RU1811029C - Device for separating chroma and luminous signals in secam decoder - Google Patents

Abstract

The invention relates to television technology and can be used in the construction of SECAM color television decoders. An object of the invention is to reduce distortion of a brightness signal. The device contains two delay lines into two lines 1 and 2, an electronic switch 3, a control unit containing a first phase detector 4 and a pulse shaper 5 and also two subtractors 6 and 11, two band-pass filters 7 and 9, an adjustable delay line 8, and a second phase detector 10 and group delay time corrector. Reducing the distortion of the luminance signal is achieved by subtracting the subcarrier of adjacent rows of the same color differences with phase matching. 1 s.p. f-ly, 2 silt,

Description

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The invention relates to television technology and can be used in the construction of decoding devices for color television of the SECAM system,

An object of the invention is to reduce distortion of a brightness signal.

Figure 1 is a structural electrical diagram of a device for separating luminance and color signals in a SECAM system decoder; figure 2 - gtoukturna electric circuit corrector group delay time.

The device comprises a first 1 and a second 2 delay lines on two lines, an electronic switch 3, a control unit comprising a first phase detector 4 and a pulse shaper 5, a first subtractor b, a first bandpass filter 7, an adjustable delay line 8, a second bandpass filter 9 , the second phase detector 10, the second subtracter 11, the corrector 12 group delay time (delay).

 The first 1 and second 2 delay lines on two lines can be constructed, for example, in the form of CCD delay lines connected in series.

An adjustable delay line 8 can be constructed, for example, based on HC TDA 4560 3. Changing the delay time, signals can be carried out by changing the amount of current flowing between the 14th leg of the IC and the common bus.

The video signal from the first input of the device is supplied to the input of the first delay line 1 and to the second input of the electronic kbmmutator 3. The output of the first delay line t is connected to the inputs of the second delay line 2 and the second band-pass filter 9, the first input of the second subtractor 11; the second inputs of the first phase detector 4 and the first subtracter 6. The output of the second delay line 2 is connected to the third input of the electronic switch 3 and the first input of the first phase detector 4. The output of the phase detector 4 is connected to the first input of the pulse generator 5, the output of which is connected to the first input. electronic switch 3 .. The second input of the device is connected to the third input of the first phase detector 4, and the third input to the second input of the pulse shaper 5. The output of the electronic switch. 3 is connected to the first input of the first subtractor 6, the output of which is connected to the input of the first band-pass filter 7 and is the first output of the device. The output of the first band-pass filter 7 is connected to the second input of the adjustable delay line 8, the output of which is connected to the second inputs of the second phase detector 10 and, of the second

subtracter 11. The output of the second band-pass filter 9 is connected to the first input of the second phase detector 10, the output of which is connected to the first input of the adjustable

delay line 8 and the second input of the hot-wire corrector 12. The output of the second subtractor 11 is connected to the first input of the TVZ-12 corrector, the output of which is the second output of the device.

0 Corrector GVZ 12 (figure 2) contains a low-pass filter (LPF) 13, the third 14 and fourth 18 delay lines, the third 15 and fourth 19 subtractor, the second adjustable delay line 16, the adder 17.

5 low-pass filter 13 can be performed on the basis of a non-recursive filter.

A second adjustable delay line 16 can be constructed similarly to the per-. howling adjustable line 8 delay.

0 At the first input of the corrector GVZ 12 receives the brightness signal to be corrected. It arrives at the inputs of the low-pass filter 13 and the third delay line 1.4. The first input of the third 15 subtractors is connected to the output

5 of the third delay line 14, the second input is connected to the output of the low-pass filter 13 and the input of the fourth delay line 18; The output of the subtractor 15 is connected to the first input of the second regulated delay line 16, the second input

0 which is connected to the output of the fourth subtractor 19, the input of which is the second input of the hot-wire corrector 12. The output of the second adjustable delay line 16 is connected to the second input of the adder 17, the first

5, the input of which is connected to the output of the fourth delay line 18, and the output is the output of the hot-wire corrector 12.

The device operates as follows.

0 The first video input of the device receives a full video signal. Each of delay lines 1 and 2 delays the signals by. the length of two lines. The second input of the first subtracter 6 receives a video signal 5 delayed by two lines. The first input of the subtracter 6 receives a signal from the output of the electronic switch 3, which switches the output signals from the first input of the device or from the output.

0 lines 2 delays. The switch 3 is switched by the control unit / assembled on the first phase detector 4 and the pulse shaper 5. In the first subtractor 6, the extracted signal pairs are subtracted. As a result, components of the luminance signal are suppressed and a color signal is extracted. .Full video signal from the output of the first

 delay line 1 is fed to the first input

the second subtractor 11, where the color signal coming from the output of the adjustable delay line 8 is subtracted from it. The phase matching of the chroma signal and the subcarrier in the video signal is carried out using a phase adjustment system 5 collected on the first and second bandpass filters 7 and 9, the second phase detector 10 and the adjustable delay line 8. The second phase detector 10 compares the phases of the subcarriers. arriving at the inputs of the second 10 subtractor 11. In case of phase mismatch, the second phase detector 10 generates an error signal that controls the adjustable delay line 8. The delay line 8 changes the delay time of the color signal 15, which allows the phases of the subtracted signals to be matched.

In this way, subtraction of the subcarrier of adjacent rows of the same color differences with phase matching 20 is achieved, which reduces the distortion of the luminance signal. To correct various delays of the high-frequency and low-frequency components of the luminance signal, the GVZ corrector 12 is used, in which 25 the delay of the high-frequency components of the luminance signal in the first1 adjustable delay line 8 is compensated by the delay of the low-frequency components of the luminance signal in the GVZ 12 corrector. 30

The corrector GVZ 12 (figure 2) works as follows.

At the first input of the corrector GVZ 12 receives a brightness signal to be corrected. The low-pass filter 13, based on a non-recursive 35 filter, isolates the low-frequency components of the luminance signal that are received. They are applied to the fourth delay line 18, where they are delayed by a value t equal to the total delay time of the signals in the first 40 and 16 second adjustable delay lines. High-frequency components of the brightness signal are extracted at the output of the third subtractor 15 and fed to the second adjustable line 16 delays, where 45 are delayed for trls 2. The delay time of the second adjustable delay line 16 is controlled by a signal from the output of the fourth subtractor 19, on. the input of which receives the signal from the output 50 of the second phase detector 10. The fourth subtractor 19 subtracts Umax-Uex, where Umax is the maximum control signal.

Thus, an increase in the signal delay time 55 in the first adjustable delay line 8 is compensated by a decrease in the signal delay time t in the second adjustable delay line 16 and vice versa. In adder 17 occurs

summation of the low-frequency and high-frequency components of the luminance signal. Thus, at the output of the GVZ .12 corrector, we get the corrected brightness signal.

Claims (2)

1. A device for separating luminance and color signals in a SECAM system decoder, comprising a first and second delay line connected in series, a control unit comprising a first phase detector and a pulse shaper, an electronic switch and a first subtractor, the output of which is the first the output of the device for separating the luminance and color signals in the SECAM system decoder, and the second input is connected to the input of the second delay line and the second input of the first phase detector, the third which is the second input of the device for separating luminance and color signals in the decoder of the SECAM system, the third input of which is the second input of the pulse former, the output of the second delay line connected to the third input of the electronic switch, the second input of which is connected to the input of the first delay line and is the first input of a device for separating luminance and color signals in a SECAM system decoder. about. in that, in order to reduce the distortion of the luminance signal, a group time or delay corrector, a first bandpass filter, a second subtractor and a second bandpass filter connected in series, a second phase detector and a first adjustable delay line, the second input of which is connected with the output of the first bandpass filter, the output is connected to the second inputs of the second phase detector and the second subtracter, the first input of which is connected to the output of the first delay line and the input. the second bandpass filter, and the output is connected to the first input of the group delay time corrector, the second input of which is connected to the output of the second phase detector, the output is the second output of the device for separating luminance and color signals in the SECAM system decoder, the input of the first bandpass filter is connected to the output first subtractor. 2. Device pop. 1, characterized in that the group delay time corrector contains a low-pass filter (LPF) connected in series, the input of which is the first input of the group delay time corrector, the fourth delay line and the adder, output which is the output of the group delay time corrector, connected in series to a third delay line, the input of which is connected to the input of the low-pass filter, a third subtractor, the second input of which is connected to the output of the low-pass filter, and the second adjustable delay line, the output of which is connected to the second input of the adder, and the second input is connected to the output of the fourth subtractor, the input of which is the second input of the group delay time corrector. 6 BxZ Figure 1