SU1626457A1 - Color synchronizer - Google Patents

Abstract

The invention relates to a color television technique. The purpose of the invention is to improve noise immunity. The device contains an amplitude limiter 1, an amplitude detector 2, the first electronic switch 3, the first and second peak detectors 4 and 5, the limiter 6 at the minimum, the differential amplifier 7, the trigger correction block 8 and the inclusion of the chroma channel, the counting trigger 9, the delay block 10, the second electronic switch 11, the adder 12. To the input of the device receives a signal containing color packages under the carrier. The delay unit 10 for the first output delays the signal by a multiple of an odd number of half periods of one of the carriers, and for the second, by a multiple of the duration of the period of the other under the carrier. Adder 12 adds delayed and non-delayed signals; moreover, if a blue signal subcarrier is present at the device input, the voltage at the output of adder 12 is zero, if the red signal subcarrier has a double amplitude, which increases the noise immunity of the device. 1 il. Yo

Description

The invention relates to the technique of color television.

The aim of the invention is to increase the noise immunity of the device.

The drawing shows a structural diagram of the image channel.

The synchronization device comprises an amplitude limiter 1, an amplitude detector 2, a first electronic switch 3, a first 4 and a second 5 peak detectors, a minimum limiter 6, a differential amplifier 7, a trigger correction and color channel switching unit 8, a counting trigger 9, a delay unit 10, second electronic switch 11, adder 12.

The color synchronization device operates as follows.

At the input of the device, a signal containing color subcarrier packets is received, which is delayed by the delay unit 10 by an amount less than half the duration of the packet of the unmodulated color subcarrier. On the first output, the delay unit 10 provides a signal delay by an amount multiple of the odd number of palperiods of one of the color signal subcarriers, and by the second output, by a multiple of the duration of the second subcarrier period. The second input of the adder 12 is fed a color subcarrier signal from the output of the amplitude limiter 1, the latter partially suppresses pulse interference. The second electronic switch 11, under the control of the signal of the counting trigger 9, interlaces the outputs of the delay unit 10 to the second input of the adder 12. When the unmodulated subcarrier receives a blue signal after a time interval equal to the delay time after the start of the unmodulated subcarrier, the delayed and undelayed signals in adder 12 cancel each other out. When a red * signal at the output of adder 12 is supplied to the input of the device by the unmodulated subcarrier 12 at similar time points, the amplitude signal takes values close to twice the amplitude of the input signal of delay unit 10, sinusoidal signals of other frequencies are greatly attenuated. Thus, depending on the frequency of the unmodulated subcarrier of the color signal, signals of various amplitudes are generated at the output of adder 12. The amplitude detector 2 selects their envelope, the electronic switch 3 separates them into two channels. To isolate color synchronization signals, the common channel is unblocked by a gating pulse applied to amplitude detector 2. At the outputs of peak detectors 4 and 5, voltages are generated that are proportional to the span of pulses detected in amplitude detector 2, which are fed to the limiter 6 to a minimum.

The threshold voltage value of the limiter 6 is selected so that when the SECAM signal is received, the voltage difference at the inputs of the limiter 6 is greater than the threshold value and the signal is supplied to the differential amplifier 7. If the operation phase of the counting trigger 9 is incorrect, the voltage polarity at the output of the differential amplifier 7 is such that the circuit block 8 correction trigger and enable the color channel generates a correction signal supplied to the installation input of the counting trigger 9 and changing its phase. After that, the sign of the signal difference at the output of the differential amplifier 7 changes and block 8 generates a control signal E _уП р, including the color channel.

Thus, in the device, the difference between the unmodulated color subcarrier signals increases and other sinusoidal signals decrease, which generally leads to an increase in the noise immunity of the device.

Claims (1)

Claim A color synchronization device containing an amplitude organizer, the input of which is the input of the device, an amplitude detector connected in series, the control input of which is the input of the strobe pulses and the first electronic switch, the control input of which is connected to the output of the counting trigger, the counting input of which is the input of the horizontal pulses, and the installation the input is connected to the first output of the trigger correction unit and the inclusion of the color channel, the second output of which is the output of the device, and the input is connected to the output of the differential amplifier, the first and second inputs of which are connected respectively to the first and second outputs of the limiter to a minimum, the first and second inputs of which are connected respectively through the first and second peak detectors with the first and second outputs of the first electronic switch, characterized in that , in order to increase the noise immunity, a delay unit is introduced into it, the first and second outputs of which are connected respectively to the first and second inputs of the second electronic switch, controlling whose first input is connected to the output of the counting trigger, and the output to the first input of the adder, the second input of which is connected to the input of the delay unit and the output of the amplitude limiter, and the output to the input of the amplitude detector.