SU1711319A1 - Frequency-modulated signal shaper - Google Patents

Abstract

The invention relates to radio engineering and can be used to form linear-to-modulated (chirp) signals and signals with a non-linear modulation law. The purpose of the invention is to reduce the frequency distortions of the output signal with a linear modulation law and to ensure the fbiration of signals with a nonlinear modulation law. The former contains a sawtooth voltage generator 1, an adder 2, a low-pass filter 3, a tunable oscillator 4, a digital frequency synthesizer (TsSCh) 5, a frequency multiplier 6, a counter 7, a memory block 8, a phase detector 9 and a reference oscillator 10. Summary of the invention is to convert the chirp signal s constant-frequency signal for comparison on the phase detector 9 is used CSCH 5, the output of which is a band-pass filter tuned to the frequency feux 1/3 - 1/2 fnr, where fnr is the frequency of the tunable generator 4. 1 Il.

Description

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The invention relates to radio engineering and can be used to generate linear frequency-modulated signals and signals with a non-linear modulation law.

The purpose of the invention is to reduce the frequency distortion of the output signal with a linear modulation law and to ensure the formation of signals with a non-linear modulation law.

The drawing shows a structural electrical circuit of a frequency-modulated signal generator.

The shaper of frequency-modulated signals contains a sawtooth voltage generator (PSG) 1, adder 2, low pass filter 3, tunable generator (PG) 4, 5 frequency digital synthesizer (CSC), frequency multiplier 6, counter 7, memory block 8, phase detector (PD) 9 and reference generator 10.

Shaper frequency-modulated. These signals work as follows.

The voltage produced by the FPG 1, through the adder 2, causes PG 4 rebuilding. With PG4, the signal arrives at the MSC 5, the output frequency of which is equal to the frequency of the reference oscillator 10 at a given linear law of frequency of the PG 4. Frequency code 8-1 ... 8 -t for controlling CSCH 5 is set using a frequency multiplier b. counter 7 and memory block 8, in the last

f on

given table NI 2K

where

.K is the adder of the CSCH 5 adder; fon is the frequency of the reference oscillator 10; fi - the desired value of the frequency of PG 4 at the time of arrival of the 1st pulse of the signal, mind. 6 frequencies.

In the initial state, the voltage from the output of the FCN 1 is constant, the counter 7 is reset. The frequency of the signal PG 4 is 0K fon

f - About That - i

Nc

. With the beginning of the formation

the linear-frequency modulated signal (chirp) starts changing the voltage of GPN 1 and simultaneously changes the output code of counter 7, because the zeroing potential is removed. The output code of counter 7 is the address code of memory block 8, which sets the code change law frequencies 8-1., 8-gp in time,

Deviation of frequency variation law

from the preset causes a deviation of the output frequency of the CSCh 5 from the frequency of the reference generator 10 and the occurrence of an error signal at the output of the phase detector 9,

which through the filter 3 and the adder 2 adjusts the frequency of PG 4.

CSCH 5 can be performed, for example, on the basis of a multi-level frequency synthesizer, to the input of the reference frequency of which the signal fnr is output from PG 4, and the output instead of a low-pass filter (not shown) uses a band-pass filter tuned to the frequency fDbixi -. Besides

In addition, the bandpass filter can also be tuned to the higher subspectra of the TSSC 5 signal,

eleven

those. Your 2 l fnr ± (- -p-) fnr, where n

1,2,3. .

Claims (1)

The formula of the shaper frequency-modulated signals, containing series-connected generator sawtooth voltage, adder and tunable generator, serially connected reference oscillator, phase detector and low-pass filter, the output of which is connected to another input of the adder, is only due to the fact that, in order to reduce the frequency distortions of the output signal with a linear modulation law, and ensuring the formation of signals with a nonlinear modulation law, a series of connected frequency multipliers, whose input is connected by a reference oscillator, a counter, a memory block and a digitalization frequency synthesizer, an output to connected to another input of the phase detector, The counter zeroing input is connected to another output of the sawtooth generator, the reference frequency input of the digital frequency synthesizer is connected to the output of a tunable generator.