SU879820A1 - Device for automatic adjusting of television receiver - Google Patents

Description

one

This invention relates to radio engineering and can be used to automatically tune television receivers.

A device for automatically tuning a television receiver, comprising a tuning control unit and a controlled tuning voltage generator, the output of which is connected to the input of the oscillator 1 frequency auto tuning unit, is known.

However, the known device is about. It gives low noise immunity and low speed.

The purpose of the invention is to increase the speed and noise immunity.

To do this, in the automatic setup of a television receiver, containing a tuning control unit and a controlled tuning voltage generator, the output of which is connected to the input of the oscillator’s automatic frequency control unit, the tuning control unit consists of a standby multivibrator, a cumulative counter, a 45-trigger, a reset counter and a coincidence element, with the input of the waiting multivibrator being the input of sync pulses, the first hour the second inputs of the cumulative counter are frame inputs 's sync and horizontal sync pulses, and a third key to exit pod10 monostable multivibrator, and the accumulating counter output soedinen.s s input -triggera ft-S and the first input of counter sbrO7 meat, the second input of which is

15 input frame sync pulses, and the output - with R. input 25-flip-flop, the output of which is connected to the first inputs of the matching element and the controlled voltage generator at 20, the second input of the matching element is connected to the output of the audio subcarrier detector, and the output to the inputs a control unit for automatic adjustment of the local oscillator frequency; and a controlled tuning voltage generator. The drawing shows the structural electrical circuit of the proposed device. The device contains a tuning control unit 1 consisting of a standby multivibrator 2, a cumulative counter 3, a R6 trigger 4, a reset counter 5 and a matching element 6, controlled by a tuning voltage generator 7, an oscillator automatic frequency tuning unit 8, a detector 9 subcarrier sound. The device works as follows. At the initial moment of time, in the absence of frame sync pulses, horizontal sync pulses and the absence of voltage at the output of the detector 9 of the audio subcarrier, there is no control signal at the output of the element 6 coincidence and, accordingly, at the control- inputs of the controlled generator 7 settings and block 8 auto-tuning the local oscillator. The output voltage of the automatic tuning device of the television receiver is the sum of the voltages of the controlled oscillator 7 of the tuning voltage and the unit 8 of the automatic tuning of the local oscillator frequency. When the output voltage approaches the value corresponding to the frequency of the television transmitter, there will be frame and line synchronization signals. Frame sync pulses the standby multivibrator 2 and sets cumulative counter 3 to the desired state. The impulse of a given duration from the output of the waiting multivibrator 2 is fed to the enable input of the cumulative counter 3, to the counting input of which the horizontal sync pulses are received. The tracing period of the horizontal sync pulses does not change depending on the transfer plot, therefore, during the duration of the pulse of the waiting multivibrator 2, accumulative counter 3 calculates a strictly definite number of fundamental sync pulses. When properly tuned, this mode will repeat with a period equal to the frame sync pulse period and the calculated number of horizontal sync pulses will correspond to the number of horizontal frequency periods stacked during the duration of the pulse of the waiting multivibrator 2. In this case, the output of accumulative counter 3 shows the signal sets the zero 5 to the zero state and translates the us-trigger 4 into the $ state. At the first input of the coincidence element 6, a resolution signal is received. The permissive signal also goes to the speed control input and reduces its value to a value that provides reliable tuning. . As the voltage of the controlled generator 7 of the tuning voltage approaches the nominal value, the signal from the detector output appears at the second input of the matching element 6. 9, a subcarrier of sound, at the output of the element 6 of coincidence, a signal appears that stops changing the tuning voltage, turns on block 8 of the automatic tuning of the local oscillator frequency, making final fine tuning. In case of a random signal occurrence (for example, under the influence of interference at the output of the cumulative counter 3, the situation does not repeat from frame to frame and the reset counter 5 is not set to zero state. After a certain number of frame sync pulses, the output signal of the reset counter 5 will set the RS-trigger 4 to the state ft, thereby causing a further change in the voltage of the controlled voltage generator O. 7 to search for the transmitter. The presence of the reset counter 5 eliminates the accidental loss found transmitter, since the reset signal is generated only with a regular absence of a signal at the output of cumulative counter 3 for a certain number of frame sync pulses. The presence of a C5 trigger 4 and a matching element 6 improves the speed of the automatic tuning system without increasing the probability of loss of the found transmitter by increasing the rate of change of the voltage of the controlled voltage

generator 7 of the tuning voltage from the beginning of the search to the moment the signal appears at the output of the RS-trigger 4, carried out using the input of the change of the tuning speed of the control of the generator 7 of the tuning voltage.

Improved noise immunity is achieved by adjusting the reliability of the settings using typical television transmission voltages of the audio subcarrier and synchronization signals that do not depend on the transmitted image plot, the strength and pitch of the sound, and allow their temporal characteristics to be used in addition to the number of characteristics.

The increase in speed is achieved due to the fact that at the moment of searching and at the moment of seizing the transmitter, the rate of change of the output voltage of the controlled oscillator 7 of the tuning voltage can vary.

The proposed device can be implemented using new elements - digital integrated circuits, which allows all nodes of the proposed device to be implemented as one or several microcircuits, including a digital-analog converter, simple logic elements and counters. As a result, the laboriousness of assembling and adjusting units and blocks is reduced while simultaneously increasing the operational characteristics of modern and advanced television receivers.

Claims (1)

1. US patent. No. 4038689, cl. 358-191, 1977 (prototype). Input f adpoffbi} (sync pulse