JP2005287057A - Transmission apparatus and reception apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and transmission/reception apparatus for performing stable transmission/reception using a cable television (CATV) transmission line or the like for a transport stream having a frame constitution and a BS digital broadcast for transmitting transmission multiplexing control information indicative of a modulation scheme in a frame or a transport stream constitution. <P>SOLUTION: Switching information of hierarchical transport stream type digital data of a BS digital broadcast is received by sending with digital modulation waves such as transmission multiplexing control information or FSK to attain a hierarchization switching timing, thereby selectively receiving the hierarchical transport stream type digital data. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention uses a cable television (CATV) transmission line or the like to transmit a BS digital broadcast in which a transport stream having a frame configuration and transmission multiplexing control information indicating a modulation scheme in the frame and a transport stream configuration are transmitted. The present invention relates to a method and a transmission / reception apparatus that perform stable transmission / reception.

Regarding the digital transmission of CATV, the Television Society Technical Report (vol. 19, No. 42: Non-Patent Document 1) published on September 21, 1995, pages 19 to 24, “Telecommunication Technology Council Provisional Method” It is shown in "Digital Cable Television Broadcasting Experiment". According to this report, a data stream of a format called a transport stream in which digital data such as an image compressed by a digital image compression technique called MPPEG 2 (MPEG2) is multiplexed is used for signal processing such as Reed-Solomon error correction. Modulated by a digital modulation technique called 64QAM (64-value quadrature amplitude modulation) and transmitted to a CATV transmission line with a transmission capacity of about 30 Mbps.

  Also, as a digital channel TV multi-channel digital video distribution method, there is a satellite digital television broadcast. The broadcast is described in the article “70” on page 149 of the Nikkei Electronics September 2, 1996 issue. As described in "Japan's first digital satellite broadcasting that realizes multi-channels near" (Non-Patent Document 2), multiple digitally compressed (MPEG2) programs and data are packet-multiplexed, scrambled, and corrected code A single transport stream is transmitted by QPSK digital modulation. The satellite digital broadcasting has a problem that the C / N deterioration due to rain attenuation or the like occurs rapidly with respect to the analog system, thereby causing a service interruption.

  In conventional digital CATV, after demodulating the digital video distributed by QPSK modulation, it is remodulated to 64QAM or other digital modulation and transmitted to the CATV transmission line. However, satellite digital video distribution is blocked by rain attenuation etc. Even if the service stopped, no particular consideration was given.

ITEJ Technical Report (vol.19, No.42) Nikkei Electronics September 2nd, 1996, page 149, "Japan's first digital satellite broadcasting that realizes nearly 70 channels"

  In the newly planned BS digital broadcast, not only a plurality of conventional digital television broadcasts but also a high-definition television broadcast is transmitted to one channel of a conventional BS analog broadcast transmission channel. The transmission of BS digital broadcasting is described in “BS Digital Broadcasting System and Equipment” on pages 24 to 31 of the Journal of the Video Media Society (vol. 52 No. 11 1998) in November 1998. BS digital broadcasting has a transmission capacity of about 60 Mbps, and a plurality of modulation schemes can be used in one repeater. A transport stream such as video, audio, and data has a frame structure, and a transmission multiplex control signal (TMCC signal) is used for transmission of control information of the modulation method and transport stream structure in the frame. TMCC, from the Ministry of Posts and Telecommunications Order No. 57, uses the synchronization signal portion of the transport stream and transmits it separately for each frame (= 48 slots, 1 slot = 204 bytes) before the main signal, and 1 superframe (= 8 Frame). The structure is shown in the Ministry of Posts and Telecommunications Notification No. 260, the transmission mode / slot information is used for selecting the digital demodulation means, and the relative TS / slot information and the relative TS / TSID correspondence are of the desired transport stream ID (TSID). Used for selective output. In addition, there are transmission / reception control information such as a change instruction number and emergency information, and an extended information area.

  In BS digital broadcasting, in order to reduce service interruption due to rain, layered transmission is possible by using a feature that enables transmission by combining a plurality of modulation schemes. The operation guidelines for layered transmission are described in “Chapter 3 Operation Guideline for Layered Modulation Service System” on pages 81 to 85 of the Radio Industry Association Standard (ARIB STD-B20 Version 1.0) of November 6, 1998. In the MPEG transport stream, a hierarchical transmission descriptor indicating the hierarchical relationship of programs is introduced. For example, trellis 8-phase PSK (TC8PSK) is transmitted as normal television broadcasting (higher layer), and QPSK and BPSK that can be received even at low C / N are transmitted as minimum information (lower layer) that can understand the contents of the same program. It is shown that the operation of the higher and lower layers by the layer transmission descriptor is performed on the basis of a signal that detects a decrease in C / N and an increase in error rate.

  However, in the above-described conventional digital CATV technology, transmission and reception of hierarchical transmission planned in BS digital broadcasting are not considered.

  The present invention relates to a method and a transmission / reception apparatus for performing stable transmission / reception of BS digital broadcasting using a CATV transmission line or the like.

In order to solve the above problems, the present invention is based on BS digital broadcast receiving means, C / N or error rate measuring means, demodulated transport stream format digital data having a hierarchical relationship, and measurement results. Means for multiplexing the switching information of the high hierarchy and the low hierarchy into a transmission multiplex control signal, for example, an extension area of the transmission multiplex control signal, a modulation means for digital modulation with multi-value QAM such as 64 values, and an output of the modulation means A transmission side means comprising a signal synthesis means for frequency-multiplexing a plurality of modulated waves including and sending out to a transmission line;
Demodulating means for demodulating digitally modulated modulated waves such as multi-level QAM such as 64-value transmitted after being frequency-multiplexed, transport stream format digital data having a hierarchical relationship, and transmission multiplexing of the transport stream Means for decoding control information, and means for selectively decoding one layered transport stream in a transport stream format having a layered relationship according to switching information of the layered transport stream in a transmission multiplex control signal. A receiving means is provided.

  As described above, according to the present invention, it is possible to provide a receiving apparatus capable of performing stable transmission / reception of a layered transmission signal when a CATV transmission line or the like is used.

  Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram illustrating a transmission device and a reception device according to an embodiment of the present invention. In FIG. 1, 100 is a digital demodulation circuit, 101 is a transmission line decoding circuit, 102 is a TS separation circuit, 103 and 109 are TS synthesis circuits, 104 and 110 are 64QAM modulation circuits, 105 is a frequency multiplexing circuit, and 106 is a TMCC decoding circuit. 107 is an error rate measurement circuit, 108 is a TMCC reconfiguration circuit, 200 is a BS digital broadcast modulation signal, 201 is a CATV transmission line, 202 is a TMCC information signal, 203 is a transport stream format data, and 204 is a video signal 205 is a voice signal, 300 is a CATV transmitter, 301 is a receiving terminal, 400 and 401 are retransmission modulation units, 500 is a frequency demultiplexing circuit, 501 is a 64QAM demodulator, 502 is an error correction circuit, and 503 is a TMCC. / TS separation circuit, 504 is a hierarchical switching determination circuit, and 505 is a TS path. 504 is an MPEG video decoder circuit, 507 is an audio decoder circuit, and 508 is a TV receiver on the receiving terminal side. In this embodiment, only main functional units are shown, and peripheral circuit blocks such as a control microcomputer are omitted.

The modulated signal 200 of the hierarchical BS digital broadcast received by the outdoor unit (not shown) is input to the retransmission units 400 and 401 in the CATV transmission apparatus via the cable, and the channel of the channel determined by the digital demodulation circuit 100 is input. Digital demodulation is performed, error correction and energy diffusion are performed by the transmission path decoding circuit 101, and the transport stream demultiplexing circuit 102 converts BS digital broadcasting of about 60 Mbps into 2 to 2 so as to correspond to about 30 Mbps of CATV transmission capacity. The signal is divided into three (in this embodiment, divided into two), and each is input to the transport stream synthesis circuit 109. After superimposing the transmission multiplex control signal TMCC on the synchronous portion, multi-level modulation is performed by the 64QAM modulation circuits 104 and 105. The output of the retransmission modulation unit 400, including the output from the other retransmission unit 401, is input to the frequency multiplexing circuit 105 and frequency multiplexed, and then output to the CATV transmission line 201.

  In the receiving side terminal device, the signal of the CATV transmission line 201 is input to the frequency demultiplexing circuit 500 to select a desired channel, the channel selection output is demodulated by a 64QAM demodulation circuit, and the error correction circuit 502 performs error correction. After that, the TMCC / TS separation circuit 503 separates the transport stream format data from the TMCC, and the separated transport stream is input to the TS packet separation circuit 505 to separate the video and audio packets. The video packet data is decoded by the MPEG video decoder 506 to obtain the video signal 204, and the audio packet is decoded by the MPEG audio decoder 507 to obtain the video signal 204 and the audio signal 205, which are input to the television receiver 508.

  In order to cope with the hierarchical BS digital broadcasting service, the transmission facility 300 includes an error rate measurement circuit 107 and a hierarchical switching determination circuit 504 on the receiving terminal side. The error rate measurement circuit 107 estimates the error rate of the received BS digital broadcast signal by comparing the input and output of, for example, a Viterbi decoding circuit (not shown, included in the transmission path decoding circuit 101), and determines in advance. When the error rate exceeds the specified error rate, the TMCC reconfiguration circuit 108 sets a flag indicating that the error rate of the transmission path is large in the transmission multiplexing control information. FIG. 2 is a reference diagram for explaining the configuration of transmission multiplexing control information. Reference numeral 600 denotes a transmission multiplex control signal, and reference numeral 601 denotes extended information in the transmission multiplex control signal. The transmission multiplexing control information has 384 bits in total, but the last 62 bits of extended information 601 are not defined. For example, a part of the extended area 601 is used as the error rate deterioration flag. The transmission multiplexing control information in which the error rate degradation flag is set in the TMCC reconfiguration circuit 108 is superimposed on the transport stream format data of the main signal by the TS synthesis circuits 103 and 109 and transmitted to the CATV transmission path. The receiving terminal 301 separates the TMCC information from the data in the transport stream format that has been error-corrected by the TMCC / TS separation circuit 503, and determines whether or not there is an error rate deterioration flag by the layer switching determination circuit 504. When set, the TS packet separation 505 selects the low-layer data and outputs it to each decoder. FIG. 3 is a reference diagram of slot assignment in hierarchical BS digital broadcasting. Reference numeral 602 denotes an example of a high-layer TC8PSK modulation slot, reference numeral 603 denotes a BPSK-modulated low-layer TV service slot, and reference numeral 604 denotes a dummy slot set by a low-layer modulation scheme. Normally, the packet separation circuit 505 selects a slot of the TC8PSK 602, but when detecting an error rate increase flag, the packet separation circuit 505 selects a lower layer, in this example, a BPSK modulation slot. In this example, the error rate measurement circuit 107 has been described for detecting the deterioration of the transmission line. However, as will be described later, C / N deterioration may be used instead of the error rate measurement.

  FIG. 4 is a block diagram showing a transmitting apparatus and a receiving apparatus according to another embodiment of the present invention. In the figure, the same numbers as in the other figures indicate the same functional blocks, 111 is a C / N measurement circuit, 112 is a hierarchical switching signal generation circuit, 113 is a downlink signal modulation circuit, 509 is a downlink signal demodulation circuit, 510 Is a hierarchy switching signal decoding circuit. In this example, the C / N measurement circuit 111 is used to detect the deterioration of the transmission path. When the C / N is deteriorated from the set C / N, a signal is generated by the layer switching signal generation circuit 112, and downlink signal modulation (for example, FSK) is performed. Flag information is superimposed on (modulation) and transmitted to the CATV transmission line 201. In the receiving terminal 301, the downlink signal is separated by the frequency demultiplexing 500, the downlink signal demodulating circuit 509 demodulates the downlink signal, and the hierarchy switching signal decoding circuit 510 decodes the hierarchy switching signal from the demodulated output. If the layer switching flag is detected, the generation of the flag is transmitted from the layer switching decoding circuit 510 to the TS packet separation 505, and the low layer slot is selected.

  FIG. 5 is a block diagram showing a transmitting apparatus and a receiving apparatus according to another embodiment of the present invention. In the figure, the same reference numerals as those in the other figures indicate the same functional blocks. In the present embodiment, the output of the TS separation circuit 102 outputs only the TC8PSK modulation slot 602 of FIG. 3, and the low-level BPSK modulation slot 601 outputs, for example, as a dummy slot. Now, when the result of the C / N measurement circuit 111 deteriorates from a set C / N value, a signal is generated from the hierarchical switching circuit 112, and the output of the TS separation circuit 102 is conversely the area of the TC8PSK modulation slot 602 is a dummy slot. BPSK modulation slot 601 is output, 68QAM modulated, and sent to CATV transmission line 201. The receiving terminal 301 has a feature that does not require a circuit for selecting hierarchization.

  FIG. 6 is a block diagram showing a transmitting apparatus and a receiving apparatus according to another embodiment of the present invention. In the figure, the same numbers as in the other figures indicate the same functional blocks, and 512 is an error measurement circuit in TS packet separation. In this embodiment, the CATV transmitting apparatus 300 side does not switch the hierarchized signal due to the error rate or C / N deterioration, and the error measuring circuit 512 is provided in the TS packet separation 505 of the receiving side terminal 301. That is, when the layered BS digital broadcast signal deteriorates C / N due to rain attenuation or the like and the error rate increases, an error occurs in the processing of the TS packet separation 505, the MPEG video decoder 506, or the audio decoder 507. In this embodiment, when these errors are measured and the errors exceed a set value, the slot selection in the TS packet separation is changed from the TC8PSK slot 602 in FIG. 3 to the BPSK modulation slot 601 for processing. It is.

The low-layer modulation examples described so far have been described using BPSK modulation. However, the present invention is not limited to this, and it is obvious that the effect can be obtained even when QPSK modulation is used.
According to the above-described embodiment, by transmitting the digital data switching information in the transport stream format hierarchized in the BS digital broadcasting by the transmission modulation control information or the digital modulation wave such as FSK,
The receiving side can know the switching timing of hierarchization and can selectively receive digital data in the hierarchized transport stream format.

  Further, by selecting and outputting a BS digital broadcast layered television on the transmission side, it is possible to deal with BS digital layered transport stream format digital data even if the reception side does not have a layer switching means.

  Alternatively, layered transport streams can be switched based on digital stream switching information decoded in the transport stream format on the receiver side, so that BS digital layering can be performed even if the transmission side does not support layered transport. Supports digital data in the transport stream format. For these reasons, it is possible to receive hierarchical transmission planned for BS digital broadcasting using a CATV transmission path or the like, and to reduce service interruption due to rainfall of BS digital broadcasting.

It is a block diagram which shows the transmitter and receiver of one Example of this invention. It is a block diagram of transmission multiplexing control information. It is an example of slot allocation in hierarchical BS digital broadcasting. It is a block diagram which shows the transmitting apparatus and receiving apparatus of another Example of this invention. It is a block diagram which shows the transmitting apparatus and receiving apparatus of another Example of this invention. It is a block diagram which shows the transmitting apparatus and receiving apparatus of another Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Digital demodulation circuit, 101 ... Transmission path decoding circuit, 102 ... TS separation circuit, 103, 109 ... TS synthesis circuit, 104, 110 ... 68QAM modulation circuit, 105 ... Frequency multiplexing circuit, 106 ... TMCC decoding circuit, 107 ... Error Rate measurement circuit 108... TMCC reconfiguration circuit 111... C / N measurement circuit 112. Hierarchical switching signal generation circuit 113. Downlink signal modulation circuit 300 300 CATV transmission device 301. , 401 ... Retransmission modulation unit, 500 ... Frequency demultiplexing circuit, 501 ... 64QAM demodulation circuit, 502 ... Error correction circuit, 503 ... TMCC / TS separation circuit, 504 ... Hierarchical switching determination circuit, 505 ... TS packet separation circuit, 506... MPEG video decoder circuit, 507. Audio decoder circuit, 508. End side of the TV receiver, 509 ... downlink signal demodulation circuit, 510 ... layered switching signal decoding circuit, 512 ... error measuring circuit.

Claims (11)

  C / N or error rate measuring means, digital data in transport stream format having a hierarchical relationship, and transmission information of the hierarchical relationship based on the result of the measuring means in transmission multiplexing control information of the transport stream A modulation means for digital modulation such as multi-level QAM such as 64-value, and a signal synthesis means for frequency-multiplexing a plurality of modulated waves including the output of the modulation means and sending them to the transmission line A transmission apparatus comprising:   C / N or error rate measurement means, transport stream format digital data having a hierarchical relationship, means for multiplexing the transmission multiplex control information of the transport stream, multi-value QAM such as 64 values, etc. First modulation means for digital modulation, second modulation means for digitally modulating the switching information of the hierarchical relationship based on the result of the measurement means, such as FSK, the output of the first modulation means, and the A transmission apparatus comprising: a signal combining unit that frequency-multiplexes a plurality of modulated waves including an output of the second modulation unit and sends the modulated wave to a transmission line.   A transport stream format digital data having a layered relationship is inputted to the transport stream and means for selecting a transport stream of an arbitrary layer, and the selected transport stream, other transport streams, and transmission multiplexing control Means for multiplexing information, modulation means for digital modulation such as multi-level QAM such as 64-value, and signal synthesis means for frequency-multiplexing a plurality of modulated waves including the output of the modulation means and sending them to the transmission line A transmission apparatus comprising:   5. The receiving unit according to claim 1, further comprising: a satellite digital broadcast receiving means, a demodulating means, a transport stream format digital data decoding means having a hierarchical relationship, and a transmission multiplexing control information decoding means. A transmitter characterized by the above.   Demodulating means for demodulating a digital modulated wave such as multilevel QAM such as 64-value transmitted by frequency multiplexing, transport stream format digital data having a hierarchical relationship, and transmission multiplexing control information of the transport stream Means for decoding, and means for selectively decoding one layered transport stream of a layered transport stream format according to the layered transport stream switching information in the transmission multiplexing control information A receiving device.   First demodulating means for demodulating a digital modulated wave such as multi-level QAM such as 64-value transmitted by frequency multiplexing, and second demodulating a digital modulated wave such as FSK transmitted by frequency multiplexing. Demodulating means; means for decoding transport stream format digital data having a layered relationship from the first demodulating means; and transmission multiplexing control information of the transport stream; and output from the second demodulating means to the layered transport Means for decoding stream switching information, and means for selectively decoding one layered transport stream in a transport stream format having a layered relationship based on the layered transport stream switching information. Receiving device.   Demodulating means for demodulating a digital modulated wave such as multi-level QAM such as 64-value transmitted by frequency multiplexing, means for decoding digital data in a transport stream format having a hierarchical relationship, and decoded transport Receiving means comprising: a means for measuring the number of errors in stream format data; and means for selectively decoding one layered transport stream having a layered relationship according to a result of the means for measuring. apparatus. A transmission device for transmitting hierarchical digital data including control information,
A transmission apparatus comprising switching information adding means for adding hierarchy switching information to the control information. A receiving device that receives hierarchical digital data including control information to which hierarchical switching information is added,
A receiving apparatus comprising switching means for switching a hierarchy of the digital data based on the hierarchy switching information. A transmission device for transmitting hierarchical digital data including control information,
Switching information adding means for adding hierarchy switching information to the control information;
A transmission apparatus comprising switching means for switching a hierarchy of the digital data based on the hierarchy switching information. A receiving device for receiving hierarchical digital data including control information,
Switching information detecting means for detecting hierarchy switching information from the digital data;
A receiving apparatus comprising switching means for switching a hierarchy of the digital data based on the hierarchy switching information.

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