SU387488A1 - - Google Patents

Description

DEVICE OF AUTOMATIC FREQUENCY REMOTE

one

This invention relates to an automatic frequency tuning device used in various radio engineering systems, in particular in radio exciters and radio transmitters.

In a known automatic frequency tuning device comprising a phase locked loop consisting of a tunable converter generator, a phase detector and a low-pass filter, a relatively long time is spent on tuning from one frequency to another.

In the proposed device, an increase in the tuning speed is achieved by the fact that an initial bias circuit is connected between the trigger output and the control input of the saw-tooth generator.

In the drawing, the block diagram of the proposed device,

The device contains: f: iltr / pizhnyh frequencies; adjustable generator 2; phase detector 3; converter 4; 5 low pass filter; DC amplifier 6; sawtooth generator 7; zero-body S; initial displacement circuit 9; differentiating chain 10; trigger //; J2 source frequency.

The device works as follows.

Elements 1, 2, 4, 3 form a ring of quick and custom, and elements 2, 4, 3, 5, 6, 7 form a ring

slow setting. When the reference frequency / s, which outputs the quick setting ring outside the setting band, is changed, the voltage at the output of the filter 5 is zero,

and generator 7 begins to produce a sawtooth control voltage, gradually rearranging the frequency of generator 2. When the frequency at the output of converter 4 becomes approximately equal to / s, appearing on

The output of the filter 5 DC voltage brakes the generator 7 of the sawtooth voltage, and further adjustment is carried out using a ring of quick tuning, which provides fine tuning. Therefore, the adjustment time consists of the search time and the adjustment time.

Supplied to the trigger input, when the frequency changes, the tuning signal sets trigger 11 to the search position, in which the initial bias circuit 9 is connected to the sawtooth generator 7. At the end of the search process, a low 1p from the output of the phase detector 3 triggers the null organ 5, the signal

from the output of which through the differentiating chain 10 enters the trigger 11, set it to the "Adjustment" position, in which the initial bias circuit 9 is disconnected from the generator 7 of the sawtooth voltage. As a result, the output voltage

generator 7 varies by pa value U, which is chosen to be approximately equal to the inertia coasting. As a result, the inertial coasting is significantly reduced, which can increase the search speed by about an order of magnitude and, consequently, reduce the tuning time (it is known that the magnitude of the inertial coasting is limited by the setting band of the quick setting ring).

Subject invention

An automatic frequency tuning device containing a phase-locked loop, consisting of a tunable converter generator, a phase detector connected by a second input to a reference frequency source, and a low-pass filter, the second output of the phase detector through a series-connected low-pass filter, amplifier of constant current and a sawtooth generator connect to the second input of the adjustable oscillator and through serially connected zero-body, differential A second circuit input and a trigger, the second input of which is connected to a control voltage source, is connected to a control input of a sawtooth generator, characterized in that a circuit is switched between the trigger output and the control input of a sawtooth generator in order to increase the tuning speed. initial displacement.

Restructuring