SU1653173A1 - Detector of frequency-modulated signals - Google Patents

Abstract

The invention relates to radio engineering and is intended to detect frequency-separated signal loops with frequency manipulation of cis sub carrier frequencies. The purpose of the invention is to reduce the influence of the Doppler effect. The detector of frequency-manipulated signals contains the first D-flip-flop 1, the first shift register 4, the first adder 6 modulo two, the generator 3 cycles of pulses, the second D flip-flop 2, the second shift register 5, the second adder 7 across module two and linear adder 8. The detector has an amplitude-frequency characteristic of the trapezoidal type, due to which the influence of the Doppler effect is reduced. 2 Il. with s

Description

The invention relates to radio engineering and can be used to detect frequency-spaced signals with frequency shift keying.

 The purpose of the invention is to reduce the influence of the Doppler effect.

Figure 1 shows the structural electrical circuit of the receiver of frequency-manipulated signals with a detector of frequency-manipulated signals; Figure 2 shows stress plots at various points in the detector.

The receiver of frequency-manipulated signals contains a detector of frequency-manipulated signals, including the first and second D-triggers 1 and 2, the generator of 3 clock pulses, the first and second registers 4 and 5 of the shift, the first and second adders

6 and 7 modulo two and linear adder 8, as well as N channel filters 9, N limiting amplifiers 10, N output filters 11, N-input adder 12, limiting amplifier 13 of the group signal, low-pass filter 14, driver 15 telegraph packages.

The device works as follows.

The frequency-spaced signal is fed to the combined inputs of the channel filters 9, by means of which the signals of each diversity path are extracted. From the outputs of the channel filters 9, the signals are fed to the inputs of the N limiting amplifiers 10, where the amplitude signals are normalized, and then the signals are additionally filtered in each channel by the output filters 11. Next, the signals are summed05

ate

oh

one

with

in the N-input adder 12, and the resulting group frequency-separated signal is converted into a discrete form using the amplifier limiter 13 of the group sigpap.

From the output of the limiting amplifier 1 of the group signal, a discrete frequency-diversity signal is fed to the combined signal inputs of the first and second D-flip-flops 1 and 2, which perform the function of frequency converters. The clock inputs of the P-flip-flops 1 and 2 are clocked from the first and second outputs of the generator 3 clock pulses g The frequencies of the clock pulses are such that at the output of the D-flip-flops signals are shifted in frequency relative to each other by an amount equal to Af / 2, where & f - separation between press and release frequencies.

From the outputs of the first and second D-flip-flops 1 and 2, the transformed CHI-streams are fed to two autocorrelators, in which the first and second registers 4 and 5 of the shift perform the function of the delay line, and the first and second adders 6 and 7 of the second and second module two. Each autocorrelator has a triangular amplitude-frequency response. The amplitude-frequency characteristics of the autocorrelators are shifted relative to each other by 90 ° in frequency (Fig „2a, b).

The detected signals from the outputs of adders 6 and 7 modulo two are linearly summed in adder 8. From the output of adder 8, which is the output of the detector of frequency-frequency signals, the signal goes to low-pass filter 14 and then to shaper 1-5 telegraph packages The output of which is the output of the entire device, which includes the frequency-controlled signal detector.

At the output of the linear adder 8, the amplitude-frequency characteristic of the device will have a trapezoidal view (FIG. 2B). From plots (g) ig. 2a-c) it can be seen that the press and release (fn, f0) frequencies are H.I in the middle of the flat part of the amplitude-frequency characteristic. Investigator-

0

five

0

However, reception of frequency-spaced signals by such a device is possible with a frequency detuning of the signal (with the Doppler effect) within 4-.

 four

without reducing noise immunity. The broadband delay line with time v is selected from the condition Ј --2U .I

where D5 is the difference between the press and release frequencies. To obtain the amplitude-frequency characteristic with the required trapezoidal shape, it is necessary that the clock inputs of the D-flip-flops 1 and 2 are respectively equal to

. f,

f

rmula of invention

The detector of frequency-manipulated signals containing connected in series the first D-flip-flop, the first shift register and the first modulo-two adder, connected in series the second D-t trigger, the second shift register and the second adder pg modules two, the outputs of the first and second D- Triggers are also connected according to the other inputs of the first and second modulo adders, and a linear adder, the first and second inputs of which are connected respectively to the outputs of the first and second modulators two, the output of the linear cell The mator is the detector output, and the signal inputs of the first and second D-flip-flops are its input, characterized in that, in order to reduce the influence of the Doppler effect, a clock pulse generator is introduced into it, the pepper and second outputs of which are connected respectively to the clock inputs. the first and second D-flip-flops, and the third output - with clockwise inputs of the first and second shift registers, and the difference in frequency of clock pulses on the first and second outputs of the generator is equal to half the value of the difference in frequency of pressing and pressed .

Claims (1)

Claim A frequency-shifted signal detector comprising a first D-flip-flop connected in series, a first shift register and a first adder modulo two, a second D-t'-flip-flop connected in series, a second shift register and a second adder ps module two, outputs of the first and second D-flip-flops also connected respectively to other inputs of the first and second adders modulo two, and a linear adder, the first and second inputs of which are connected respectively to the outputs of the first and second adders modulo two, the output of linear sums the torus is the detector output, and the signal inputs of the first and second D triggers are its input, characterized in that, in order to reduce the influence of the Doppler effect, a clock pulse generator is introduced into it, the first and second outputs of which are connected respectively to the clock inputs of the first and second D-flip-flops, and the third output with clock inputs of the first and second shift registers, and the frequency difference of the clock pulses at the first and second outputs of the generator is equal to half the magnitude of the difference in the frequencies of pressing and pressing. Fig 7