RU1809307C - Indication device - Google Patents

Description

a resident 47, the second input of which is connected to the output of the narrow-band filter 42, a phase detector 50 and an indicator 51.

To the output of the narrow-band filter 43, a 90 ° phase shifter 47 and a scaling multiplier 49 are connected, the second input of which is connected to the output of the narrow-band filter 43, and the output is connected to the input of the phase detector 50.

The detector 25 is provided with a first spectral width meter 55 and a third eight frequency multiplier 54 connected in series, a second spectral width meter 56, a comparison unit 57 and a threshold unit 58 connected via a reset input 53 to the output of the delay element 26. In this case, the third frequency multiplier 54 by eight is connected to the intermediate frequency amplifier 9 by means of an information input 52 connected via the first spectral width meter 55 to the input of the comparison unit 40.

Direction finding of the radiation source of the complex signal in the proposed device is carried out by the phase method, which is characterized by a contradiction between the requirements of measurement accuracy and the ambiguity of the angle reading. Indeed, according to the formula (figure 4)

 Dr 2 gu-8ta.

where a is the distance between the antennas (measuring base); - A is the wavelength; A is the angle of arrival of radio waves; the structure is the more sensitive to the angle change, the larger the relative size of the base a / R. However, with increasing CE / A, the value of the angular coordinate decreases at which the phase difference exceeds 2 l, i.e. ambiguity of counting occurs.

In order to increase the accuracy of measurements and to avoid ambiguity in reading the angular coordinate, the proposed device uses two measuring bases di and. At the same time, a smaller base is an accurate, but ambiguous reference scale. Moreover, the second measuring base da is formed electrically by multiplying the phase of harmonic oscillations by half in shape

2cos f sin f

The indicator device operates as follows. The preset frequency range Df is viewed using the search unit 28, which periodically with the period Tn, according to the sawtooth law, tunes the frequencies of the local oscillators 29 and 37. At the same time, the search unit 28 forms a horizontal scan of the cathode ray tube (CRT) 33, which

is used as the frequency axis and corresponds to the span of a given frequency range. Received signals with combined linear frequency modulation and multiple phase shift keying

(LFM-MFMn)

Ui (t) Uc cps Uct + у t2 + pv. (0+ +

U2 (t) UЈ COS ft) ct + riy t2 + p ic (t) + P2, 0 t

where Uc, to s, p 1 p 2 amplitude, initial carrier frequency, initial phases and signal duration; . Afd

at.

Gee

- is the rate of change of frequency within the pulse;

Af 5-frequency deviation;

p ic (t) is the manipulated component phase, which displays the law of phase manipulation in accordance with the modulating code M (t) (Fig. 5a), and (t) const

at k Ge, t (k + 1) r3 and can change abruptly at ge. those. at the borders between elementary premises (, 2, ..., M-1);

r3N - duration and number of elementary premises of which it is composed

a signal of duration g and (t N ge) from the outputs of the receiving antennas 3 and 36 through the broadband amplifiers 4 and 36, respectively, are fed to the first inputs of the mixers 8 and 38. to the second inputs of which

the voltage of the local oscillators 29 and 37 of the ramp frequencies

Uri (t) DM cos (a) rit + lu r t2 + p ri),

Ur2 (t) Ur2 -COS (yr2t + yau r t2 + pa),

where Ur1, Ur2, 0) r1, O) r2, p r1. (p g2 — EMPLITUDES, initial frequencies, and initial phases of the local oscillator stresses;

D f

ym t - rate of change of frequencies ge- I p

terodinov. Moreover, the frequencies (ohm and (О Г2 local oscillators are spaced by twice the intermediate frequency

(O g2-O) g1 2 O) pr

and are chosen symmetrical with respect to the frequency from the main channel

U) c-U)) r2-ft) c L) pr-5

At the outputs of the mixers 8 and 38, combinational frequency voltages are generated. Amplifiers 9 and 39 isolated only the voltage of the intermediate (differential) frequency of 10

Unpi (t) Unpi cos with npt + пУ t2 + (р K (t) - -jryrt2 + pnpi,

t Unp2 (t) Unp2 COS ft) npt - LGU t2 - p tc (t) + jryrt - pnp2,

Where

UnPi 1/2 KiUcUri,

Unp2 1 / 2KlUcUr2,

Ki is the transmission coefficient of the mixers, ft) np (О с- (о r2-ft) с-intermediate frequency;

  gg, p pr2 #.

The voltage Unpi (t) from the output of the intermediate frequency amplifier 9 is fed to the input of the detector 25. At the output of the frequency multiplier 54, a voltage is generated by eight

U3 (t) Unpl cos (8 ft) npt + 8 Yaug t2-8 rr + 8 pnpi), 0 t gy

ugg

in which phase manipulation is already absent.

The width of the spectrum L fe of the eighth harmonic of the signal is determined by the duration m and the signal (A fs 1 / t u), while the width of the spectrum A fc of the received signal is determined by the duration Ge of its elementary transmissions (D fc - 1 / t e), i.e. . the spectrum width of the eighth harmonic of the spectrum is N times smaller than the spectrum width of the input signal

Afc schw

 N

Therefore, when the phase (frequency) of the LFM-MPSM signal is multiplied by eight, its spectrum is compressed N times. This circumstance makes it possible to detect the LFM-MPSK signal even when its power at

0

5

0

5

0

5

0

5

0

the input of the device has less noise and interference power.

. The spectral width A fc of the input signal is measured using a meter 55, the spectral width A fs of the eighth harmonic of the signal is measured using a meter 56. The voltages U and Us are proportional to A fc and A fs, respectively, from the outputs of the meters 55 and 56 of the spectrum width arrive at two inputs of comparing unit 57. Since U Us, a positive pulse is generated at the output of the comparison unit 57, which is fed to the input of the threshold unit 58, where it is compared with the threshold voltage Unop. The threshold voltage Unop is selected so that this level does not exceed random interference. The threshold voltage Unop is exceeded only when an LFM-MPSK signal is detected. When the threshold voltage Unop is exceeded, a constant voltage is generated in the threshold block 58, which enters the control input of the search block 28, transfers it to the stop mode, to the input of the delay line 26, to the control inputs of the keys 10 and 27, opening them , and to the vertical-deflecting plates of the CRT 33. From this moment on, viewing the specified frequency range Df and searching for the LFM-MFMn signals stops for the time of visual analysis of the main parameters of the detected LFM-MFMn signal, which is determined by the delay time of the delay line ki 26. Thus on the CRT screen 33 is formed pulse (frequency notch), whose position on the horizontal sweep uniquely determines an initial carrier frequency m MFMn detected chirped signal (fig.Za).

When you stop viewing the specified frequency range Df (when the search unit 28 stops), the amplifiers 9 and 39 of the intermediate frequency are allocated the voltage:

Unp3 (t) Unp1) npt + pu t2 +

+ 9Mt) +,

Unp4 (t) UnP2 cos u) npt-: уЧ2 + (г) 0 t ГИ.

The voltage Unp3 (t) (Fig. 56) from the output of the intermediate frequency amplifier 9 through the public key 10 is fed to the input of the frequency multiplier 11 by eight, the output of which is voltage

Ui (t) Unpi cos (8 ft) npt 8 at t2 + + 8), 0 t gy

which is extracted by the bandpass filter 12 and fed to the input of the frequency divider 13 by eight. At the output of the latter, a voltage is generated (Fig. Bv)

U5 (t) Unpi cos (u) npt + у t2 + + pnpO, 0 t $ ty

which is an LFM signal at an intermediate frequency and is extracted by a bandpass filter 14. This voltage is applied to the input of the frequency detector 5. At the output of which a video pulse is generated (Fig. 5d), the shape of which corresponds to the law of linear frequency modulation. The specified video pulse from the output of the frequency detector 5 is fed to the input of the differentiating circuit 6, the output pulse (Fig. 5e) which is supplied to the vertically-deflecting plates of the CRT 2 and to the input of the differentiating circuit 7. At the output of the differentiating circuit 7, short multipolar pulses are generated (Fig. 5e). Moreover, a positive short pulse is started, and a negative short pulse is closed by the oscillator 1 scan.

The generated sawtooth voltage (Fig. BJ) is used as the scan voltage and is fed to the horizontally deflecting plates of the CRT 2. A pulse is generated on the screen of the CRT2 (fig. Зб.Бд), the duration of which is proportional to the duration t and the received LFM- The MPSF of the signal, the amplitude is proportional to the rate of change of the frequency y inside the pulse, and the area of the waveforms is proportional to the frequency deviation A fg. (D fg Y Ti) of the received LFM-MPSK signal.

To visually assess the main parameters of the received signal, a coordinate-time-frequency grid is applied to the screen of the CRT 2.

The voltage Us (t) (Fig. 5c) from the output of the bandpass filter 14 is simultaneously fed to the input of the adjustable delay element 24, at the output of which a voltage is generated

Ue (t)) UnPi cos unp (t- т)

+ 7Ty (t-rr +

This voltage is applied to the second input of the multiplier 15, the first input of which receives the voltage Unp3 (t) (Fig. 56) from the output of the intermediate frequency amplifier 9. At the output of the multiplier 15, a beating voltage is generated (Fig. Bz)

U6l (t) U6 COS (0 & + p k® + p b 0 t GI,

where 11b 1/2 K2U2nPi

K 2 - transfer coefficient of the multiplier,

yv 2lut- beat frequency.

r o) prT - gut2 - the initial phase of the beats;

which is an FMN signal at a beat frequency. Moreover, the beat frequency is determined by the rate of change of the signal frequency y and the delay value g.

The voltage Ue i (t) is extracted by a band-pass filter 16 and fed to the input of the frequency multiplier 17 by eight, at the output of which a harmonic oscillation is generated

U 62 (t) U b; cos (8 + b), t ty

(Obi

The voltage Ue2 (t) is extracted by a narrow-band bandpass filter 18, and is fed to the input of the frequency divider 19 by eight, at the output of which a voltage is generated (Fig. 5i)

thirty

U63 (tj U6 COS (G) b t +) 6),

This voltage is a harmonic oscillation at the beat frequency, is distinguished by a narrow-band bandpass filter 20, and is fed to the first input of the phase detector 21, the second input of which is supplied with the voltage from the output of the reference voltage generator 32

Uo (t) COS ((00t + р о),

where Uo, (and o, p0 is the amplitude, frequency, and initial phase of the local oscillator voltage.

If the indicated voltage differs from each other in frequency (phase), then a control voltage is generated at the output of the phase detector 21. Moreover, the amplitude and polarity of this voltage depends on the degree and direction of the deviation of the beat frequency s 0, on the frequency (about the generator 32 of the reference voltage. The control voltage is selected by the low-pass filter 22 and using the control driver 23 the signal acts on the element 24 of the controlled delay, changing the delay value r so that the equality

(05 27GuT (Wo

A circular CRT 34 is used to visually assess the magnitude of the phase jumps Dy and the multiplicity m of phase manipulation of the received LFM-MPSK signal. Moreover, the circular scan is generated using the reference voltage generator 32, the frequency Sh0 of which is maintained equal to the beat frequency of the soda ((Oo%) using a phase-locked loop. The voltage U6i (t) (Fig. Bz) from the output of the bandpass filter 16 through the public key 27 arrives at the input of the frequency detector 30, at the output of which a sequence of short different-pulse pulses is formed (Fig. Bq), the temporary position of which corresponds to the moments of the abrupt change in the phase of the signal (Fig. Bz).

The voltage U0 (t) from the output of the reference voltage generator 32 goes directly to the vertically deflecting plates, and through the phase shifter 31 to 90 ° to the horizontally deflecting plates of the EDT 34. forming a circular scan on its screen. The generated sequence of short bipolar pulses (Fig. 5k) from the output of the frequency detector 30 is fed to a CRT modulating electrode 34 and modulates its electron beam in brightness. On the CRT34 screen, an image is formed in the form of several bright points located on a circle (Fig. Sv, d, e). The number of points determines the multiplicity m of the phase shift keying., And the angular distance between them is equal to the value of the phase jump Dy of the received LFM-MPSM signal.

In case of frequency inequality (), the brightness marks will move around the circle with the difference frequency, and the reliability of the visual estimation of the multiplicity m of phase manipulation and the magnitude of the phase jumps D # of the received LFM-MPSM signal decreases sharply. To eliminate this, a phase locked loop system is used.

The voltages Unps (t) and Unp4 (t) from the outputs of the amplifiers 9 and 39 of the intermediate frequency are fed to the two inputs of the multiplier 40, the output of which forms the voltage

U (t) Uy cos (2 с npt + г Др 1.) О S t ги

where U 1/2 K2Unpi UnP2.

2sh Pr O) l-s g1, D # g r g2- (r g1,

  1 is an rg phase shift defining a direction to a radiation source of a complex signal.

The voltage U (t) is distinguished by a narrow-band filter 42 tuned to double. value of the intermediate frequency, and is fed to the input of the phase detector 44.

The voltages Uri (t) and Ur2 (t) of the local oscillators 29 and 37 are fed to two inputs of the multipliers 41, at the output of which a voltage is generated

Ue (t) U8 cos (2 with npt + Д г), rAeU8 1 / 2K2UriUr2.

The voltage Ue (t) is extracted by a narrow-band filter 43, tuned to a double value of the intermediate frequency, and is fed to the second input of the phase detector 44, at the output of which a constant voltage is generated

25

UHi (G) UHI cos where U.1 1/2 Kz U Us,

thirty

C3 is the transfer coefficient of the phase detector;

 (p - pi - 2 p-g - sin a

which are fixed by indicator 45.

The voltage L) 7 (t) and Ue (t) from the outputs of the narrow-band filters 42 and 43 are simultaneously supplied to the inputs of the phase shifters 46 and 47 by 90 ° and to the first inputs of the scaling multipliers 48 and 49, respectively. On the

the outputs of the phase shifters 46 and 47 are formed voltage

Ug (t) U7 sin (2w npt + Du + Aydyj), Uio (t) Us sin (2 a) npt +), 0 t ty

which are fed to the second inputs of the scaling multipliers 48 and 49. At the outputs of the latter, voltages are generated

Un (t) Un sin (4 "onpt +2 + 2afr)

55

Ul2 (t) U12

, 0 t gi

sin (4 to npt + 2),

where 1/2 1/2 K3U27; Ui2 1/2 K3U28; which are fed to the two inputs of the phase detector 50. At the output of the latter, a constant voltage is generated

IM a UH2 cos 2 D 1 UH2 cos

 Ap2.

where H2 1 / 2Kz - Un Ui2.

H9

  2 2 yy-j- sin a, d2 2 di,

which is fixed by indicator 51.

Thus, the proposed device in comparison with the prototype provides direction finding of the radiation source of the received complex signals by the phase method, which is characterized by a contradiction between the requirements of measurement accuracy and the uniqueness of the angle reading. To eliminate this contradiction, the proposed device uses two measuring bases di and dz. Moreover, a smaller base di forms a rough but unambiguous reference scale, and a larger base d2 .- accurate; but an ambiguous reference scale.

di. 1 . d2

- -.

Moreover, the second measuring base d2 is formed electrically by multiplying the phase of harmonic oscillations Uy (t) and L) 8 (t) twice by the formula

2cos F sin F sin 2F

In addition, the proposed device provides an increase in the sensitivity of the device. This is achieved by multiplying the channel voltages Unps (t) and Unp4 (t), as a result of which the spectrum of the received signals is convolved. This circumstance makes it possible to isolate harmonic oscillations UyW b Ue (t) using narrow-band filters 42 and 43 tuned to a double value of the intermediate frequency 2 a) pr, and filter out a significant part of noise and interference, thereby increasing the real sensitivity of the device. Therefore, the proposed device, when detecting the radiation source of complex signals, is invariant to the form of their modulation. Thus, the functionality of the device is expanded.

SUMMARY OF THE INVENTION An indicator device comprising a first antenna in series, a first broadband amplifier, a first mixer, a second input of which is connected through a first local oscillator to a first output of a sawtooth voltage generator, a first intermediate frequency amplifier, a first switch, a second input of which is connected to a detector output , the first frequency multiplier by eight, the first bandpass filter, the first frequency divider by eight, the second bandpass filter, the first frequency detector, the first differentiate circuit, a second differentiating circuit, a sweep generator, and horizontal deflecting plates of a first cathode ray tube, vertical deflecting plates of which are connected to the output of the first differentiating circuit, connected in series to the output of the first

intermediate frequency amplifier, the first multiplier, the second input of which is connected through the controlled delay element to the output of the second bandpass filter, the third bandpass filter, the second multiplier

eight, fourth bandpass filter, second eight divider, fifth bandpass filter, first phase detector, the second input of which is connected to the output of the reference voltage generator, a low-pass filter and a driver of the control signal, the output of which is connected to the second input of the element controlled delay, connected in series to the output of the first intermediate amplifier

frequency detector, the second input of which is connected to the output of the delay element, a sawtooth voltage generator and horizontally-deflecting plates of the second cathode ray tube, vertically-deflecting plates of which are connected to the output of the detector, as well as connected in series to the output of the generator

reference voltage 90 ° phase shifter and horizontal deflection plates

a third cathode ray tube, the vertically deflecting plates of which are connected to the output of the reference voltage generator, and the modulating electrode through the second series connected

the key and the second frequency detector are connected to the output of the third band-pass filter and detector, from which it can be found in that, p. in order to expand the functionality by direction finding a radiation source of a complex signal, a second antenna, a second broadband amplifier, a second mixer, a second intermediate frequency amplifier, a second local oscillator, a second and third multipliers are introduced into it;

the first and second narrow-band filters, the first and second scaling multipliers, the second and third phase shifters by 90 °, the second and third phase detectors, the second broadband are connected in series to the first and second antennas

an amplifier, a second mixer, a second input through a second local oscillator connected to the first output of a sawtooth voltage generator, a second intermediate frequency amplifier, a second multiplier, a second input of which is connected to the output of a first intermediate frequency amplifier, a first narrow-band filter, a second phase detector, a second input which through a series-connected third multiplier and a second narrow-band filter is connected to the second outputs of the first and second local oscillators, and the first indicator, to the output of the first copolosny

0

the second phase shifter 90 ° is connected in series, the first scaling multiplier, the second input of which is connected to the output of the first narrow-band filter, the third phase detector and the second indicator; the third phase shifter 90 ° and the second scaling multiplier, the second input of which is connected to the output of the second narrow-band filter with the output of the second narrow-band filter, and the output is connected to the second input of the third phase detector.

Figure 1

/1

a -1

j

Urip 3ft)

Editor

Tehred M. Morgenthal

Order 1280

VNIIIPI of the State Committee for Inventions and Discoveries under the USSR SCST 113035, Moscow. Zh-35, Rauska embankment. 4/5

pue.5

Proofreader M. Keretsman