SU684785A1 - Method and apparatus for transmitting and receiving simultaneous colour television signals - Google Patents

Description

on the quadrature modulation of the chroma color frequency subnetwork by the 1I color signal, its summation with the luminous signal and the subsequent amplitude modulation of the image carrier frequency by the full color television signal on the forward side, and on the receiving side - detection of the full color television signal, extracted from it chrominance signal with its subsequent synchronous detection using a chrominance subcarrier frequency signal; in the full color television signal the phase of the subcarrier frequency is inverted color modulated in amplitude by the additionally generated second carrier frequency of the image and summed with the full color television, and on the receiving side, before detection, the full color television signal is divided into two signals and suppressed one of the carrier frequencies of the image in each of the separated signals and in case of synchronous detection of the chrominance signal of an additional full color television signal, the phase of the chrominance carrying frequency is inverted and after detection in pairs the sum cosiness of the same color difference signals. In a device that implements this method and contains a color television signal sensor on the transmitting side, the output of the luminance signal is connected via a delay line to the first input of the first adder, and the output of the modulated signal of the color subcarrier is connected to the second input of the first clock connected to its first input the first amplitude modulator, the second input of which is connected to the output of the generator of the main carrier frequency, and the output to the input of the high-frequency amplifier, on the receiving side of the amplifier is high Frequency, the output of which is connected to the detector of the luminance signal through the converter and the amplifier of the intermediate frequency and to the main band-pass filter whose output is connected to the main detector of the color subcarrier, on the transmitting side are connected in series a phase-inverter, a second adder and a second amplitude modulator, another the input of which is connected to the output of the input generator of an additional carrier frequency, and the output to another input of the high-frequency amplifier, while another input of the second adder is connected Inen with another output of the delay line, and the phase inverter input is connected to the second input of the first adder, and on the receiving side there are serially connected additional bandpass 54 filters, an additional detector of a color sub-network and an adder, the other input of which is connected to the main detector of the color subcarrier, and an input of an additional bandpass the filter is connected to the output of the intermediate frequency amplifier. The method consists in the fact that in a color television system with amplitude modulated frequency, with transmission of chrominance signals at the subcarrier frequency and transmission of sound signals at the moments of transmission of clock signals of the television signal, the empty space of the sound carrier is used to transmit an additional carrier of the same luminous video signal with a color subcarrier , having the opposite phase compared to the main video signal. In this case, the separation between the carriers remains the same, and the amplitude-frequency characteristic of the high-frequency path of the transmitter becomes symmetrical. In this case, the low-frequency spectral components, as well as all the others in the same frequency band, are transmitted twice, which gives an energy gain. In addition, the transmission of the same signal simultaneously on one carrier in the upper frequency band and on the other carrier in the lower frequency band is equivalent to the transmission of a two-band signal. This minimizes quadrature distortion of the video signal. In order to achieve full compatibility on the additional carrier, the same luminous video signal is transmitted, and the phase of the color subcarrier is rotated 180 with respect to the phase of the color subcarrier of the main signal. Taking into account only the color subcarrier in the first channel, a signal is received: (co5S2t4) J. In the second channel, a signal is received; U t-Kco552t-cos "t}. (2) the signal (1) modulates the carrier oscillation: ufcflstUgt-i- (s „+ Sl) t 4 cos (0o + 5i j) t {3). The signal (2) modulates the additional carrier wave: Utcosw, t + Ocos () t-fflcDS (() t (4) (3) and (4) pass a common path with a symmetrical arrangement of carriers on its amplitude-frequency characteristic and are radiated broadcast. In a black and white television receiver after transforming and amplifying

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signal with two carriers arrives at the detector. The color subcarriers arriving after demodulation of the two carriers in the detector load are destroyed without a trace and do not appear on the image. The luminance signal is summed. In this case, the phase distortion of the luminous signal caused by single-band transmission is mutually compensated. The beats generated by the carrier between one signal and the subcarrier of another are also mutually compensated. This can be seen if the first term of expression (3) is multiplied by the third term of length of time (4). The result is:

CDS (cou (t - I CDS (u, -u, -52) t. (5

At the same time, the first term of expression (4) is multiplied by the third term of expression (3). The result is:

COSaJ, t | cosK -a) tr mcQs (u) - (Oo-Pz) 1,

where UQ is the main carrier frequency; j- - additional carrier

frequency;

uj, the subcarrier of the signal of realness, transmitted on the carrier and); g-5g. - subcarrier signal

chromaticity transmitted on the UQ carrier.

The drawing shows a structural electrical circuit of a device implementing the proposed method.

A device for transmitting and receiving a simultaneous color television system contains on the receiving side a color television signal sensor 1, a delay line 2, a first adder 3, a first g-module modulator 4, a main carrier generator 5, a high-frequency amplifier 6, a phase inverter 7, a second adder 8, the second amplitude modulator 9, the additional carrier frequency generator 10 introduced, and on the receiving side — a high frequency amplifier 11, a converter 12, an intermediate frequency amplifier 13, a luminance signal detector 14, basically bandpass filter 15, the main detector 16 color subcarrier polosoyy additional filter 17, an additional detector 18 the color subcarrier and an adder 19.

The device works as follows.

The luminance signal and the modulated color subcarrier signal from the outputs of sensor 1 of the color television signal are fed to the first and second inputs of the first adder 3. The full color television signal from the output of the adder 3 is supplied

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on the first amplitude modulator 4, i to which the generator 5 of the main carrier frequency is connected. The output of the first amplitude modulator 4 is connected to a high frequency / 6 amplitude.

At the same time, the modulated color subcarrier signal through the phase inverter 7 is fed to the second adder 8, where the full color television signal is also generated. However, unlike the first adder

10 3, in the second adder 8, the subcarrier is obtained in anti-phaea. From the output of the second adder 8, the signal is fed to the second amplitude modulator 9, to which the inputted

J5 generator 10 additional carrier frequency. The output of the second amplitude modulator 9 is connected to the amplifier b high frequency. The carrier frequency generated by the entered

The additional carrier generator 10 on the amplitude-frequency characteristic of the high-frequency amplifier 6 is located on the opposite edge of the symmetrically main carrier.

This solution is equivalent to transmitting a two-band signal, since the signal at the main carrier frequency is transmitted with a partially suppressed lower sideband and at an additional one with a partially suppressed upper sideband.

At the receiving side of the signal from the amplifier 11 high frequency through the converter 12 and the amplifier 13

intermediate frequency is supplied simultaneously to the inputs of the main and additional band-pass filters 15, 17. The main band-pass filter 15 passes the main intermediate

the frequency uj ,, and the frequency band of the modulated color subcarrier (ujg t + 5). Additional bandpass filter

17- additional intermediate frequency uj and frequency band (s) ,. At the output of the main and additional bandpass filters 15, 17, the main and additional detectors 16, 18 of the color subcarrier are included, the outputs of which are connected to the adder 19. From the output of the adder 19, the subcarrier is removed, modulated by the chroma signal. Primary and secondary detectors 16,

18 color subcarrier included in opposite. Thus, the subcarrier

adder 19 comes from both detectors with the same phase.

Claims (2)

1. A method of transmitting and receiving signals of a simultaneous color television system based on quadrature modulation of the chroma subcarrier frequency by color difference signals, summing this a signal with a luminous signal and subsequent amplitude modulation of the carrier frequency of the image with a full color television signal on the transmitting side, and at the receiving side - detecting the full color television signal, extracting from it a chrominance signal with its subsequent synchronous detection with using a chrominance subcarrier signal, characterized in that, in order to improve the quality of transmitted signals by reducing quadrature distortions, the full color television signal inverts the phase of the chrominance subcarrier frequency modulated in amplitude by the additionally generated second carrier frequency of the image and sucked to the full signal color television, and on the receiving side, before detection, the full color television signal is divided into two signals and suppress one of the carriers Image frequency in each of the divided signals, and at synchronous detection of the chrominance signal of an additional full color television signal, they invert the FER of the chrominance frequency subcarrier and, after detection, sum up the same color difference signals in pairs 2. A device for transmitting and receiving signals of a simultaneous color television system, containing on the front side a color television signal sensor, the output of the luminance signal of which is connected via a delay line to the first input of the first adder, and the output of the modulated signal of the color subcarrier connected to the second input of the first adder connected to it first exit the input of the first amplitude modulator, the second input of which is connected to the output of the generator of the main carrier frequency and the output to the input of the high-frequency amplifier, on the receiving side a high-frequency amplifier whose output is connected to the detector of the luminance signal and the main bandwidth a filter whose output is connected to the main color subcarrier detector, characterized in that, in order to improve the quality of the transmitted signals by reducing the quadrature distortion, phase-invertor, the second corematter and the second amplitude modulator, the other input of which is connected to the output of the inputted additional carrier frequency generator and the output to another input of the high-frequency amplifier, are input to the transmitting side, while the other input of the second adder is connected to another output of the delay line and the phase inverter input is connected to the second input of the first adder, and an additional band-pass filter is added at the receiving side, an additional color detector howl subcarrier and an adder, the other input of which is connected to the main detector of the color subcarrier, and the additional bandpass filter input is connected to the output of the intermediate frequency amplifier. Sources of information taken into account in the examination 1. Pevzner B.M. Color TV system. L., Energie, 1968, p. 143 (prototype).