SU73127A1 - Device for automatically maintaining constant carrier frequency - Google Patents

Description

Devices are known for automatically maintaining a constant carrier frequency of spgnals with one lateral band at npneNie with PEMONIUM superheteronic reception. equipped with a frequency discriminator and a local oscillator frequency controller.

The main disadvantage of single-pole transmission schemes using a pilot signal at the transmitter, which works stably at frequency sweep and for x, is the limitation of the range of transmitted frequencies. For example, if the frequency f of the nilot signal is 200 Hz. It is not possible to transmit frequencies below 200 Hz, i.e. it is impossible to conduct high-quality transmission.

This disadvantage does not occur with the known single-band transmission method while retaining part of the pesui; it has a frequency, but then a complicated device is required to adjust the receiver.

In the described device, in order to eliminate this drawback, a part of the non-primary frequency is also transmitted, but a pilot signal is also created by the receiver. In this case, the nodrostrochny system is just as nasty as when it is not with a conventional pilot, and does not allow for the transmission of low frequency modulation.

A special feature of the device described is that in order to achieve a new accuracy of the discriminator, a generator whose frequency must be equal to the mismatched frequency of the incoming signal is connected to the modulator, in which the frequency is added to the auxiliary low frequency f. To the discriminator tuned to the auxiliary frequency, the output current of the frequency modulator of the carrier frequency / is simultaneously connected through the appropriate filters.

.V 73127

The block diagram of the receiver of signals is double odnopolnon pe ;; a -: n using the onisable device shown in the drawing. In the case of transmission of one channel and the voice (and often non-elastic), the channel .4 or B will be missing.

The receiver works in the following way.

From the antenna to the high frequency amplification (UHF) cascade, two sidebands and bands, each of which is modulated by a separate carrier and a frequency carrier, are suitable. Then they come along with a converter together with the oscillations of the first local oscillator, and their frequencies are lowered so that the carrier frequency is converted into frequency /.

With an ideal tuning, the frequency / should be equal to the frequency / g of the own oscillator and the generator serving for the isoccTairoiici and the transformed carrier frequency.

In the intermediate frequency amplifier (PRC), the transform sidebands and nonsunch frequencies are amplified (1C) ts and there are also three band-pass filters with strictly flat pass bands. Iloc.ie filters each side of the band and jesun and the frequency (conversion of the carrier frequency) is set on the lialeum.

The sanding frequency (") arrives at the detector-discriminator, where it is connected to its own receiving frequency (1 ns). The latter is obtained by modulating the geyeromerically stadardT1P51m generator)) frequency / g frequency /, which is played by an auxiliary 111m1m geierato | Yu. With the help of a sideband filter (/: / "c) In the detector-discriminator and the resin, the frequency /, forms a beat with the frequency / -I /" c.

If setting 1 is heterodyne irravilla, then / e - // and as a result a difference frequency (n) is obtained, which does not create conditions for iodation of the local oscillator frequency controller. If the frequencies f d and / are not equal and the difference and a certain frequency A /, then the beat frequency will be /,., (. -f L / nln / ,,, -D /. Such a frequency Byzg) the influence of the frequency regulator 1 heterodyne. The adjustment of the heterodyne frequency will occur until It will be equal to zero, that is, until the setting is correct.

Each of the transformational sidebands, as usual, is fed to the detector together with the frequency, which replaces the necyniyio frequency. After the detector, a snooper enters the ordinary usn.1ptel1) pptskoG | frequency (ULF).

The initial tuning of the receiver should be performed with an open control circuit and reduced to tuning only the high frequency and local oscillator.

In the receiver, the automatic frequency control is implemented, the frequency (.RLSP), for which there is 1 key detector .ARC in the circuit of this regulator.

PREPARATION AND RESULTS

A device for automatically maintaining the carrier frequency constant of signals with a single sideband when using a superheterodyne receiver supplied with a frequency discriminator and a heterodyne frequency regulator, characterized in that, in order to improve the accuracy of the discriminator, the generator used to receive the current, frequency / which must be exactly equal to the non-frequency / „signal, connected to the modulator, in