SU1580569A2 - Device for identifying pulse signals with intrapulse modulation - Google Patents

Abstract

The invention relates to telecommunications and can be used in radio receiving systems for the detection, automatic and visual recognition of signals with combined linear frequency modulation and phase shift manipulation. The object of the invention is to increase the reliability of recognition of signals with combined linear frequency modulation by visual inspection of their main parameters. The goal is achieved by introducing the first amplifier 21, the generator of the reference voltage 20, the phase shifter 23, the second amplifier 22, the additional display unit 24, the additional switch 25, the first frequency multiplier 26, the first frequency divider 27, the adjustable delay unit 28, the multiplier 29, the band pass filter 30, additional frequency detector 18, rectifier 19, second frequency multiplier 31, second frequency divider 32, narrowband filter 33, phase detector 34 and control unit 35. The device selects pulse signals with combined linear frequency modulation among signals with other modulation laws. 3 il.

Description

The invention relates to the field of telecommunications, can be used in radio receiving systems for the detection, automatic and visual recognition of signals with combined linear frequency modulation and phase shift manipulation and is an improvement of the known device by author. St. No. 1515372.

The aim of the invention is to increase the reliability of recognition of signals with combined linear frequency modulation and phase shift manipulation by visual inspection of their basic parameters.

FIG. 1 shows a block diagram of the device} in FIG. 3 - stress plots showing his work.

The device contains a high-frequency amplifier 1, a frequency converter 2, a broadband intermediate-frequency amplifier 3, an amplitude detector 4, a main frequency detector 5, a main differentiating element 6, a coincidence element 7, a drive 8, a threshold element 9, a main delay unit 10, a mixer 11 , intermediate frequency amplifier 12, subtraction unit 13, additional differentiating element 14, main display unit 15, main key 16, additional delay block 17, additional frequency detector 18, rectifier 19, generator 20 reference voltage, the first amplifier 21, built-in amplifier 22, the phase shifter 23, the additional display unit 24, the additional switch 25, the first frequency multiplier 26, the first frequency divider 27, the adjustable delay unit 28, the multiplier 29, the band-pass filter 30, the second multiplier 31 frequencies, a second divider 32 frequencies, a narrowband filter 33, a phase detector 34 and a control unit 35, the main display unit 15 containing a cathode ray tube 35 and a sawtooth voltage generator 37.

The device works as follows.

Received pulse signal with combined linear frequency modulation h phase shift keying

uc (t) uc cos {coct4.,

0Ј t Јtu,

ten

15

20

25

thirty

35

where Uc, cdc,

C) ,, Ј c - amppituda, initial

frequency and duration of the signal respectively

- Af

 --and. -

X 0 t-u

the rate of change of frequency within the pulse;

Ufa - frequency deviation of the signal;

CfK is the manipulated component of the phase of the signal, representing the law of phase manipulation, in

according to the modulating code M (t) (Fig. 3a), moreover, C const at (1c-H) s and may vary in a jump at t and Cc, i.e. on the borders between the elementary premises (, 2, ..., N-1),,

Ј% | the duration and the number of elementary parcels from which the signal is composed of the duration of the SC (Su

NЈ)

through the high frequency amplifier 1 is supplied simultaneously to the Inputs of the main unit 10 delay and frequency converter 2. At the output of the main delay unit 10, a signal appears.

U, (t) Uc (t-T3l) Uacos a c (t-Ј3l) +

+ fty (t-C5l) zHpK +,,

where C is the delay time of the main unit 10 delay,

which arrives at the first entrance

stirrer 11. At the second entrance of the mixer

11, the voltage of the local oscillator included in the 2 frequency converter is applied:

Un (t) Ur-cos (Ug t + Cff),

where Ur, Qr, srg - amplitude, frequency

and the initial phase of the heterodyne voltage. In the frequency converter and the mixer 11, the intra-pulse filling frequency shifts along the frequency axis to the intermediate frequency region

In this case, a broadband usi-3 intermediate frequency oscillates

dispenser

Unp, (t) "Wnp-co8 (OOnpt + t + Cfr + Cfy),

where is un

R

c

 Ms °

k. one

frequency converter transmission gain} intermediate frequency1,

intermediate initial phase.

Simultaneously at the mixer outlet

oscillation appears

«Pr S-SOG Us-Chg

Unpz (t) Unp t- G) cЈ3 «+ (t-Cj,) 2,,

whose frequency

0)

  .)

np + 27j (t-, per lane

  WITH

,)

frequency pass.

Wuxi Intermediate Delay T5, selectable

does not hit lite 12 disguise

so that the frequency transformed signal Unp2 (t) does not fall into the passband of intermediate frequency amplifier 12. The noise and interference voltages, whose carrier frequency does not vary in time, fall into the passband of intermediate frequency amplifier 12. As a result, the output of the broadband amplifier 3 of the intermediate frequency contains oscillations of the signal converted by frequency Unp, (t), and noise and interference, and the output of the amplifier 12 of the intermediate frequency contains only the fluctuations of noise and interference. As a result of the subtract operation, the output of the subtracting unit 13 is compensated for noise and interference. The degree of compensation depends on the value of Ј31 and the more, the smaller the value of s "

Frequency converted signal Upp | (t) FIG. 2a), significantly cleared of noise and interference, from the output of subtraction unit 13 is fed to the inputs of amplitude 4 and main frequency

0

five

0

five

5 detectors. The amplitude detector 4 highlights the envelope of the signal U (Fig. 2B), which is fed to the first input of the coincidence element 1. From the output of the main frequency detector 5, the video signal UU (fig.2g), the shape of which corresponds to the law of frequency variation of the signal (fig.2b), and short opposite-sized pulses correspond to the moments of a jump-like change in the phase of the received signal (fig.2a) the input of the differentiating link 6, the output signal (fig.2d) of which is fed to the second input of the coincidence element 7. At the output of the latter, a signal appears (Fig. 2e), which then enters the drive 8, where it is integrated in order to reduce the number of false alarms. The output voltage of the accumulator 8 acts on the input of the threshold element 9, where it is compared with the threshold level Upop, and at time t, at which it exceeds this level (Fig. 2g), an output signal is generated (Fig. 2h), which is a sign that a pulse signal with an intrapulse modulation is present at the input of the device.

If signals with intrapulse frequency modulation or intrapulse phase modulation are input to the device, then threshold element 9 does not work.

Consequently, the device implements the selection of pulse signals with combined linear frequency modulation and phase shift among signals with other modulation laws.

The output signal of the amplitude detector 4 (Fig. 2b) simultaneously arrives at the input of the additional differentiating element 14, where it is converted into two short wavelength pulses (Fig. 3). Moreover, the positive short pulse is triggered, and the sawtooth generator 37 closes the negative one. The output voltage of the latter (Fig. 2k) is used to form a horizontal scan of the cathode-ray tube 36. As a result, the oscillogram is formed on the screen of the latter in the form of a regular rectangular pulse with short polarized pulses at its top. And the duration of them0

five

0

the pulse is proportional to the duration of the MF of the received pulse signal, the amplitude of the pulse is proportional to the rate of change of frequency y inside the pulse, and the area of the pulse is proportional to the frequency deviation A f & y-Ci received signal.

The number of short opposite-polarity pulses is equal to the number of phase jumps m of the received signal. Between the number of phase jumps tn and the number of elementary connections N there is the following analytic relationship:

N 0V5 (m + 1).

By counting the number of phase jumps m, you can determine the number of elementary parcels N.

By estimating and N, you can determine the duration of the elementary dressing Ce:

-E- ff For an visual assessment of the magnitude of the UCf phase jumps and the multiplicity n of the phase manipulation of the recognizable signal, an additional 30 block of indications, made in the form of an electron of an O-beam tube with a circular scan, is used. Moreover, the circular sweep is formed with the help of a voltage-generating generator 20, the frequency of which is chosen to be approximately equal to the beat frequency (OO0 GJЈ). The voltage of the generator 20 is supplied through the first amplifier 21 to the vertical; electrode, and through the phases o- 4a

swivel 23 on

and the second amplifier 22 - to the horizontal electrode of the additional display unit 24.

The frequency-converted Ipr- (fc) signal (Fig. 2a), significantly cleared of noise and interference, from the output of the subtraction unit 13 simultaneously arrives at the first input of the primary carrier 29 and through the public auxiliary key 25 ya input of the first multiplier 26 frequency jaa eight. At the output of the latter, a voltage is generated.

URp5 (t) U, y coe {8 SOPr t + 87Ј t +

8lfnp,.

Since, SlT- with single phase manipulation,, 47.8 n with double phase manipulation, 8 (f, 0.2f, 4, 6 7.87,107,127,14 - with three phase manipulation, then in the indicated voltage phase manipulation is already absent. The voltage Unp3 (t) is fed to the input of the first frequency divider 27 at eight, the output of which is the voltage

) unp cos (COppt + yta + C | p),,

which is a linear frequency modulated intermediate frequency signal. The voltage Upn.Ct) is fed to the first input of the block 28 of the adjustable delay, the output of which is the voltage

) -Un (t-0-Unp. (T- «) (t -«) a + cfJi, 5

0 $$ 4а

45 jq

l

where c / is the delay time of the adjustable delay block 28, which is fed to the second input of the multiplier 29. At the output of the latter,

beat voltage (Fig. 36)

and & (cos tOst + (V KPj)

where u & - - k2Unp;

k2 is the transfer coefficient of the multipliers%,

 2 s - beat frequency; - in Y - the initial phase

beat,

which is a phase-manipulated signal at the beat frequency. Moreover, the beat frequency is determined by the rate of change of the frequency Y of the signal and the magnitude of the delay 6.

The voltage Ug, (t) is separated by a bandpass filter 30 and is fed to the input of an additional detector 1U. The output of which forms a sequence of short polarized pulses (Fig. 3b), the temporal position of which corresponds to the moments of the phase-changing phase-shifting signal at the frequency beat (fig.Zb). The output of the rectifier 19 is a sequence of positive short pulses.

9158

(Fig. 3d), which is supplied to the modulating electrode of the additional display unit 24 and modulates its electron beam by brightness. By this, an image in the form of several bright points located on a circle is formed on the screen of the additional display unit 24. The number of points determines the multiplicity of n phase manipulation, and the angular distance between them is equal to the magnitude of the phase jumps of the DMS of the received signal.

ten

If these voltages differ from each other in frequency and phase, then a control voltage is generated at the output of phase detector 24. Moreover, the amplitude and polarity of this voltage depend on the degree and direction of the deviation of the beat frequency tog- from the frequency C00 of the reference voltage generator 20. The control voltage with the help of the control unit 35 acts on the block 28 of the adjustable delay, changing the value of the delay Ј

so that equality is fulfilled

Ep inequality of frequencies С0Ј

COg (C30t- COg) The velocity labels move in a circle at the difference frequency.

To obtain a stable waveform on the screen of the additional display unit 24, a phase locked loop system is used, consisting of an adjustable delay block 28 of multiplier 29, band-pass filter 38, second frequency multiplier 31 not eight, second frequency divider 32 by eight, narrowband filter 33, phase detector 34 and control unit 35.

The voltage U ((t) (Fig. 36) from the output of the bandpass filter 30 enters the input of the frequency multiplier 31 by eight, the output of which forms a harmonic voltage (Fig. "3d)

and & (O-Ifc-coeteWjt + eCfu + ecfj)

Uj-c0B (8eOjt-Kfs),

in which phase manipulation is eliminated. The voltage Uj2 (t) is fed to the input to the second frequency divider 32 at the boarder, at the output of which napkin is formed (fig.ze)

ug (t) -Ug-cos (coj t + q),,

 "

allocated by a narrow-band filter 33 and supplied to the first input of the phase detector 34, the second input of which is supplied with a voltage from the output of the generator 20 of the reference voltage

 c ° s (co0t + q 0),

where UQ, G) 0, - amplitude, frequency

and the initial phase of the voltage of the generator 20.

15

GO C00.

0 5

about

five

0

five

0

five

R

The delay time with Зг of the additional delay block 17 is chosen in such a way that the main parameters of the received signal can be visually assessed, the oscillograms are observed on the screens of the display blocks 15 and 24. After this time, the voltage from the output of the additional block 17 of the delay arrives at the reset input of the accumulator 8 and resets its contents to zero. In this case, the keys 16 and 25 are closed, i.e. is returned to its original state, and the device is ready to receive the next signal.

Claims (1)

Invention Formula A device for the recognition of pulse signals with intrapulse modulation according to the author. St. No. 1515372, in order to increase the reliability of recognition of signals with combined linear frequency modulation and phase shift by visual control of their basic parameters, a first amplifier, series-connected reference voltage generator, phase shifter, second amplifier and additional display unit are inserted, serially connected additional key, first frequency multiplier, first frequency divider, adjustable delay unit, multiplier, hollow filter, complementary ny frequency detector and a rectifier connected in series the second frequency multiplier, the second frequency divider, a narrow band filter, a phase detector and a control unit, whose output is connected to the second input of the adjustable delay unit, the output of the reference voltage generator is connected to the second input of the phase detector and the input of the first amplifier, the output of which is connected to the second additional display unit, the third input of which is connected to the output of the rectifier, the output of the block W / Vift) / fntfjl 1 6  U FIG 2 The subtraction is connected to the second input of the multiplier and the first input of the additional key, the second input of which is connected to the output of the threshold unit, and the output of the bandpass filter is connected to the input of the second frequency multiplier. Fig.Z