SU62927A1 - Automatic finder - Google Patents

Description

An automatic direction finder with a cathode ray tube as a bearing indicator and the simultaneous use of one non-directional and two directional antennas is known. In such a direction finder, oscillations perceived by the omnidirectional antenna affect the receiver input directly, and oscillations sensed by the omnidirectional antennas affect the input after they are modulated in two separate modulators by 90 ° shifted local oscillator signals.

In the proposed design of the radio direction finder, for the implementation of circular rotation of the light spot of the tube, oscillations obtained from the receiver output are used, and for time stamping are pulses synchronous with the oscillations of the local generator.

Unlike dual-channel systems, this direction finder uses only one gain channel. This channel is a normal receiver, which can be used in the usual way for auditory direction finding using simple switching. In addition, the bearing is unidirectional, without 180 ° uncertainty. This simplifies the direction finder, eliminating the need to introduce additional elements to determine the "side.

FIG. 1 shows an electric circuit -3- direction finder; in fig. 2 (A, B and C) are explanatory diagrams; in FIG. 3 is a view of a screen of a cathode ray tube with light shchim image.

The action of the proposed radio finder is as follows.

Two pairs / -1 and 2-2 (Fig. 1) of the separated directional antennas are equally connected with the lamps L-i and L. The grids of these lamps are subject to high-frequency voltages

ttj and sin 9 sin в and and cos cos c sin w t, where ф is the angle between the plane of one of the antenna pairs and the direction

№ 62927

arrival of the wave. At the same time, the / 7ioo 2 lamps are modulated by the same low-frequency voltages from the sound generator (in this case, heterodyne grids are used), the modulating voltage on the lamp L being out of phase with the voltage on the lamp L by 90 °. The gains of the lamps are thus equal.

Ki - K (1 + m siniCi O and Kg: K (1 + from cos O t)

The current frequency in the circuit AB, equal to the sum of the anode currents of both lamps, is determined by the expression

4b pi sin cf (1 4- / and sin O. t) -j- cos cf (1 -f- tn cos O 2) sin w g "tt (sin ff-cos f) -j- / n (sin tp sin i -f-cosf cs il g) sin ш - “к (sin f -j- cos cp) - | - from cos (il t - cp) sin ш,

where n is the proportionality coefficient. The input to the receiver, in this case the coil, is supplied with voltage from the circuit, which creates a current

Zj Y (sin p -f- cos f) - (- ha cos (O t - cp) sin w t and the voltage from the non-directional antenna creating a current

and matched

 L L (sin p - f cos f) -f / and cos (ut - (p); the total current will be equal to

r Il 2 L (sin f cos cp) -f-L cos (Q.t - cp) -f J sin co Ha the output of the receiver after detection will be allocated to the modulation frequency voltage

"Ij cos (O; -)

where F1 is the phase shift generated in the low frequency path of the receiver. With the help of a phase shifter do and then

  and cos (Oh - cf)

The voltage from the receiver output goes to the cathode ray tube and provides a circular scan.

To do this, for one pair of deflecting plates the voltage is removed from the resistance R, to the other from capacitance C, and

Therefore, the angle made up by a radius - a vector of a light point with a certain line on the screen of the cathode ray tube, for example, vertical, will be equal to

- a arctg () and at 2tc; 4l; "Wed, as used when counting the bearing.

The moment is fixed on the tube screen with the help of a lamp L. A voltage proportional to sinQ is applied to its control grid, and a transformer is connected to the anode circuit, the secondary winding of which is connected in series with the anode circuit of the cathode ray tube. The lamp mode Ls and the parameters of the transformer are selected so that the current i in the primary winding of the transformer takes the form of trapezoidal pulses shown in FIG. 2a Then the current in the secondary winding of the transformer will have the form shown in FIG. 26, and the anodic voltage

/ 2/3 sin 0),

R -

 cathode ray tube - the shape shown in FIG. 2c. The impulses of lowering the anode voltage correspond to an increase in the sensitivity of the tube, i.e. an increase in the spot deviation from the center of the screen. Thus, the image on the tube screen (Fig. 3) will have the shape of a circle with a bright strip N protruding from it and a strip NZ entering into it. The angle φ is directly indicated by the light stripe A on the circular bar, marked in degrees. Note that the bearing is unidirectional, without 180 ° uncertainty.

In the case of receiving modulated oscillations or signals of telegraph stations, the frequency spectrum of the receiver output voltage will include frequencies different from the frequency of the modulating sound generator, and the amplitude of the output voltage will be ivized according to the nature of the received oscillations (modulation or manipulation). In order to eliminate the preemptive action of the components of the output voltage of the receiver with frequencies other than the frequency of the modulating oscillator, a band-pass filter is provided that permits the oscillator frequency and delays other frequencies. If a filter is present, the image will be rippled by a change in the amplitude of the output voltage as a result of the filter passing a modulation signal close to the oscillator frequency. This pulsation of the eyes will be perceived as the transformation of a narrow bright ring into a wider illuminated circle, which, however, will not interfere with the counting of the bearing, since the light bar A will remain. For the reference frame, it is enough to close the key I. Then the signal will come only from a pair of U-1 antennas, which should correspond to the count set using the phase shifter. It is possible to provide an automatic closure: a key once or twice per second (using a relay and a relaxation generator) and then the control image will periodically appear on the screen, which will eliminate the error from inaccurate alignment of the direction finder.

The subject matter of the invention

An automatic direction finder with a cathode ray tube as a bearing indicator with simultaneous use of one omnidirectional and two directional antennas; modulators of a local generator shifted by 90 °, characterized in that for the implementation of circular rotation the light of the spot of the tube is used Receiver outputs, and for time stamping, pulses synchronous with local oscillator oscillations.

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