SU1192165A2 - Device for filtering television signal - Google Patents

Description

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Oi SP l. The invention relates to television technology. The purpose of the invention is to improve the transmission of high-frequency components of the signal while maintaining the suppression of high-frequency noise. ; FIG. Figure 1 shows a structural electrical circuit for filing a television signal; in fig. 2 - time diagrams for his work. The television signal filtering device contains a delay line 1, the first adder 2, the second adder 3, the first low pass filter 4 (LPF), the switch 5, the voltage divider 6, the differentiating amplifier 7, the high pass filter 8 (HPF), the second LPF 9, the first 10-1, the second 10-2, the third 10-3, and the quarters 10-4 threshold blocks, the encoder 11, the third adder 12 and the fourth adder 13. The television signal filtering device works as follows. The phone receives a visual signal at the input of the device (Fig. 2c (), which is to be filtered. The specified signal passes through the delay line 1 to the first input of the first adder 2. Line 1 delays the delay of the signals at the inputs of the first adder 2, and also the second adder 3, the first input of which receives a delayed input signal from the second output (retraction) of the delay line 1, and a second signal passing through the first low-pass filter 4. As a result, the high-frequency components of the television signal are extracted at the output of the second adder 3. sent to the first and second inputs of the switch 5 through the voltage divider 6 and directly, while the third input of the switch 5 is connected to a common bus. The operating mode of the switch 5 is determined by the control channel containing the differentiating amplifier 7, the second low pass filter 9, and also the first 10-1, the second 10-2, the third 10-3 and the fourth 10-4 threshold blocks and the encoder 11, the control channel provides three modes of operation of the device, depending on the spectral composition of the input signal, the high-frequency components of which are differentiated m. The second low-pass filter 9 provides an increase in the signal-to-noise ratio at the inputs of the third 10-3 and fourth 10-4 threshold blocks, which detect the input signal components from single small parts and brightness differences. Highpass filter 8 increases the signal-to-noise ratio at the inputs of the first 10-1 and second 10-2 threshold blocks, which detect the components of the input signal from repetitive small parts (group structures). The first 10-1 and third 10-3 threshold blocks have a threshold d, and the second 10-2 and fourth 10-4 threshold blocks are the 3d threshold, where (e is the rms noise level given to the device input. The device has three modes of operation. I mode - no signal at the outputs of the threshold blocks 10-1 10-4. In this case, a signal is generated at the first output of the encoder 11, which arrives at the fourth input of the switch 5 and ensures that the signal at the second input passes through its output. input signal components at the output of the first adder 2. The output of the third adder 12 (one of the inputs of which is inverting) is zero and only low-frequency components of the input signal are received at the output of the device through the quarter adder 13. Second mode - the presence of signals at the outputs of the first 10-1 and the third 10-3 threshold blocks, in this case, a signal is generated at the second output of the encoder 11, which arrives at the fifth input of the switch 5 and ensures that the signal from the first input passes to its output. In this case, partial compensation of the high-frequency components 1x 1x in the first adder 2 and the addition of the high-frequency components in the fourth adder 13 is carried out in proportion to the division factor of the voltage divider 6 and the transmission coefficient of the third adder 12, which provides a partial increase in the frequency response in the high frequencies . Mode III - the presence of signals at the outputs of all threshold units 10-110-4. In this case, a sigal is formed on the third output of the encoder 11, which connects the output of the switch 5 to its third input (to the common bus). In this case, the high-frequency components of the input signal in the first adder 2 are not compensated, and the high-frequency components of the input signal are formed at the output of the third adder, ensuring, when they are added to the original signal, in the fourth adder 13 the maximum rise in the frequency response in the high frequency region.

Thus, the proposed device, in addition to suppressing high-frequency noise, also provides a rise in the high-frequency components of the input signal when the threshold is equal to d, which corresponds to the correction of the television image definition. The output signal of the device is shown in FIG. 2G, where the operation of the device is also marked.

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Claims (1)

DEVICE FOR FILTRATION OF A TV SIGNAL according to ed. St. N = 10612 90, characterized in that, in order to improve the transmission of high-frequency components of a television signal while maintaining the suppression of high-frequency noise, a third and fourth adder are connected to the device in series, while the first and second inputs of the third adder are connected respectively to the outputs of the second adder and switch, the second input of the fourth adder is connected to the output of the first adder, and the output is the output of the device. fig 1