JPS62236288A - Multiplex signal transmission system - Google Patents

Abstract

PURPOSE:To multiplex information such as character broadcast in the period other than vertical blanking time by band restricting signals other than color television and modulating and multiplexing subcarrier that becomes in-phase and opposite phase in each field by the same frequency with chrominance subcarrier of standard system. CONSTITUTION:Clock pulses for generating data signals are inputted to input terminals 101,102 and one pulse is inputted in (n) frames and (m) frames respec tively. Generated data are passed through a vertical low pass filter 111 and a time low pass filter 112. Subcarrier fsca to be modulated inputted to a modula tor 121 is the same in frequency with subcarrier fsc to be modulated inputted to a modulator 118, and switched to in-phase and opposite phase at every field.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a multiplex transmission system for television signals, and in particular to a multiplex transmission system for multiplexing data or color signals while maintaining compatibility with current color television systems. This relates to transmission methods.

(Prior Art) Conventionally, as data multiplex transmission using television signals, a method of multiplexing during a vertical blanking period (VBL) has been used, and the teletext method is one such method. Regarding transmission of color signals of color television signals, NTSC
In the standard color television system, the I signal is 1.5 MII.
The z band and Q signal are up to 0.5 MHz band, and the color subcarrier (fsc) is modulated and multiplexed on the luminance signal.

(Problems to be Solved by the Invention) Conventionally, multiplexing of data signals other than standard color television signals requires the color television (No. 8 No. 11)
I was using period VBL, but VI was used for period VBL.
TS (Video 1nterval Te5t Si
gnal), etc., and the number of lines in the period VBL that can actually be used for multiplexing data signals is at most about 4 lines per field, which limits the transmission speed.

Regarding the color signals of standard color television signals,
In the NTSC system, the I signal was transmitted up to the 1.5M1lz band and the 01 word was transmitted up to the 0.5MIIz band, but there was color blurring in the details of the color image.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned limitations and provide a data multiplex signal transmission system that does not interfere with the original image signal and has a higher transmission speed.

Another object of the present invention is to provide a multiplexed signal transmission system that can obtain high-quality images by multiplexing higher-frequency parts of Q signals instead of data signals, if necessary. be.

(Means for Solving the Problems) Therefore, in the multiplex signal transmission system of the present invention, when transmitting a standard color television signal by multiplexing other signals, as a result of multiplexing, the original color television signal is The other signals are band-limited so as not to cause crosstalk, and the band-limited signals have the same frequency as the color subcarrier of the standard method and are in phase and opposite phase for each field. This method is characterized in that the subcarrier is modulated, multiplexed with the standard color television signal, and transmitted.

Further, in the first embodiment of the present invention, when the other signal is a data signal that has no correlation with the standard color television signal, and n and m are each positive integers exceeding 3.1. , a clock pulse every n frames and m lines, a temporal low-pass filter with a cutoff range of 30/nflz, and a vertical low-pass filter with a cutoff range of 525/4m cph.

In a preferred first embodiment of the present invention, n is 4 and m is 2. .

Furthermore, a second embodiment of the present invention is characterized in that the other signal is a Q signal in a higher frequency range than the Q signal of the standard color television signal.

A second preferred embodiment of the present invention is characterized in that the multiplexing of the higher frequency Q signals is controlled in accordance with the movement of the image.

Furthermore, a third embodiment of the present invention is characterized in that the uncorrelated data signal and the higher-frequency Q signal are appropriately switched and used.

(Examples) The present invention will be described in detail below by way of examples with reference to the accompanying drawings.

A data signal (hereinafter abbreviated as data signal) that has no correlation with the standard color television signal according to the present invention, and a color signal in a higher range than the color signal of the standard color television signal (hereinafter abbreviated as high range color signal) ) is shown in FIG. 1. In Figure 1, the I and Q signals are 2Ml1z by multiplexing the Q signal, and widening the band of the horizontal low-pass filter for the ■ signal.
It is assumed that transmission is possible up to the band.

Clock pulses for generating data signals are input to input terminals 101 and 102, respectively.
and one pulse is input to the m line. As will be explained later, in order to prevent crosstalk with the standard image signal, the multiplexing area of the multiplexed signal must be limited and the multiplexed signal must be band-limited, and all lines and frames must be Since signals cannot be multiplexed, a lock signal like this is used. The data generator 10B generates data based on this clock signal. The data generated for the band-limiting reasons mentioned above is then passed through a vertical low-pass filter 1.
11 and a temporal low-pass filter 112. These filters have n frames (fL), m lines (11
In the NTSC color television system, the cutoff frequency is
25/4m cph (cycle per height)
A vertical low-pass filter of t) and a temporal low-pass filter of 30/n1lz are used.

On the other hand, the input terminal 104゜1 shown at the bottom of Figure 1
The first two of the Q signal, ■ signal, and luminance signal Y, which are color signals of the NTSC color television system inputted from 05 and 106, are 525/2m cph, 30/(n/2
)llz and passes through spatiotemporal two-dimensional low-pass filters 109 and 110 having a cutoff frequency of 109, 110 to limit the band in order to prevent crosstalk with multiplexed data. As a result, compared to the luminance signal Y, n=4. When m=2, the vertical band is reduced to about half, but the color signal itself originally has a horizontal band less than half that of the luminance signal, so this is sufficient in terms of balance.

Horizontal low-pass filter (0,5MHz) 113 , horizontal low-pass filter (2, OMIIz) 114 , and horizontal low-pass filter (4,2MIIz) 115 are all horizontal filters for image signals, and compared to the current standard system, one signal is 2Ml1z. It's in the band. The horizontal low-pass filter (2,0 MHz) 116 is a filter for multiplexing a Q signal with a higher frequency than a conventional Q signal instead of a data signal.
．． OMIIz exists. The modulation of the modulator 121 is the same as the modulation of the modulator 118, but the modulated subcarrier rsc" input to the modulator 121 (terminal 120) is the same as the modulated subcarrier rsc" input to the modulator 118 (terminal 117). The frequency of the modulated color subcarrier f is switched between in-phase and anti-phase for each field.The switch 119 is used to determine whether to multiplex the data signal, the higher frequency part of the Q signal, or nothing. The switching information and data signal multiplexing timing information are multiplexed into the vertical granking period VBL 122 of the standard color television system and transmitted to the receiver side.

The above is the explanation of the encoder side, and next, the decoder of the receiver side will be explained with reference to FIG.

First, the control signal separator 202 separates switching information and multiplex timing information from the period VBL of the transmitted color television signal (input terminal 201). The luminance signal separator 205 separates and extracts only the luminance signal, and the standard color signal and other signals are separated and extracted by the color/multiplex signal separator 20.
6, and each is demodulated by demodulators 208 and 210. Here, the input terminal 207 of the demodulator 208, 210
．． 209, color subcarrier f sc + subcarrier r
sc" is input. Below, a switch 219, a horizontal low-pass filter (2, OMIIz) 212, a horizontal low-pass filter (0,5M1lz) 213, a horizontal low-pass filter (2,0MHz) 214, and a data reader 21
1, the Y, I, Q signals and data signals are regenerated. Note that the Y signal is 4.2MHz, and the I signal is 2MHz.
．． The OMIIz, Q signal has a band of 0.5 MHz, and when the higher frequency portion of the Q signal is multiplexed, it has a band of 2.0 MHz.

The above is an explanation of the encoder and decoder on the transmitter side and the receiver side related to the present invention. Regarding the decoder, when receiving with the current standard receiver, the advantage of multiplexing cannot be obtained, but it will continue as before. image reproduction is possible and compatibility with the conventional standard method is established.

Next, the spatio-temporal frequency spectrum when signals other than those mentioned above are multiplexed will be explained.

FIGS. 3 and 4 are diagrams showing spectral characteristics when data signals are multiplexed. In FIG. 3, a region 302 represents standard I and Q signals band-limited by spatiotemporal low-pass filters 109 and 110, a region 301 represents a data signal multiplexing section, and a straight line 303 represents a Y signal. Since the spectrum characteristics after multiplexing are as shown in FIG. 3, it is necessary to limit the bands of the data signal and the standard I and Q signals as shown in the figure in order to prevent crosstalk between them. FIG. 4 shows this one-dimensionally. Although the luminance signal is omitted in the figure, it is interleaved with the color signal and multiplexed data signal at an interval of 1511z, and the waveform is 40.
1.402.403 are an I signal, a Q signal modulated at frequency fic, and a data signal modulated at frequency f sca, respectively.

Figures 5 and 6 show the spectral characteristics when a high-frequency Q signal is multiplexed instead of the data signal, and the area 50 in Figure 5 is
1.502 and straight line 503 are the high frequency Q signal multiplexing section, I, Q signal multiplexing section, and Y signal, respectively, and the waveforms 601, 602, and 603 in FIG. It is a high-band Q signal modulated at a frequency rsc''.

(Effects of the Invention) By using the system of the present invention, it becomes possible to multiplex information other than color television signals, such as teletext, in addition to the vertical blanking period in the standard color television system. It has become possible to increase the speed of information transmission.

If the band of this multiplexed data signal is about 1 MHz, the transmission speed will be about 70 Kbit/sec, which is almost the same speed as the current teletext broadcasting using 4 field lines, and if this is combined with the method of the present invention. The transmission speed is approximately twice that of the conventional method.

Furthermore, if the method of the present invention is applied to the high frequency portion of the Q signal of the color signal of the standard color television system, both the I and Q signals will have a higher frequency band than the current one, and a clearer image than before can be obtained.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 respectively show an encoder according to the present invention method;
Block diagrams showing an example of a decoder configuration, FIGS. 3 and 4
The figure shows the vertical and temporal frequency characteristics and the band frequency characteristic when multiplexing the data signal of the present invention, respectively. FIG. 3 is a diagram showing band frequency characteristics. iot, 102.103.104.105.106・
...Each input terminal 108...Data generators 109, 110...Spatio-temporal two-dimensional low-pass filter U
t... Vertical low-pass filter 112... Temporal low-pass filter 113, 114.115.116... Each horizontal low-pass filter 117, 120... Input terminal 119...
・Switcher 118, 121...Each modulator 122...Vertical blanking period 123...Output terminal 201...Input terminal 2
02...Control signal separator 205...Y signal separator 206...Color/multiple signal separator 207, 209...Each input terminal 208.210...
・Each demodulator 211...Data reader 212, 213.214...Horizontal low-pass filter 2
15, 216.217.218... each output terminal 301
...Data signal multiplexing unit 302...I, Q signal multiplexing unit 303...Y signals 401, 402...■ modulated by fsc and Q signal 403...data signal modulated by r sca 50
1...High-band Q signal multiplexing section

Claims (1)

[Claims] 1. When multiplexing and transmitting a standard color television signal with other signals, the other signals should be The signal is band-limited, and the other band-limited signal is used to modulate subcarriers that have the same frequency as the color subcarrier of the standard method and are in-phase and anti-phase for each field. A multiplex signal transmission method characterized by multiplexing and transmitting television signals. 2. In the system according to claim 1, the other signal is a data signal that has no correlation with the standard color television signal, and n and m are each 3.
, a positive integer exceeding 1, the band limitation is performed using a clock pulse every n frames and m lines, a temporal low-pass filter with a cut-off band of 30/nHz, and a vertical low-pass filter with a cut-off band of 525/4 mcph. Features multiple signal transmission method. 3. The multiplex signal transmission system according to claim 2, wherein n is 4 and m is 2. 4. The system according to claim 1, wherein the other signal is a Q signal in a higher frequency range than the Q signal of the standard color television signal. . 5. The multiplexed signal transmission method according to claim 4, wherein multiplexing of the higher frequency Q signals is controlled in accordance with the movement of the image. 6. A multiplex signal transmission system according to claim 1, characterized in that the uncorrelated data signal and the higher frequency Q signal are used by appropriately switching between them.