SU1345133A2 - Oscillographic phase-meter - Google Patents

Abstract

The invention relates to a radio metering technique and can be used in radar and communication where phase shift keyed signals are used. The purpose of the invention is to increase the accuracy and uniqueness of the visual assessment of the main parameters of the received phase-shift keyed signal — achieved by suppressing spurious signals received via the channel and combination channels. For this, an adder 6, a multiplier 8, a delay line 11, phase shifters 16 and 20 per +90 and a mixer 21 are additionally entered into the device. In addition, the device contains a sweep generator 1, a switch 2, a local oscillator 3, a mixer 4, intermediate frequency amplifiers 5 n 22, delay line 7, band-pass filter 9, accumulator 10, CRT 12 and 18, input 13 of the delay line, switch 14, reference voltage generator 15, amplifiers 17 and 19, phase shifter 23 at +90. The proposed device, compared with the prototype, provides increased accuracy and uniqueness of the visual assessment of the main parameters of the received phase-shift keyed signal. 1 il. S W with 4 joint ventures with with 14)

Description

The invention relates to a radio measuring technique and can be used in radiolocation and communication, where phase shift keyed signals are widely used.

The purpose of the invention is to improve the accuracy and unambiguity of the visual assessment of the main parameters of the received phase-shift keyed signal by suppressing spurious signals received on the specular and combinational channels.

The drawing shows a structural diagram of the proposed phase meter.

The phase meter contains a series-connected sweep generator 1, an electronic switch 2, the local oscillator 3, a mixer 4, the second input of which is connected to the phase meter input, the intermediate frequency amplifier 5, the adder 6, the delay line 7, the multiplier 8, the second input of which is connected to the adder output 6, the band-pass filter 9, the accumulator 10, the second input of which is connected to the output of the delay line 11, and the output is connected to the vertical electrode of the cathode-ray tube 12, the horizontal electrode of which is connected to the second output of the generator 1 the rods to the input 13 of the delay line 11, to the control inputs of the electronic switch 2 and the keys 14. To the output of the generator 15 of the reference voltage, the phase shifter 16 is connected in series to +90, the amplifier 17 and the horizontal electrode of the cathode ray tube 18, the vertical electrode of which is connected via an amplifier 19 to the output of the generator 15 of the reference voltage. A phase shifter 20 at + 90 °., A mixer 21, the second input of which is connected to the second output of the local oscillator 3, an intermediate frequency amplifier 22 and a phase switch 26 at + 90 °, are connected in series to the phase meter input. Line 7 delay, multiplier 8 and bandpass filter 9 form an autocorrelator torus.

Phase meter works as follows.

Viewing a given frequency range D. is performed using

sweep generator 1, which periodically with a period of Tf, re-tunes the frequency of the local oscillator according to the sawtooth law 3. Simultaneously, the sweep generator 1 forms a horizontal scan of the CRT-12, which uses

with as the frequency axis. Moreover, its length corresponds to the bandwidth of the frequency range.

Received FSK signal

U (t) UpCos o t + 4 (t) +4 ,, where and ", and, T,

H, (t)

4oN

with

the amplitude, the carrier frequency, the duration and the initial phase of the signal, respectively j, are the manipulated component of the phase, which reflects the law of phase manipulation, with Ч (t) const with KVt (K + 1) ii; may change abruptly at dC for (), i.e. at the boundaries between the elementary parcels (, 2,3, ..., N-1), the duration and the number of elementary parcels from which the signal is made is the duration of N-tJ,

is fed to the first input of the mixer 4 and to the input of the phase shifter 20 to +90, at the output of which a signal is formed

u; (t) U.,) + V90 °,.

The signal Uj, (t) is fed to the first input of the mixer 21. To the second inputs of the mixers 4 and 21, the voltage is applied; heterodynIs on 3 linearly varying frequencies

Up (t) Upcos (u t + l jf t + fp,

T (Tr

where and with.

amplitude, initial frequency and initial phase of a heterodyne voltage, respectively,

rate of change of the local oscillator frequency. At the outputs of mixers 4 and 21, voltage combinations are generated. Amplifiers 5 and 22 of the intermediate frequency are respectively the following voltage

,

, (t) +

1345133

U (t) Upcos u, pt + 1 y t2-Cf (t) + H, p,. 4, (t) L, (t-t3,) - (t).

0 t t s

U2 (t) U, p-c: os np-90 ° j,

where u ,,,

K - mixer transfer coefficient;

u) j, p. - (jj, - intermediate frequency;

pr g s

The voltage UgCt) from the output of the amplifier 22 of the intermediate frequency is fed to the input of the phase shifter 23 to + 90, the output of which forms a voltage

ten

The indicated voltage of the QPSK signal at frequencies and, linear frequency mode, is no longer present. For example, from the output, the bandpass filter goes to the input of the storage device 10 after accumulation and above the level of the impact

the equal input of the electron torus 2, disconnecting the local oscillator 1 sweep, on the input delay, on the control

15 14, opening it, and on the vertex the electrode of the CRT 12, the horizon of which has a lead connected to the inside of the generator of the time sweep 1

, -.

Uj (t) U, p-cos

-4 (t) -90% 904% p U p., Pt -b + t)%. ,

The voltages U (t) and Uj (t) are fed to two inputs of the adder 6, at the output of which voltage is generated

Uj, (t) U (t) + U2 (t) U5. cos tJnpt + + 1), (t) +%,,

where u is 2.

This voltage is fed to the first input of the multiplier 8 and to the input of the delay line 7, the output of which is the voltage

- np (t-t ,,) - H

U4 (t) Ug (t-t3)),

+ lf, (.) -4, (t: - tj,) + f, p,,

where tj, is the delay time of the delay line 7,

which is fed to the second input of the multiplier 8.

At the output, the autocorrelator torus (bandpass filter 9). The following beat voltage is formed:

, (t) U5, t + vp (t) + 4j, 0 t T.

U 1/2;

Kj - transfer coefficient of the multiplier 8;

 beat frequency; 4, W (, ptj- | - irj- initial beat voltage phase;

The indicated voltage is a QPSK signal at the beat frequency and linear frequency modulation is no longer present. The voltage Ug (t) from the output of the bandpass filter 9 enters the input of accumulator 10, where, after accumulating and exceeding the threshold level, it acts on the control input of the electronic switch 2, disconnecting the local oscillator 3 from the sweep generator 1, on the input of the delay line 7, on the control key input

14, opening it, and on the vertical electrode of the CRT 12, the horizontal electrode of which is connected to the second output of the sweep generator 1. From this point on, the search for QPSK signals

is terminated.

If the input of the accumulator 10 receives the OFMS signal t P ,,. (t) 0, ifj, its output tones form the following harmonic oscillations

U, j (t) and cos (2i05t + 24); U6 (t) Us cos (4ujt + 44);

U7 (t) Us cos (8to t + 84 j),, 0 t T,

a, since 2 (t) 0.2 L, 44, (t) 0.47, 84 n (t) 0.8 ", TO does not already have phase manipulation in these oscillations. The width of the spectrum of the second harmonic Afg, the fourth jif and the eighth

Af. is determined by the duration T of the signal (Af Af, ifg 1 / T), while the width of the spectrum of the OPMN signal is determined by the duration of its elementary premises (f 1 / t), i.e. the width of the spectrum of these harmonics was N times smaller than the width of the input signal spectrum:

Ll if.

with

4ft Af,

N

s

2 4

Consequently, when the frequency of the OFMS signal is multiplied by two, four and eight, its spectrum is folded N times. This circumstance makes it possible to detect the OFMS signal, even when its input power of the storage device is less than the noise power.

The accumulation time and threshold level Ufiop in drive 10 is selected so that this level does not exceed random interference.

In this case, a pulse (frequency mark) is formed on the screen of the CRT 12, the position of which on the horizontal scan uniquely determines the carrier frequency of the received QPSK signal.

For a visual assessment of the magnitude of the phase jumps and the multiplicity of phase manipulation of the received QPSK signal, CRT 18 with a circular scan is used. Moreover, the circular sweep is formed using the reference voltage generator 15, the frequency oij, which is chosen equal to the beat frequency w of the received QPSK signal () j). The voltage of the generator 15 goes through the amplifier 19 to the vertical electrode, and through the phase shifter 16 to + 90 ° and the amplifier 17 to the horizontal electrode of the CRT 18, to the control electrode, which through the public key 14, receives a QPSK signal output of the band-pass filter 9. Consequently, the voltage of the generator 15 is used to form a circular sweep of the beam of a CRT 18, and the received FMNS signal at the beat frequency modulates its brightness. On the screen of a CRT 18, an image is formed in the form of several bright points located on a circle. The number of points determines the multiplicity of phase shift, and the angular distance between

ten

15

The next FMN-signal of a phase meter is similar in time.

The operation of the phase meter described above corresponds to the case of receiving the QPSK of the main channel at the frequency of CO.

If the QPSK signal is received in the mirror channel at frequency i), the following voltages are output at the output of amplifiers 5 and 22 of intermediate frequency:

U (t) Unp-cos u) pt- i j, t +% (t) Uj (t) U, p.

 pr +

where w W - Yy - intermediate hour 1

BUT

 t-) iy, t2 + (ty 90,

-np

about t .: t ,,

20

tota.

Voltage U.Ct)

25

from the output of amplifier 22 of the intermediate frequency to the input of the phase shifter 23 at the output of which a voltage is formed

Uz (t) U „pcos w, pt- / J t2 (t) - -Ч„ p + 90% 90 -U, p.), Pt - 30 (t), T,

The voltages U (t) and Uj {t) applied to the inputs of adder 6 are compensated for at its inputs. For this, both ka la are chosen identically. The following is equal to the magnitude of phase jumps permissively, a spurious signal received

Nimaya FMN signal. With the inequality of the frequencies Wj, the intensity labels move in a circle with the difference frequency.

The delay time of the 1-delay line 11 is chosen so that the main parameters of the received QPSK signal can be visually assessed, the oscillograms on the CRT screens 12 and 18 are observed. After this time, the voltage from the output of the delay line 11 is fed to the reset input of the accumulator 10 and resets it to the initial state. In this case, the electronic switch 2 is transferred to its initial state, in which the local oscillator 3 is connected to the output of the sweep generator 1, and the key 14 is closed, i.e. transferred to its original state. From this point on, the review of the specified frequency range Do and the search for QPSK signals continues. In case of detection

45

at mirror frequency u, suppressed

about

If the QPSK signal is received on the first combination channel per frequency l), then the output voltage of the amplifiers and 22 intermediate frequencies includes the following voltages:

U, (t) Upp-cos cJ pt + i j; t -4, (t) + M np

C0s c0 pt4lfy t -4 (t) +

4 np-90 ° J, O t T

Ujt) uop

, .. etc

where to

 WITH

etc

 2i

., intermediate

50

55

frequency; Yg is the rate of change of the second harmonic of the heterode frequency by.

The voltage Uj (t) from the output of the amplifier 22 of the intermediate frequency at the input of the phase shifter 23 to f +90, the output of which forms a voltage

five

For the next QPSK signal, the phase meter operates in the same way.

The operation of the phase meter described above corresponds to the case of receiving a QPSK signal on the main channel at the frequency of CO.

If the QPSK signal is received in the mirror channel at the frequency u), then at the output of amplifiers 5 and 22 are inter-. The following frequencies are allocated to the exact frequency:

U (t) Unp-cos u) pt- i j, t +% (t) Uj (t) U, p.

 pr +

where w W - Yr - intermediate hour - 1

BUT

 t-) iy, t2 + (ty 90,

-np

about t .: t ,,

0

tota.

Voltage U.Ct)

the output of the intermediate frequency amplifier 22 is fed to the input of the phase shifter 23, at the output of which a voltage is generated

Uz (t) U „pcos w, pt- / J t2 (t) - -Ч„ p + 90% 90 -U, p.), Pt - (t), T,

The voltages U (t) and Uj {t) applied to the inputs of the adder 6 are compensated at its output. For this, both channels are selected identically. Therefore, the false signal received

0

five

at the mirror frequency and, is suppressed.

about

If the QPSK signal is received on the first combination channel at frequency l), then the following voltages are output at the output of amplifiers 5 and 22 of intermediate frequency:

U, (t) Upp-cos cJ pt + i j; t -4, (t) + M np,

C0s c0 pt4lfy t -4 (t) +

4 np-90 ° J, O t T

Ujt) uop

, .. etc

where to

 WITH

etc

 2i

., intermediate

0

five

frequency; Yg is the rate of change of the second harmonic frequency of the local oscillator.

The voltage Uj (t) from the output of the intermediate frequency amplifier 22 is fed to the input of the phase shifter 23 to f +90, at the output of which a voltage is formed

U3 (t)

(t) + +, -90490 U np- cos. - -4, (t), 0.,.

The voltages U (t) and UnCt) are fed to the two inputs of the adder 6, the output of which is the voltage

(t} V -coslc t +, (t) + ,,,. 0 ti Tg.

The specified voltage is 15

the first input of the multiplier 8 and the input of the oscillographic phase meter along the line 7 delay, at the output of which aut. St. No. 1247778, it is distinguished by the tension and with the fact that, in order to increase the accuracy and uniqueness of the visibility (t) U., - cosj Wpp (t-tj + Л tj,)

received a phase-shift keyed signal by suppressing false sitals received via specular and combinational channels, (t -%) + is inserted into it,

which is fed to the second input of the multiplier 8. At the output, multiply U (t) Uf-cos (, / t) ,, where U) g V7. voltage frequency

thirty

l 8 the following voltage 25 De ™ is connected in series with the beats: the phase meter input is the first phase shifter

on +90, the second mixer, the second input of which is connected to the second output of the local oscillator, the second amplifier of the intermediate frequency, the second fazobeny.

Since the voltage U (t) connected between the output of the first usi falls into the passband of the intermediate frequency psellor and the key and accumulator inputs, the adder, the second delay line, the multiplier, the second input of which is connected to the output of the adder, and the bandpass filter.

not

a deluge filter 9, and a spurious signal received on the first combination channel at a frequency.

1, serving

Compiled by A.Shubin Editor L.Povkhan Tehred I.Popovich

 Order 4915/44 Edition 730 Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and polygraphic enterprise, Uzhgorod, st. Project, 4

A false signal received on the second combinational channel at frequency W, is also suppressed.

2

Thus, the proposed device in comparison with the known one provides an increase in the accuracy and unambiguity of the visual assessment of the main parameters of the received QPSK signal. This is achieved by suppressing spurious signals received by the mirror and combination channels.

Claims (1)

Invention Formula Proofreader M. Demchik