SU63512A1 - Superheterodyne telegraph receiver - Google Patents

Description

The contents of the present proposal relate to the reception of unmodulated telegraphy oscillations in suterheterodyne and receivers, in which the N-frequency amplifier of the intermediate frequency is higher than the frequency of the received signal (in particular, relates to multi-band receivers).

The schemes for receiving continuous oscillations are known, in which, for the purpose of economin lamps, one lamp is used, which serves simultaneously as the last stage of the intermediate frequency amplifier and the second local oscillator.

The proposed superheavydine receiver of telegraphing signals using the beat method using one mixing lamp as the last stage of the intermediate frequency amplifier and the second heterodyne is characterized in that the frequency of the secondary heterodyne circuit is approximately twice the frequency of the tuning of the intermediate frequency amplifier of the receiver.

The invention is illustrated in the drawing; in FIG. U, 2, 3 of which shows possible options for the simultaneous use of lamps of three types, and on: 4 - the scheme of the proposed device.

FIG. I shows b-A-8 of the last stage of the amplifier, the n-th day frequency of the receiver, the current part of which includes a heterodyne loop G, feedback LC.

Yo anode circuit of the bandpass filter F is included, consisting of two circuits, the pro nastroenHbix mozhutochnuyu chastr.tu, naked ruzhenn1Y rbychnym stsrsobom on detektaraD second diode, dmeyuSchogo polezn1uyu load / c of ipptivleni kondensatrry C and D at which the voltage is removed | I have rectified the sound frequency.

Usually, in this scheme, the heterodyne circuit G is tuned to a much lower frequency than the bands of the bandpass filter F. In this case, the beating of the oscillations of the intermediate frequency with the corresponding harmonic of the second local oscillator is used to receive continuous signals. The latter is made on the grounds of excluding the possibility of overloading the ARF circuit (automatic sensitivity adjustment) of the receiver and a corresponding decrease in the sensitivity of the latter when receiving telegraph signals.

Some of the considerations for using lamps of the same type in the procession and gaining more amplification on the cascade use the Continuous Oscillation reception circuit shown in FIG. 2. In the anode circuit of the BL-7 lamp in series with the first loop of the bandpass filter F, a loop G of the second local oscillator is connected, which has an LC feedback to the heterodyne grid of this lamp.

Due to the fact that the frequency of the loop G of the local oscillator is very different (harmonics are used for reception) from the frequency of the intermediate frequency loop, the mutual influence of these circuits is an exception. Otherwise, the action of the circuit of FIG. 2 does not differ from that of FIG. one.

The action of the circuit of FIG. 3 is also clear from the drawing.

The disadvantage of these schemes, however, is (when receiving a signal "lower than the frequency tuning frequency of the intermediate frequency amplifier) entering the range of the received WAVES of the main frequency or the second LO, which creates false whistles at the receiver output in the absence of stations.

In order to eliminate this drawback of this kind of circuit, it is proposed to adjust the circuit of the second heterogeneous circuit in the latter to take about twice the frequency of tuning the circuit of the intermediate frequency amplifier of the receiver.

An explanation of the present proposals in relation to the scheme of FIG. 2, is shown in FIG. 4. Let the oscillating voltage of the frequency f signal be applied to the control grid of the lamp 6-L-7.

When the second heterodyne with the frequency fr is switched on, there will be oscillations with the frequencies f, fr, r +. In the anode circuit of the lamp (we neglect the combination beats of higher order).

If the frequency of the second local oscillator is fr 2f4-f, i.e., approximately twice the signal frequency, it is not difficult to see that oscillations with frequencies will exist in the anode circuit of the B-L-7

f, 21+ M, 3f-l- Af, f + Af.

Oscillations with frequencies 2 f + f and 3 f-f Af are filtered by contours F of the bandpass filter; oscillations with frequencies f and f + - | -Af, acting on diode D of the second detector, form beats used to receive an unmodulated telegraphy signal.

Subject invention

Superheterodyne receiver

beat telegraphy signals using one mixing lamp as the last stage of the intermediate frequency amplifier and the second local oscillator, characterized in that the frequency of the second local oscillator circuit is approximately two times higher than the frequency tuning frequency of the intermediate frequency amplifier of the receiver.

Mr.

FIG. one