SU1497762A1 - Decoder of digital tv signal transmission system - Google Patents

Abstract

The invention relates to the field of digital television signal transmission systems. The purpose of the invention is to improve the decoding accuracy of a television signal. The device contains a serially connected decoder 1 and an amplifier 2. A block 3 is assigned to the zero level, a comparator 4, a control voltage r 5 and a selector 6 of the television signal. The output of the generator 5 is connected to the input of the reference voltage of the decoder 1. The reference voltage at the input of the decoder 1 oscillates about a certain average level, which ensures that the output of the decoder 1 maintains the nominal amplitude of the synchronizing pulses of the line and, accordingly, the television signal. The magnitude of the voltage fluctuations of the reference level in this case does not exceed the quantization step of the television signal, which leads to a high decoding accuracy of the television signal and its insignificant distortion m. 1 sludge.

Description

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ISD

31497

The invention relates to digital television signal transmission systems and can be used in decoding devices of digital television signal receivers.

The purpose of the invention is to improve the decoding accuracy of a television signal.

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

The device contains a serially connected decoder 1, an amplifier 2, a block of 3 assignment to the zero level, a comparator 4, a controlled oscillator

5 voltage and selector 6 television signal.

The input of decoder 1 is the input of a received digital television signal. The output of decoder 1 is connected to the selector-oor 6 input of the television signal and is the output of the television signal. The first output of the television signal selector 6 is connected to the second input of the block 3 to zero. Second output selector

6 TV signal is connected to the comparator clock input

4, The second input of the comparator 4 is the amplitude input of the television signal. The output of the controlled voltage generator 5 is connected to the input voltage of the decoder 1 reference voltage.

The device works as follows.

Decoder 1, which is a digital-to-analog converter, converts a digital television signal arriving at its input into analog form. From the received television signal e to the selector 6 of the television signal, the blanking pulses of the rows at the first output and the clock pulses of the rows at the second output are extracted. The extinguished pulses of the lines supplied to the second input of the block 3 to the zero level provide a reference to the zero level of the blanking in the television signal amplified in the amplification 2. In the comparator 4, synchronized

pulses of rows, the amplitude of synchronizing pulses of rows in a television signal from the output of block 3 is zero compared to the amplitude of the signal

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set the amplitude of the television signal. In the event that the amplitude of the synchronizing pulses of the lines is equal to the amplitude of the signal of setting the amplitude of the television signal, then the controlled voltage generator 5 will output to the decoder 1 nominal level of the reference voltage. When the amplitude of the synchronizing pulses of the rows decreases, the controlled voltage generator 5 will produce a linearly increasing reference voltage. it

ABOUT

leads to an increase in the amplitude of the television signal at the output of the decoder I and, accordingly, to an increase in the amplitude of the clock pulses. When the amplitude of the synchronizing pulses of the rows reaches the amplitude of the signal, the amplitude setting of the television signal, the controlled voltage generator 5 will produce a linearly decreasing reference voltage, which leads to a decrease in the amplitude of the television signal at the output of the decoder 1. Thus, the reference voltage at the input of the decoder 1 will fluctuate with respect to a certain average level, which ensures that the output of decoder 1 maintains the nominal amplitude of the clock pulses of the lines and, accordingly, m signal. The magnitude of the voltage fluctuations of the reference level does not exceed the quantization step of the television signal, which leads to high decoding accuracy of the television signal and its insignificant distortion.

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Claims (1)

Invention Formula ow A decoder for a digital television signal transmission system containing a serially connected decoder and an amplifier, the decoder input being the input of a received digital television signal, characterized in that, in order to increase the decoding accuracy of the television signal, a television signal selector and serially connected the block of reference to the zero level, the comparator and the controlled generator of the voltage, the decoder output being the output of the television signal and united with the input of the selector t levi 1A977626, of a hot signal, the output of the amplifier is connected by a comparator input, the second is dinene with the first input block, whose input is a signal input to the zero level, the second input of which the amplitude setting of the television is connected to the first output of the select signal, the output of the controlled oscillator the torus of the television signal, the second voltage side is connected to the input of the support; the output of which is connected to the synchronization voltage of the decoder.