SU409352A1 - DEVICE SETTING TELEVISION CHANNEL SELECTORS - Google Patents

Description

one

The invention relates to television technology.

A device for tuning television channel selectors is known, comprising a oscillating frequency generator, a dummy load and an indicator.

The aim of the invention is to automate the tuning of the local oscillators.

In the proposed device, this is achieved by introducing a wide strobe shaper, a coincidence circuit, a narrow strobe shaper, and a step voltage generator into it.

The drawing shows a block diagram of the proposed device.

It contains a 1-step voltage generator, the equivalent of 2 selector loads, a shaper of 3 wide strobe pulses, 4 coincidence circuit, a shaper of 5 narrow strobe pulses, an oscillating frequency generator 6. The drawing also shows the block 7 selectors television channels.

The device works as follows.

The 3 strobe pulse shaper contains reference oscillators (not shown) of the carrier frequencies of the image of 12 television channels, and at the oscillating frequency value of -F (where / is the carrier frequency of the image of the channel being tested; F is the strobe pulse advance frequency)

forms a wide strobe pulse of this channel.

The narrow strobe pulse shaper 5 contains a reference oscillator (not shown) of the nominal value of the intermediate frequency flip, and at the value of the oscillating intermediate frequency / pr-F it produces a narrow strobe pulse. Both strobe pulses are applied to the coincidence circuit.

The step voltage generator 1 is synchronized by the corresponding signals and produces each voltage step synchronously with the next sweep of the sweep frequency signal. The output voltage of oscillator 1 changes the frequency of the local oscillator. This changes the temporary position of the narrow strobe with respect to the wide. At the time of coincidence of wide and narrow strobe pulses, the coincidence circuit produces a signal for stopping generator 1, which indicates that the local oscillator frequency is equal to its nominal value, since in this case the frequencies at the selector input and at

its output is spaced respectively from / and / pr by the same value of the F frequency ahead of the strobe pulse formation.

The values of the frequency F and the duration of the wide and narrow strobe pulses are determined by

required tuning accuracy.

Subject invention

A device for setting up television channel selectors containing a oscillating frequency generator, the output of which is connected to the inputs of television channel selectors with electronic tuning of the local oscillators loaded at the load equivalent, and an indicator that in order to automate the tuning of the local oscillators, the second output of the oscillating frequency generator is connected

through a wide strobe driver to one of the inputs of a coincidence circuit connected by its second input through a narrow strobe driver with a selector load equivalent, and the output of the coincidence circuit is connected to the stop input of a stepped voltage generator, with the clock inputs of a sweeping frequency generator and a stepped voltage generator Startup pulses given.