JPS62264784A - Two-channel multiplex transmission system for television signal - Google Patents

Abstract

PURPOSE:To transmit a 2-channel NTSC color television signal through a one- channel NTSC transmission line by extracting alternately two luminance signals and two chrominance signals after time base compression, multiplexing and transmitting them. CONSTITUTION:Signals of two programs 1, 2 are separated into luminance signals Y1, Y2 and chrominance signals C1, C2 by two YC separating circuits 1, 2 respectively. Line/field subsamplers 3, 4 sample the luminance signals Y1, Y2 according to output moving modes M1, M2 of detectors 5, 6 detecting moving information of the programs 1, 2. The output is subjected to time compression by time base compressors 7, 8, selected by a switch S1 to form a luminance signal Y multiplexed with the luminance signals Y1, Y2. The chrominance signals C1, C2 are added to the luminance signal Y while being switched at each field by a switch S2. Further, the moving modes M1, M2, a synchronizing signal and a color burst are added by an adder circuit 9 and the result is sent to the NTSC transmission line as a signal NT.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a color television signal transmission signal processing technology for transmitting two NDC color television signals through a single channel transmission path. In particular, there is one related to a television signal sampling method and a color signal multiplexing method.

(Prior Art) Various methods have been proposed and put into practical use in order to transmit two NTS C television signals over a single channel transmission path.

(1) Line cutting method In this method, the transmitting side switches two video channels line by line and sends them, and the receiving side interpolates the lines separated into each channel and thinned out lines by line interpolation. .

(2> Vertical compression/synthesis method This method compresses two video channels by half in the vertical direction on the transmitting side, separates the upper and lower images, combines them, and sends them.
Receiving side U-fI! It is reconstructed by enlarging it twice in the horizontal direction. For 1/2 compression on the transmitting side, scanning lines are thinned out one tree at a time and written into memory, and on the receiving side the thinned out information is interpolated by line interpolation.

(3) Field switching method (Thomson Vidyflex) This method transmits two channels by alternately switching odd and even fields, and after separating the odd and even fields on the receiving side, field interpolation is performed to remove the missing intermediate fields. Save the field.

(4) Underwater compression/synthesis method This method compresses each of the 12 video channels (!) to 1/2 in the horizontal direction on the transmitting side, and distributes them left and right to create a composite signal and transmit it. Kaisho No. 56-529
According to No. 81 Mei 1 Il 1, two types of video signals are sampled only in the horizontal direction, the number of ripples is thinned out to half, and then the time axis is
/2 and time-division multiplexed and transmitted within the horizontal scanning period, and on the receiving side, the two types of signals within the horizontal scanning period are separated,
In each case, the time axis is expanded only in the horizontal direction, and missing sample values are interpolated to restore the original video signal. Furthermore, prior to the above-mentioned time axis FF reduction, the band of the invaded Y signal which has been subjected to YC separation is limited to approximately 2 M fiz, and the band of the C signal is limited to 1/2 of the conventional subcarrier frequency of 1"sc. A composite signal is created by modulating the signal with λ21! rear.

(Problem that the invention attempts to solve) The typical conventional example described above is method (1).

Regarding method (2), the resolution of the received image in the vertical direction deteriorates slightly, and it lacks practicality as a broadcast image quality. Regarding method (3), the deterioration of vertical resolution is not as bad as on the left, but
When restoring an image with movement, frames are dropped, and when the camera is panned, the movement of the image becomes unnatural and causes severe flickering.

In addition, method (4) has the drawback that the Y signal band is as narrow as 2 Mllz, resulting in blurred images, and the subcarrier A of the C signal.
Since A has a frequency C that is 1/2 of the conventional one, cross color,
This method has the disadvantage that the deterioration of cross luminance is much greater than that of the conventional method.

The purpose of the present invention is to solve the above-mentioned problems, to transmit two programs on one conventional NTSC transmission line while maintaining the NTSC standard, and to reduce the transmission cost by half. Provides channel multiplex transmission system! /V.

(Means for Solving the Problems) In order to achieve the first objective, the 21-Yannel multiplex transmission system of the present invention television No. 15 transmits two luminance signals of two color television signals separated by YC, respectively. are the two color signals (, (, each of N T S
If the color signal is modulated by the color subcarrier 7 at the time of YC separation, the two color signals are taken out alternately for each field, These are multiplexed with the two luminance signals after the time axis ff reduction and transmitted.
2 channels of NTS on Chisennel's NTSC transmission line
It is characterized by transmitting a C color television signal.

(Function) As described above, even if the C signal is transmitted field-sequentially and alternately, deterioration will not be a problem from the viewpoint of the visual spatial and temporal resolution of the color difference signal, and this C signal will not be affected by the subsampled Y signal. However, since it is multiplexed in the high frequency range, it is cross-colored.

Deterioration due to cross luminance is small.

These matters will be explained below using a three-dimensional spatiotemporal frequency domain.

For the sake of explanation, the band of the transmission path is assumed to be 4.5M1lz, and to indicate a point on the three-dimensional spatiotemporal frequency domain (horizontal frequency (Ml
lz), vertical frequency (CP l-1>, ff, expressed as 1 frequency (+12>), i.e. (0, 0, 0)
is the DC component, (3,58,525/4.15) is the color sub-key relay, and (0,525/2.30) is the key 1 due to interlacing. Shows the rear. For details about this, see the literature, Mt. S.

Ohno: Image quality of low-level families in component coding, Television Society Technical Report, TEBS89-
2. This became clear on May 25, 1981.

Figure 4 shows the signal band of the current NTSC color television system, and depending on the characteristics of the camera, the Y signal is O, A, B,
It exists in the solid line area 113i1 surrounded by C, D, E, F, and G. -10,000C signal is N (3,58.

525/4.15).

FIG. 5 shows this Y signal as O, A, B, C, D.

After limiting the band to region 2 surrounded by G, (4,5°5
2/4. This figure shows how one line offset, one knob, and one numbering are performed using the key VSUA/ at point 0).

In this case, the components of 2.25 Mm or more, which is half of 4.5 MHz, are folded back and exist in the H, I, J, D, and G regions, so it is 2.25 M! Information in region 2 can be transmitted even if the bandwidth of the transmission path is limited to i and II for fz.

FIG. 6 shows a situation in which the Y signal sent to the line off cell 1 is compressed between 11 and 1 by 2, and then the C signal) J is multiplexed. FIG. 7 is a diagram in which FIG. 6 is projected onto the horizontal/vertical plane and the horizontal/time plane, and the C signal is multiplexed in the hatched area. In this figure, the vertical band of the C signal is 5
It can be seen that if the signal is limited to 25/8 and multiplexed line sequentially, signal components of 2.25 Mtlz or less of the original Y signal are not affected.

Of course, in an image with a small C signal component, the Y signal can be transmitted up to 4.5M112.

Similar consideration is given to (4,5,525/2.0), (4,
If field offset subsampling is performed using a carrier of 5°0.30), then FIGS. 8 and 9 will be obtained, which correspond to FIGS. 5 and 7. In other words, in this case, the folding of the horizontal high frequency component is vertically separated from the low frequency component, so the C signal is vertically separated by 52! ]/'8, it is possible to transmit up to 4.5 MHz.

Furthermore, if the image is a still image C or moves slowly, the Y and C signals can be separated in the time axis direction. That is, the C signal may be band-limited in the time direction and transmitted field sequentially. In this case, the C signal does not need to be band limited in the vertical direction, so both the Y and C signals are horizontal, ! l!
It can be transmitted without reducing resolution. In addition, even when the image moves quickly, the band is limited to a triangular area in time and horizontal space as shown in Figure 9, so crosstalk between Y and 0 is small and it can be used if some degradation is tolerated. can.

(Embodiment 1!111) The signal processing systems on the transmitting side and the receiving side according to the method of the present invention will be sequentially explained below using a large M example with reference to the drawings.

FIG. 1 <a> is a block diagram of an example of the transmitting side signal processing system. The signals of the two programs 1 and 2 are the two YCs.
A separation circuit 1.2 separates the signals into luminance signals Yl, Y2 and color signals C1, C2, respectively. This luminance signal Y1. Y2 each has two line/field sublimpers3.
Sent to 4.

The line/field sub-streamers 3 and 4 are equipped with motion detectors 5 and 6 for detecting information on program 1 and program 2.
According to the contents of the output motion modes M1 and M2, either field innoset subsampling (a) or line offlet subsampling (b) shown in the second figure is selected and the luminance signals Y1 to Y2 are sampled. The outputs of the line/field sub-samplers 3 and 4 are each sent to a time-base compressor 7.8, and after being time-base compressed, the output is selected by a switch S1 for one line period (one line is one horizontal scanning period, and the NTSC system is used). 63.5μsec in case of
A luminance signal 8Y is obtained by multiplexing the luminance signals Yl and Y2. In FIG. 2, 0 marks are image sample points, X marks are unsigned points, solid lines are odd field lines, and broken lines are even field lines.

Figure 3 shows this relationship on the time axis, where the luminance signal Y
1. T1.Y2 has an effective scanning period T of T/2 hours each. Luminance signal F compressed and multiplexed on time axis F at time T2,
3 This shows that it has become Y.

The color signals C1 and C2 are switched for each field by a switch S2 and added to the luminance signal Y. Further movement 7-do M
1. M2. Synchronization signal No. 8, color burst, etc. are added by an additional circuit 9 to form a regular NTSC signal, which is sent to the NTSC transmission line as a signal NT. Note that various methods have been proposed for interference detection, and for example, judgment is made based on the integral value of a difference signal between one frame.

Figure 1 (b) shows the block diagram of the receiving side (g processing system example).
). 1(1)) In the illustrated YC separation unit 11, the luminance signal Y and the color signal C are separated from No. 18 N. Therefore, the A/D converted Jogetsu NT from the NTSG transmission line is transmitted through the horizontal high-pass filter 12 and the ff Nobiki Sakuko v.
13. Sent to Dt 14. Horizontal high pass filter 1
The output of 2 is the vertical B castle filter 15 and the time lr! i
It is sent to a bandpass filter 16. Delay element Dv13, [)
The delay amount of t14 is the same as that of filter 15 and filter 1 described above.
6 R extension ψ. Seven from the transmission signal
Do Shingetsu 11? Mode signal Ml separated by A17
, M2, the outputs of the vertical arithmetic filter 15, the temporal high-pass filter 16, the delay element DV13, and the eight delay elements [)C14 are selected by the switch 33.84, and the switch S
The output of No. 3 is sent to the color signal field interpolation unit 24 as the color signal C.
sent to. Further, by subtracting this color signal C from the output of the switch S4, a signal corresponding to the luminance signal Y is obtained, and this is sent to the subsample interpolation 1i18.

The sub-sample interpolation section 18 shown in FIG. 1<b> is sub-sampled! ! This is an example of a circuit that restores the original signal from the i-degree signal Y by interpolation. Delay element <OL
) 19. D L20. D L21 is 1 each
Field - 1 clock, 1 line - 1 clock.

The delay is one clock time and the switch S5. S6 is connected to the mode signal M1. Controlled by M2, tilting upward performs interpolation for field offset subsampling, and tilting downward performs interpolation for line offset rib sampling. The output of the sub-sample interpolation unit 18 is expanded in the time axis by the time axis expanders 22 and 23 to obtain the original luminance signal Y1. Revenge Y2! l
do.

The fish signal f3 sends the color signal C output of the YC divider 11 to the color signal field interpolator 24, and the signal delayed by one field time d and the undelayed signal by the field delay element 25 are sent to the switch S7. , 38 are alternately switched in the middle of the field to interpolate the color signals of fields that are not being transmitted and demodulate the colors f and + corresponding to the original color signals C1 and C2.

(Effect of the invention) By implementing the method of the present invention, one channel of NT
Two NTSC color programs can be transmitted using the NrSC standard on the SC transmission line. Therefore, it is economical to use in transmission lines where lines are expensive, such as satellite relays, and it is also economical to use in transmission lines where lines are expensive, such as in satellite relays.
If two FPUs (field repeaters) cannot be used due to limitations, one FPU can transmit images from two cameras,
It also has a great effect on the production of news programs.

[Brief explanation of drawings]

Figure 1 shows the transmitting side (a) and receiving side (a) according to the method of the present invention.
b) Diagram showing the signal processing system; FIG. 2 (J, diagram schematically showing field offset (a), line offset (b) each +) in the line/field sub-sampler of the present invention system; Figure 3 is a diagram showing the waveforms of various parts in Figure 1<a>. Figure 4 is a diagram showing the spectrum of the current NTSC system signal. Figure 5 is the spectrum of the line offset sub-sampling system. Figure 6 is a diagram showing the spectrum compressed on the time axis after line offset subsampling. Figure 7 is a diagram showing the spectrum shown in Figure 5 projected onto the horizontal/vertical and horizontal/time planes. The figure shows the spectrum of the field offset sub-sampling method. Figure 9 shows the spectrum shown in Figure 8 horizontally, vertically, horizontally
It is a diagram projected onto a time plane. 1.2...YC separation circuit 3.4...Line/field sub-sampler 5.
6...Motion detector 7.8...Time axis compression=9...
-Additional circuit 11...YC separation section 12...Horizontal high-pass filter 13, 14...Delay elements Dv and Dt 15...Vertical high-pass filter 16...Temporal high-pass filter 11...Mode Signal separator 18...V sample interpolation section 19, 20.21...Various delay elements 22, 23...Time axis expander 24...Color signal field interpolation section 25...Field ■ extension element Patent applicant Japan Broadcasting Corporation
Golden Brother Figure 1 (a) NTSC Yiyun Ieum Figure 1 (b) 24t! : (gi field MtfJvr Figure 2 N-in-1] -- Fu Figure 4 β Darkness (H engineering) Figure 5 Figure 6 Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] 1. The two luminance signals of the two color television signals, each separated by YC, are subjected to time axis compression after field or line offset subsampling,
The two color signals of the two color television signals are:
After each modulation with the color subcarrier of the NTSC signal, or if the color signal is modulated with the color subcarrier at the time of YC separation, the two color signals are taken out alternately for each field, and these two color signals are extracted at each time. It is multiplexed with the two luminance signals after axial compression and transmitted, and is transmitted as a 2-channel NTSC signal on a 1-channel NTSC transmission path.
A two-channel multiplex transmission system for television signals, characterized by transmitting color television signals. 2. In the multiplex transmission system according to claim 1, the two YC-separated color television signals are separated from the two NTSC color television signals by YC and YC, respectively.
A two-channel multiplex transmission system for television signals that is characterized in that they are obtained separately. 3. A two-channel multiplex transmission system for television signals according to claim 1 or 2, characterized in that switching of the field or line offset subsampling is controlled by motion information. method. 4. A two-channel multiplex transmission system for television signals according to claim 3, characterized in that the switching is performed in units of image blocks or fields. 5. A two-channel multiplex transmission of television signals in the multiplex transmission system according to claim 3 or 4, characterized in that the switching information is multiplexed in a horizontal or vertical retrace period. method.