SU777826A1 - Device for automatic tuning of frequency - Google Patents

Description

A video pulse, a key and a high-pass filter are connected to one of the mixer inputs, through a serially connected synchronizer and modulator to a first 30My generator input with linear frequency modulation, through a series connected frequency multiplier, phase detector and gated amplifier, the other of which is connected to synchronizer output - “about the second input of a generator with linear frequency multiplication,. the third input of which is connected via an error signal amplifier to the output of the low-pass filter, and the output to other inputs of the mixer and phase detector, the mixer output and the low-pass filter input are connected in series with a bandpass amplifier, a differentiating circuit, an amplitude detector, a first band pass filter a detector, between other inputs of which a variable frequency divider with a variable division factor, a balanced mixer and a second one are connected in series with the output of the reference crystal oscillator; a band-pass filter, between the output of the reference crystal oscillator and the other input of the balanced mixer, the phase shifter is turned on, and the output of the frequency multiplier is connected to another key input.

The drawing shows an electric circuit of a device for auto tuning a frequency.

The device contains a reference crystal oscillator / connected to a generator with chirp 2 through three circuits, the first of which contains synchronizer 3 connected in series and modulator 4. The second circuit consists of frequency multiplier 5 connected in series, phase detector 6 and gated amplifier 7 controlling the input of which is connected to the output of the synchronizer 3, the third circuit contains a video pulse generator 8 connected in series, a key 9, the second input of which is connected to the output of the frequency multiplier 5, the upper filter That 10, mixer //, band-pass amplifier 12, differentiating circuit 13, amplitude detector 14, band-pass filter / 5, phase detector 16, low-pass filter 17 and signal amplifier Oscillator 18. Moreover, the second input of phase detector 16 is connected through band pass filter 19 with the output of the balanced mixer 20, two inputs of which are connected to the output of the reference generator / through a divider with a variable division factor 21 II phase shifter 22, respectively, and the second input of the mixer // to the output of the generator 2 and the input of the phase detector 6.

The device works as follows.

The chirp signal from generator 1 is fed to the mixer input //. The second input of the mixer // is provided with a reference frequency grid, formed from the signal of the reference generator / in the circuit consisting of key 9, frequency multiplier 5, driver of video pulses S and high pass filter / ft. The converted signal, whose maximum frequency is less than the frequency deviation ( A /) of the original chirp signal t times, (t D /// "," / "- the frequency of the oscillator of the reference oscillator /) is amplified in the band-pass amplifier 12 and, after passing the differentiation circuit 13, necessary for a clear fixation of the coincidence moments Chirp signal and the corresponding reference grid frequency harmonics, is supplied to an amplitude detector 14, which detects the envelope of the transformed signal. A band-pass filter / 5 connected to the T5-INPUT of the amplitude detector 14 provides the selection of the first harmonic of the indicated envelope, the frequency of which is determined by the expression

  D // 2ti / pl, where m „is the duration of the chirp signal.

From the filter / 5, the oscillation frequency f is applied to the phase detector 16, the second input of which receives the reference oscillations formed from the generator signal / with a circuit consisting of a balanced mixer 20, a phase shifter 22, a divider with a variable division factor 21 and a band-pass filter 19 The use of this cei allows you to quickly change the frequency of the reference oscillations F, which is necessary, for example, in the formation of several chirp signals with different frequency deviations by one pathogen.

From the output of the phase detector 16, the error signal is fed through a low-pass filter 17 and an error signal amplifier / 8 to the input of oscillator 2 and compensates for the frequency deviation from the linear law.

Claims (2)

Invention Formula A device for automatic tuning, containing a reference crystal oscillator, the output of which through a serially connected driver of video pulses, a key and a high-pass filter is connected to one} of the mixer inputs, through series-connected synchronizer and modulator - to the first generator input with linear frequency modulation, through series-connected multiplier frequency, phase detector and gated amplifier, another input is connected to the synchronizer output to the second input of the generator with linear frequency modulation, the third input of which is connected to the output through an error signal amplifier low pass filter, and the output with other inputs of the mixer and the phase detector, characterized in that, in order to reduce the residual frequency distortion, between the output of the mixer and the low pass filter, a frequency amplifier, a differentiating circuit, an amplitude detector, a first band filter and additional phase detector, between which another input and the output of the reference crystal oscillator are connected in series with a variable frequency divider, a balanced mixer and a second p vacuum filter, between the output reference quartz oscillator and another balanced mixer input to: the phase shifter is on, and the output of the frequency multiplier is connected to another key input. 1z. Sources of information used in attention during examination: To US Patent No. 3621450, cl. H 03 B 3/04, 1971, 2. Campbell B. D. High-Resolution Radar. Coherent Linear FM Microwave Source. “IEEE Transactions on Aerospace and Electronic Sistems, 1970, No. 1, AES-6, p. 62 (prototype).