JP2001078158A - Transmitting device, multiplexing device and receiving device for cable television - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmitting device that the operations of a multiplexing device and a receiving device are reduced and the performance in the multiplexing and receiving devices is sufficiently exhibited by multiplexing digital data and a null transport stream and multiplexing a plurality of transport streams as one digital data output. SOLUTION: In TS synthesizing circuits 1031a and 1031b, transport stream form digital data TS 151, transport stream form digital data TS 152, transport stream form null TS 153 from null packet generating circuits 1032a and 1032b and a TSMF signal 161 from a TSMF constituting circuit 1034 are multiplexed by time division and synthesized into the plurality of TS 154. Then multi-level digital modulation is executed in 64 QAM modulating circuits 104a and 104b. The output of a re-transmission unit 101a and the output of the other re- transmission unit 101b are inputted to a frequency multiplexing circuit 105, multiplexed by frequency and outputted to a CATV transmission line 300.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmitting apparatus, a multiplexing apparatus, and a digital broadcasting system for transmitting digital broadcasting having a plurality of transport streams through a cable television (hereinafter, referred to as CATV) transmission line or the like. The present invention relates to a receiving device for receiving.

[0002]

2. Description of the Related Art For digital transmission of CATV, 1
"Technical Report of the Institute of Television Engineers of Japan (vol. 19, No. 42) published on September 21, 995, pp. 19 to 24" I have. According to this report,
A transport stream in which digital data such as an image compressed by a digital image compression technique called MPEG2 (MPEG2) is multiplexed and a data stream in a format called (TS), and signal processing such as Reed-Solomon error correction The signal is modulated by a digital modulation technique called 64QAM (64-level quadrature amplitude modulation) and transmitted to a CATV transmission line with a transmission capacity of about 30 Mbps.

As a method of distributing multi-channel digitized video as an input of a digital CATV, there is satellite digital television broadcasting, which is described in Nikkei Electronics, September 2, 1996, 149.
As described in the paper "The First Digital Satellite Broadcasting to Realize Nearly 70 Multi-Channels" on page, a plurality of digitally compressed (MPEG2) programs and data are packet-multiplexed, scrambled, and corrected and encoded. The transmitted single TS is transmitted by QPSK digital modulation. A remultiplexing apparatus that remultiplexes digital data composed of a plurality of bit streams such as a digital broadcasting service using a single TS is disclosed in Japanese Patent Application Laid-Open No. H10-41909.
Is shown in According to this publication, a single TS is 18
It is composed of an 8-byte TS packet.
It is shown that it consists of 84 bytes of packet data and 4 bytes of packet header. By re-editing and transmitting program control information etc. in the packet header in re-multiplexing, it is possible to receive data from multiple broadcasters at the receiving terminal. At the same time.

On the other hand, in a newly planned BS digital broadcast, transmission channel 1 of the conventional BS analog broadcast is used.
It plans to transmit not only a plurality of conventional standard television broadcasts but also high-definition television broadcasts to channels. Regarding the transmission of BS digital broadcasting, see the journal of the Visual Media Society of Japan (vol.
52 No. 11 1998) "B
S Digital Broadcasting System and Equipment ". BS
In digital broadcasting, by using a transmission capacity of about 60 Mbps, a plurality of modulation schemes can be used in a single repeater, and a plurality of TSs (hereinafter, referred to as video, audio, data, etc.) have a frame configuration. And transmit a new data format. In this data format, a transmission multiplex control signal (hereinafter, referred to as a TMCC signal) is used for transmitting modulation information in a frame and control information of a configuration of a plurality of TSs. TMCC signal is the Ministry of Posts and Ordinance No. 5
From No. 7, using the synchronization signal portion of the TS, the main signal is divided and transmitted in units of one frame (= 48 slots, 1 slot = 204 bytes), and transmitted with one superframe (= 8 frames) as a cycle. You. The configuration is shown in the Ministry of Posts and Telecommunications Notice No. 260, where 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 correspond to the ID of the desired TS (TS
ID). In addition, there are transmission / reception control information such as a change instruction number and emergency information and an extended information area.

In the conventional digital CATV technology described above, B
Since the transmission and reception of multiple TS transmissions planned for S digital broadcasting were not considered, July 27, 1999
Technical Report of the Institute of Image Information and Television Engineers (vo
l. 23, no. 48), "Proposal of Multiple MPEG-TS Cable TV Multiplexing System" on pages 7 to 12, and "Report on Cable MPEG Multi-TS Transmission Experiment of Multiple MPEG-TS" on pages 13 to 18 of the same report. I have.
In these reports, a T consisting of N 188 bytes
A TSMF header has been proposed in which S packets are collected to form a multiplexed frame, and the first packet describes TS arrangement information in the frame and the like. According to this proposal, a plurality of TS signals of BS digital broadcasting can be efficiently transmitted to a cable television. In this proposal, synchronization is performed to match the difference in transmission speed between BS digital broadcasting and digital CATV, a null TS is inserted for synchronization, and program clock information for reproducing a system clock on the receiving side. (Hereinafter referred to as PCR information).

[0006]

According to the above report, BS digital broadcasting at a transmission rate of 52.17 Mbps is transmitted over two carrier waves of digital CATV at a transmission rate of 29.162 Mbps. As an example, 4TS
5A and 5B, and FIG. 5 and FIG. 6 show an example of one frame configuration which is a presentation example thereof. The number of packets of each TS and the transmission speed of 188 bytes are as follows:
TS1 is 24.210 Mbps in 44 packets, TS2
Is 4.402 Mbps with 8 packets, TS3 is 15.406 Mbps with 28 packets, TS4 is 8.804 Mbps with 16 packets, the total transmission speed of TS1 and TS2 is 28.612 Mbps, and the total transmission speed of TS3 and TS4 is 24.210. That is, TS1
TSMF of 1 packet for a total of 52 packets of TS2 and TS2
The transmission rate for inserting the header is 64 QAM transmission rate 2
The transmission speed for inserting one TSMF header into a total of 44 packets of TS3 and TS4 and for inserting eight null packets is made to match the transmission speed of 64QAM of 29.162 Mbps.

[0007] However, the frame configuration in the multiplexing merely arranges the TSs in order, so that the load on the receiving apparatus can be reduced, and the need to re-describe the PCR information in the multiplexing of a plurality of TSs can be eliminated. There have been no proposals to reduce the operations of the multiplexing device and the receiving device so that the performance of those devices can be sufficiently exhibited.

An object of the present invention is to transmit a BS digital broadcast having a plurality of transport streams to a CATV transmission line or the like.
By eliminating the need to re-describe the PCR information in the multiplexing, it is possible to reduce the operations of the multiplexing device and the receiving device, and to provide a transmitting device and a receiving device for fully exhibiting the performance of those devices. is there.

[0009]

In order to solve the above-mentioned problems, according to the present invention, digital data in the form of a transport stream is selected from digital broadcasting such as satellite or terrestrial broadcasting, and adjusted in accordance with the digital transmission data rate of a cable television. In the transmitting apparatus of the cable television for transmitting, the digital data in the transport stream format and the null transport stream in the transport stream format for transmission data rate matching are multiplexed to multiplex a plurality of transport streams as one digital data output. And a multi-level QA such as a 64-level QA transmitted in a frequency multiplexed manner.
Demodulation means for demodulating a digital modulated wave by M or the like;
A data selection / separation unit input in a transport stream format; and a digital data in a transport stream format selected from a plurality of digital data sequences in the transport stream format, which are output from the demodulation unit, are output to the data selection / separation unit. A receiving device for a cable television provided with a plurality of transport stream separating means, or a demodulating means for demodulating a digital modulated wave by multi-valued QAM such as 64 values transmitted in a frequency multiplexed manner, and an input in a transport stream format A transport stream separation data validity information signal indicating a period not selected from a plurality of transport stream format digital data sequences output from the demodulation means, and a transport stream format digital data. When provided with a receiving device of a cable television that includes a plurality transport stream separating means for outputting a clock signal of the digital data to said data selecting separating means. Further, in a cable television transmitting apparatus for selecting digital data in a transport stream format from digital broadcasting such as satellite or terrestrial broadcasting and transmitting the digital data in accordance with the digital transmission data rate of the cable television, the digital broadcast is received and demodulated and transported. Digital data decoding means for outputting digital data in a stream format; and digital data decoding means for multiplexing the digital data in the transport stream format with a null transport stream in a transport stream format for transmission data rate matching to form a plurality of transport streams. Re-multiplexing means for multiplexing the port stream as one digital data sequence;
Transmission of a cable television, comprising: digital modulation means for digitally modulating with a multivalued QAM such as a value, and signal synthesizing means for frequency-multiplexing a plurality of modulated waves including the output of the digital modulation means and transmitting the modulated waves to a transmission path. An apparatus, demodulation means for demodulating a digital modulated wave by multi-level QAM such as 64-values transmitted in a frequency multiplexed manner, data selection / separation means for input in a transport stream format, and an output of the demodulation means. A cable television receiving apparatus comprising: a plurality of transport stream separating means for outputting digital data in a transport stream format selected from a plurality of digital data streams in a transport stream format to the data selection / separating means; or Modulated by multi-level QAM such as 64-level transmitted Demodulating means for demodulating a data selection separating means for inputting a transport stream format,
A transport stream separated data valid information signal indicating a period that is not selected from a plurality of transport stream format digital data sequences output from the demodulation means, a transport stream format digital data, and a clock signal of the digital data And a plurality of transport stream separation means for outputting the data stream to the data selection / separation means. Further, in a cable television transmitting apparatus for selecting digital data in a transport stream format from digital broadcasting such as satellite or terrestrial broadcasting and transmitting the digital data in accordance with the digital transmission data rate of the cable television, the digital broadcast is received and demodulated and transported. Digital data decoding means for outputting digital data in a stream format, and a transport stream of null data in a transport stream format for transmission data rate matching, wherein the generation frequency is variable according to the input of speed error information A transport stream generating means for multiplexing a transport stream of digital data in a transport stream format of the digital data decoding means with a null data transport stream output from the null transport stream generating means, and Re-multiplexing means for multiplexing a stream as one digital data sequence, digital modulation means for digitally modulating output data of the re-multiplexing means by multi-valued QAM such as 64 values, and reference from the digital modulation means A transport stream transmission rate for comparing a signal with a transmission rate of a plurality of multiplexed transport streams output from the remultiplexing means to obtain information on a transmission rate error and outputting the information to the null transport stream generating means. A transmitting device for a cable television, comprising: comparing means; and a signal synthesizing means for frequency-multiplexing a plurality of modulated waves including the output of the digital modulation means and transmitting the modulated waves to a transmission path. Multi-value Q such as
Demodulation means for demodulating a digital modulated wave by AM or the like, data selection / separation means for inputting in a transport stream format, and a transport selected from a plurality of transport stream format digital data sequences output from the demodulation means A receiving device for a cable television having a plurality of transport stream separating means for outputting digital data in a stream format to the data selecting / separating means, or digitally modulated by multi-valued QAM such as 64 values which are frequency-multiplexed and transmitted. Demodulation means for demodulating waves, data selection / separation means for inputting in a transport stream format, and transport stream separation indicating a period not selected from a plurality of transport stream format digital data sequences output from the demodulation means. Data validity information Signal, and the digital data transport stream format, the receiving apparatus of a cable television that includes a plurality transport stream separating means for outputting a clock signal of the digital data to said data selecting separating means provided. Further, in a cable television transmitting apparatus for selecting digital data in a transport stream format from digital broadcasting such as satellite or terrestrial broadcasting and transmitting the digital data in accordance with the digital transmission data rate of the cable television, the digital broadcast is received and demodulated and transported. Digital data decoding means for outputting digital data in a stream format, and a transport stream of null data in a transport stream format for transmission data rate matching, wherein the generation frequency is variable according to the input of speed error information A transport stream generating means for multiplexing a transport stream of digital data in a transport stream format of the digital data decoding means with a null data transport stream output from the null transport stream generating means, and And re-multiplexing means for multiplexing the stream as a digital data sequence, can be finely adjusted transmission rate according to a signal from the transmission rate control input, the output data of the re-multiplexing means 6
Variable transmission rate digital modulation means for digitally modulating the signal with multi-level QAM such as quaternary transmission, and transmission of a plurality of multiplexed transport streams output from the retransmission means and a reference signal from the variable transmission rate digital modulation means. A transport stream transmission rate comparison control which obtains information on a transmission rate error by comparing the transmission rate with the transmission rate output of the null transport stream generating means and a transmission rate control input of the variable transmission rate digital modulation means. Means, and signal combining means for frequency-multiplexing a plurality of modulated waves including the output of the variable transmission rate digital modulation means and transmitting the modulated waves to a transmission path. If there is a large error greater than the value, the speed of the null transport stream generating means The transmission rate error is coarsened through the difference information input, and when the error of the transport stream transmission rate comparison control means has a small error smaller than a certain reference value, the transmission rate control of the variable transmission rate digital modulation means is performed. A cable television transmission device for fine-tuning a transmission speed error via an input, demodulation means for demodulating a digitally modulated wave by multi-valued QAM such as 64-values transmitted in a frequency multiplexed manner, and input in a transport stream format And a plurality of transport stream separating means for outputting to the data selecting / separating means digital data of a transport stream format selected from a plurality of digital data streams of the transport stream format output from the demodulating means. Cable television receiver with 6, which is transmitted in
Demodulation means for demodulating a digital modulated wave by multi-level QAM such as quaternary, data selection / separation means for inputting in a transport stream format, and digital data sequences in a plurality of transport stream formats which are outputs of the demodulation means A transport stream separation data validity information signal indicating a period not selected from, a transport stream format digital data, and a plurality of transport stream separation means for outputting a clock signal of the digital data to the data selection separation means. Provided cable television receiver.

[0010] The remultiplexing means of the cable television transmitting apparatus may leave program clock information for reproducing a system clock on the receiving side in the digital data as it is (without rewriting) the position of the data packet. A null transport stream in a transport stream format for transmission data rate matching is configured with a plurality of packets so that the relationship is given priority (as little as possible) and multiplexed sparsely so as to be as time-sequential as possible.

By the above means, when transmitting a BS digital broadcast having a plurality of transport streams to a CATV transmission line or the like, it is possible to synchronize with the input / output of the multiplexer by synchronizing the transport stream of null data. In addition, since time information such as time stamps and PCR information can be left as it is, there is no need to change the inside of a transport stream including broadcast video and audio data. A multiplexing device that does not require re-description of PCR information in multiplexing port streams can be realized.

[0012] The transport stream T after selecting to receive from a plurality of transport streams.
Since S is sent evenly in time, the receiving device does not need a memory circuit for extending the time axis, and can perform image reproduction without passing through the circuit. A receiving device capable of reducing the time of the present invention can be realized.

Further, a slight difference in the transmission speed between the input and the output of the multiplexer can be adjusted by fine-tuning the transmission speed of the digital modulator using multi-valued QAM such as 64 values, so that null data can be synchronized. In some cases, the generation of a transport stream may be simplified, and the generation of a null data transport stream may not be necessary.In addition, the processing load of the multiplexer may be reduced, and the performance of the multiplexer may be fully exhibited. it can.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a transmitting apparatus and a receiving apparatus for a cable television according to an embodiment of the present invention. In FIG. 1, 100 is a CATV station transmitting apparatus, 101a and 101b are retransmission modulation units, 102 is a CATV station BS digital receiver, 103 is a multiplexing circuit, 104a and 104b are 64QAM modulation circuits, and 105
Is a frequency multiplexing circuit, 1021 is a digital demodulation / decoding and TS separation circuit, 1022 is a TMCC decoding & error rate measurement or reception CN ratio measurement circuit, 1031a, 1031
b is a TS synthesis circuit, 1032a and 1032b are null packet generation circuits, 1033a and 1033b are TS speed comparison circuits, 1034 is a TSMF configuration circuit, 1041a and
41b is a clock generation circuit, 151 and 152 are transport stream format digital data TS, 153 is a transport stream format null TS, 154 is a plurality of time-division multiplexed TSs, 161 is a TSMF signal, 17
1 is TS speed information, 172 is 64QAM transmission speed information,
173 is a speed error signal, 200 is a modulated signal of BS digital broadcasting, 300 is a CATV transmission line, 500 is a receiving terminal device, 501 is a frequency multiplexing / demultiplexing circuit, and 502 is 64QA.
M demodulation circuit, 503 error correction circuit, 504 TSMF
Decoding / TS separation circuit, 505 is a TS packet separation circuit,
506 is an MPEG video decoder circuit, 507 is an audio decoder circuit, 508 is a TV receiver on the receiving terminal side,
509 is a control circuit based on TSMF information, 551 is TS data, 552 is a clock signal for TS data, 553 is T
S separated data valid information signal, 554 is a video signal, 55
5 is an audio signal, 560 is a signal of TSMF information, 561 is a separation control signal by TSMF, and 562 is an activation control signal by TSMF. In this embodiment, only the main functional units are shown, and peripheral circuit blocks such as a control microcomputer are omitted. Further, in FIG. 1, the dotted line indicates that there are two or more retransmission modulation units. This number changes as appropriate depending on the number of TSs.

The modulated signal 200 of the BS digital broadcast received by the outdoor unit (not shown) is transmitted to the retransmission unit 10 in the CATV station transmitting apparatus 100 by a cable.
1a, 101b, digital demodulation / decoding in the BS digital receiver 102 for the CATV station, digital demodulation of channels determined by the TS separation circuit 1021, and transmission path decoding processing such as error correction and energy spreading. The received BS digital broadcast is divided into TSs (4 TSs in this embodiment), and is added to the TS combining circuits 1031a and 1031b in the multiplexing circuit 103. In the TS combining circuits 1031a and 1031b, the transport stream format digital data TS151 and the transport stream format digital data TS152 are added to the transport stream format null TS153 from the null packet generating circuits 1032a and 1032b, and the TSMF configuration. After the TSMF signal 161 from the circuit 1034 is combined with a plurality of time-division multiplexed TSs 154, the 64QAM modulation circuit 104a and the 64QAM modulation circuit 104b perform multi-level digital modulation. The output of the retransmission unit 101a;
The output of the other retransmission unit 101b is input to the frequency multiplexing circuit 105, frequency multiplexed, and then output to the CATV transmission line 300.

In order to control the transmission rates of the plurality of time-division multiplexed TSs 154, the TS rate comparing circuits 1033a and 1033b use the TS combining circuit 1
031a and the TS speed information 171 from the TS synthesis circuit 1031b and the 64QAM modulation circuits 104a and 104
Clock generation circuit 104 in 4QAM modulation circuit 104b
1a and 64Q from the clock generation circuit 1041b
The speed information is compared with the AM transmission speed information 172 by comparing the clock frequency and the like, and the speed error signal 173 is compared.
And a null packet generation circuit 1 according to the speed error.
A null TS 153 in a transport stream format is transmitted from 032a and 1032b. This null TS
Accordingly, the input and output of the multiplexing circuit can be synchronized, so that the inside of the broadcast data TS does not need to be changed, and the re-description of the PCR information is unnecessary. That is, the processing load on the multiplexer is reduced.

MPEG-TS is a single TS signal,
In addition to video and audio digital data,
There is a presentation time stamp to reproduce the temporally continuous signal such as video and audio at the correct time, and a decoding time stamp to give the decoding start time. It can be displayed in a format. As these standards, a PC called a program clock reference is used.
R information is also multiplexed and transmitted. Since the PCR information has digital data timing information of video and audio, inserting a null packet to change the transmission speed of TS and deleting a data packet to delete unnecessary video and audio digital data, etc. Therefore, if the time-series relationship inside the TS is changed, it is necessary to re-describe the PCR information.

However, in a plurality of TSs, even if another TS is inserted and deleted for the purpose of changing the transmission speed, etc.,
Is not changed. In other words, in a plurality of TSs, time-division multiplexing is performed between a plurality of TSs and transmitted. However, after a receiving apparatus selects and separates a TS required for reproduction to receive a service, the TS is expanded in time axis. Since the original MPEG-TS is returned, the time information such as the time stamp and the PCR information remains as the original information. Therefore, it is unnecessary to re-describe the PCR information in the TS.

TSMF from TSMF configuration circuit 1034
The signal 161 is formed from a signal obtained from the TMCC decoding & error rate measurement or the reception CN ratio measurement circuit 1022. As an example, there is a start flag for emergency alert broadcasting that activates a receiver for BS digital broadcast at the time of emergency alert broadcast, which is information transmitted by BS digital broadcast. Since the information is transmitted as a TMCC signal for BS digital broadcasting, the TMCC signal is decoded and transmitted to the TSMF configuration circuit 1034. Another example is hierarchized transmission using a feature that allows a combination of a plurality of modulation schemes to be transmitted to reduce service interruption due to rain in BS digital broadcasting. In hierarchical transmission, for example, QPSK that can receive trellis 8-phase PSK (TC8PSK) for normal television broadcasting (higher hierarchy) even at a low CN ratio
BPSK or BPSK is transmitted to the minimum broadcast (low hierarchy) in which the contents of the same program can be understood. Switching between the high hierarchy and the low hierarchy using the hierarchy transmission descriptor is performed by detecting a signal that detects a decrease in the CN ratio or an increase in the error rate. Perform on the basis. Since this information is known only at the point where the BS digital broadcast is being received, the BS digital signal obtained from the TMCC decoding & error rate measurement or the reception CN ratio measurement circuit 1022 is transmitted to the CATV receiving terminal device. The broadcast reception status is transmitted to the TSMF configuration circuit 1034.

In the receiving terminal device 500, a signal on the CATV transmission line 300 is input to a frequency division multiplexing / demultiplexing circuit 501 to select a desired channel. The selected channel is demodulated by a 64QAM demodulation circuit 502, and an error correction circuit is provided. At 503, error correction is performed. Thereafter, the TSMF decoding / TS separation circuit 504
Then, as shown in FIG. 1, the transport stream format digital data and the TSMF information are separated, and the separated TS data 551 and the TS data 551 in the transport stream format are separated.
A data clock signal 552 is output or, as shown in FIG. 7, a plurality of TS data 551 and a TS data clock signal 552 in a plurality of transport stream formats before being separated.
And a TS separated data valid information signal 553 is output. The output signal is input to a TS packet separation circuit 505 to separate video and audio packets. The video packet data is decoded by an MPEG video decoder 506, and the audio packet is output to an MPEG audio decoder 507.
To obtain a video signal 554 and an audio signal 555, which are input to the television receiver 508.

In a plurality of TSs, after selecting and separating a TS necessary for reproduction desired to receive a service by the receiving device,
Basically, S is extended on the time axis. However, by transmitting the signal as shown in FIGS. 2 and 3 described later, a position close to the case where each TS is extended on the time axis while being selectively separated on the receiving side. Therefore, a memory circuit for extending the time axis can be dispensed with, and the TS data 551 and the TS data clock signal 5 in the separated transport stream format can be eliminated.
By inputting 52 into the TS packet separation circuit 505 for separating video and audio data in the MPEG-TS, it is possible to separate packets required for reproduction desired to receive a service.

The TS packet separation circuit 505 generally operates with an MPEG-TS input, which is a packet of 188 bytes. However, the TS packet separation circuit 505 has 204 bytes obtained by adding a 16-byte correction code to a transmission line coding error correction code. Sent and corrected on the receiving side using the 16-byte signal.
20 with 16 bytes used for processing attached to 8 bytes
In many cases, a 4-byte signal is added to the TS packet separating circuit 505. In this case, a signal indicating a data valid / invalid period called enable is input to indicate a necessary 188-byte period and an unnecessary 16-byte period. You. TS
The packet separation circuit 505 operates by inputting three types of signals of MPEG-TS data, a clock, and an enable signal. Therefore, a plurality of transport stream format TS data 551 and a TS data clock signal 5 before separation are input.
52 and the TS separated data valid information signal 553.

FIGS. 2 and 3 show examples of the frame structure of the present invention. 13 of the Technical Report of the Institute of Image Information and Television Engineers (vol. 23, No. 48) published on July 27, 1999.
For example, in the "Experiment on Cable TV Transmission of Multiple MPEG-TSs" from page 18 to the example shown in FIG. 5 in which the repeater information of a 4TS BS digital broadcast is transmitted by two 64QAM signals each of 2TS (FIG. 5) And the same T as in Figure 6)
FIGS. 2 and 3 show examples in which S has a frame configuration proposed in the present invention. FIG. 2 shows retransmission of TS1 and TS2, and FIG. 3 shows retransmission of TS3 and TS4. In these figures, an 188-byte MPE consisting of a 4-byte packet header and 184-byte packet data sent in time is shown.
The G-TS packet is represented by one line, and packets transmitted at the next time after the packet are sequentially shown vertically.
The number of packets of each TS and the transmission speed of 188 bytes are the same as those in FIGS. 5 and 6, and TS1 is 44 packets and 24.21.
0Mbps, TS2 is 8.402Mbps with 8 packets
s, TS3 is 15.406 Mbps in 28 packets, T
S4 is 8.804 Mbps with 16 packets, and TS
The total transmission rate of 1 and TS2 is 28.612 Mbps,
The total transmission speed of TS3 and TS4 is 24.210, and the transmission speed of inserting a TSMF header of one packet into 52 packets of TS1 and TS2 is equal to the transmission speed of 64QAM of 29.162 Mbps.
TSMF of 1 packet for a total of 44 packets
By inserting a header and inserting 8 null packets, the transmission rate is 64 QAM transmission rate 29.162.
Mbps.

In the present invention, the digital data of TS1 and TS2 is digitally transmitted to the CATV, as shown in FIG. 2, after the TSMF header of packet number 0, TS1 is transmitted to packet numbers 1 to 5, TS at 6
2 is TS1 in packet numbers 7 to 11, TS2 is in packet number 12, and TS1 is in packet numbers 13 to 17.
The packet number 18 has TS2, the packet numbers 19 to 23 have TS1, the packet number 24 has TS2, the packet numbers 25 to 29 have TS1, the packet number 30 has TS2, and the packet numbers 31 to 35 have TS1. TS2 is the packet number 36, TS1 is the packet number 37 to 41, TS2 is the packet number 42, TS1 is the packet number 43 to 47, and TS2 is the packet number 48.
However, TS1 is sequentially transmitted to packet numbers 49 to 52, and is repeatedly transmitted from packet 0 again. Thus, for TS1, the packet numbers are 1 to 5, 7
From 11, 13 to 17, 19 to 23, 25 to 2
9, 31 to 35, 37 to 41, 43 to 47, 49
To 52, for TS2, the packet number is 6,
12, 18, 24, 30, 36, 42, and 48.

An example of digital transmission of digital data of TS3 and TS4 to CATV is shown in FIG.
A null packet in the TS format is added, followed by the TSMF header of packet number 0, TS3 in packet numbers 1, 3, and 5, TS4 in packet numbers 2 and 4, and a null TS in packet number 6. Sent alternately as shown.

Here, the digital data of a plurality of TSs transmitted in the example of the frame configuration shown in FIG. 2 are received, and the digital data of the TS1 or TS2 is separated into TSs. The PCR jitter due to the described change in the position of the PCR information will be described in comparison with FIG. In the case of a plurality of TSs, it is basically that the time axis is expanded after the selection and separation of the TS necessary for reproduction desired to be received by the receiving apparatus. However, it will be explained that the time axis expansion circuit can be eliminated by the present invention. In the frame configuration of FIG. 2 or FIG. 5, if the time axis expansion circuit is used and TS1 is connected so as to be continuous at the time of packet number 1 packet and time axis expansion is performed, Even if there is PCR information in the packet of packet number 1, almost no error occurs. However, since TS1 of the packet number 44 in FIG. 5 is equivalent to the time of the packet number 0 when the time axis is expanded, if the PCR information is included in the packet, the time of nine packets is shifted by about 0.46. The time error is distributed in a range of 0 to about 0.464 milliseconds, and differs depending on whether the PCR information is in the packet number 1 or the packet number 44. This means that the time error of millisecond fluctuates. This variation in the time error affects the reference clock recovery of the receiving device. About 0.
The value of 464 milliseconds was obtained by multiplying the reciprocal (1 bit transmission time) of the transmission rate of a 188-byte 64QAM signal of 29.162 Mbps (1 bit transmission time) by (8 × 188) to obtain the time of one packet, and multiplying the value by 9. . On the other hand, in FIG. 2, there is almost no error fluctuation because the signals are equally divided and transmitted.
A time error of about 0.05 millisecond corresponding to a packet occurs, and a time error of about 0.05 millisecond fluctuates. The variation of the time error of the PCR information of TS1 is about 0.464 ms in FIG.
In FIG. 2, it has been reduced to about 0.05 ms.

Considering TS2, there is a possibility that the time is shifted by 45 packets in FIG.
A time error of 2 milliseconds occurs. In FIG. 2, although the signal is distributed evenly in units of 5 packets, the signal is interrupted for a time interval of 5 packets, and a time error of about 0.26 milliseconds corresponding to 5 packets occurs. A time error variation of about 0.26 ms will occur. The variation of the time error of the PCR information of TS2 is about 2.32 ms in FIG. 5, but is reduced to about 0.26 ms in FIG.

Next, the permissible value of the receiving apparatus in the fluctuation of the time error of the PCR information will be described. Receiving device PC
Fluctuations in the time error of the clock recovery circuit reproduced by the MPEG-TS separation circuit based on the R information are absorbed by the time constant representing the response characteristic of the reproduction circuit. M for receiving frequency switching
The response is poor when the PEG-TS is switched to a different one, so the value is set to an appropriate value. As a standard of the value, there is a frequency of inputting PCR information of the receiving apparatus (determined by a frequency of transmission from the transmitting side), and the frequency is about once every 100 milliseconds. A time error of about 1 to 2 milliseconds is considered to be an allowable value of the fluctuation. Above that value, variations in receiver clock recovery may appear in image playback.

From the above considerations, by adopting the frame configuration of the present invention (TS1 and TS2 in the example of FIG. 2, and TS3 and TS4 in the example of FIG. 3), even after each TS is selected to be received, the TS Are evenly received in time,
The memory circuit for extending the time axis can be eliminated,
Since image reproduction can be performed without passing through the circuit, time from reception to image output can be reduced. In addition, since a multiplexing apparatus that does not require re-description of PCR information in multiplexing a plurality of TSs can be realized, the operation load of the multiplexing apparatus can be reduced, and the performance of the apparatus can be fully exhibited.

In a plurality of TSs, a TS necessary for reproduction to be received by the receiving device is selected and separated, and then the T
Basically, S is extended on the time axis.
By transmitting as shown in (1), each TS exists at a position close to the case where the time axis is extended while being selectively separated on the receiving side, so that a memory circuit for extending the time axis becomes unnecessary.

FIG. 4 is a block diagram showing a transmitting apparatus and a receiving apparatus for a cable television according to another embodiment of the present invention. In the figure, 4033a, 4033b
Is a TS speed comparison control circuit, 4041a and 4041b are frequency fine adjustment clock generation circuits, 471 is a frequency fine adjustment control signal, and the same numbers as those in FIG. 1 indicate the same functional blocks.

In order to control the transmission rate of the plurality of time-division multiplexed TSs 154, a TS rate comparison control circuit 4033a
In the TS speed comparison control circuit 4033b, the TS speed information 155 from the TS synthesis circuit 1031a and the TS speed synthesis circuit 1031b, the 64QAM modulation circuit 104a, and the frequency fine clock generation circuit 4041a and the frequency fine clock generation circuit 4041b in the 64QAM modulation circuit 104b. 64QAM transmission rate information 156
The speed information is compared by comparing the clock frequency and the like to obtain a speed error signal 157, and the null packet generation circuits 1032a and 1032 according to the speed error.
Null TS1 in transport stream format from 2b
53 is sent out. The input and the output of the multiplexing circuit are synchronized by this null TS, but the slight difference is obtained by using the frequency fine-tuning control signal 471 and the 64QAM modulation circuit 10.
The frequency fine-tuning clock generation circuit 4041a and the frequency fine-tuning clock generation circuit 4041b in the 4a and 64QAM modulation circuits 104b are controlled and synchronized. By doing so, in the multiplexing of TS as shown in FIG. 2, the generation of an extra null TS becomes unnecessary, and the processing load of the multiplexing device is further reduced. Also, in FIG. 3, the generation of the null TS may be performed only at a fixed period, and the null TS may be generated.
This also has the effect of simplifying the calculation of occurrence of.

[0034]

According to the present invention, in order to transmit a BS digital broadcast having a plurality of transport streams to a CATV transmission line or the like, synchronization with the input / output of the multiplexer by synchronizing with the transport stream of null data. Since the time information such as the time stamp and PCR information remains as it is, it is not necessary to change the inside of the transport stream including the broadcasted video and audio data, Since the multiplexing apparatus can eliminate the need to re-describe the PCR information in multiplexing a plurality of transport streams, the operation of the multiplexing apparatus can be reduced, and the performance of the apparatus can be sufficiently exhibited.

Further, according to the present invention, the transport stream TS selected to be received from a plurality of transport streams is transmitted evenly in time, so that the memory for expanding the time axis to the receiving apparatus is provided. Since image reproduction can be performed without a circuit and without passing through the circuit, the time from reception to image output can be reduced.

Further, the slight difference in the transmission speed between the input and the output of the multiplexer can be fine-tuned and synchronized with the transmission speed of a digital modulator such as a multi-level QAM such as a 64-level, so that null data can be obtained. In some cases, the calculation of transport stream generation may be simplified, and the generation of a transport stream of null data may not be required.In addition, the processing load on the multiplexing device may be reduced, and the performance of the device may be fully exhibited. Become.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a cable television transmission device and a reception device thereof according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a frame configuration of the present invention.

FIG. 3 is a diagram illustrating another example of a frame configuration according to the present invention;

FIG. 4 is a block diagram showing a cable television transmission device and a reception device thereof according to another embodiment of the present invention.

FIG. 5 is a diagram of a conventional one-frame configuration example.

FIG. 6 is a diagram of another conventional frame configuration example.

FIG. 7 is a block diagram showing a transmission device and a reception device of the cable television according to one embodiment of the present invention.

[Explanation of symbols]

100: CATV station transmitter, 101a, 101b: Retransmission modulation unit, 102: BS digital receiver for CATV station, 103: Multiplexer, 104a, 104b ... 64
QAM modulation circuit, 105 ... frequency multiplexing circuit, 1021 ...
A digital demodulation / decoding and TS separation circuit 1022 is a TMCC decoding & error rate measurement or reception CN ratio measurement circuit, 1031a, 1031b ... TS synthesis circuit, 1032
a, 1032b ... null packet generation circuit, 1033a,
1033b: TS speed comparison circuit, 1034: TSMF configuration circuit, 1041a, 1041b: Clock generation circuit,
151, 152... Transport stream format digital data TS, 153... Transport stream format null TS, 154...
61 ... TSMF signal, 171 ... TS speed information, 172 ...
64QAM transmission rate information, 173 ... speed error signal, 20
0: BS digital broadcast modulated signal, 300: CATV transmission line, 500: receiving terminal device, 501: frequency multiplexing / demultiplexing circuit, 502: 64QAM demodulation circuit, 503: error correction circuit, 504: TSMF decoding / TS separation circuit, 505
... TS packet separation circuit, 506 ... MPEG video decoder circuit, 507 ... Audio decoder circuit, 508 ...
TV receiver on the receiving terminal side, 509... Control circuit based on TSMF information, 551... TS separated data, 552... TS data clock signal, 553... TS separated data valid information signal, 554... Video signal, 555. …
TSMF information signal, 561... TSMF separation control signal, 562... TSMF start control signal, 4033
a, 4033b... TS speed comparison control circuit, 4041a,
4041b: Frequency fine-tuning clock generation circuit, 471: Frequency fine-tuning control signal.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Masaki Noda 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture F-term in the Digital Media Development Division, Hitachi, Ltd. 5C064 BA01 BB05 BC16 BC21 BD07 BD13 5K004 AA08 JA09 JE03 5K028 AA07 FF13 KK01 KK03 LL02 MM05

Claims (12)

[Claims] 1. A cable television transmitting apparatus for selecting digital data in a transport stream format from digital broadcasting including a satellite system and a terrestrial system and transmitting the digital data in accordance with a digital transmission data rate of the cable television.
Re-multiplexing means for multiplexing the transport stream format digital data and a transport stream format null transport stream for transmission data rate matching and multiplexing a plurality of transport streams as one digital data output. A transmission device for a cable television, comprising: 2. A cable television transmitting apparatus for selecting digital data in a transport stream format from digital broadcasting such as satellite or terrestrial broadcasting and transmitting the digital data in accordance with the digital transmission data rate of the cable television. Digital data decoding means for outputting digital data in a transport stream format, and digital data in the transport stream format of the digital data decoding means and a null transport stream in a transport stream format for transmission data rate matching. Remultiplexing means for multiplexing a plurality of transport streams as one digital data sequence,
The output data of the remultiplexing means is multi-valued QA such as 64 values.
Cable transmission means comprising: digital modulation means for digitally modulating with M or the like; and signal synthesizing means for frequency-multiplexing a plurality of modulated waves including the output of the digital modulation means and transmitting the multiplexed waves to a transmission path. apparatus. 3. A cable television transmission apparatus for selecting digital data in a transport stream format from digital broadcasting such as satellite or terrestrial broadcasting and transmitting the digital data in accordance with the digital transmission data rate of the cable television. Digital data decoding means for outputting digital data in a transport stream format, and a transport stream of null data in a transport stream format for transmission data rate matching, the frequency of occurrence of which is variable according to the speed error information input Null transport stream generating means, and a transport stream of digital data in the form of a transport stream of the digital data decoding means and a transport stream of null data output from the null transport stream generating means are multiplexed into a plurality of transport streams. Re-multiplexing means for multiplexing the port stream as one digital data sequence, digital modulation means for digitally modulating output data of the re-multiplexing means with multi-valued QAM such as 64 values, and A transport stream transmission for comparing a reference signal with a transmission rate of a plurality of multiplexed transport streams output from the remultiplexing means to obtain information on a transmission rate error and outputting the information to the null transport stream generating means. A transmission apparatus for a cable television, comprising: a speed comparison unit; and a signal synthesis unit that frequency-multiplexes a plurality of modulated waves including the output of the digital modulation unit and transmits the multiplexed wave to a transmission path. 4. A cable television transmission apparatus for selecting digital data in a transport stream format from satellite or terrestrial digital broadcasting and transmitting the digital data in accordance with the digital transmission data rate of the cable television. Digital data decoding means for outputting digital data in a transport stream format, and a transport stream of null data in a transport stream format for transmission data rate matching, the frequency of occurrence of which is variable according to the speed error information input Null transport stream generating means, and a transport stream of digital data in the form of a transport stream of the digital data decoding means and a transport stream of null data output from the null transport stream generating means are multiplexed into a plurality of transport streams. And re-multiplexing means for multiplexing the transport stream as one of the digital data sequence, it can be finely adjusted transmission rate according to a signal from the transmission rate control input,
The output data of the remultiplexing means is multi-valued QA such as 64 values.
A variable transmission rate digital modulation means for digitally modulating the signal by M, a reference signal from the variable transmission rate digital modulation means and a transmission rate of a plurality of multiplexed transport streams output from the re-multiplexing means. A transport stream transmission rate comparison control means for obtaining information on a transmission rate error and outputting the information to the speed error information input of the null transport stream generating means and a transmission rate control input of the variable transmission rate digital modulation means; Signal synthesizing means for frequency-multiplexing a plurality of modulated waves including the output of the velocity digital modulation means and transmitting the modulated waves to a transmission path, wherein the error of the transport stream transmission rate comparison control means is larger than a certain reference value. If it has, through the information input of the speed error of the null transport stream generating means If the error of the transport stream transmission rate comparison control means has a small error equal to or less than a certain reference value, the transmission rate error is transmitted through the transmission rate control input of the variable transmission rate digital modulation means. A transmission device for a cable television, wherein an error is finely adjusted. 5. The remultiplexing means does not rewrite the program clock information for reproducing a system clock on the receiving side in the digital data, and transmits the digital data so that the positional relationship of the packets of the digital data is prioritized. The cable television according to any one of claims 1 to 4, wherein a null transport stream in a transport stream format for speed matching is composed of a plurality of packets and multiplexed so that at least a part of the null transport stream is equal in time series. Transmission device. 6. A demodulation means for demodulating a digital modulated wave by multi-level QAM such as 64-values transmitted in a frequency multiplexed manner, and a plurality of transport stream digital data sequences output from said demodulation means. A plurality of transport stream separating means for outputting digital data of the selected transport stream format; and a data selecting / separating means for inputting digital data of the transport stream format selected by the plurality of transport stream separating means. A receiving device for a cable television. 7. A demodulation means for demodulating a digital modulated wave by multi-level QAM such as 64 values transmitted by frequency multiplexing and transmission, and a digital data sequence in a plurality of transport stream formats output from said demodulation means. A plurality of transport stream separation means for outputting a transport stream separation data validity information signal indicating a period for selecting and a period for not selecting digital data in the transport stream format, and a transport stream output by the plurality of transport stream separation means A receiving device for a cable television, comprising a data selection / separation unit for inputting a separated data valid information signal. 8. A transmitting apparatus for receiving a plurality of digital data in the TS format and transmitting the digital data in a cable, comprising: synthesizing means for synthesizing the digital data in the plurality of TS formats; and modulating an output signal of the synthesizing means. A transmission device for a cable television, comprising: a modulation unit that transmits at a predetermined transmission speed; and a speed information comparison unit that compares the transmission speed information of the modulation unit with the transmission speed information of the combining unit. 9. A transmitting apparatus for receiving digital data in a plurality of TS formats and transmitting the digital data in a cable, comprising: synthesizing means for synthesizing the digital data in the plurality of TS formats; and speed information on the TS of the synthesizing means. And a speed information comparing means for comparing speed information of an output destination of the synthesizing means with the speed information. 10. A receiving apparatus for receiving digital data in a plurality of TS formats transmitted on a cable, comprising: a TS separating unit for selecting digital data in a desired TS format from the digital data in the plurality of TS formats; A cable television receiving apparatus comprising: a TS packet separating unit that separates a TS packet from digital data of a desired TS format output from the separating unit. 11. A receiving apparatus for receiving a plurality of digital data in a TS format transmitted over a cable, comprising: outputting a plurality of the digital data in the TS format; and selecting a digital data in the TS format. A TS separating unit that outputs TS separated data indicating a non-selection period; a TS from a plurality of TS format digital data output from the TS separating unit and a desired TS format digital data input based on the TS separated data; A cable television receiving device comprising a TS packet separating means for separating packets. 12. A decoding means for decoding TS packets separated by said TS packet separation means and outputting video / audio information, and outputting video / audio based on the video / audio information output from said decoding means. A receiving device for a cable television, comprising: