JPS62188484A - Transmission system for television signal - Google Patents

Abstract

PURPOSE:To attain image reproduction prevented from the deterioration in picture quality by transmitting component television signals distributed into plural systems in parallel through plural optical transmission lines and correcting the deviation of delay times among the plural optical transmission lines. CONSTITUTION:Component television signals are distributed into plural systems and transmitted in parallel through plural optical transmission lines, and in this case, a time axis correcting circuit 36 is inserted between a decoder 32 and a channel integrating circuit 33 in a signal processor 35. The circuit 36 is mainly constituted of a write address generating circuit 37, a read address generating circuit 38 and a two-port RAM 39. The correcting capacity of the circuit 36 is deined as 1H when both the signal processors 10, 35 are connected through an optical fiber OF13, and when a recording/reproducing part 20 is inserted between both the signal processors, 4H correcting capacity is required. Thus, the deviation among the transmission times of the optical fiber OF13 or the like can be corrected by using the circuit 36. Consequently, image reproduction prevented from the extension of a transmission distance and the deterioration of picture quality.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a television signal transmission system suitable for surface quality television signals.

[Summary of the invention]

The present invention distributes television signals to a plurality of systems, transmits them in parallel through a plurality of optical transmission lines, and compensates for deviations in delay time between the plurality of optical transmission lines. This is designed to extend the transmission distance and reproduce images without deterioration in image quality.

[Conventional technology]

As is well known, the screen quality television signal (hereinafter referred to as HD video signal) is based on the current standard system (NTSC system, etc.).
The bandwidth is much wider than that of video signals. It is desirable to record (transmit) such an HD video signal using a digital method, which allows a high-quality reproduced image to be obtained and which causes very little deterioration in image quality due to (transmission or) dubbing.

[Problem that the invention seeks to solve]

However, the bandwidth and sampling frequency required to digitally record an HD video signal are, for example, as follows.

■Video signal bandwidth Y 25. OMHzCw
12.5MIIZ CM 12.5MIIZ ■Sampling frequency Y 64.8MHzCw
32.4MHz CM 32.4MHz For example, in the case of 8-pi I-quantization per sample, the data rate of digital data based on these specifications is 10
37Mb/s, current standard method (NTSC method)
Compared to the 27 Mb/s per channel of a so-called 4-2'-2 type digital VTR (sampling frequency is 14.3 MHz, 4-channel parallel recording), this is much higher. Even when recording, the data rate per channel is, for example, 2.
50 Mb/s, which makes it extremely difficult to manufacture magnetic head systems capable of such high-speed recording and signal processing circuit devices that process signals to be supplied to each magnetic head system. there were.

In view of the above, the applicant has filed Japanese Patent Application No. 60-25545.
In No. 4, we have already proposed a transmission method for television signals that can easily transmit broadband and high-speed data.
There is.

First, with reference to FIGS. 3 and 4, a configuration example in which a previously proposed television signal transmission system is applied to digital magnetic recording of an HD video signal will be described.

In FIG. 3, (lO) indicates the recording (transmission) side signal processing device as a whole, and the luminance signal component Y and color signal components Cw and CM of an HD video signal from an HD television camera or the like (not shown) are A. - is supplied to the converter (11). The frequency bandwidth of each signal Y, C and CN is
For example, as mentioned above, 25 MHz and 12 MHz, respectively.
．． 5 MHz and 12.5°ζ, respectively 64.8 MIIz in the A-D converter (11).

It is sampled at 32.4 MHz and 32.4 frequency. The quantization number of each sample is 8 bits.

The signals y, cv, and CM each digitized by the A-D converter (11) are supplied to a channel distribution circuit (parallelization circuit) (12). As shown in FIG. 4, this channel distribution circuit (parallelization circuit) (12) divides each signal Y, C%d, and CM into equal intervals in the horizontal direction on the surface of the television, and further, Each of the divided signals is distributed to two channels, and in this configuration example, there are eight channels in total.

(13) is an encoder, which is a channel distribution circuit (
12) Error correction encoding of the data of each signal Y, Cw and CM distributed from the recording change II (for example, scramble N
RZ modulation) etc. are performed. The outputs of the eight channels of the encoder (13) are each supplied to an electrical-optical conversion circuit (14). A light emitting diode is used in this electric-optical conversion circuit (14) because it can directly modulate the intensity of light, simplifies peripheral circuitry, and is suitable for miniaturization.

The optical outputs of the eight channels of the electric-to-optical conversion circuit (14) are respectively supplied to the optical-to-electrical conversion circuit (21) of the recording/reproducing section (20) via the optical fiber 0F12. The interference caused by the incorporation of electrical noise in the signal is prevented and the signal is converted back into an electrical signal. The outputs of the optical-electrical conversion circuits (21) are each supplied to an 8,000-channel recording magnetic head (not shown) of a tape running system (22).

The output of the 8-channel reproducing magnetic head [1 is not shown] of the tape running thread (22) is supplied to an electrical-optical conversion circuit (23).

(30) shows the reproduction (receiving) side signal processing device as a whole, and the optical output of the electrical-to-optical conversion circuit (23) of the recording/reproducing section (20) is transmitted via the optical fiber OF 23 to the optical-to-electrical conversion circuit. It is supplied to the circuit (31).

The output of this optical-electrical conversion circuit (31) is transmitted to the decoder (32).
), and undergoes signal processing opposite to that in the encoder (13), ie, demodulation, error correction, etc.

The outputs of the eight channels of the decoder (32) are supplied to the channel integration circuit (33), and the signals of the eight channels are integrated by means opposite to those in the channel distribution circuit (12) described above, and the luminance signal component Y and the color Signal component Cw
and CM data are obtained. Each signal Y, Cw and C
M data is supplied to the D-A conversion circuit (34) to restore the analog HD video signal, and the output switcher,
It is supplied to a monitor, etc. (all not shown).

Next, channel distribution in this configuration example will be explained with reference to FIG.

In parallel processing using screen division, the output sampling frequency is 16.2M, which is 1/4 of the previously mentioned 64.8MHz.
down to Hz. The parallelization process by internal division is described in Japanese Patent Application No. 59-99867 filed by the present applicant.
Details are disclosed in the issue. For simplicity, it is assumed that 8 (11d) data exists for each signal Y, Cv, and CN on one scanning line of each divided screen, as shown in FIG.

Odd-numbered data Y1゜Y3 of the Y signal on the first divided inner surface
．． Y5 and Y7 are distributed to the first channel, and even-numbered data Y2 . Y4°Y6 and yt+ are distributed to the second channel.

At this time, Cw4'f1 and CM double signal data are also distributed, but as mentioned above, flesh color signal components Cw and C
The bandwidth of N is originally 1/2 of each luminance signal component Y.
Therefore, it is sufficient to transmit half each of the data of the reconnaissance signal CW and CN.

Therefore, in this configuration example, among the data of the flesh color signal, for example, even numbered C2+C is used. , C6 and C
8 and CN21 CN4I CNG and CN8
are thinned out, Cut, CNt+ CWs and CNS are distributed to the first channel, and CN3.
CN3. CS7 and CN? is distributed to the second channel, so that the luminance data of each sample point and the color data in its vicinity are distributed evenly.

Each of the 8 channels of encoder (13) output data is 1
It is converted to serial data at a data rate of 29.6 Mb/s. A magnetic head capable of recording data at a data rate of this order can be manufactured without much difficulty using current magnetic head technology.

According to this configuration example, since the parallel transmission system has a total of 8 channels, the data rate to be transmitted for each channel can be reduced, making it easy to record (transmit) digital data of HD video signals. .

By the way, conventionally, in broadcasting stations and the like, television cameras are often placed in the studio, VTRs are placed in the repeating room, and the two are connected by a coaxial cable.

If the VTR uses the above-mentioned 4-2-2 digital system, the signal processing device on the recording side is installed in the studio (or sub-t) I11 control room), and the digital video signal is transmitted to the VTR itself (in the studio and operation room). (tape running system). In this case, twisted pair cables are used instead of coaxial cables due to ease of handling, but the use of twisted pair cables is significantly reduced! Since the amount of i is large, the transmission distance is limited to approximately 100 m even at a transmission rate of 27 Mb/s in the 4-2-2 system.

In the case of the digitized HD system, even in the aforementioned 8-channel parallel transmission, the transmission rate is significantly higher at 130 Mb/s, so the possible transmission distance using a rice 1-bare cable is extremely short, for example, about 20 m. Become,
Restricted by this distance, it becomes impossible to arrange equipment for smooth transportation of broadcast stations.

However, when an optical fiber is used as the transmission medium as in the previously proposed system, the possible transmission distance is extended to one unit, and the same station can be sufficiently covered.

However, the delay time of an optical fiber is, for example, 5±0.
Since there is a variation of 2nS/m, in the case of multi-channel optical transmission as described above, the phase difference between the signals of each channel increases as the transmission distance increases due to the deviation in delay time between each channel. , a problem arises in that the reproduced lll1l image is disturbed to the extent that it cannot be distinguished.

In view of the above, an object of the present invention is to provide a television signal transmission system that can extend transmission distance and reproduce images without deterioration in image quality.

[Means for solving problems]

The present invention distributes a component television signal to a plurality of systems, transmits the component television signal distributed to the plurality of systems in parallel via a plurality of optical transmission lines, and connects the plurality of optical transmission lines. This is a television signal transmission system that corrects deviations in delay time.

[Effect]

According to this configuration, the phase difference between the signals transmitted in parallel is removed, the transmission distance is extended, and an image without deterioration in image quality is reproduced.

〔Example〕

Hereinafter, an embodiment of a television signal transmission system according to the present invention will be described with reference to FIGS. 1 and 2.

The configuration of an embodiment of the present invention is shown in FIG. 1. In FIG. 1, parts corresponding to those in FIG. 3 are designated by the same reference numerals and redundant explanation will be omitted.

In FIG. 1, (35) indicates the receiving side signal processing device as a whole, and a time axis correction circuit is provided between the decoder (32) and the channel integration circuit (33) of the signal processing device (30) in FIG. (36) is inserted. This signal processing device (35) is an 8-channel optical fiber OF
13, it is connected to the transmitting side signal processing device (10). The rest of the configuration is +ji7 output 3rd color output 3 figure.

As shown in FIG. 2, the time axis correction circuit (36) is composed of a write address generation circuit (37), a read address generation circuit (38), and a 2-bot RAM (39).

A synchronization signal is inserted into the data supplied to the RAM (39) at regular intervals, and the write address generation circuit (39)
7) generates a write address from this synchronization signal and the address signal in the input data, and in response to this, data is written to a predetermined position in the RAM (39). Further, the read address generation circuit (38) is supplied with a synchronization signal to generate a read address, and accordingly, the read address generation circuit (38) generates a read address.
Data at a predetermined position (39) is read out.

Note that when the clock and data are sent separately, a delay line having a delay time corresponding to the transmission distance is inserted for each channel to prevent latch errors due to timing deviations.

The correction capability of the time axis correction circuit (36) configured as described above is IH when both the signal processing devices (10) and (35) are connected by the optical fiber 0F13. Also,
When a recording/reproducing unit (2o) is interposed between both signal processing devices (10) and (35) as indicated by a broken line in FIG.
The time axis correction circuit (36) is required to have a correction capability of 4I.

By using such a time axis correction circuit (36), deviations in the transmission time of the optical fiber 0F13, etc. are corrected, phase differences between digital signals of each channel are removed, and images without image quality deterioration due to digital transmission are obtained. can be played.

〔Effect of the invention〕

As detailed above, according to the present invention, deviations in delay times of a plurality of optical transmission paths are corrected, so that transmission distance can be extended and images can be reproduced without deterioration in image quality. This provides a television signal transmission system that allows for

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the television signal transmission system according to the present invention, FIG. 2 is a block diagram showing the configuration of the main part of the embodiment of the present invention, and FIG. FIG. 4 is a block diagram showing a configuration example of the proposed television signal transmission method, and is a conceptual diagram of signal processing of the already proposed method. (12) is a channel distribution circuit, (14), (2
3) is an electrical-optical conversion circuit, (21), (31) is an optical-electrical conversion circuit, (36) is a time axis correction circuit, 0FL
2°0F13 and 0F23 are optical fibers.

Claims (1)

[Claims] Distributing a component television signal to a plurality of systems, transmitting the component television signals distributed to the plurality of systems in parallel via a plurality of optical transmission lines, and transmitting the component television signal to the plurality of optical transmission lines in parallel. A television signal transmission system characterized by correcting deviations in delay time between channels.