SU1417195A2 - Device for identifying pulsed signals with inter-pulse modulation - Google Patents

Abstract

This invention relates to radio. The purpose of the invention is to increase the reliability of recognition. The device contains high frequency 1, transducers 2 and 15 frequency5, wideband amplifiers 3 and 16 intermediate frequency, amplitude detectors 4, and 17, frequency detector 5, differentiating link 6, el-elements 7, P and 18, accumulators 8 and 12, threshold elements 9 and 13, phase shifter 10, recording unit 14 and key 19. The goal is achieved by suppressing interference received via additional (mirror and Raman) channels. In this, the suppression of spurious signals (interference) is achieved by using two reception channels of the LO frequencies which are separated by four values of the intermediate frequency, and the tuning frequencies and bandwidths are selected from the given ratios. 3 il. i (o

Description

four::

i; O

cl

N

Shh. /

eleven

The invention relates to radio, can be used in devices for the detection and automatic recognition of signals with frequency modulation and is additional to auth. No. 1053293.

The aim of the invention is to increase the reliability of recognition by suppressing interference received on additional channels.

Figure 1 shows the structural electrical circuit diagram of the device; Figures 2 and 3 are voltage diagrams explaining the operation of the device.

The device comprises a high-frequency amplifier 1, a main frequency converter 2, an intermediate-frequency main wideband amplifier 3, a main amplitude detector 4, a frequency detector 5, a differentiating element 6, a main coincidence element 7, a drive 8, a threshold element 9, a phase shifter 10, an additional coincidence element 11, accumulator 12, threshold element 13, registration unit 14 additional frequency converter 15 additional intermediate frequency wideband amplifier 16, additional amplitude children 17 Torr, the second mounting parts 18 and key matcher 19.

The device works as follows.

The device receives a signal with linear frequency modulation; whose frequency varies by

the linearly increasing law U (t) (2 "fct + irj t +

+ qi (,), О t T

from 7

where Uj ,, f g, TC, H with amplitude, initial frequency, duration and initial phase of the signal, respectively;

y -

fa T.

- rate of change of the signal frequency;

& fg - frequency deviation After amplification, this signal is fed to the first inputs of mixers (not shown) of frequency converters 2 and 15, to the second inputs of which

52

Voltage of the local oscillators (not shown) respectively

and, (t) (,, t,) J Ur., (t) - (2 irf ,, t 4-Cfr).

The frequency of the local oscillators pa3V-. carried by four intermediate frequency values.

H - G, fnp. ,

The tuning frequency f, and the passband if, of the main wideband amplifier 3 of the intermediate frequency are selected as follows;

20

n, 2 pg l

R

The tuning frequency f, and the passband f, J of the additional broadband amplifier of intermediate frequency 16 are chosen as follows:

2 H-

(if.

fnp.

thirty

In frequency converters 2 and 15, the received signal is converted to signals of the following frequencies:

c, f

Cr W

WITH(

(r1 cr

fc - Jt - f ,,, fnp «yf; fe - yt - - jt;

2fr, - fc - Yt;

2fr, - fc - Jt,

five

0

five

where is 2ff. , 2fp - second harmonics of the local oscillators, the first index indicates the channel through which the signal is received; the second index indicates the number of local oscillators participating in the signal frequency conversion institute; the exponent indicates the second harmonic frequency of the corresponding local oscillator.

However, only these streams at frequencies c, Co fall into the skip bands bf, and U f, j 1

3 amplifiers 3 and 16 of intermediate frequency, detected by amplitude detectors 4 and i and fed to two inputs of the second additional element 18 of coincidence | Second add

The coincident element 18 coincides, its output voltage tioc blunt to the control input of the switch 19, opening it. Key 19 in its original state is always closed.

The frequency-converted pulse (Fig. 2a) from the output of the main wideband amplifier 3 of the intermediate frequency simultaneously arrives at the inputs of the main amplitude and frequency 5 detectors. At the same time, the pulse arrives at the input of the frequency child 5 through the public key 19. The main amplitude detector 4 selects the pulse U envelope (Fig. 2b) with intra-pulse frequency modulation according to the monotonically increasing law (Fig. 2e). From the output of the frequency detector 5, the video signal Uj (Fig. 2d) is fed to the input of the differentiating element 6, the output signal Ug (Fig. 2e) of which is fed to the second inputs of the elements 7 and 11 of the match. The first inputs of elements 7 and II match, the voltage U (fg.2c) comes from the code of the main amplitude detector 4. At the same time, the first additional matching element 11 matches the specified voltage arrives after a preliminary phase inversion of 180 ° in the phase inverter 10 ( figd). Since the voltages U (Fig. 2c) and Ug (Fig. 2e) arriving at the two inputs of the main element 7 coincidence occupy the same interval on the time axis and have the same polarity, the main element 7 coincides. The output voltage U (Fig. 2g) of the main element 7 coincidence enters the drive 8, where it is integrated in order to reduce the number of false alarms due to noise. The output voltage Ug (Fig. 2z) of the accumulator 8 is fed to the input of the threshold element 9, where it is compared with the threshold level. At the instant t the threshold level of the pairs, the threshold element 9 generates a voltage and (fig.2i), which is registered in the block 14 of the registration as a sign of recognition

five

ten

15

20

25

thirty

35

40

45

yala with monotonous growing law; (Intra-Pulse Modulation.

If the signal received on the main channel at the frequency fj. has a monotone-decrement law of intrapulse frequency modulation (Fig, 3a), then the lower threshold level in the threshold element 13 intersects (Fig. 3i). The output voltage U, (fig.Zi) of the threshold element 13 is registered in the registration unit 14. The operation of the remaining units of the device is illustrated in FIG. 3b.

If the signals received on the main channel, at frequency f, have a symmetric JV.-shaped or V-shaped law of intrapulse Frequency Modulation, the device operates analogously. At the same time, the output voltages Ug and the accumulators 8 and I2 arrive at the inputs of the threshold elements 9 and. 1 to 3, where they are compared to two threshold levels, op and -and pop, respectively.

If the upper threshold level + Unop (t) is crossed first and then the lower threshold level -C | op (t), then this indicates that a signal is present at the device input, the frequency of which varies according to the symmetric -L-shape. If the lower threshold level - and (t /) is crossed first, and then the upper threshold level + Uf, op (t), then this is a sign of receiving a signal with a symmetric V-like frequency variation rule.

In the case when signals with intrapulse discrete frequency modulation or intrapulse phase shift manipulation are received at the device input, the threshold levels + U

and -Uflop do not intersect

and

1E

50

55

The device does not work,

The output voltages Uq and U of the threshold elements 9 and 13 are respectively recorded by the registration unit 14.

If a false signal (interferer) is received on the first mirror channel at frequency f, (FIG. 26), then in frequency converters 2 and 15 it is converted into signals of the following frequencies:

J11

“- f. -

However, none of these signals falls into the passband & f, and uf wideband amplifiers TH 3 and 16 of the intermediate frequency. The second additional coincidence element 18 does not trigger and the spurious signal (noise) received on the first mirror channel at the frequency fj is suppressed.

If a false signal (interferer) is received on the second image channel at frequency f, then in frequency converters 2 and 15 it is converted into signals of the next frequency. thats:.

f

g

,;

jt - f, fnp

Of -f Vi n НF

2fr -f. -Yt.

1 bga

However, none of these signals fall into the bandwidths ufI and & f of the wideband amplifiers 3 and 16 of the intermediate frequency. The second additional coincidence element 18 is not triggered and a false signal (interferer), when it is sent over the second mirror channel at the frequency, is suppressed.

If spurious signals (interference) are simultaneously received on the first and second mirror channels; at frequencies f 3 and f5, for a similar reason, they are also suppressed.

If a false signal (interferer) is received over the first combinational channel at frequency fj, then in converters 2 and 15, the frequency is converted into signals of the following frequencies:

f, fK, t - f ,,;

f.i fR, + t - f ,;

, - f ,, f.p- Jt;

 -f, - Jt,

U171956

However, none of these signals fall into the bf bandwidth, and the & fj wideband amplifiers 3 and 16 of the intermediate frequency. The second additional element 18 of the match does not fail, and the false signal (interference) received on the first combination channel at the frequency

CK is suppressed.

For a similar reason, false signals (interference) received via additional (specular and combinational) channels are also suppressed. In this case, the suppression of spurious signals () is achieved using two reception channels, the frequencies of the local oscillators and fp of which are spaced apart by

The values of the intermediate frequency (ff - fr, f no) of the tuning frequency f c ,, c and the passband & f ,, th amplifiers of the intermediate frequency are chosen as follows:

-3. f

by

f I -1- i f

 U l -1

np

& f, (, f 1. formula of invention

50

five

0

five

A device for recognizing pulsed signals with intrapulse modulation according to auth. No. 1053293, due to the fact that, in order to increase the recognition accuracy by suppressing the noise received via additional channels, a key and a serially connected additional frequency converter, an additional wideband intermediate frequency amplifier, an additional amplitude detector and a second additional element of coincidence were introduced the output of the main broadband intermediate frequency amplifier is connected to the input of the frequency detector via a switch, the control input of which is connected to the output ode of the second additional element of coincidence, the second input of which is connected to the output of the main amplitude detector, and output I

a high frequency amplifier is connected to the input of an additional frequency converter.

Unp ({

a

fK

Uf.

and

U.S

tl

(rig 2

Unp (il

i

Uz

f

a

Claims (1)

The claims __ A device for the recognition of pulsed signals with intrapulse modulation by autosw. No. 1053293, characterized in that, in order to increase the reliability of recognition of the signal by suppressing interference received through additional channels, a key and a series-connected additional frequency converter, an additional wide4 _5- band intermediate frequency amplifier, an additional amplitude detector and a second additional elec · The coincidence moment, and the output of the main broadband amplifier of the intermediate frequency 5θ is connected to the input of the frequency detector through a key, the control input of which is connected to the output of the second additional matching element, the second input gg of which is connected to the output of the main amplitude detector, and the output I high-frequency amplifier is connected to the input of an additional frequency converter.