 106.

[0009] The host processor 159 controls the entire receiver 182 in accordance with the operation of the viewer, and also transmits the received pay program information (program viewing information) to the IC card 16.
Record at 0. Further, the host processor 159 includes an IC
The descramble information recorded on the card 160 is read and supplied to the descrambler 156. Further, the host processor 159 controls the communication unit 161 to periodically notify the viewing information management unit 114 of the program viewing information recorded on the IC card 160. Viewing information management unit 114
Calculates the viewing fee based on the input viewing information,
Notify the customer management unit 115.

[0010]

However, in order to distribute the digital multi-channel satellite broadcast signal to the cable television network, the cable television station 103 receives the digital multi-channel satellite broadcast signal and separates the multiplexed signal. Therefore, processing such as multiplexing is required again, and the equipment is very expensive.

In order to provide digital multi-channel services in a plurality of cable networks, a device for digitizing a plurality of programs in each cable network and multiplexing the programs and a facility for customer management are required.
Requires enormous capital investment and operating costs.

[0012] Further, since the service provision method differs for each medium such as CS digital service, BS digital service, terrestrial digital service, etc., in order to receive these with a common receiver, each cable network requires:
It is necessary to arrange transmission systems.

[0013] Further, in a system in which a service from a satellite is reconfigured and transmitted in a cable network, services unique to digital services such as an EPG service and a download service cannot actually be received.

[0014] The present invention has been made in view of such circumstances, and an information distribution system and a low-cost information distribution system capable of distributing a program broadcast in digital satellite broadcasting to a plurality of cable television networks. The purpose is to provide an information distribution method.

[0015]

An information distribution system according to the present invention comprises: a center station for distributing a digital multi-channel service signal via a satellite line; and a digital multi-channel distributed from the center station via a satellite line. A plurality of cable networks for receiving a service signal by a receiving means, converting the digital multi-channel service signal received by the receiving means into a digital multi-channel service signal for cable transmission by a modulation conversion means, and sending the converted signal to its own cable network. And a plurality of receiving terminal devices for receiving digital multi-channel service signals distributed from the cable network station via the cable network.

Also, the information distribution method according to the present invention distributes a digital multi-channel service signal from a center station to a plurality of cable network stations via a satellite line, and distributes the digital multi-channel service signal from the center station via a satellite line. The multi-channel service signal is converted into a digital multi-channel service signal for cable transmission by modulation conversion,
It is characterized in that distribution is made from each cable network station to the receiving terminal device via the cable network.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is applied to, for example, an information distribution system having a configuration as shown in FIG.

In this specification, the term "system" refers to an entire device including a plurality of devices and means.

This information distribution system receives a center station 1 for transmitting program information and managing customers, and receives a digital multi-channel service signal transmitted from the center station 1 via a satellite line by a communication satellite 2. , formed by their cable television network 4 ₁ and a plurality of cable television station 3 ₁ to 3 _n to be transmitted to the to 4 _n, a plurality of receiving terminal devices 5 ₁₁ to 5 _nm which is connected to the cable television network 4 ₁ to 4 _n Is done.

As shown in FIG. 2, the center station 1 includes a transmission section 11 for transmitting program information and a viewer management section 12 for managing customers. The transmission unit 11
Performs scramble on the MPEG-compressed program information supplied from the program supplier, and provides electronic program guide information (E
It is multiplexed with service information such as PG (Electoric Program Guide) and viewer management information, and transmitted to the communication satellite 2 as a linearly polarized CS wave. Further, the viewer management unit 12 issues the 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. Further, the viewing information processing unit 1
4 calculates the viewing fee based on the viewing information notified from the receiver 6 of the receiving terminal device 5 and notifies the customer management unit 35 of the cable television station 3 of the calculation.

The cable television station 3 receives a CS wave transmitted from the communication satellite 2 by a CS antenna 31, receives a radio wave of a television broadcast using a terrestrial wave by a terrestrial antenna 32, and receives a broadcast satellite (not shown). )) Is received by the BS antenna 33, and the distribution section 34 receives the input CS wave and analog broadcast wave (terrestrial wave and BS wave). And distributes the mixed wave to the receiver 6 of the receiving terminal device 5 via the cable television network 4. The customer management unit 35
Charges the viewer to the viewing fee based on the viewing fee information from the viewing information processing unit 14 of the satellite broadcast service provider 1.

Then, the receiver 6 of the receiving terminal device 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.

Here, the digital multi-channel service signal transmitted from the communication satellite 2 will be described. In this embodiment, this digital multi-channel service signal is compatible with a DVB (Digital Video Broadcasting) system. FIG. 3B shows a frame structure of digital broadcast data in the DVB system, and includes eight MPEG2 transport packets (FIG. 3).
(A)) constitutes one frame. in this case,
Using the synchronization byte (= 47H) in the packet, the synchronization byte is inverted once every eight packets (= B8H) to obtain frame synchronization. An error correction code by Reed-Solomon (204,188) is added to each MPEG2 transport packet (MPEG2TS packet). The digital broadcast data shown in FIG. 3B is further convolutionally coded in the satellite system (in DVB, the bankture code rate; 1/2, 2/3, 3/4, 5/6, 7).
/ 8 is specified. ), QPSK (Qua
The frequency is converted to a transmission frequency band and transmitted from the communication satellite 2 via a communication line.

FIG. 4 shows a packet structure of an MPEG2 transport packet, wherein the first 4 bytes of 188 bytes constitute a packet header. The packet header contains an individual stream (data string) for the packet
(PID: Packet Identificat)
ion). As is well known, the payload (data portion) of the MPEG2 transport packet has a PES (Packetized Elementary Strea
m) The packet is subdivided and distributed, and M
A program association table (PAT: Program Asss) as program specification information (PSI: Program Specific Information) specified in the PEG2 system
Association Table), Program Map Table (PM
Tables such as T: ProgramMap Table) and Network Information Table (NIT) are also arranged in section format.

Here, the PSI is information necessary for realizing simple channel selection operation and program selection. PAT
Shows the PID of the PMT that transmits information on the packets constituting the program for each program number (16 bits). FIG. 6 shows the table structure of the PAT. The PID of the PAT itself is fixed as PID =
“0x0000” is assigned.

The main contents will be described. Table ID
Indicates the type of the table, and is “0x00” (hexadecimal notation) in the PAT. The TS ID identifies a stream (multiplexed coded data), and corresponds to a transponder in the case of a satellite. The version number is incremented each time the contents of the table are updated. The current next indicator is used for identification when the new and old versions are transmitted simultaneously. The program number identifies each channel. The network PID has a program number of “0x0000”
Indicates the PID of the NIT. The program map PID indicates the PID of the PMT.

The PMT is provided for each program number.
It indicates the PID of a packet that transmits a stream of video, audio, additional data, and the like that constitute the program. The PID of the PMT itself is specified by the PAT as described above. FIG. 7 shows a table structure of the PMT. Main contents not overlapping with the PAT will be described. The table ID indicates the type of the table.
In MT, it is “0x02”. The PCR PID is a reference clock for decoding (PCR: Program Clock Reference).
This indicates the PID of the packet containing e). The stream type indicates the type of signal transmitted in a stream, such as video, audio, and additional data.

The NIT indicates physical information on the transmission path, that is, for a satellite, the orbit of the satellite, the polarization, the frequency of each transponder, and the like. The PID of the NIT itself is specified by the PAT as described above. FIG.
Indicates the table structure of the NIT. PAT, PM
Main contents that do not overlap with T will be described. Table I
D indicates the type of the table. The network is “0x40”, and the other networks are “0x4”.
1 ". The network ID identifies a network. In the case of a satellite, it corresponds to each satellite.

When a satellite digital multi-channel broadcast signal is retransmitted on a cable television by a modulation conversion method, the NIT is rewritten. Here, the descriptor that is included in the NIT and needs to be rewritten will be described.

First, the satellite delivery system descriptor in the satellite-based NIT will be described.
This descriptor is used as the first of a descriptor repeated according to a TS (Transport Stream) descriptor length,
D and a pair.

FIG. 9 shows the structure of the satellite delivery system descriptor. The descriptor tag is defined by DVB and indicates the type of the descriptor. In this descriptor,
It becomes “0x43”. The frequency indicates a transmission frequency for each stream (here, a 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 the specifications regarding the transmission system.

At the time of retransmission at a cable television station, the satellite delivery system descriptor is replaced with a cable delivery descriptor as shown in FIG. In the descriptor, "0x4
4 ". The frequency indicates the transmission frequency for each physical channel in the cable television to be retransmitted.
The symbol rate / inner error correction coding rate indicates a specification related to a transmission system. This descriptor has the same overall length for the satellite and the cable, and can be simply replaced.

Next, the service list descriptor will be described. This descriptor is used as the second and subsequent descriptors repeated according to the TS descriptor length, and indicates the ID of a service (channel) multiplexed on the stream (here, transponder). That is, a plurality of service list descriptors are attached to one TSID.

FIG. 11 shows the structure of the service list descriptor. The descriptor tag is D
It is defined by VB and indicates the type of descriptor. In this descriptor, it is “0x41”. The service ID identifies a service.
Usually, the service matches the channel that the viewer tunes to. The service type indicates the content of the service, such as video, audio, and data.

At the time of retransmission at a cable television station, when a program for all transponders from a satellite is serviced within a cable, the information of this descriptor remains unchanged, but when only a signal of a specific transponder is serviced. Deletes the service ID of the program included in the transponder that is not retransmitted. In this case, dummy data is added to the information that has been deleted and reduced, and
A simple substitution can be made by making the total length of the list descriptor the same as the satellite system.

The MPEG2 system defines that the transmission of the PSI table is segmented by a format called a 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,
Until the section number matches the last section number, a series of NIT data is formed.

Next, a specific configuration example of the distribution unit 34 of the cable television station 3 in the cable transmission system shown in FIG. 2 will be described with reference to FIG.

In the distribution unit 34 having the configuration shown in FIG. 12, the signal distributor 41 converts the CS wave input via the CS antenna 31 into a TS (Transport Stream) for each channel.
, And each of the modulation conversion devices 42-1 through 42-
N (N is the number of channels included in the CS wave). Note that the above-described channel is one propagation wave including a plurality of programs multiplexed by one transponder, unlike a channel (broadcasting station) in the terrestrial wave. FIG. 13 shows an example of a state of the CS wave before being input to the signal distributor 41. That is, C
The H polarization of the S wave includes TS1, TS3, and TS5, and the V polarization of the CS wave includes TS2, TS4, and TS6.
Is included.

The modulation converter 42 converts the input TS into a signal (QAM signal) for one channel of a cable television.
And outputs it to the signal mixer 45.

The terrestrial retransmission device 43 converts the terrestrial wave received via the terrestrial reception antenna 32 into an RF signal and outputs it to the signal mixer 45.
The BS wave received by the antenna 33 is RF-converted and output to the signal mixer 45.

FIG. 14 shows a specific configuration example of the modulation conversion device 42. In the modulation conversion device 42 having the configuration shown in FIG. 14, the QPSK demodulation circuit 421 performs QPSK demodulation on the input TS and outputs it to the error correction circuit 422. The error correction circuit 422 corrects the error of the input signal and outputs the error-corrected TS to the network information (NIT: Netw
ork Information Table) output to the conversion circuit 423.

The NIT conversion circuit 423 is an NI for CS wave.
T (Information common to all channels of the CS wave, indicating information of a program included in the channel (propagation wave). Necessary when the receiver receives a desired program.)
Is replaced with NIT for cable television and output to the QAM modulation circuit 424.

The QAM modulation circuit 424 performs QAM modulation on 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.

The signal mixer 45 includes a modulation conversion device 42-1.
, 42-N, the terrestrial retransmission device 43, and the satellite signal retransmission device 44, respectively, and mixes the QAM-modulated signals as shown in FIG. The amplifier 46 amplifies the input mixed wave and supplies the mixed wave to the receiver 6 via the cable television network 4.

Here, in cable transmission, since the quality of the transmission path is better than that of a satellite line, only Reed-Solomon (204, 188) is added as an error correction code. At this time, for example, if data of 42.192 Mbps is transmitted per transponder at the convolution rate 3/4 encoding in the satellite system, 31.644 Mbps data is transmitted in the cable system.
In order to transmit this information amount over one channel of a cable having a bandwidth of 6 MHz, it is appropriate to use 64QAM as a modulation method. Separately, when encoding is performed at a convolution rate of 7/8 in a satellite system, data of 36.918 Mbps is transmitted in a cable system, and 128QAM is appropriate as a modulation method. Since the level of the QAM modulation scheme for each channel is indicated by the NIT indicating the physical information of the transmission path, the receiver 6 can change the reception scheme by referring to this to receive the signal.

Here, a specific configuration example of the NIT conversion circuit 423 will be described with reference to FIGS.

As shown in FIG. 16, 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 is sequentially output from the error correction circuit 422. The error-corrected TS is sent to the NIT extraction unit 440 and the NIT
It is supplied to the reinsertion section 450.

The NIT extraction section 440 includes a NIT detection circuit 441 to which the TS is supplied, and a memory 442 for temporarily storing the NIT detected from the TS by the NIT detection circuit 441.

As shown in FIG. 17, a specific example of the configuration of the NIT extraction unit 440 is shown in FIG.
Is NIT · PI controlled by the control unit 443.
D filter 444 and this NIT / PID filter 44
4 comprises an NIT packet output circuit 445 for outputting the NIT detected by the N.4 to the memory 442. The memory 442 is formed of a FIFO (First In First Out) memory, and data writing and reading are controlled by the control device 431 via the interface 432.

If the service is provided by a plurality of satellites, the NITa related to the TS is included in the TS.
(Actual Network Information Table) and NITo (Other Network Information) related to TS transmitted by other satellites.
Information Table), which can be identified by the table ID. In the NIT extraction unit 440, the NIT detection circuit 441 sets the NIT for both NITa and NITo.
T detection is performed, and the FIFO memory 44
2 is written. Writing to the FIFO memory 442 is performed by a write clock write_clk synchronized with the TS.
And the IIT by the NIT detection circuit 441 is used.
The detection of NT and the process of writing to the FIFO memory 442 are performed in real time.

The NIT extraction unit 440 performs NIT extraction processing according to the procedure shown in the flowchart of FIG.

That is, the NIT extraction section 440 sends the detection start signal start from the control device 431 to the control section 443.
Becomes active by receiving the PID (= ”
0x0010 "), N
An IT detection operation is performed.

The control unit 443 transmits the TS packet to the NI · P
Captured by the ID filter 444 (step S1), NI
The PID of T is determined (step S2). When the PID of NIT is detected, it is determined whether or not it is the head data of NIT (step S3), and the table ID is added to the packet in which the PID of NIT is detected. If it is included, whether it is the table of the own network or the table of the other network is confirmed by referring to the table ID (the own network “0x40”, the other network “0x41”) (step S4), and the NIT / PID is checked. The NIT detected by the filter 444 is output from the NIT packet output circuit 445, and after the detection is started, the NIT is written to the FIFO memory 442 from the first data of the table received first (that is, the table ID) (steps S5 and S6).

Further, the control unit 443 provides both the NITa of the own network and the NITO of the other network.
It is determined whether or not T has been extracted (step S7). If the extraction has not been completed, the process returns to step S1 so that T
The NIT extraction process is repeated for every 188 bytes of the S packet (step S8).

Then, the control unit 443 checks the NIT of both the NITa of its own network and the NITo of the other network.
Is detected once and written into the FIFO memory 442,
The control device is notified of the end of the extraction, and a series of detection operations ends. After the writing is completed, the NIT data is held in the FIFO as shown in FIG.

Also, the NIT reinsertion section 450
As shown in FIG. 0, the memory unit 451 to which NIT data for a cable is transmitted from the control device 431 via the interface 432 and the NIT replacement unit 452 to which the TS is supplied are provided. The NIT data for the cable is stored in the memory unit 451,
The NIT of the TS sent from the satellite system is changed to N for the cable.
It is sequentially replaced with IT data by the NIT replacement circuit 452.

The memory unit 451 includes the control unit 43
1 through interface 432 for cable N
A FIFO memory 453 to which the IT data is sent, and two SRAMs 454A, 454 for extracting and storing cable NIT data from the FIFO memory 453.
54B and an address counter 455 for generating addresses of the SRAMs 454A and 454B. In the memory section 451, writing and reading of data to and from the FIFO memory 453 are controlled by the control device 431 via the interface 432, and sent from the control device 431 via the interface 432. The NIT data for the cable is held in the FIFO memory 453, and the NIT data for the cable is extracted from the FIFO memory 453, and the SRAM 454 is retrieved.
A or the NIT data for the cable is stored in the SRAM 454B, and each time the NIT of the TS is repeatedly sent from the satellite system to the NIT replacement circuit 452, the NIT data for the cable is stored in the SRAM4.
54A or SRAM 454B to NIT replacement circuit 4
Send to 52.

The NIT replacement circuit 452 includes an NIT packet detection circuit 456 to which the TS is supplied,
A control unit 457 to which the detection output of the T packet detection circuit 456 is supplied, a RAM switching circuit 458 that is switched by the control unit 457, and an NIT switching circuit 459 that is switched by the detection output of the NIT packet detection circuit 456. Consists of

The two SRAMs 454A and 454B of the memory unit 451 in the NIT reinsertion unit 450
The writing and reading of data are controlled by the control unit 457 of the NIT replacement circuit 452, and are used alternately each time NIT is rewritten. That is, the control unit 457 of the NIT replacement circuit 452 outputs, for example, the data written in one SRAM 454A to the NIT replacement circuit 452,
The output of the AM 454B is turned off, and the latest cable NIT data is written to the SRAM 454B via the FIFO memory 454A. Then, the SRAM 45
When writing of the latest cable NIT data to 4B 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. Wait until the next rewrite. From the FIFO memory 453 to the SRAMs 454A and 454B
The rewriting of NIT data to be transferred to and written to is performed in real time with a clock synchronized with the TS.

Here, the FIFO memory 453 has:
The NIT data for the cable is transmitted by the control device 431 via the interface 432 to the NI of the own network.
It is written in the order of Ta and NITo of another network.
As a result, the NITa of the own network and the NITo of the other network are stored in the FIFO memory 453 as shown in FIG.

The NIT replacement circuit 452 sends a transfer start signal start from the control unit 431 to the control unit 45.
7 is received from the FIFO memory 453 to the SRAM
The NIT data is transferred to the 454A or the SRAM 454B. Transfer operation starts from NITa of own network,
After writing all the data of NITa to SRAM,
NITO data of other network is transferred to SRAM NIT
The data is written to a storage location different from the storage location of a. SR
FIG. 22 shows an example of writing NIT data to AMs 454A and 454B.

In this NIT replacement circuit 452, FI
The process of transferring the NIT data from the FO memory 453 to the SRAMs 454A and 454B is performed according to the procedure shown in the flowchart of FIG.

That is, in the NIT replacement circuit 452, the control unit 457 controls the switching of the RAM switching circuit 458 for each TS packet, and, for example, selects one SRAM 454A corresponding to the TS packet (step S11). ), The NIT packet detected by the NIT packet detection circuit 456
It is determined whether the packet is a Ta packet (step S12),
If the packet is a NITa packet, the control unit 457 is allowed to write to the memory unit 451, and the address counter 455 is started (step S13), and an address is generated by the address counter 455 (step S14). SRAM
Transfer and write the NITa data of the own network to 454B (step S15).

When the writing of the NITa data of the own network to the SRAM 454B is completed (step S15), or when the NIT packet detected by the NIT packet detecting circuit 456 in the step S12 is reached.
If the IT packet is not the NITa packet of the own network, the NIT packet detected by the NIT packet detecting circuit 456 is replaced by the NITo packet of the other network.
It is determined whether or not the packet is a packet (step S17).
If the packet is not a To packet, the process returns to step S11, and the NIT packet detection circuit 456 causes the NITA packet of the own network or the NITA packet of another network to return.
It waits for the detection of an ITo packet. If the packet is a NITo packet, it issues a write permission to the memory unit 451 to the control unit 457, and sends an address counter 455.
Is started (step S18), and the address counter 4
55 to generate an address (step S19), and
Write the NITo data of the other network to the RAM 454B (step S20).

N of other network to SRAM 454B
When the writing of the ITo data is completed (step S2)
1) It is determined whether or not the processing for one TS packet has been completed (step S22). If the processing for one TS packet has not been completed, the process returns to step S11. If the processing for one TS packet has been completed. , The control device is notified of the end, and the other SRAM 454B
The RAM switching circuit 458 is controlled so as to select (step S23), and the FIFO memory 453 transfers the SRAM4
The process of transferring the NIT data to the 54B ends.

Thus, the newly rewritten N
The SRAM 454B storing the IT data is put into a use state, and the SRAM 454A that has been used so far is replaced with the next N
It is in a standby state for IT rewriting.

In the NIT replacement circuit 452, the other SRA is read from the FIFO memory 453 as described above.
While transferring NIT data to M454B,
Using the NIT data stored in one SRAM 454A, a replacement process for replacing the NIT of the TS transmitted from the satellite system with the NIT data for the cable is performed according to the procedure shown in the flowchart of FIG.

That is, the NIT replacement circuit 452 determines whether or not the NIT packet detected by the NIT packet detection circuit 456 is an NITa packet of its own network (step S31). The read permission from the unit 451 is issued, and the address counter 455 is started (step S32), and an address is generated by the address counter 455 (step S33).
It reads the NITa data of its own network from 4A and supplies it to the NIT switching circuit 457 via the RAM switching circuit 458 (step S34).

The NIT switching circuit 457 is connected to the NIT
In response to the detection output from the packet detection circuit 456, the error correction circuit 422 is switched to the RAM switching circuit 458 during the NIT packet period. As a result, the contents of the TS NIT packet transmitted from the satellite system are replaced with the cable NITa data (step S35).

When the 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 detecting circuit 456 in the step S31 is not the NITa packet of the own network. , The NIT packet detected by the NIT packet detection circuit 456 is the NIT packet of another network.
o is determined (step S37).
If the packet is not an ITo packet, the process returns to step S31, and the NIT packet detection circuit 456 causes the NITA packet of the own network or the N
It waits for the detection of the ITo packet, and when the packet is a NITo packet, permits reading from the memory unit 451, starts the address counter 455 (step S38), and causes the address counter 455 to generate an address (step S39). ), SRAM 454
Read the NITo data of the other network from A (step S40).

When the reading of the NITo data of the other network from the SRAM 454A is completed (step S41), the flow returns to step S31, and the NIT packet detecting circuit 456 causes the NITa of the next own network to return.
It waits until a packet or a NITo packet of another network is detected.

In the NIT conversion circuit 423 having such a configuration, the satellite-based 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 restores the satellite-based NIT by software processing and generates an NIT suitable for cable transmission. Then, the NIT data converted for the cable is transmitted from the control device 431 to the FIFO memory 453 of the NIT replacement unit 450 via the interface 432.
Supplied to NIT replacement unit 4 in this embodiment
At 50, the FIFO memory 4 is stored in the order of NITa and NITo.
Data is written to 53.

In the NIT conversion circuit 423 having such a configuration, the NIT conversion circuit 423 follows the procedure shown in the flowchart of FIG.
Perform T processing.

That is, first, the version number is changed (step S51), and if necessary, the network ID is also changed (step S52).

Then, the process enters a processing loop for TS from the satellite network (step S53), and determines whether or not the stream (here, transponder) from the satellite network is a transponder to retransmit to the cable network (step S54). . If the transponder is to retransmit, the service list descriptor
(Service_list_descriptor) (step S55), and determine whether the service is a retransmission service.
(Step S56).

If the service is not a retransmission service, the service I
Delete D and service type. That is, the information (service ID) and service type of the non-serviced program in the retransmitted stream are deleted (step S5).
7).

If the service is a retransmission service, or after deleting the service ID and service type, the descriptor length is confirmed (step S58), and the service list
Descriptor (Service_list_descriptor) Replacement of length, stuffing descriptor (Stuff_descripto)
r) is inserted (step S59), and a satellite delivery descriptor (Sattelite_delivery_descri
ptor) to the cable delivery descriptor (Cable
_delivery_descriptor) (Step S6)
0).

As described above, in rewriting NIT, for example, when retransmitting a stream (here, a transponder) from the satellite network to the cable network, at least the satellite delivery descriptor (Sattelite_delivery_descriptor) is transmitted to the cable network.
Delivery Descriptor (Cable_delivery_descript
or) to match the frequency information. This is the minimum necessary processing to enable the receiving operation in the cable receiver. In addition, information on a stream that is not retransmitted to the cable network (here, a transponder) and information (service ID) of a program that does not provide service in the retransmitted stream are deleted, and the reduced data is replaced with dummy data or the like. Further, if necessary, the portion relating to the data length such as the section length and the descriptor length in the NIT is matched with the NIT version number and the bit error index.

It is necessary to make an agreement with the dummy data so as not to cause a malfunction in the receiver. For example, a stuffing table ID, a stuffing descriptor tag, and the like are determined, and the specifications of the transmitter are determined. If such a table ID or descriptor tag is transmitted, the receiver ignores it. What should I do?

When the transponder is not a retransmitting transponder, the service list descriptor (Service_lis
t_descriptor) and the satellite delivery descriptor (Sattelite_delivery_descriptor) are replaced with a stuffing descriptor (Stuff_descriptor) (step S61).

Processing for the retransmitted transponder
(Steps S55 to S60) or every time a process for a transponder that does not retransmit (Step S61) is performed, T
After confirming the loop length of S, the process returns to step S53, and the processes of steps S53 to S62 are repeated over the loop length of TS (step S62). Thereafter, the CRC 32 is replaced (step S63), and the NIT rewriting process is performed. To end.

Similarly, it is possible to rewrite network information relating to another network. For example, when a service is provided by two satellites, if only one service is retransmitted into the cable network, the NITo section of the other network is converted into 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.

Next, a specific configuration example of the receiver 6 in the cable transmission system shown in FIG. 2 will be described with reference to FIG.

In the receiver 6 having the configuration shown in FIG. 26, the reception tuner 62 of the cable front end unit 61
Extracts a TS including a predetermined program from a mixed wave and performs QAM
Output to the demodulation circuit 63. The QAM demodulation circuit 63 performs QAM demodulation on the input TS and outputs the result to the error correction circuit 64. The error correction circuit 64 corrects the input TS error information and outputs the same to the transport unit 65. The descrambler 66 of the transport unit 65 decodes (descrambles) the scramble applied to the TS using descrambling information recorded on the IC card 60 issued by the satellite broadcasting service provider 1, and performs descrambling. Output to the multiplexer 67.

The demultiplexer 67 extracts predetermined program information from a TS in which a plurality of pieces of program information are multiplexed,
It is supplied to the EG decoding section 68. MPEG decoding unit 6
8 generates video signals and audio signals by MPEG-expanding the input program information, and outputs them to the television receiver 7.

The host processor 69 controls the entire receiver 6 based on the channel selection operation of the viewer, and records the information of the received pay program (program viewing information) on the IC card 60. The host processor 69 reads descramble information recorded on the IC card 60 and supplies the descramble information to the descrambler 66. Further, the host processor 69 controls the communication unit 70 to periodically notify the program viewing information recorded in the IC card 60 to the viewing information processing unit 14 of the satellite broadcast service provider 1 via a public telephone line. .

Next, information distribution processing by the distribution unit 34 in the cable television station 3 will be described with reference to the flowchart in FIG.

In step S71, the CS antenna 3
1 receives a CS wave via the communication satellite 2 and
Output to The terrestrial antenna 32 receives the terrestrial wave and outputs it to the distribution unit 34. The BS antenna 33 receives a BS wave via a broadcasting satellite and outputs the BS wave to the distribution unit 34.

In step S72, the signal distributor 41
Divides a CS wave into TSs corresponding to one transponder, and divides the CS waves into modulation converters 42-1 to 42-N.
Output to The terrestrial retransmission device 44 converts the input terrestrial wave into an RF signal and outputs it to the signal mixer 45. The satellite signal retransmission device 44 converts the input BS wave into an RF signal and outputs the RF signal to the signal mixer 45.

In step S73, the modulation conversion device 4
2 QPSK demodulation circuit 421 converts the input TS
SK demodulation is performed and output to the error correction circuit 422.

In step S74, the error correction circuit 4
Reference numeral 22 corrects the error of the input signal and outputs the result to the NIT conversion circuit 423.

In step S75, the NIT conversion circuit 423 converts the NIT for the CS wave into the NIT for the cable television.
It is output to the QAM modulation circuit 424 in place of IT.

In step S 76, QAM modulation circuit 424 performs QAM modulation on the input signal and outputs the result to frequency conversion circuit 425.

In step S77, 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
5 is output.

In step S78, the signal mixer 45
Mixes the QAM-modulated signals input from the modulation conversion devices 42-1 to 42-N, the terrestrial retransmission device 43, and the satellite signal retransmission device 44, respectively, and outputs the mixed signals to the amplifier 46.

In step S79, the amplifier 46
The input mixed wave is amplified and distributed to the receiver 6 via the cable television network 4.

Next, the program receiving process of the receiver 6 will be described.
This will be described with reference to the flowchart in FIG.

In step S 81, the reception tuner 62 of the cable front end unit 61 extracts a TS including a program (a program included in the CS wave) selected by the viewer from the mixed wave, and outputs the extracted TS to the QAM demodulation circuit 63.

In step S 82, the QAM demodulation circuit 63 performs QAM demodulation on the input TS and outputs it to the error correction circuit 64.

In step S83, the error correction circuit 6
4 corrects the input TS error information and outputs it to the transport unit 65.

In step S84, the descrambler 66 of the transport unit 65 converts the scramble applied to the TS into an I-issue issued by the satellite broadcast service provider 1.
The data is decoded using the descrambling information recorded on the C card 60 and output to the demultiplexer 67.

In step S85, the demultiplexer 67 demultiplexes the TS, extracts information on the program selected by the viewer, and supplies the information to the MPEG decoding unit 68.

In step S86, the MPEG decoding section 68 MPEG expands the input program information to generate a video signal and an audio signal, and outputs the video signal and the audio signal to the television receiver 7. The television receiver 7 reproduces the input video signal and audio signal.

In step S87, if the received program is a pay (pay-per-view) program, the host processor 69 stores the information (program viewing information) in the IC card 60.
To record. The communication unit 70 periodically notifies the customer management unit 15 of the program viewing information recorded on the IC card 60 via the public telephone line and the viewing information processing unit 14.

When the viewer selects a program transmitted by a terrestrial or BS wave, the program information is not multiplexed and is not MPEG-compressed. The MPEG decompression in step S86 is not performed.

Next, an example of the operation of the receiver 6 of the receiving terminal device 5 for receiving a signal transmitted from the cable television station 3 will be described with reference to the flowchart shown in FIG.

The program number in PAT and PMT and the service ID in NIT correspond to the channel number selected by each viewer. Furthermore, while the NIT contains information of the whole network, ie all transponders, and the same table is transmitted in parallel by all transponders, PAT and PM
T consists only of information of the program in the physical channel to be transmitted, and has different contents for each physical channel.

For example, if the viewer selects the "M" channel, the host processor 69 controls the demultiplexer 67 to acquire the NIT with a fixed PID, and attaches the NIT to each TSID. "M" is searched for the service ID in the service list descriptor (step S91).

When there is a service ID "M"
(Step S92) The host processor 69 determines the frequency of the transponder transmitting the “M” channel from the CATV delivery system descriptor combined before the service list descriptor including the service ID “M”. Is recognized, and the reception frequency of the tuner 62 is controlled (step S93). As a result, the tuner 62 selects a digital broadcast signal from the modulation converter 42 transmitting the “M” channel.

Then, the host processor 69 controls the demultiplexer 67 to acquire the PAT by the fixed PID, searches for “M” for the program number in the PAT, and searches for the program number “M” in the PAT. , And a program map PID associated with the program number "M" is obtained (step S94). Then, the host processor 69 supplies the demultiplexer 67
In the PMT so that the PMT is obtained by the program map PID, and the program number “M” is stored in the PMT.
Is recognized for each elementary PID for each stream type (video, audio, etc.) (step S95).

Then, the host processor 69 uses the demultiplexer 67 to set the PI that matches the elementary PID.
Control is performed so that TS packets having D are separated (step S96). In this case, the host processor 69 separates the packet of the video data and audio data of the “M” channel, and also separates the packet of the additional data of the “M” channel.

The host processor 69 supplies the limited reception information extracted from the additional data stream SDS to the IC card 60. The IC card 60 determines whether or not viewing is possible based on the limited reception information. If the information is acceptable, the IC card 60 sends the scramble key information to the host processor 69. This key information is set in the descrambler 66 by the host processor 69. Thereby, the descrambler 66
In this case, the scrambled video data and audio data packets are descrambled, so that the video data
The stream and the audio data stream relate to the descrambled data.

The video data and audio data output from the demultiplexer 67 are decoded,
A video signal and an audio signal of the "M" channel are obtained (step S97). That is, the demultiplexer 6
The MPEG decoder 68 performs processing such as data decompression on the video data stream VDS output from 7 to generate a video signal SV, and outputs this video signal. Further, the audio data stream output from the demultiplexer 67 is subjected to processing such as data expansion by the MPEG decoding unit 68 to generate an audio signal, and this audio signal is output. MP
By supplying the video signal and the audio signal obtained by the EG decoding unit 68 to the television receiver 7,
An image of the “M” channel can be displayed, and audio of the “M” channel can be output.

Also, in step S92, each TSID
As a result of searching "M" for the service ID in the service list descriptor attached to
If there is no D "M", the host processor 69 displays on the display unit (not shown) that reception is not possible (step S98), and ends the reception operation. Therefore, as described above, in the NIT conversion circuit 423, when the information on the TSID and the information on the service of the service list descriptor are deleted from the NIT as the information on the service (program) to be restricted, the receiver 6 Then, the service (program) cannot be received.

In the flowchart of FIG. 29,
Every time there is a channel selection of the "M" channel, NI
T has been described and a search for “M” is performed using the NIT. However, every time there is a change in the contents, the NIT is obtained and stored in the internal memory of the host processor 69, and the NIT is stored. May be used to search for “M”. Incidentally, the change of the contents of the NIT is recognized by the version number.

Receiver 6 of the present embodiment shown in FIG.
Is a digital satellite broadcast receiver 182 shown in FIG.
This can be realized by replacing the satellite front end unit 191 with the cable front end unit 61, so that the manufacturing cost can be reduced.

Further, according to the present embodiment, since the viewing information management such as billing calculation, which is the most costly for the cable television, can be shared with the satellite broadcasting service provider, the cost can be reduced. It is.

[0118]

As described above, according to the information distribution system and the information distribution method according to the present invention, a digital multi-channel service signal is distributed from a center station to a plurality of cable network stations via a satellite line. A digital multi-channel service signal distributed from a station via a satellite line is converted into a digital multi-channel service signal for cable transmission by modulation conversion, and is distributed from each cable network station to a receiving terminal device via a cable network. Thus, a program being broadcast in digital satellite broadcasting can be distributed to a cable television network at low cost.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a configuration of a cable transmission system to which the present invention has been applied.

FIG. 2 is a diagram showing each configuration of a center station, a cable television station, and a receiving terminal device showing the configuration of the cable transmission system.

FIG. 3 is a diagram showing an MPEG2 transport packet and a frame configuration of a DVB system.

FIG. 4 is a diagram showing a packet structure of an MPEG2 transport packet.

FIG. 5 is a diagram showing a packet structure of a PES packet.

FIG. 6 shows a program association table (P
FIG. 3 is a diagram showing a table structure of AT).

FIG. 7 is a diagram showing a table structure of a program map table (PMT).

FIG. 8 is a network information table.
It is a figure showing the table structure of (NIT).

FIG. 9 is a diagram showing a structure of a satellite delivery system descriptor in NIT.

FIG. 10 is a diagram showing a structure of a CATV delivery system descriptor in NIT.

FIG. 11 is a diagram showing a structure of a service list descriptor in NIT.

FIG. 12 is a block diagram illustrating a configuration example of a distribution unit of a cable television station in the cable transmission system.

FIG. 13 is a diagram illustrating linear polarization of a CS wave.

FIG. 14 is a block diagram illustrating a configuration example of a modulation conversion device in the distribution unit.

FIG. 15 is a diagram illustrating a mixed wave.

FIG. 16 is a block diagram illustrating a configuration example of a NIT conversion circuit in the modulation conversion device.

FIG. 17 is a block diagram illustrating a configuration example of a NIT extraction unit in the NIT conversion circuit.

FIG. 18 is a flowchart illustrating NIT extraction processing by the NIT extraction unit.

FIG. 19 is a diagram showing an example of writing to a FIFO memory in the NIT extraction unit.

FIG. 20 is a block diagram illustrating a configuration example of a NIT replacement unit in the NIT conversion circuit.

FIG. 21 is a diagram illustrating an example of writing to a FIFO memory in the NIT replacement unit.

FIG. 22 is a diagram illustrating an example of writing to an SRAM in the NIT replacement unit.

FIG. 23 is a flowchart illustrating a data transfer process from a FIFO memory to an SRAM in the NIT replacement unit.

FIG. 24 is a flowchart illustrating NIT replacement processing by a NIT replacement circuit in the NIT replacement unit.

FIG. 25 is a flowchart illustrating NIT replacement processing in the NIT replacement unit.

FIG. 26 is a block diagram illustrating a configuration example of a receiver in the cable transmission system.

FIG. 27 is a flowchart illustrating an information distribution process performed by the distribution unit.

FIG. 28 is a flowchart illustrating a program receiving process by the receiver.

FIG. 29 is a flowchart illustrating channel selection processing of the “M” channel by the receiver.

FIG. 30 is a block diagram illustrating an example of a configuration of a conventional cable television receiver.

FIG. 31 is a conceptual diagram showing a configuration of a digital multi-channel satellite broadcasting system.

FIG. 32 is a block diagram illustrating an example of a configuration of a receiver in the digital multi-channel satellite broadcasting system.

[Explanation of symbols]

1 center station, 2 communication satellite, 3,3 ₁ to 3 _n cable TV station, 4 ₁ to 4 _n cable television network,
5,5 _{11 to} 5 _nm receiving terminal device, 6 receiver, 7 television receiver, 11 transmitting unit, 12 viewer management unit, 1
3 key management unit, 14 viewing information processing unit, 34 distribution unit,
35 Customer management unit, 41 signal distributor, 42 _{1 to} 42 _N
Modulation converter, 45 signal mixer, 60 IC card,
61 Cable front end, 62 receiving tuner, 63 QAM demodulation circuit, 64 error correction circuit, 65
Transport unit, 66 descrambler, 67 demultiplexer, 68 MPEG decoding unit, 69 host processor, 71 communication unit

Claims (6)

[Claims] 1. A center station for delivering a digital multi-channel service signal via a satellite line, and a digital multi-channel service signal distributed from the center station via a satellite line is received by a receiving means.
A plurality of cable network stations for converting the digital multi-channel service signal received by the receiving means into a digital multi-channel service signal for cable transmission by a modulation conversion means and transmitting the converted signal to its own cable network; An information distribution system comprising a plurality of receiving terminal devices for receiving a digital multi-channel service signal distributed via a network. 2. The modulation / conversion means: demodulation means for demodulating a digital multi-channel service signal received by the reception means; and network information replacement for replacing network information of the signal demodulated by the demodulation means with information for cable transmission. 2. The information distribution system according to claim 1, further comprising: means for modulating a signal in which network information has been replaced with information for cable transmission by said network information replacing means. 3. The cable network station includes multiplexing means for multiplexing another service signal with a digital multi-channel service signal distributed from the center station via a satellite line and transmitting the multiplexed service signal to its own cable network. The information distribution system according to claim 1, wherein: 4. The receiving terminal device according to claim 1, wherein said receiving terminal device extracts a signal of an arbitrary channel from a digital multi-channel service signal transmitted via a cable network, and demodulates the signal of the channel extracted by said extracting device. 2. The information distribution system according to claim 1, further comprising: demodulation means, recording means for recording the viewing information, and notification means for notifying the center station of the viewing information recorded by the recording means. 5. A digital multi-channel service signal is distributed from a center station to a plurality of cable network stations via a satellite line, and the digital multi-channel service signal distributed from the center station via a satellite line is modulated and converted to a cable. An information distribution method, wherein the information is converted into a digital multi-channel service signal for transmission and is distributed from each cable network station to a receiving terminal device via a cable network. 6. The cable network station multiplexes another service signal with a digital multi-channel service signal distributed from the center station via a satellite line, and transmits the multiplexed service signal from the cable network station to the cable network.
Information delivery method.