RU1818709C - Cross-colour compensator - Google Patents

Abstract

The invention relates to television technology and can be used, for example, as part of the receiving apparatus of color television systems, for correcting cross-distortions of the brightness-color type. The purpose of the invention: improving the accuracy of the correction of crosstalk. The inventive cross-distortion correction device comprises a band-pass filter (1), three amplitude limiters (2.5, 14), five delay units (6, 8. 10. 15, 19), a low-pass filter (4), two adders ( 12.16). two multipliers (7.9), an inverter (11), a parallel resonant circuit (13), two amplitude detectors (3, 17), a controlled notch filter (18). 1 ill.

Description

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The invention relates to television technology and can be used, for example, as part of the receiving equipment of color television systems.

The purpose of the invention is to improve the accuracy of correction for crosstalk such as brightness-color.

The drawing shows a structural electrical circuit of the device.

The device for correcting cross-distortions of the brightness-color type (Fig. 1) contains a band-pass filter 1, a first amplitude limiter 2, a first amplitude detector 3, a low-pass filter 4, a second amplitude limiter 5, a second delay block b, a first multiplier 7, a first block delays 8, second multiplier 9, third delay unit 10, inverter 11, first adder 12, parallel resonant circuit 13, third amperage limiter 14, fourth delay unit 15, second adder 16, second amplitude detector 17, controllable rejector second filter 18, a fifth delay unit 19.

The device operates as follows. At the input of the band-pass filter 1 (PF 1) receives a full television signal - PAL (NTSC). In the FS t, a color signal and interference from the high-frequency components of the luminance signal are allocated - the response of a step-like change in the luminance signal, which, due to the wide passband of PF 1, has a large peak value (outliers). In order to detect an emission from interference, the color signal passes the first amplitude limiter 2 (AO-2), which can be used as a two-sided amplitude limiter to a minimum. The introduction of a minimum limiter provides an account of the possibility of penetration of emissions at the output of PF 1, above the span of the color signal, i.e. limiter 2 can be considered as a threshold block. In the case of the presence of emissions at the output of AO 2, the latter go to the input of the first amplitude detector 3 (AD 3) (rectifier), a low-pass filter 4 (LPF 4) and the second amplitude limiter 5 (AO 5) - a lower limiter, which will allow to get rid of from a part of the constant component of the control signal, the restriction levels are lower and upper 0. The low-pass filter 4 provides the necessary duration of the control signal (CS). Thus, at the output of AO 5, we obtain the CS with the amplitude equal to unity, but in the absence of emissions the CS is zero. SU goes to the control input of the first multiplier 7 (UM 7) and through the first block

delay 8 (BZ 8) to the control input of the second multiplier 9 (UM 9). Denote the current amplitude modulated color signal that has undergone interfering

the action of the response of a step-like change in the brightness signal at the output of PF1, like u1 + 112, where Ui is the amplitude-modulated color signal without interference; 1) 2 is the response from a step-by-step change

0- luminance signal (interference) at the output of PF 1. These signals are fed to the information input of UM 7 through a matching BR 6, where they are multiplied by one or zero depending on the values of the control system, thus

5, the output of UM 7 is allocated Ut + Ua, which is fed to the second input of the first adder 12 through the third BZ 10 and inverter 11 connected in series 11. To compare the current signal (Ut + Ua) with the previous one

0 i.e. Ui, SU is delayed by the first BZ 8 by an interval multiple of the period of the subcarrier of the PAL system (NTSC). In this case, at the output of the UM 9, a color signal 1I is extracted, which is fed to the first input of the first adder 12, the output of which is the response from an abrupt change in the luminance signal (noise), but this time with the opposite sign. Since the output of the PF 1 oscillation occurs (response - Ua), the frequency

0 which is equal to the resonant frequency of PF 1, therefore, a parallel resonant circuit 13 (PRK13) is turned on, tuned to the same frequency, i.e. PPH 13 isolates the interference (-Ua) and filters the emerging harmonics,

5 that may arise due to nonlinear processing in the first 7 and second 9 multipliers x, then the extracted interference from the luminance signal is fed simultaneously to the input of the third AO 14 and to the first input of the second

0 of the adder 16, to the second input of which a color signal Ui + Ua is supplied. At the same time, the color signal is output without interference (the output of the second adder 16 is the output of the color signal of the device 5 ve). As the PRK 13 can, with interference, make up the remainder from the signal Ui (to the left and to the right of the resonant frequency), which may violate the control principle of the controlled notch filter 18

0 (URF 18} (they change the value of its variable resistance), then the third limiter 14 (its amplitude characteristic as in AO 2) is turned on, the output of which is connected to the input of the second amplitude

5 of the detector 17. The control signal from the output of the second HELL 17 is fed to the control input of the URF 18.

Thus, the passband of the luminance channel is adaptively controlled depending on the level of the pilot signal in the color region of the subcarrier; there is a decrease in the degree of rejection of the jump-like drop in the brightness signal. The reduction in the rejection of the jump-like difference in the brightness signal guarantees the correctness of the further formation of color signals in the matrix, i.e., in this case, the brightness signal from the output of PF 1 through the fifth БЗ 19 is fed to the information input of the URF 18, which passes the brightness signal at its output without changes, the output of the URF 18 being the output of the luminance signal of the device.

Delay units 6, 8, 10, 15, 19 are used to match the operating and control signals of the device over time.

It should be noted that the option of using the corresponding keys K 7 and K 9 instead of MIND 7 and MIND 9 is a variant of the proposed device.

Compared with the known invention, the present invention provides enhanced clarity of a color image (color sharpness). This is ensured by disabling the notch of the luminance signal at the moment of its abrupt change (at the boundary of parts), which ultimately maintains sharpness, i.e. sharpness of transitions in the color signal (R.G.B), at the output of the matrix. This is due to the fact that the latter are obtained as a result of the addition of color-difference signals and the RF components of the luminance signal (spasmodic changes), an increase in color sharpness improves visibility when reproducing text material (letters). Compensation of the response from a jump in the difference in the luminance signal in the color channel of the device reduces the duration of transitions in color-difference signals, the duration of the transitions of the latter will be longer in the absence of compensation due to the smaller bandwidth of these signals compared to the frequency band of the brightness signal.

Formula s A device for correcting cross-distortions of the brightness-color type, containing a controllable notch

a filter, a first amplitude limiter, a first amplitude detector, a first adder and a band-pass filter, the input of which is an input for a full color television image signal, and so on, in order to improve the accuracy of crosstalk correction such as brightness-color, the first, second, third, fourth and fifth delay units, the first and second multipliers, the second and third amplitude limiters, and the inverter are introduced. a parallel resonant circuit, a second adder, a low-pass filter, a second amplitude filter, a detector, the output of the bandpass filter being connected to the input of the second delay unit and the first amplitude limiter,. the output of which is connected to the control input of the first multiplier and the input of the first delay unit via series-connected first amplitude detector, a low-pass filter and a second amplitude limiter, the information input of the first multiplier connected to the output of the second delay unit and the inputs of the fourth delay unit m of the second multiplier, the input of which is connected to the output of the first delay unit, the output of the second multiplier is connected to the first input of the first adder, the second input of which is connected to as the first multiplier passes through the inverter and the third delay unit in series, and the output of the first adder is connected to the first input of the second adder and the input of the third amplitude limiter through a parallel resonant circuit, the second input of the second adder is connected to the output of the fourth delay unit, and its output is the output signal is the color of the device, and the output of the third amplitude limiter is connected to the control input of the controlled notch filter through the second amplitude detector or, the information input of the controlled notch filter is connected through the fifth delay unit to the input of the band-pass filter, and the output of the controlled notch filter is the output of the device brightness signal.