SU66078A1 - Semi Automatic Direction Finder - Google Patents

Description

This invention relates to radio half-compasses with addition of sigpals at an intermediate frequency.

Radio pulp compasses are known, based on the principle of comparing the phases of low frequency, constructed according to the scheme shown in FIG. 1. Here the signal coming from the antenna is converted in the first detector A / D to an intermediate frequency and goes to the adding lamp. The signal going out of the frame is converted in the other first detector to an intermediate frequency, and the last passage through the balanced modulator BM, gives two side frequencies, which also go to the addition lamp.

In the anode circuit of this lamp, a spectrum is thus obtained that corresponds to a normal oscillation modulated by a low-frequency oscillator voltage and having a fundamental frequency equal to the intermediate one.

Phase change e. d. in the frame causes a change in the phase of the side frequencies and, consequently, the phase of the low frequency at the receiver output. Changing the phase of the low frequency gives the deviation of the indicators in the other direction.

The described scheme has some drawbacks.

The main disadvantage is the communication of the antenna and frame channels through the communication elements with the high frequency local oscillator. The connection between the channels causes a fracture of the bearing axis by 3 ° or more.

A second disadvantage is the deviation of the arrow of the heading indicator from noise, which is a consequence of the modulation of the lamp noise by a low frequency in a balanced modulator.

Finally, the third disadvantage of the above scheme is the operation of a balanced modulator with a large range of high-frequency voltages at the input, which does not allow for a good suppression of the carrier frequency in the balanced modulator and, as a result, the heading indicator symmetry.

No. 66078

To eliminate or reduce these drawbacks in the proposed scheme, the balanced modulator works as a high-frequency oscillation oscillator and. sound frequency.

FIG. 2 and 3 two variants of the proposed scheme are shown.

In the embodiment of FIG. 2 oscillations from the frame in the first detector are mixed with two arrivals, from the balanced modulator by the frequencies and F-F, where the F-frequency of the high-frequency local oscillator, F is the frequency of the low-frequency local oscillator.

As a result, the frequencies P -} - F- / and F-F-f are obtained; here f is the frequency of the signal. This is nothing but two side frequencies due to modulation by the frequency F of the intermediate frequency F - f.

From the antenna channel after the first detector, the frequency F - f is obtained, which acts as a carrier for these side frequencies.

If a balanced modulator is inserted between the first antenna detector antenna and the high frequency local oscillator (cf. fng. 3), then the side frequencies are obtained in the antenna channel, and the carrier frequencies are in the frame channel.

The advantages of transferring a balanced modulator from a signal channel are as follows:

1) a balanced modulator, connected according to the stated principle, greatly reduces the connection between the antenna and frame channels;

2) the balanced modulator operates with very small changes in the input voltage, and therefore good carrier frequency suppression is possible;

3) the lack of an extra non-linear element in the channels of the signal makes the course indicators less dependent on noise.

Subject invention

Semi-automatic direction finder using electrical switching of the voltage removed from the frame or antenna using a balanced modulator, superheterodyne-type receiver and indicator, characterized in that the balanced modulator is connected between the local oscillator and the antenna or frame channel transducer.

RigZ