SU63879A1 - Auto-tuning generator - Google Patents

Description

When solving many radio problems, it is necessary to select one of the frequencies of a complex vibration spectrum. Hitherto known genfators with enthusiasm, cutting filters, etc., do not satisfy this requirement, as they select a fairly wide range of frequencies adjacent to the frequency to be distinguished. The proposed self-tuning oscillator on the oscillation frequency of an external source allows one to isolate almost one frequency without noticeable influence from the side of nearby frequencies, in particular, the side frequencies of the oscillation spectrum with amplitude or frequency modulation.

The essence of the invention is explained in FIG. 1-5 of the attached drawing.

FIG. I shows the electrical circuit of the generator, on which the designations are accepted: L1-generator lamp; L2 - trimmer

lamp; Lz - doubled diode discriminator; LK - Ck - oscillatory circuit; G — clamps to which the synchronizing voltage of the frequency to be extracted is supplied; R, Ri, Rj - resistance.

As can be seen from the diagram, parallel to the oscillatory circuit LK - CK

the generator lamp L1 is connected to the trimmer lamp L3, which is a reactance (C or L). The magnitude of the reactivity of the lamp L2, and hence the generation frequency of the lamp L: generator, is determined by the effective slope S, which in turn is determined by the bias voltage UD on the grid.

The magnitude of the bias voltage Ufl is regulated by the discriminator, which reacts to the difference in the generator frequency U) and the average frequency from. Thus, if l9-11), then at the output of the discriminator a control voltage appears that changes Uo, which in the CBOFO queue changes the reactivity value of the lamp L2 so that dynamic equilibrium is established at H SOC.

The operation of the circuit is illustrated by the vector diagram (Fig. 2). The resistance RI is affected by the sum of two voltages: the voltage of the frequency o of the generator, equal to Uj ШМ, Г,

and the voltage U of the frequency according to which the generator adjusts. Similarly, the resistance R2 will be the voltage U2 - jwM, I (the voltage U2 is taken with a minus sign, since it is in antiphase with respect to Ui). Then, if the mutual induction coefficients are equal to (), the vector diagram will look like that shown in FIG. 2. Moreover, if w если w, the vector U will rotate relative to the vectors Ui and U2.

The voltages, on Ri and Ra, are the image of the TC with the vectors OA and OB and the rectified voltage. Uo will be equal to the difference of rectified voltages obtained at the resistors RI and Rz.

If we assume that w oz, then the vector will rotate relative to the vectors Ui and Uo with the speed AO; ojg - with. At the same time, the relationship between Up and the angle cf f (L) will have the form of a curve shown in FIG. 3

Since the voltage Uo is applied to the reactance lamp, the generator frequency will vary. The function w f (Up) usually has the form of a curve shown in FIG. 4. If, then angle 9 will, for example, increase, which will cause an increase in Uo and, therefore, w This will continue until the frequencies w and 1 ° become equal (synchronous) and in-phase or phase-wise at some angle R.

The slightest violation of the equality of the frequencies ω and WQ will cause an additional change in the angle, p and, therefore, Up and CU. A new dynamic equilibrium will come at a new value of the angle f.

Thus, the peculiarity of the proposed generator is an adjustment with an accuracy of a certain phase angle, whereas in conventional systems the adjustment is carried out to a certain frequency difference.

In this way, the scheme will work in the case of a reasonable choice of adjustment limits, i.e., a must lie within C (Fig. 4), and Up, and Lp, corresponding to angles p and f, not

should be more up

and Un that is quite doable.

In the case of amplitude modulation, the vector and (Fig. 2) can be represented as the sum of three constant-sized vectors: the vectors Uo corresponding to the carrier frequency, and the vectors UQI and Uo2 equal in size and corresponding to the two sidebands (Fig. 5). In this case, the vectors Uoi and Uo2 will rotate relative to the vector Uo in different directions with a speed determined by the modulation frequency -. In sum, these three vectors will give the vector Ub constant in direction, but variable in magnitude.

Due to the presence of a constant RC time (Fig. 1), the ripple of the voltage Up on the grid of the reactance lamp will be substantially smoothed and the instantaneous value of the frequency w generated by the generator will be very small from its average frequency, i.e. it is possible to speak as if about a significant decrease in the modulation depth.

In the case of frequency modulation, the vector and will oscillate around its mean value. In this case, the angle of rotation of vector II will be determined by the depth of modulation, and the frequency of swing will be determined by the frequency of modulation. To reduce the voltage ripple Up on the JIi lamp, a sufficiently large time constant value can also be used here. In this case, just as in the case of amplitude modulation, one can speak of a significant decrease in the coefficient

Dsh

modulation depths equal to

I.) Q

Subject invention

The generator is automatically adjusted to a frequency equal to the frequency of oscillations of the external source, using a reactance lamp and a phase discriminator, characterized in that oscillations of the external source and oscillations of the generator are applied to the discriminator.

FIG. five

- jUp

c r L - gr

- “C-O 4 o

Uf-JlONfJ} CM: J - U-f- I

FIG.