SU320008A1 - DEVICE FOR AUTOMATIC ADJUSTMENT OF THE HETERODINE FREQUENCY TREATMENT OF SIGNALS OF THE FREQUENCY TELEPHONE - Google Patents

Description

The invention can find application in systems for receiving signals of frequency telegraphy with a "-quality code of any value (arbitrary ratio between zero and one in the code) and for any relationship between the instability of the frequencies being manipulated and the spacing between them.

The known device for automatically adjusting the frequency of the local oscillator of the receiver contains a frequency discriminator, pulse counters, an adder, a reference oscillator and a control element.

The purpose of the invention is to eliminate the effect of code unevenness on the accuracy of the frequency control and to provide frequency control for any relationship between the instability of the manipulated frequencies and their spacing.

For this, in the proposed device, the output of the frequency discriminator through a threshold cascade with a number of trigger thresholds depending on the code base and keys controlled by the organic voltage of the receiver intermediate frequency and voltage of the reference oscillator are connected to the inputs of digital discriminators that generate pulses in the case of difference the frequency of the signals at the input of the frequency discriminator from the nominal value and including two pulse counters with mutual reset as they accumulate.

The drawing shows the block diagram of the proposed device.

The frequency telegraphy signal with frequencies fb fz,, fn is fed to input 1 of mixer 2. The signal from the controlled local oscillator 3, the frequency of which is lower than the signal frequency, is also fed to the mixer. From the output of the mixer 2, the intermediate frequency signal passes through the amplifier-limiter 4 and is fed to

the keys 5, 6 and the linear discriminator 7. The signal demodulated by the linear discriminator is fed to the threshold circuit 8, which, in turn, controls the keys 5, 6, 9 and 10.

The discriminator 7, the circuit 8 and the keys 5, 6, 9 and 10 are a switchgear with which the signals from the limiter 4 and the reference generator 11 are fed to the inputs of pulse counters 12 and

13 of the digital discriminator 14 at those points in time when the frequency goes in the input signal / s and to the inputs of pulse counters 12 and 13 of the digital discriminator 15 at those moments when the frequency goes / n- Quantity

Digital discriminators are determined by the number of frequencies to be manipulated and the requirement for auto-tuning speed.

reference generator / et - Since the frequency / prp values differ by the separation frequency, and are compared with the same frequency of the reference oscillator, it is necessary to choose the capacitances of the pulse meters U2 and 13 in such a way that equality / prp Dp / et, where / Cn - coefficient of proportionality.

The signal with frequency / when arrives at the counter 13, and the signal with frequency / et - at the counter 12. Upon filling the counter 13 at its output, a pulse appears, the presence of which indicates that / prn Cn / et, and in THIS The moment the device is reset, which clears the counters / 2 and U5 to the zero state. By filling the counter 12, an impulse appears at its output, indicating that / at - / Cn / et - Device 17 resets the counters 12 and 13 before the counter 13 is filled and there is no impulse on the counter 13.

In this scheme, the frequency of the local oscillator 3 is chosen below the frequency / pA / w where A / C is the maximum frequency deviation of the signal caused by destabilizing factors and the Doppler effect. Therefore, at the moment the device is turned on, when the output voltage of the control voltage shaping circuit 18 is zero, a / prp has changed in the direction of decreasing, when the condition / prp Cp / et is met and the control voltage is generated. Pulses at the output of digital discriminators appear as long as / prn Kp / et, and arrive at the adder 19. The output pulses of the latter blast the waiting relaxation generator of circuit 18. In scheme 18, the pulses of the relaxation generator are formed in the most stable case of the integrating 7 C-circuit to the control voltage and, acting on the control element 20, increase the frequency of the controlled local oscillator until fnpn becomes equal to or less than / (p / etPr / prp 1 / Cn / et pulses from the digital discriminators do not like counter 12 resets before it is filled, and in the circuit 18 the capacitor of the integrating circuit discharges, which causes a decrease in the frequency of the local oscillator 3 (increase / prp) At the output of the digital discriminators 14 and 15 pulses appear again, and / prn tends to Knfai - as a result, the control voltage oscillates around a certain average value, maintaining / prp / cn / et with an accuracy of the adjustment step selected in the device.

Subject invention

A device for automatically adjusting the heterodyne frequency of a frequency telegraphy signal receiver, comprising a frequency discriminator, impulse counters, an adder, a reference oscillator and a control element, characterized in x between the instability of the manipulated frequencies and their separation, the output of the frequency discriminator through the threshold stage with the number of thresholds depending on the basis code, and keys, controlled by the limited intermediate voltage of the receiver and the voltage of the reference oscillator, are connected to the inputs of digital discriminators that generate pulses when the frequency of the signals at the input of the frequency discriminator differs from the nominal value and include two pulse counters with mutual discharge as it accumulates.