SU75353A1 - An apparatus for performing frequency modulation - Google Patents

Description

A device is proposed for frequency modulation with the application of a reactance that is connected in parallel to the loop of the downhole generator.

A feature of the device is the use of two parallel-connected jet lamps, in which the equivalent resistance has equal signs and the initial displacements on the control grids are chosen so that (In the absence of modulation, the lamps are locked and the modulating voltage is applied to the control grids two-stroke. This allows an increase in frequency deviations and an increase in frequency stability.

The invention is explained in the schematic diagram of the device shown in the drawing.

The frequency of the generator, in which the lamp is used —a 1, is determined by the circuit LK Ck. Reactive lamps 2 and 3 are connected in parallel to the contour. Negative displacement is applied to the grids of the lam.mp through leakage resistance R, chosen so that the operating point lies at the bend of the lamp's characteristic, and therefore, if the lamp is not modulated. The anode voltage is supplied from an ES battery.

The modulation frequency voltage through the transformer 4 is fed in antiphase to the grids of lamps 2 and 3, with the result that these lamps are alternately unlocked. Lamp 2 is Inductive resistance and, when unlocked, increases the frequency of the loop; Lamp 3 is a capacitance and, therefore, lowers the frequency of the circuit.

Due to the presence of a certain curvilinear part of the characteristic, the jet lamps, in the absence of modulation, are not completely locked, which is permeable by the frequency of the circuit.

This would have caused the frequency to be dependent. for example, from the power mode of the device. But jet lamps are under the same conditions and compensate for the work of one another. When choosing lamps with a sharp cut-off current, the initial torsion is very small.

In practice, the frequency stability of the oscillator modulated by the proposed method Majio differs from the stability of a conventional unmodulated oscillator.

Use as jet lamps - lamps, | Having a characteristic with a sharp cut-off a-nodnogo current, suitable for the case of ma253

frequency hypothesis. When modulating the transmitter frequency, speaking with speech or in all other cases when it is desirable to preserve the shape of the modulating voltage (also in the case of automatic frequency tuning), the lamia have to choose characteristics in a certain way, otherwise the distortion will have to be compensated. In the drawing, the blocking capacitors are indicated Sol.

C. subject of the invention

A device for performing frequency modulation with the use of a reactance connected in parallel to the controller of the master oscillator, characterized in that, in order to increase the frequency of the oscillations and improve the stability of the center frequency, two reactance lamps with equivalent resistances are used as the reactance have equal signs, and the initial displacements on the control grids are chosen so that, in the absence of modulation, the lamps are locked, and the modulating voltage is The flow is fed to the control grids push-pull.