JPS60100889A - Catv system - Google Patents

Abstract

PURPOSE:To supply high quality satellite broadcasting to a terminal without damagig at a CATV center by sending a voice signal to the terminal in a PCM signal condition. CONSTITUTION:The radio wave of respective channels arrived from a broadcasting satellite 1 are received with a parabolic antenna 21, and supplied to a CATV center 2. first, image signals V1-V4 and voice signals P1-P4 of respective channels are extracted at a center 2. Next, television signals T1-T4 are formed from video signals V1-V4 and are supplied to a mixing circuit 25. On the other hand, voice signals P1-P4 in the PCM signal condition are converted to one PCM signal SP at an interface circuit 27. The signal SP is supplied through a VSB modulation circuit 265 to a mixing circuit 25. Next, the output of the mixing circuit 25 is sent to respective terminals 3. In such a way, the high quality satellite broadcasting are supplied without damaging the quality at a CATV center.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a joint reception system for satellite broadcasting.

Background technology and its problems When satellite broadcasting and CATV systems are combined, the first
The result will be as shown in the figure.

That is, in Figure 1, (1) is a broadcasting satellite, (2)
is the C/ITV center, (3) is the terminal (terminal receiver) installed in each home, (61 is the coaxial cable, and, for example, 4 channels of radio waves (
In the case of Japan, when a maximum of 8 channels of radio waves are transmitted, this is received by a parabolic antenna (21), and the received signal is sent to an outdoor unit (22) placed on the back of the antenna (21). The frequency is converted into an intermediate frequency signal by , and the intermediate frequency signal is supplied to four indoor units (231) to (234) through coaxial cables, and the video signals V, ~v4 and audio signals S~S4 of each channel are Each is demodulated. And these signals v1
~V4. S1 to S4 are modulation circuits (241) to (244)
As shown in Fig. 2, TV signals T1 to T4 are provided in the same format as the TV signals in current TV broadcasting, but have different channels (for simplicity, in Fig. 2, each channel is adjacent to the other). These signals 'rt-'r4 are sent out to the coaxial cable (6) through the mixing circuit (25). Therefore, terminal (3)
Smell ζ can watch any satellite broadcast channel.

Togoro C1 In this case, in satellite broadcasting, audio signal 3
1 to S4 are converted into PCM and transmitted from the satellite 111, and are decoded from each PCM signal to each audio signal S1 to S4 in indoor units (231) to (234). In other words, the audio signals SR to S4 are of very high quality up to the indoor units (231) to (234).

However, these audio signals 81 to S4 are also connected to the coaxial cable (6).
At the stage when it is sent to FM, the same FM as general TV broadcasting
(Fj ■ - °C, and as shown in Figure 2, it is multiplexed with the video signal by frequency division, so P
The sound quality that was created through commercials is lost.

OBJECT OF THE INVENTION The present invention aims to solve these problems and to supply a highly crystalline audio signal to the terminal (3).

SUMMARY OF THE INVENTION Therefore, in the present invention, each audio signal is sent to each terminal (3) in the form of a PCM signal, and the PCM signal is sent in a format similar to that shown in FIG.

In other words, this PCM signal is as shown in Neo in Figure 3A.
It is a double-stranded code that has many frames, and one frame is composed of 256 words W1 to W256, and one word is composed of 168 bits as shown in FIG. 3B. , the period is 1/44.1kHz. Each word is an 8-bit synchronization code 5Y.
NC, 4-bit service bit SB, 32-bit x 4 data bit CIA-CHD, and 7-bit x 4 error correction bit ECC are sequentially provided.

In this case, the synchronization code 5YNC is the frame sync F in the first word W1 of the frame, as shown in FIG.
The other 255 swords W2 to W256 are word sync WS, and the frame sync FS and word sync WS have different bit patterns.

In addition, the service bit SB consists of the address signal for each terminal (3) and the service content (paid voice This is a signal that indicates permission to listen to broadcasts, etc.).

Furthermore, data bits CHA-CHD each have 3
It is composed of 2 bits and constitutes four independent channels CI A-CHD. So ζ,
Each of the channels CIA-CHD can be in any of the modes A%-D to D as shown in FIG. 3C.

Mode A is a mode in which the stereo left and right channel audio signals J+L and R are sampled at a frequency of 44.1 kHz and encoded into 16-bit PCM signals.
It is also the same format as I). Therefore, this A mode can provide an extremely high quality stereo audio signal.

Moreover, the B mode has two sets of stereo signals Lr.

R1 and L2. In this mode, R2 is sampled at a frequency of 44.1 kHz and encoded into 8-bit PCM signals. Note that in this B mode, noise reduction by compression/expansion of the audio signals L1 to R2 is also used. Therefore, in this B mode, two channels of high-quality stereo broadcasting can be provided.

Furthermore, in C mode, 8 channels of monaural signal M
In this mode, L to M e are sampled at a frequency of 22.05 kllz and each is encoded into an 8-bit PCM signal, but some of the signals M1 to Ms are used for coax etc. depending on the purpose. Therefore, in this C mode, news and weather forecast.

Services such as emergency broadcasting and corex can be realized.

Furthermore, D mode realizes B mode and C mode in one channel, and can support more detailed services.

The combinations of these AD and channels CHA to CHD are free.

Further, the error correction code ECC is for performing error correction for each of the channels CHA to CHD, and is a B CH code.

The PCM signal sp having the above format has a transmission bit rate of 168 bits x 44. Ikllz = 7.4Mb/s
This is the band 6 for one channel of television broadcasting.
'C transmission can be performed using MIIZ.

In the example shown in FIG. 4, C is the broadcasting satellite (1) to 4.
This is a case where the radio waves of the channel are received and sent to the terminal (3).

At the CATV center (2), the video signals Vt from the indoor units (231) to (234)
V4 is supplied to the VSB variable circuits (261) to (264), respectively, so that, for example, the 5th rI! As shown in J, television signals T1 to T4 have different channels (however, they do not have audio signals 81 to S4), and this signal T
L-T4 is supplied to the mixing circuit (25).

In addition, PCM from indoor units (231) to (234)
Audio signals, that is, audio signals P1 to P4 in the state of PCM signals that have been subjected to error correction and correction but have not been subjected to D/A conversion, are extracted, and these signals P
The signals I to P4 are supplied to the interface circuit (27), and the PCM signal S described in FIG. 3 is exchanged. In this case, signals P1-P4 are channel CHA-C
Each channel is assigned to the HD, and all channels are set to A mode.

Then, this PCM signal sp is transmitted to the VSB modulation circuit (265
) and has an occupied bandwidth of 6 MHz.
．． That is, the signal T5 has the same format as the modulated signal when the video carrier wave is modulated by the video signal in current television broadcasting, and this signal T6 is sent to the mixing circuit (25).
A mixed signal of signals T1 to T5 is sent from the mixing circuit (25) to the coaxial cable (6).

On the other hand, at the terminal (3), the number 1 from the cable (6) is supplied to the tuner (31), and the TV signal T1 of the desired channel (1 is any one of 1 to 4)
is frequency-converted to a video intermediate frequency signal, and this signal is passed through a video intermediate frequency amplifier (32) to a video detection circuit (33).
The video signal is demodulated, and this signal is supplied to the video circuit (34) to convert the three primary color signals 1? , G, and B, and these signals R-B are supplied to a color picture tube (35) to reproduce a color image.

Further, the signal from the cable (6) is supplied to the front end (tuner circuit') (41), and the signal T5 is frequency-converted to an intermediate frequency signal, and this signal is passed through the intermediate frequency amplifier (42) to the 'ζ demodulation circuit ( 43) CP supplied to
CM (The fK signal Sp is tuned to fjf, the Kono signal Sp is supplied to the channel selector (44), and the channel CI
Channel C11i corresponding to the channel (signal Ti) selected by the tuner (31) among IA-CHD
The data bits are extracted and supplied to a decoder (45) for error correction and correction, and then supplied to D/A converters (46L) and (46R) to produce the original audio signal. Then, R is taken out, and these signals are sent to the speaker (48L) through the amplifier (47L) and (47R).

(48R) for stereo reproduction.

Thus, according to the present invention, television broadcasts transmitted through the artificial satellite (11) can be viewed using the CATV system.
) The audio signal sent in the form of a PCM signal is converted to the format and sent to each terminal as a PCM signal (
3), so there is no loss of sound quality.
It can reproduce extremely Western quality audio.

Furthermore, if consecutive channels are allocated as shown in Fig. 2 in the CATV system shown in Fig. 1, the occupied band of the audio signal 5l=S+ must be narrowed in order to reduce interference from adjacent channels at the terminal (3). Therefore, in reality, signals Tl to T4 are assigned to every other channel, and therefore a wide band as a whole, for example, 42Ml1z
(= 6 MHz x 7) band is required,
According to this invention, the signal T11'4 includes the signals 81 to S4.
are not included, so the signals T1 to TL are not included as shown in FIG.
I can be assigned to consecutive channels, and even if there is a signal Ts, the overall required bandwidth is e.g. 30M
)Iz.

Furthermore, when it is permitted to allocate the signals '1'' 1 to Ts to every other channel, the video signals ■1 to V4 are allocated to each channel by shifting the band of
Therefore, a higher quality signal can be sent out as the video signal V, to (4).

Furthermore, high quality video and audio via satellite broadcasting can be supplied to each terminal (3) without the need to make any special changes to the existing CATV system. Furthermore, in Fig. 3,
Using the mat, audio signals other than satellite broadcasting or information signals such as fax can be simultaneously supplied, making it possible to provide a wide range of detailed services.

Effects of the invention Since the sound is sent to each terminal by PCM, the high sound quality of satellite broadcasting can be sent to the terminal without loss at the CATν center. In addition, since the audio signal is sent on a separate channel, the audio component that was present in conventional TV channels can be allocated to the video signal, which widens the video signal band and allows high-quality video to be sent. Can be done. Furthermore, it is compatible with multi-channel audio satellite broadcasting, and is a system that takes future development into consideration.

[Brief explanation of drawings]

1 to 3 and 5 are diagrams for explaining this invention, and FIG. 4 is a system diagram of an example of this invention. (2) is a CATV center, and (3) is a terminal.

Claims (1)

[Claims] A single channel signal consists of a video signal and a PCM audio signal, and when the signals of multiple channels are transmitted from a broadcasting satellite, the CATV center hears the "C" signal that is transmitted from the broadcasting satellite. The PCM-converted audio signals are each extracted from the received signals of the plurality of channels and reconfigured into a PCM signal of another channel, and the received signals of the plurality of channels are received. A CATV system that extracts each of the video signals from a channel signal, and sends the extracted plurality of video signals and arranged PCM signals to a plurality of terminals.