SU995376A1 - Television signal transmitting and receiving device - Google Patents

Description

The invention relates to television technology and can be used to simultaneously transmit two color television programs over one standard communication channel.

A device for transmitting and receiving television signals is known, which contains two recalculating matrices of a private signal interleaving unit, three: matching delay lines, a precompaction block, a multipole switch, a program identification pulse insertion circuit, an electronic interleaving switch, a signal regeneration regenerator, a pulse generation generator, flj interleaving control unit.

This device is very complicated and expensive due to the presence of a memory for several fields.

Closest to the present invention, there is a device for transmitting and receiving television signals, containing on the transmitting side first and second low-pass filters whose inputs are respectively the inputs of the first and second television signals sequentially connected to the first sub-channel generator.

the first phase shifter and the first modulator, the second modulator, the first input of which is connected to the output of the first subcarrier generator, and the first adder, the output of which is the output of the transmission devices, and on the receiving side - the first synchronous detector and the consecutive subdivision separation unit, the second generator the subcarrier, the second phase shifter and the second synchronous detector, the second input of which is connected to the input of the subcarrier extraction unit, with the first input of the first synchronous detector and is the input of devices and reception, with the output of the second sub-carrier generator connected to the second input of the first synchronous detector and to the second input of the subcarrier allocation unit 2.

However, the known device does not provide for the suppression of mutual interference caused by cross-quadrature distortion during transmission

25 two television signals with equivalent spectra, when one of the sidebands of the signal is partially suppressed.

The purpose of the invention is to reduce interference in the transmission of two television signals over one standard communication channel. To achieve THIS goal, a television transmission device that receives television signals containing, on the transmitter side, the first and second low-pass filters, whose inputs are the inputs to the first and second television signals, in series, connected by the first generator of the torus, the first phase shifter and the first the modulator, the second modulator, the first input of which is connected to the output of the first subcarrier generator, and the first adder, the output of which is the output of the transmission device, and on the receiving side the first sync The pioneer detector and the subcarrier allocation unit connected in series, the second subcarrier generator, the second phase shifter and the second synchronous detector, the second input of which is connected to the sublight outlet allocation unit, the first input of the first synchronous detector, and is the input of the receiving device to the second input of the first synchronous detector and to the second input, the subcarrier allocation unit is inserted between the output of the first low-pass filter and the second input of the second module a series-connected first delay unit and a second adder, between the output of the second low-pass filter and the second input of the first modulator, a series-connected second delay unit and the third adder, between the output of the first modulator and the first input of the first adder, first band pass filter, between the output of the second modulator and the second input of the first adder second band-pass filter, between the output of the first low-pass filter and the second input of the third adder, the third modulator connected in series, thirds a bandpass filter, a third synchronous detector and a first inverter between the output of the second lowpass filter and a second input of the adder BTOpoj-o soedi- sequentially. Fourth modulator, fourth bandpass filter, fourth synchronous detector and second inverter, while the second input of the third modulator is connected to the second input of the fourth synchronous detector and the output of a negative subcarrier generator, the second input of the fourth modulator and output first phase shifter. The drawing shows a structural electrical circuit of the proposed device. The device for transmitting and receiving television signals on the transmitting side includes the first and second low pass filters 1 and 2, the first and second blocks 3 and 4 delays, the first subcarrier generator 5, the first (phase shifter 6, the first, second third and fourth modulators 7-10 the first, second, third and fourth bandpass filters 11-14, the first, second and third adders 15 and 17, the third and fourth synchronous detectors 18 and 19, the first and second inverters 20 and 21, and on the receiving side the first and second synchronous the detectors 22 and 23, the subcarrier allocation unit 24, the second the subcarrier generator 25 and the second phase shifter 26. The device operates as follows: The first and second television signals are fed to the inputs of the first 1 and second 2 low pass filters, respectively. Next, the first television signal is fed to the first input of the delay unit 3, where it is delayed by the time equal to the quadrature interference time. The same signal is also fed to the input of the third modulator 9, to the second input of which the signal of the subcarrier frequency is received with the O® phase from the output of the first generator 5 of the subcarrier. From the output of the third modulator 9, the first television signal transferred to the subcarrier is fed to the input of the third bandpass filter 13, which partially suppresses its upper sideband. The signal is then fed to the input of the third synchronous detector 18, to the second input of which a subcarrier frequency signal is fed with the phase 90 from the output of the first phase shifter B. The output of the third synchronous detector 18 is allocated a quadrature disturbance, which through the first inverter 20 goes to the second. This is the input of the third adder 17, the first input of which receives the second television signal delayed by the second delay unit 4. From the output of the first delay unit 3, the delayed first television signal is fed to the first input of the second adder 16, the second input of which receives an inverted quadrature interference signal generated by the fourth modulator 10, the fourth band-pass filter 14, the fourth synchronous detector 19 and the second inverter 21. Pre-distorted first the television signal from the output of the second adder 16 is fed to the second input of the second modulator 8, to the first input of which a signal of the subcarrier frequency with the O® phase is output from the first generator Ator 5 subdivision. From the output of the second modulator 8, the pre-distorted signal transferred to the subcarrier enters through the second bandpass filter 12 to the second input of the first adder 15, to the first input of which a second predistorted signal is transferred to the subcarrier in modulator 1 whose spectrum is formed by filter 11.

From the output of the first adder 15, through the communication channel, the compressed signal is fed to the inputs of the first and second synchronous detectors 22 and 23 of the receiving device and the input of the subcarrier allocation unit 24. In subcarrier extraction unit 24, a comparison is made between the frequency and phase of the subcarrier signal generated by the second subcarrier generator 25 and the subcarrier signal transmitted in the interval of the fixed flash located on the rear step of the horizontal damping pulse. As a result of the comparison, a control voltage is generated which adjusts the frequency and phase of oscillations of the second subcarrier generator 25. From the output of the second oscillator 25, the subcarrier signal is fed to the second input of the first synchronous detector 22 and through the second phase shifter 26 to the first input: the second synchronous detector 23. At the output of the first 2: 2 synchronous detector, the first television signal is output, and at the output of the second synchronous detector 23 - the second television signal. l

At the receiving side, as a result of synchronous detection, a quadrature interference of the second (first television signal) is added to the pre-distorted first (second) television signal. As a result, the quadrature interference occurring in the receiving part of the device is compensated for by interference introduced into the transmitted signal.

 Thus, the proposed device reduces the mutual interference of television signals transmitted over ONE standard communication channel.

Claims (2)

1. Author's certificate of the USSR 520725, cl. H 04 and 7/08, 1976. 2.Novakovsky S.V. Standard color television systems. M., Svy, 1976, p. 171 (prototype).  ff I - f /  J 2  fff