JPH01125093A - Encoding device for high-definition tv signal transmission - Google Patents

Abstract

PURPOSE:To simplify the constitution of a part of data that is converted to a time series signal by sampling a luminance signal at a speed double that for other two color difference signals and replacing the part corresponding to the least-significant bit of at least either of said two color signals with a frame signal. CONSTITUTION:A component signal input (a luminance signal Y and two color signals R-Y, B-Y) of encoded high-definition TV signal is converted to parallel 8-bit digital signals by respective three A/D converters l, 2, 3. At this conversion, the sampling frequency of the luminance signal is so selected as double that of other two color signals. Thus digitized luminance signal is fetched by a first and a second ECL parallel-serial converters(P/S) 4, 5 alternately. And the digitized two color difference signals are converted to time series signals by a third and a fourth P/S 6, 7 of the same constitution as that of those 4, 5. And the part corresponding to the least significant bit of at least either of said two signals is replaced with a frame signal.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is used in optical fiber communications, and is particularly applicable to transmission systems for transmitting high-definition TV signals point-to-point with high quality over long distances. This was done in order to provide a practical encoding device.

BACKGROUND OF THE INVENTION Transmission of high definition TV signals requires a wider bandwidth than conventional TV signals. Therefore, various methods have been proposed for transmitting this TV signal. For the purpose of transmitting this signal over a long distance, a method of converting it into PCM and transmitting it is suitable. However, when high-definition signals are converted to PCM, the transmission rate becomes extremely high. for example,
In the case of RGB signals, each signal requires a 30 MHz band. In addition, even in the case of component signals, the frequency is 20 to 30 MHz for luminance signals, and 5 to 15 MHz for other color signals.
z band is required. In order to convert such a signal into PCM and transmit it, each signal must be decomposed into 8 bits.
00M (luminance signal: 20MHz, color signal: 5MHz,
2.5 times sampling) ~1B00M (RC; B each signal: 30MHz.

A transmission rate of 2.5 times sampling) bps is required. In order to process such high-speed signals, an IC that can operate at high speed is required. Currently, there is ECL, which has a maximum speed of several hundred MHz, that can be performed manually. It is relatively easy to obtain and comes in many varieties. There are devices using CaAs that are faster than this, but they are expensive and difficult to operate reliably.

In addition, as a method of lowering the transmission rate, so-called TCM (TI
ME COMPLEXED MULTIPLICATI
ON) and TCI (TIME COMPLEXED IN)
TEGRATION) and the MUSE method have been proposed. References include (Sokuta, Ninomiya, “Signal system and transmission J. TV Society Journal, Vol. 36, No.
, 10 p., 882-p., 88B) and (Yamada et al., “Study of digital transmission system for high-definition TV signals,” IEICE Technical Report,
C382-97).

Problems to be Solved by the Invention As mentioned in the conventional example, in order to convert high-definition signals into PCM and send them, the transmission rate becomes extremely high. An IC that operates at a very high speed is required, which increases the technical difficulty in this part, and as a result, the cost of the encoder increases, which hinders its practical use.

In addition, as a method of lowering the transmission rate, so-called TCM and TC, which adopt a signal band compression method when converting to PCM,
Methods such as I, MUSE method, etc. have been proposed.

However, such a method requires complicated signal processing for band compression, and the cost of the CODEC (encoding and decoding unit) becomes extremely high.

In any case, general point-to-point transmission is expensive and requires complicated equipment.

SUMMARY OF THE INVENTION In view of the above-mentioned prior art, it is an object of the present invention to provide a high-performance encoding device for high-definition TV signal transmission with a simple configuration.

Means for Solving the Problems The present invention provides a component of a high-definition TV signal.
A high definition device characterized by sampling the luminance signal at twice the speed of sampling the other two color difference signals, and replacing the part corresponding to the least significant bit of at least one of the two color difference signals with a frame signal. This is a TV signal encoding device.

The component signals of the active high-definition signal are individually A/D converted with the sampling frequency ratio of the luminance signal and the other two color difference signals set to 2=1. When converting these individually digitized signals into time-series signals for transmission, a portion corresponding to the least significant bit of at least one of the two color difference signals is replaced with a frame signal. By doing so, the configuration of the part that converts into a time series signal can be simplified.

Embodiment FIG. 1 shows a schematic diagram of a high-definition signal encoding apparatus according to an embodiment of the present invention. There are several types of component signals of high-definition TV signals. - For boat fishing, there is a luminance signal (Y) and two color signals (CW, Cnl or R).
-Y, BY). Here, Y, R
-Y and B-Y will be explained as examples.

Component signal input of high-definition TV signal to be encoded (luminance signal: Y and two color signals: R-Y, B-Y)
) are each three A/D converters l.

2.3, it is converted into an 8-bit parallel digital signal.

At this time, the sampling frequency of the luminance signal is selected to be twice the sampling frequency of the other two color signals. The digitized luminance signal is taken alternately into two ECL parallel-to-serial converters (P/S) 4.5, a first and a second.

On the other hand, the two digitized color difference signals are converted into time-series signals by the third and fourth P/S 6.7 having the same configuration.

By doing so, digitized signals of each component signal are obtained as outputs of the four P/Ss.

When transmitting digital signals through optical fibers, data is generally sent in frames. This framing is performed by replacing the least significant bit of one of the two color difference signals with a frame signal. In this embodiment, the least significant bit of the third S/P is
It is replaced with a frame signal F consisting of an alternating pattern of 1'' and '0''. Further, the least significant bit of the fourth S/P is a data bit D. At least one of these two least significant bits may be a frame signal, and two
Both may be used as a frame signal, or one may be used for data as in this case.

It is considered that if the outputs of the four P/Ss are bit-multiplexed as they are, a framed time-series signal can be obtained.

The time series signals of the second four P/S outputs are independently scrambled by four parallel scramblers 8, 9, 10, 11, and then scrambled by first and second multiplexers 12,
13, the signals are bit-multiplexed in two sequences, resulting in two time-series signals, a luminance signal and a color signal. The scrambler is used to set the mark rate of data to 172, and is necessary when transmitting data through optical fiber. This consists of several gates and EX
.

Consists of OR and DFF (D flip-flop).

There are various ways to place this scrambler and how to configure it, but by doing it in this part, it can be operated at a relatively low speed, so there is less technical difficulty.

A final signal (a high-definition PCM signal) is obtained by bit-multiplexing the two time-series signals output from the two multiplexers 12 and 13 by the third multiplexer 14. Note that the order of multiplexing by the multiplexer is arbitrary.

The bit multiplexing section using this multiplexer will be explained using FIG. 2. It consists of three sund gates. The two signals AI and A2 to be multiplexed are extracted by two Nant gates 15 and 16, a first and a second, using clock signals C1 and C2 that are 180 degrees out of phase,
Thereafter, they are added together by a third Nant gate 17. Since the multiplexer with this configuration is composed of three gates, it can be operated at a very high speed if careful timing is taken. Although this example uses a Nant gate, other types of gates are also possible. A multiplexer with this configuration is particularly suitable for creating a high-speed data stream because it operates stably up to a frequency corresponding to the maximum operating speed of the gate, although it has a very simple configuration.

By sampling the luminance signal at twice the speed of the two color difference signals and replacing the least significant bit of the color difference signal with a frame signal, the outputs of the four P/S are transferred to three multiplexers consisting only of gates. By bit multiplexing, a framed time-series transmission signal can be obtained.

Next, a high-definition TV double signal encoded in this manner will be described. The resolution of the color difference signal is 1/1 of the luminance signal.
It becomes 2. Therefore, deterioration in image quality is expected. However, normally the luminance signal is lvρ-p and the color difference signal is 0. 7Vp-p.

Therefore, even if the resolution is reduced to 1/2, the resolution of the luminance signal and color difference signal is not doubled, so the image quality does not deteriorate significantly. Furthermore, since this is a method in which each component signal is A/D converted separately, better image quality can be obtained compared to a method in which a composite signal is PCM'd at once using one A/D converter.

In addition, it is generally said that it is desirable for the band ratio of high-definition TV double signal component signals to be 4:2:2, but with this method, it is possible to perform PCM encoding without destroying this frequency band ratio. It is.

Effects of the Invention According to the present invention, the part that operates at the highest speed can be configured using only gates, and moreover, it can be configured using high-definition T.
The PCM signal of the V signal can be obtained as a framed time-series transmission signal with a simple circuit configuration. Further, it is possible to transmit while maintaining the desired band ratio of 4:2:2 for component signals of a high-definition TV signal.

Therefore, it is possible to provide an encoding device that operates stably at a very low cost without impairing the quality of high-definition signals. Furthermore, the output signal of this encoder is
By using a light source as a light source and transmitting through a transmission system using a single mode fiber, it becomes possible to transmit high-definition TV signals over long distances and with high quality.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the basic configuration of an encoding device according to an embodiment of the present invention, and FIG. 2 is a configuration diagram of a multiplexer. 1-3...A/D converter, 4-7...P/S,
8-11...Scrambler-112-14...Multiplexer, 15-17...Nant Gate.

Claims (2)

[Claims] (1) For component signals of high-definition TV signals, the luminance signal is sampled at twice the speed of sampling the other two color difference signals, and the portion corresponding to the least significant bit of at least one of the two color difference signals is A coding device for high-definition TV signal transmission, characterized in that it is replaced with a frame signal. (2) It has three A/D converters that individually convert the luminance signal and the two color difference signals, and the luminance signal is sampled at twice the speed of sampling the other two color difference signals, The first and second serial-to-parallel converters alternately convert the digital luminance signal for two samples into a time-series signal, and the maximum of at least one of the other two digital signals for one sample. It is characterized by having third and fourth serial-parallel converters that replace lower bits with frame signals and convert them into time-series signals, and three multiplexers that time-division multiplex two systems each of the four time-series signals. An encoding device for high-definition TV signal transmission according to claim 1.