SU1390785A1 - Device for automatic tuning of oscillatory circuit - Google Patents

Abstract

This invention relates to radio engineering and provides for an increase in tuning accuracy. The device contains a high-frequency amplifier 1, tunable oscillatory circuit (NCC) 2, adder 3, amplitude detectors 4, 6, amplifiers 5.7 low-frequency, synchronous detector 8, control element 9, source 10 of low-frequency signal, state from the generator

Description

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11 low frequency oscillations and a frequency divider 12, a generator of 13 side frequency oscillations consisting of a generator 11, quadrature phase shifters (KFW) 14,17, a bipolar switch 15, balanced mixers 16, an adder 18 and an attenuator 19. A high frequency signal (Ud excites NKK 2 with the resonant frequency O) and is simultaneously split in phase by the KFW 1 7 into two components. The signal from the generator 11 of the frequency A is split by the FFC 14 into two components. The result of multiplying the quadrature signals

in the balanced mixers 16, the signals of the difference frequency (s-I) and the total frequency (w + Q) are formed. Depending on the state of the bipolar switch 15, one of these signals passes through the adder 18. To NKK 2 sideband signals (w + z). (a - CU) are low levels compared to the main signal. If the frequency does not match with the resonant frequency oud, the amplitudes of the beats differ. Using blocks 4-9, a signal is generated to control the NCC 2 setting. 2 Il.

one

This invention relates to radio engineering and can be used to automatically tune an oscillating circuit to the frequency of a signal H in receiving and transmitting devices.

The purpose of the invention is to increase the tuning accuracy,

Figure 1 shows the structural and electrical circuit of the device for automatic tuning of the oscillating circuit; 2 shows timing diagrams for the operation of the device.

The automatic tuning device of the oscillating circuit contains a high-frequency amplifier 1, an adjustable oscillating circuit 2, an adder 3, an amplitude detector 4, a low-frequency amplifier 5, an additional amplitude detector 6, an additional low-frequency amplifier 7, a synchronous detector 8, a control element 9, a source 10 a low-frequency signal, implemented, for example, in the form of a generator of 11 low frequency oscillations and a frequency divider 12, and a generator of 13 side frequency oscillations, containing a generator of 11 low frequency oscillations, quadrature phase shifter 14, bipolar switch 15, balanced mixers 16, additional quadrature phase shifter 17, additional adder 18 and attenuator 19

The device works as follows.

The high frequency signal s (Fig. 2a) excites a tunable oscillator circuit 2 with a resonant frequency w and is simultaneously split in phase by an additional quadrature phase shifter 17 into two components, which are then used in balanced mixing. Low-frequency signal generator frequency 11

I (Fig. 26) is split by a quadrature phase shifter 14 into two components, which, after passing through a bipolar switch 15, are used in balanced mixing, B

multiplying the quadrature signals in balanced mixers 16, the signals of the difference () and sum (ω + L) frequencies are formed.

At the output of the additional adder 18, depending on the state of the bipolar switch 15, only the signal of either a difference (co-L) or sum (cJ + S) frequency is obtained. In this case, the state change

bipolar switch 15, leading to a change in the phase relationships between low-frequency signals at the inputs of balanced mixers 16, leads to a change in the frequency at the output of the additional adder 18 and attenuator 19, i.e., at the input of the tunable oscillator circuit 2. The bipolar switch 15 is controlled rectangular voltage

(Fig. 2c) frequency divider 12, as a result of which the output frequency of attenuator 19 is changed to twice the low frequency 2П value without changing its amplitude, the side frequency signal (w + fl) or (w - L) is tuned to tunable oscillatory circuit 2 small in comparison with the main signal, as a result of which beats are formed (FIG. 2d).

When the frequency w with the resonant attenuation of the side frequencies does not coincide, the tuned oscillator circuit 2 becomes different, therefore, the beat amplitudes are different depending on the position of the bipolar switch 15. As a result of amplitude detection at the output of the amplitude detector 4 and low frequency amplifier 5, a low-frequency envelope is detected (Fig. 2d), which is amplitude modulated with the switching frequency of phase alternation, and the modulation rate of the beat voltage increases with increasing detuning frequency t to about / about.

An additional amplitude detector 6 and a low frequency amplifier 7 isolate the voltage of the switching frequency envelope (Fig. 2e), which is further processed by the synchronous detector 8, and its output voltage through the control element 9 (integrating unit, motor) affects the control input of the tunable oscillatory circuit 2. This leads to a decrease in the variance of 0

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nor between the frequencies ω and tu ,, when tuning the tuned oscillatory circuit 2 into resonance. The modulation depth of the beats does not change during the switching process (changing the side frequency), and the voltage at the output of the synchronous detector 8 vanishes.

Claims (1)

Claims; The device automatically adjusts the oscillating circuit, which contains series-connected a high frequency generator, a side-frequency oscillator, the control input of which is connected to a low-frequency signal source, an adder, another input of which is connected to the high-frequency amplifier output, an adjustable oscillating circuit, an amplitude detector, a low-frequency amplifier, and a series-connected synchronous detector ,, input the control of which is connected to the source of the low-frequency signal and the control element, the output of which is connected to the control input of the oscillating circuit, It is understood that, in order to improve accuracy, an additional amplitude detector and an additional low frequency amplifier are connected in series between the output of the low-frequency amplifier and the input of the synchronous detector. FIG. 2