JP2011097602A - Signal processing apparatus and signal processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To readily perform distribution service of a digital broadcast program over a cable network. <P>SOLUTION: A signal processor includes a reception processing means; a descrambler; a table replacement means for replacing, for a plurality of descrambled transport stream signals, a network information table (NIT) having physical information on a transmission line and included in each of the signals, with an NIT suitable for a cable line and outputting a plurality of replaced transport stream signals; an arrangement means for arranging the transport stream signal for each slot of a frame that serves as a transmission unit, and outputting a frame signal; a scrambler; a modulation means for modulating the scrambled frame signal; and a transmission means for transmitting the frame signal modulated by the modulation means to the cable line. The NIT suited for cable line contains modulated information. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a signal processing apparatus and a signal processing method suitable for use when, for example, a digital broadcasting program broadcast by BS digital broadcasting is distributed over a cable network. Specifically, after descrambling and modulating the scramble applied to the transport streams individually extracted from a plurality of transport stream signals, the scramble is different from the scramble and converted into signals having different frequencies. The present invention relates to a signal processing apparatus and a signal processing method that can easily provide a digital broadcast program broadcast on, for example, BS digital broadcasting on a cable network by obtaining a digital signal on the cable network. .

  BS (Broadcasting Satellite) digital broadcasting uses a satellite repeater (transponder) with a transmission band of 34.5 MHz to transmit an amount of information with a transmission rate of about 58 Mbps. It is a standard that can include a transport stream signal (TS signal).

  It is conceivable to provide a digital broadcast program broadcasted by BS digital broadcasting via a cable network. However, the domestic cable transmission standard does not correspond to the BS digital broadcast transmission format described above and transmits a data amount of about 32 Mbps with respect to the transmission rate. I couldn't get it out.

  Accordingly, an object of the present invention is to provide a signal processing apparatus and a signal processing method that enable a digital broadcast program broadcast on, for example, a BS digital broadcast to be easily distributed over a cable network.

  The signal processing apparatus according to the present invention includes a reception processing means for individually extracting and outputting any one of the transport stream signals from a plurality of transport stream signals including satellite line digital signals, and the reception processing means for output. A descrambler for descrambling the transport stream signal, and a plurality of transport stream signals descrambled by the descrambler, each of which has physical information regarding a transmission path included in the signal. The network information table is replaced with a network information table suitable for a cable line, and a table replacing means for outputting a plurality of transport stream signals after replacement, and this table replacing means Arrangement means for outputting the frame signal by arranging the transport stream signal in which the work information table is replaced for each slot of the frame as a transmission unit, and the transport stream signal selected by this arrangement means for each slot A scrambler that scrambles other than the scrambled frame signal, a modulation unit that modulates the frame signal scrambled by the scrambler, and the frame signal modulated by the modulation unit to the cable line The network information table including transmission means and adapted to the cable line includes modulation information. The modulation information may be information indicating 64QAM modulation.

  The signal processing method according to the present invention includes a reception processing step of individually extracting and outputting any one of the transport stream signals including a plurality of transport stream signals including satellite channel digital signals, and the reception processing step. A descrambler step for releasing the scramble applied to the transport stream signal to be output, and a plurality of transport stream signals descrambled by the descrambler step, and each of the physical signals related to the transmission path included in the signal. Table replacement step that replaces the network information table with typical information with a network information table that matches the cable line, and outputs multiple transport stream signals after replacement, and this A transport stream signal in which the network information table has been replaced in the cable replacement step is disposed in each frame slot serving as a transmission unit, and a frame signal is output, and the transport stream selected in this placement step A scrambler step that scrambles the frame signal in which the signal is arranged for each slot, which is different from the scrambler, a modulation step that modulates the frame signal scrambled by the scrambler step, and a modulation step that modulates the frame signal. A network information table adapted to the cable line includes modulation information. The modulation information may be information indicating 64QAM modulation.

  In the present invention, the digital signal of the satellite line includes a plurality of transport stream signals. A plurality of transport stream signals are individually extracted from the digital signal of the satellite line, and the scramble applied to the extracted transport stream signals is released. After the scrambled transport stream signal is subjected to other scrambles different from the above scramble, a plurality of transport stream signals are individually modulated and then converted to signals of different frequencies. Thus, a digital signal on the cable network is generated. In this case, each of the plurality of transport stream signals is allocated to one physical channel of the cable transmission path. For example, when a satellite line digital signal includes three transport stream signals and all the transport stream signals are sent to a cable transmission line, three physical channels of the cable transmission line are used. In this way, for example, a digital broadcast program broadcast by BS digital broadcasting can be easily distributed over the cable network.

  According to the present invention, a plurality of transport stream signals are individually extracted from a satellite digital broadcast signal, modulated, and then converted into signals having different frequencies to obtain a digital broadcast signal on a cable network. is there. Therefore, for example, a digital broadcast program broadcast by BS digital broadcasting can be easily distributed over the cable network.

It is a block diagram which shows the structure of the digital CATV system as embodiment. It is a figure which shows the packet structure of an MPEG2 transport packet. It is a figure which shows the packet structure of a PES packet. It is a figure which shows the table structure of a program association table (PAT). It is a figure which shows the table structure of a program map table (PMT). It is a figure which shows the table structure of a network information table (NIT). It is a figure which shows the structure of the satellite delivery system descriptor in NIT. It is a figure for demonstrating the signal processing procedure in the transmission-line encoding part of BS digital broadcast signal. It is a figure which shows the structure of a frame signal process. It is a figure which shows the information structure of a TMCC signal. It is a figure for demonstrating a modulation process. 1 shows a configuration of a transmission system. It is a figure which shows the structure of a CATV delivery system descriptor. It is a figure which shows the frame structure of an MPEG2 transport packet and a DVB system. It is a block diagram which shows the structural example of a receiving system.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a digital CATV (cable television) system 10 using BS digital broadcasting as an embodiment.

  The system 10 includes an antenna 11 that receives a BS digital broadcast signal from a satellite repeater of a broadcast satellite 20, and processes the received BS digital broadcast signal to generate a digital broadcast signal of a plurality of channels to generate a cable transmission line. 13 and a transmission system 12 for transmission to the network. The cable transmission path 13 is connected to set top boxes (in-home receivers) 14-1 to 14-m, which are receiving terminals, and is selected by these set top boxes 14-1 to 14-m. The channel number images are displayed on the monitors 15-1 to 15-m.

  Hereinafter, (a) the structure of the transport stream, (b) the basic structure of the BS digital broadcast signal, (c) the structure of the transmission system, and (d) the structure of the receiving system (set top box) will be described in this order.

(A) Structure of Transport Stream The structure of the transport stream in BS digital broadcasting will be described. The basic form of this transport stream conforms to the MPEG2 (Moving Picture Experts Group 2) system. FIG. 2 shows the packet structure of an MPEG2 transport packet, and the first 4 bytes of 188 bytes form a packet header. The first byte is a synchronization byte and has a fixed value (47H) ("H" indicates hexadecimal notation). Further, PID (Packet Identification) indicating the attribute of the individual stream (data string) of the packet is arranged in the packet header. As is well known, a PES (Packetized Elementary Stream) packet whose packet structure is shown in FIG. 3 is subdivided and arranged in the payload (data part) of the MPEG2 transport packet, and is further defined in the MPEG2 system. Tables such as PAT (Program Association Table), PMT (Program Map Table), and NIT (Network Information Table) as PSI (Program Specific Information) are also arranged in a section format.

  Here, the 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. 4 shows the table structure of the PAT. As the PID of the PAT itself, “0 × 0000” (“0 ×” indicates hexadecimal notation) is fixedly assigned.

  The main contents will be described. The table ID indicates the type of the table and is “0 × 00” in the PAT. The TS (Transport Stream) ID identifies a stream (multiplexed encoded data), and corresponds to a transponder in the case of a satellite, for example. 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 is selected when the program number is “0 × 0000”, and indicates the PID (= “0 × 0010”) of the NIT. The program map PID indicates the PID of the PMT.

  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. 5 shows a table structure of the PMT. The main contents 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 a stream such as video, audio, and additional data.

  The NIT indicates physical information related to the transmission path, that is, transmission signal specifications, transmission frequency information, and the like. The PID of the NIT itself is specified by the PAT as described above. FIG. 6 shows an example of the NIT table structure. Since NIT is a private rule, it may be different between BS digital broadcasting and current CS digital broadcasting. The main contents will be described. The table ID indicates the type of table. In the case of CS digital broadcasting, 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.

  In addition, a satellite delivery system descriptor that plays an important role as part of the NIT is described. This descriptor is used as the first descriptor repeated according to the TS descriptor length, and is paired with the TSID.

  FIG. 7 shows an example of the structure of the satellite delivery system descriptor. The descriptor tag is defined by DVB and indicates the type of descriptor. In this descriptor, it is “0 × 43”. The frequency indicates the transmission frequency of the 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.

(B) Basic configuration of BS digital broadcast signal In BS digital broadcast, a plurality of transport stream signals are transmitted by a digital broadcast signal handled by one repeater, and a broadcaster can switch operation of a plurality of modulation schemes. Therefore, it is necessary to perform control related to transmission system information other than MPEG system control items. For this reason, a transmission multiplexing control (TMCC) signal is multiplexed as information for clarifying the relationship between the transport streams and the transmission mode (modulation method).

  FIG. 8 shows a signal processing procedure in the transmission channel encoding unit of the BS digital broadcast signal. FIG. 9 shows a configuration of frame signal processing.

  First, Reed-Solomon (204, 188) is obtained for each packet (MPEG2 transport packet) constituting a combined packet sequence (FIG. 9A) in which a plurality of MPEG2 transport stream signals TS1 to TSN are synchronized and rearranged for each packet. ) Is added as an outer code (FIG. 9B).

  Next, a frame consisting of 48 slots is formed with a 204-byte period (slot period) obtained by adding an error correction code (16 bytes) to an MPEG2 transport packet (188 bytes) as a transport stream and modulation method selection unit. (FIG. 9C). This frame is a basic transmission unit of transmission coding. Then, a super frame is composed of 8 frames (FIG. 9D).

  Next, a 203 × 48 × 8 byte signal (main signal) in the superframe excluding the first byte of each slot is subjected to energy spreading and interleaving processing as transmission scramble processing. The energy spreading process is performed by adding, for example, a 15th order M-sequence pseudo-random signal generated at a superframe period. In this case, the initial value of the above-mentioned 15th order M-sequence is set so that the long continuous portion of “0” or “1” decreases. The interleaving process is a block interleaving of 8 × 203 bytes for the main signal, and is performed for each slot having the same slot number in the superframe direction (interleaving depth is 8).

  Further, TMCC signals to be multiplexed are generated based on TMCC information 1 to TMCC information N corresponding to the signals TS1 to TSN, respectively. This TMCC signal has a transport stream, modulation scheme information, and the like for each slot in the frame structure. On the receiving side, the transport stream signals TS1 to TSN can be extracted and demodulated according to the TMCC signal.

  The TMCC signal is a signal having a fixed length of 384 bits (48 bytes) for one superframe. FIG. 10 shows the information structure of the TMCC signal. This information configuration will be briefly described. The change instruction is a signal that is incremented by one every time the content of the TMCC signal is changed, and the value returns to “00000” after “11111”. The transmission mode / slot information is an item indicating a combination of a modulation scheme and an inner code. The relative TS / slot information is an item for indicating a transport stream (TS) transmitted in each slot in order from the slot 1 using a relative TS number. The relative TS number is 3 bits so that a maximum of 8 TS can be transmitted within the signal for one repeater. The relative TS / TS number table is an item for indicating a correspondence table for converting a relative TS number used in an item of relative TS / slot information into a TS ID of the MPEG2 system. The transmission / reception control information transmits a signal for receiver activation control in emergency alert broadcasting and a control signal for uplink station switching. Further, the extension information is a field used for future TMCC signal extension.

  Transmission coding is performed by adding an error correction code according to Reed-Solomon (64, 48) to the TMCC signal described above. Using the fact that the synchronization code of the MPEG2 transport packet is known (= 47H), the first byte of each slot of the frame after transmission scramble processing is replaced with the frame synchronization signal and the above-described transmission-encoded TMCC signal.

As described later, the TMCC signal is transmitted by BPSK modulation so that it can be received at the lowest C / N. In this case, transmission of 12 bytes per frame is possible, but in addition to the 8-byte (128 symbols) TMCC signal, the configuration is arranged by 2 bytes (32 symbols) of synchronization signals (unique words) at the front and rear. Note that energy diffusion processing is also performed on a 64-bit TMCC code subjected to transmission coding for one superframe by adding, for example, a 15th-order M-sequence pseudo-random signal.

  As described above, after replacing the first byte of each slot of the frame with the frame synchronization signal and the transmission-encoded TMCC signal, an error correction code as an inner code is added. In this case, for the main signal, trellis coding is used when 8PSK modulation is performed, and convolutional coding is used when QPSK / BPSK modulation is performed. Since the frame synchronization signal and TMCC signal perform BPSK modulation, convolutional coding is used for these frame synchronization signal and TMCC signal.

  Modulation processing is performed on the signal of each frame after the inner code is added. In this case, as shown in FIG. 11, the frame synchronization signal and the TMCC signal portion are first BPSK modulated, and then the main signal of 203 symbols of each slot is subjected to 8PSK modulation, QPSK modulation or BPSK modulation to obtain a modulated signal. Get. In this case, in order to enable stable reception at low C / N, a 4-symbol BPSK signal is added as a phase reference burst signal for each 203-symbol main signal.

  The modulated signal obtained as described above is up-converted and transmitted to the broadcast satellite 20, and after being amplified by the satellite repeater, transmitted to the ground as a BS digital broadcast signal.

(C) Configuration of Transmission System FIG. 12 shows the configuration of the transmission system 12 in the digital CATV system 10 of FIG.

  Domestic cable transmission standards basically conform to the DVB (Digital Video Broadcasting) system, and the transmission rate is about 32 Mbps due to the limitation of the transmission bandwidth of 6 MHz. For this reason, even if a signal of a BS digital broadcast transmission format (multiple transport stream signals, TMCC signals, etc.) not defined in DVB is modulated and sent to the cable transmission line 13, it cannot be received. Also, it is impossible to transmit information for one repeater of a BS digital broadcast signal, which is about 58 Mbps, from a transmission rate point through one channel on a cable transmission path.

  Therefore, in the transmission system 12 shown in FIG. 12, a plurality of transport stream signals TS1 to TSN are individually extracted and modulated from the received BS digital broadcast signal Sbs, and then converted into signals having different frequencies to be converted into a cable network. The above digital broadcast signals Sb1 to SbN are obtained.

  The transmission system 12 includes a computer, and a plurality of transport stream signals TS1 to TSN based on a BS digital broadcast signal Sbs received by a control unit 100 that controls the operation of the entire system and an antenna 11 (shown in FIG. 1). BS front-end unit 200 for individually extracting a plurality of transport stream signals TS1 to TSN and performing cable modulation and frequency conversion individually to obtain digital broadcast signals Sb1 to SbN on the cable network. Modulation units 300-1 to 300-N and an adder 400 that adds these digital broadcast signals Sb1 to SbN and sends them to the cable transmission line 13 are configured. Connected to the control unit 100 are an operation unit 101 for setting by the user and a display unit 102 for displaying the status of the transmission system.

  In the transmission system 12 shown in FIG. 12, when the received BS digital broadcast signal Sbs is input to the BS front end unit 200, the BS front end unit 200 transmits a plurality of transport streams included in the BS digital broadcast signal Sbs. The signals TS1 to TSN are individually extracted and output. The plurality of transport stream signals TS1 to TSN are supplied to cable remodulation units 300-1 to 300-N, respectively. The cable remodulators 300-1 to 300-N generate digital broadcast signals Sb1 to SbN of the first to Nth physical channels on the cable network from the transport stream signals TS1 to TSN, respectively. These digital broadcast signals Sb1 to SbN are added by an adder 400 and sent to the cable transmission path 13.

  Details of the BS front end unit 200 will be described. The BS front-end unit 200 down-converts the BS digital broadcast signal Sbs to obtain the above-described modulation signal, and demodulates the modulation signal to signal each frame (encoded with an internal code error correction code). A demodulator 202 to be obtained, and an inner code error correction circuit 203 that performs error correction by an inner code on the signal of each frame.

  The BS front-end unit 200 also transmits TMCC signal transmission scrambled from the inner code error correction circuit 203, that is, a transmission descrambling circuit 204 for returning the energy spread, and 1 output from the transmission descrambling circuit 204. A TMCC error correction circuit 205 that performs error correction processing using Reed-Solomon (64, 48) codes on the TMCC signal for each superframe, and TMCC information 1 to TMCC information 1 through TMCC signal that has been error-corrected by the TMCC error correction circuit 205. And a TMCC information acquisition circuit 206 for acquiring N.

  The BS front-end unit 200 also includes a transmission descrambling circuit 207 that restores transmission scramble of each frame signal output from the inner code error correction circuit 203, that is, energy spreading and interleaving, and a transmission descrambling circuit 207 An error correction process using Reed-Solomon (204, 188) code is performed on the signal of each slot of the sequentially output frame signal, and the transport is performed based on the TMCC information 1 to N acquired by the TMCC information acquisition circuit 206. A Reed-Solomon error correction circuit 208 that individually extracts and outputs the stream signals TS1 to TSN. Note that the demodulation operation in the demodulator 202 is also controlled based on the TMCC information 1 to N acquired by the TMCC information acquisition circuit 206.

  In the BS front end unit 200 configured as described above, when the BS digital broadcast signal Sbs is supplied to the tuner 201, the demodulator 202, the inner code error correction circuit 203, the transmission descrambling circuit 207, the Reed-Solomon error correction. The circuit 208 or the like performs processing on the BS digital broadcast signal Sbs according to a procedure almost opposite to the signal processing procedure in the transmission side encoding unit on the transmission side. The Reed-Solomon error correction circuit 208 extracts N transport stream signals TS1 to TSN included in the BS digital broadcast signal Sbs and outputs them individually.

  Next, details of the cable remodulation unit 300-1 will be described. The cable remodulation unit 300-1 is detected by the NIT detection circuit 301 that detects the NIT (network information table) from the transport stream signal TS1 output from the BS front end unit 200, and is detected by the NIT detection circuit 301. A memory 302 for storing the table NITa, and a memory 303 for storing the table NITb obtained by changing the table NITa stored in the memory 302 so as to be adapted to the cable network by the control unit 100.

  The NIT detection circuit 301 detects NIT based on a fixed PID. As described above, since the NIT table structure in the digital broadcast data related to the broadcast satellite 20 is as shown in FIG. 6, the table structure of the table NITa detected by the NIT detection circuit 301 is the same. Writing to and reading from the memories 302 and 303 are controlled by the control unit 100 via the interface 304.

  In the control unit 100, in obtaining the table NITb, the satellite delivery system descriptor (see FIG. 7) having the transmission frequency information and the like in the table NITa is, for example, the CATV delivery system system shown in FIG. Change to descriptor. Since the total length of the CATV delivery system descriptor is the same as that of the satellite delivery system descriptor, it can be simply replaced.

  The main contents will be explained. The descriptor tag is defined by DVB and indicates the type of descriptor. The frequency indicates a transmission frequency for each stream in CATV. FEC (outer code) indicates an error correction code as an outer code. Modulation / symbol rate / FEC (inner code) indicates a specification related to a transmission method.

  The cable remodulation unit 300-1 has an NIT replacement circuit 305 that detects NIT from the transport stream signal TS1 and replaces the NIT with a table NITb stored in the memory 303. The NIT replacement circuit 305 also detects NIT based on a fixed PID.

  In addition, the cable remodulation unit 300-1 re-synchronizes the synchronization byte (= 47H) to the head byte portion of each 188-byte MEG2 transport packet (MPEG2TS packet) constituting the transport stream signal TS1 in which NIT is replaced. From a synchronous byte reinsertion circuit 306 to be inserted, a synchronous inversion circuit 307 that inverts the synchronization byte at a rate of once every eight packets (= B8H) for each packet in which the synchronization byte is reinserted, and a synchronous inversion circuit 307 A Reed-Solomon code adding circuit 308 for adding an error correction code according to Reed-Solomon (204, 188) to each output packet. As described above, the synchronization inversion circuit 307 inverts the synchronization byte to obtain frame synchronization, and is matched with the DVB system.

FIG. 14B shows the frame structure of digital broadcast data in the DVB system, and one frame is composed of eight MPEG2 transport packets (see FIG. 14A). In this case, the synchronization byte (= 47 _H ) in the packet is used, and the frame is synchronized by inverting the synchronization byte (= B8 _H ) once every 8 packets. Note that an error correction code according to Reed-Solomon (204, 188) is added to each MPEG2 transport packet (MPEG2TS packet) as described above.

  Also, the cable remodulation unit 300-1 performs a 64QAM (Quadrature Amplitude Modulation) modulation process on the DVB frame configuration signal output from the DVB synchronous inversion circuit 308, and the 64QAM modulator. And a frequency converter 310 for converting the frequency of the modulation signal output from 309 to obtain the digital broadcast signal Sb1 of the first physical channel on the cable network.

  When the transport stream signal TS1 is supplied in the cable remodulation unit 300-1 configured as described above, the NIT replacement circuit 305 changes the NIT in the transport stream signal TS1 to the NIT suitable for the cable network. Replaced. Then, a sync byte (= 47H) is inserted into the first byte of each packet with respect to the transport stream signal in which NIT is replaced by the sync byte reinsertion circuit 306, and the DVB sync inversion circuit 307 once in 8 packets. Then, the sync byte is inverted to form a DVB frame signal, and the Reed-Solomon (204,188) code is added to each packet by the Reed-Solomon code adding circuit 308. The DVB frame configuration signal is subjected to 64QAM modulation by the 64QAM modulation circuit 309, and the modulated signal is frequency-converted by the frequency converter 310, so that digital broadcasting of the first physical channel in the cable transmission line 13 is performed. The signal Sb1 is generated, and the digital broadcast signal Sb1 is output from the cable remodulator 300-1.

  Note that the cable remodulators 300-2 to 300-N respectively include the NIT replacement circuit 305, the synchronization byte reinsertion circuit 306, the DVB synchronization inversion circuit 307, and the Reed-Solomon encoding circuit 308 in the cable remodulation unit 300-1. , 64QAM modulation circuit 309 and frequency converter 310. In the NIT replacement circuit 305 of the cable remodulation units 300-2 to 300-N, the NIT replacement is performed using the table NITb stored in the memory 303 of the cable remodulation unit 300-1. Further, the frequency converter 310 of the cable remodulators 300-2 to 300-N performs frequency conversion so that the digital broadcast signals Sb2 to SbN of the second to Nth physical channels in the cable transmission path 13 are generated, respectively. The

(D) Configuration of Receiving System FIG. 15 shows a configuration example of the receiving system 50 used as the set top boxes 14-1 to 14-m of the digital CATV system 10 of FIG. The receiving system 50 includes a digital cable receiver 60 and a digital BS receiver 80.

  The configuration of the cable receiver 60 will be described. The cable receiver 60 includes a terminal 61 connected to the cable transmission path 13, a microcomputer, a controller 62 for controlling the operation of the entire receiver, and a digital supplied from the cable transmission path 13 to the terminal 61. And a front end unit 65 for selecting a digital broadcast signal of a predetermined RF channel from the broadcast signal CDBS and obtaining a transport stream signal TS corresponding to the selected digital broadcast signal.

  The front end unit 65 further selects a digital broadcast signal of a predetermined RF channel from the digital broadcast signal CDBS, obtains digital modulation data corresponding to the digital broadcast signal, and the digital modulation data It comprises a demodulator 67 that performs demodulation processing, and an error correction circuit 68 that obtains a transport stream signal TS by performing error correction processing on the output data of the demodulator 67.

  Connected to the controller 62 are a key input unit 63 for accepting operations such as channel selection by the viewer, and a display unit 104 constituted by a liquid crystal display element for displaying the operation state of the apparatus and the like. . The channel selection operation in the tuner 66 is controlled by the controller 62 based on the operation of the viewer's key input unit 63.

  Also, the cable receiver 60 separates the video data and audio data packets of the channel designated by the user's operation of the key input unit 63 from the transport signal TS output from the front end unit 65, and these packets are transmitted. And a demultiplexer 69 for separating the additional data packet of the channel and outputting the additional data stream consisting of the packet.

  The demultiplexer 69 also acquires NIT, PAT, and PMT as the above-described program specification information (PSI) based on the control of the controller 62. The acquired information is supplied from the demultiplexer 69 to the controller 62. However, as will be described later, since the processing of the back end unit for the transport stream signal TS output from the front end unit 65 is performed by the digital BS receiver 80, only the NIT is actually used for channel selection. The Although not shown, a video processing unit, an audio processing unit, and the like are arranged at the subsequent stage of the demultiplexer 69 of the cable receiver 60. However, these portions are not used, and the description thereof is omitted.

  The cable receiver 60 has a terminal 70 for outputting the transport stream signal TS output from the front end unit 65. This terminal 70 is connected to a terminal for inputting the transport stream signal TS of the digital BS receiver 80. As a result, the processing of the back-end unit for the output transport stream signal TS is performed by the digital BS receiver 80. This eliminates the need for the cable receiver 60 to have an HD decoder or BS-specific EPG (Electronic Program Guide) data processing unit.

  The configuration of the BS receiver 80 will be described. The BS receiver 80 includes a microcomputer, and includes a controller 81 for controlling the operation of the entire receiver, a tuner 84, a demodulator 85, and an error correction circuit 86, and is included in the received BS digital broadcast signal. The front end unit 87 that selectively outputs one of the plurality of transport stream signals, and the transport stream signal TS that is output to the terminal 70 of the cable receiver 60 as described above are input. Terminal 88. Here, the front-end unit 87 is not used, and back-end processing is performed on the transport stream signal TS input to the terminal 88.

  The BS receiver 80 also outputs a descrambler 89 that performs a descrambling process on video data and audio data packets included in the transport stream signal TS input from the terminal 88, and a scrambler 89. From the transport stream signal TS, the video data and audio data packets of the channel specified by the user's operation of the key input unit 82 are separated, and the video data stream VDS and audio data stream ADS composed of these packets are output. And a demultiplexer 90 that separates the additional data packet of the channel and outputs an additional data stream SDS composed of the packet.

  The demultiplexer 90 also acquires NIT, PAT, and PMT as the above-described program specification information (PSI) based on the control of the controller 81. The acquired information is supplied to the controller 81. The NIT is used on the cable receiver 60 side as described above and becomes unnecessary information on the BS receiver 80 side.

  The BS receiver 80 also includes a video processing unit 91 that obtains a video signal SV by performing a data expansion process on the video data stream VDS, a video output terminal 92 that outputs the video signal SV, and a video processing unit. 91 and a video output terminal 92, and a synthesizer 93 for synthesizing a character display signal SCH such as program guide information, and an audio signal SA is obtained by performing a data expansion process on the audio data stream ADS. An audio processing unit 94 and an audio output terminal 95 for outputting the audio signal SA are provided.

  The BS receiver 80 has an IC card interface unit 97 to which an IC card 96 is connected. The IC card interface unit 97 is connected to the controller 81. The IC card 96 stores scramble key information and determines whether or not viewing is possible based on the limited reception information sent from the controller 81 via the IC card interface unit 97. Has a function of sending scramble key information to the controller 81 via the IC card interface unit 97.

  The BS receiver 80 includes an OSD (On Screen Display) circuit 98 for generating a character display signal SCH for displaying characters on the screen. The OSD circuit 98 is connected to the controller 81, and the character display signal generation operation is controlled by the controller 81.

  Next, the operation of the receiving system 50 shown in FIG. 15 will be briefly described. The digital broadcast signal CDBS is supplied through the terminal 61 from the cable transmission path 13 to the front end portion 65 of the cable receiver 60. The front end unit 65 selects a digital broadcast signal of a predetermined RF channel from the digital broadcast signal CDBS, and outputs a transport stream signal TS corresponding to the selected digital broadcast signal. The transport stream signal TS is output from the terminal 70.

  The transport stream signal TS is supplied to a terminal 88 of the BS receiver 80. The transport stream signal TS is supplied from a terminal 88 to a demultiplexer 89 via a descrambler 89, and video data and audio data of a predetermined program included in the transport stream signal TS, and further additional data thereof. Are separated. Here, data of one program is usually arranged in the transport stream signal TS.

  Here, the controller 81 supplies the limited reception information extracted from the additional data stream SDS to the IC card 96 via the IC card interface unit 97. The IC card 96 determines whether or not viewing is possible based on the limited reception information. If it is possible, the IC card 96 sends scramble key information to the controller 81 via the IC card interface unit 97. This key information is set in the descrambler 89 by the controller 81. As a result, the descrambler 89 descrambles the scrambled video data and audio data packets, and thus the video data stream VDS and audio data stream ADS obtained from the demultiplexer 90 are unscrambled. It will be related to the data.

  The video data stream VDS output from the demultiplexer 90 is subjected to processing such as data decompression in the video processing unit 91 to generate a video signal SV. This video signal SV is output via the synthesizer 93 to the output terminal 92. To be derived. Also, the audio data stream ADS output from the demultiplexer 90 is subjected to processing such as data expansion by the audio processing unit 94 to generate an audio signal SA, and this audio signal SA is derived to the output terminal 95. .

  In the receiving system 50 shown in FIG. 15, the back-end processing is performed by using the BS receiver 80 as it is, and the cost of the set top box can be reduced. It is possible to receive the same service as when the BS digital broadcast signal is directly received.

  As described above, in the present embodiment, as shown in FIG. 12, a plurality of transport stream signals TS1 to TSN are individually extracted and modulated from the BS digital broadcast signal Sbs, and thereafter, different frequencies are used. The digital broadcast signals Sb1 to SbN on the cable network are obtained by converting the signals into a signal. Therefore, a digital broadcast program broadcast by the BS digital broadcast can be easily distributed on the cable network.

  In the above-described embodiment, the cable network uses scramble information applied to the plurality of transport stream signals TS1 to TSN included in the BS digital broadcast signal Sbs as it is. You may make it utilize a scramble. In that case, in the transmission system 12 shown in FIG. 12, a descrambler for releasing the scramble applied to the transport stream signals TS1 to TSN, respectively, before the cable remodulators 300-1 to 300-N, Thereafter, a scrambler for performing unique scramble on the transport stream signals TS1 to TSN that have been descrambled is arranged.

DESCRIPTION OF SYMBOLS 10 Digital CATV system 11 Antenna 12 Transmission system 13 Cable transmission line 14-1-14-m Set top box 15-1-15-m Monitor 20 Broadcasting satellite 100 Control part 200 BS front end part 201 Tuner 203 Demodulator 204 , 207 Transmission scrambling circuit 205 TMCC error correction circuit 206 TMCC information acquisition circuit 208 Reed-Solomon error correction circuit 300-1 to 300-N cable remodulation unit 301 NIT detection circuit 302, 303 Memory 304 Interface 305 NIT replacement circuit 306 Synchronization byte re-transmission Insertion circuit 307 DVB synchronous inversion circuit 308 Reed-Solomon code addition circuit 309 64QAM modulator 310 Frequency converter 400 Adder

Claims (4)

Receiving processing means for individually extracting and outputting one of the transport stream signals from a plurality of transport stream signals including digital signals of the satellite line;
A descrambler for releasing scramble applied to the transport stream signal output by the reception processing means;
For the plurality of transport stream signals that have been descrambled by the descrambler, a network information table that includes physical information related to a transmission path and that is included in each of the signals is adapted to a cable line. And table replacement means for outputting the plurality of transport stream signals after replacement,
Arrangement means for arranging the transport stream signal in which the network information table has been replaced by the table replacement means for each frame slot serving as a transmission unit and outputting a frame signal;
A scrambler that performs other scrambles different from the scramble on the frame signal output by the arrangement means;
Modulation means for modulating the frame signal scrambled by the scrambler;
Transmission means for transmitting the frame signal modulated by the modulation means to the cable line,
The network information table suitable for the cable line is a signal processing device including modulation information.   The signal processing apparatus according to claim 1, wherein the modulation information is information indicating 64QAM modulation. A reception processing step of individually extracting and outputting any one of a plurality of transport stream signals including a digital signal of a satellite line; and
A descrambler step for releasing scrambling applied to the transport stream signal output in the reception processing step;
For the plurality of transport stream signals that have been descrambled in the descrambler step, a network information table that includes physical information related to the transmission path and is included in each of the signals is adapted to the cable line. Table replacement step for replacing the table and outputting the plurality of transport stream signals after replacement,
An arrangement step of outputting the frame signal by arranging the transport stream signal in which the network information table is replaced in the table replacement step for each slot of a frame serving as a transmission unit;
A scrambler step of performing another scramble different from the scramble on the frame signal output in the arrangement step;
A modulation step for modulating the frame signal scrambled in the scrambler step;
A transmission step for transmitting the frame signal modulated in the modulation step to the cable line;
The network information table suitable for the cable line is a signal processing method including modulation information. The signal processing method according to claim 3, wherein the modulation information is information indicating 64QAM modulation.

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