SU1330581A2 - Oscillographic phase meter - Google Patents

Abstract

The invention relates to a radio measuring technique and can be used in radiolocation and communication where phase shift keyed signals are used. The invention provides an increase in the measurement accuracy and the uniqueness of a visual assessment of the main parameters of the received phase-shift keyed signal by suppressing spurious signals received via the mirror and combination channels. The proposed phase meter contains a sweep generator 1, an electronic switch 2, a local oscillator 3, a mixer 4, intermediate frequency amplifiers 5 and 14, keys 6 and 23, a delay line 7, a drive 8, a CRT 9, a reference voltage generator 10, a phase shifter 11 by 90, amplifier 12, horizontal electrode of a second CRT 13, amplitude detector 20, second and third delay lines 21 and 24, coincidence element 22, multiplier 25 and filter 26. Drive 8, the functional diagram of which is given in the description of the invention, contains three frequency multiplying units, two analyzer spectrum, two blocks of comparison, two threshold elements and the element OR. 3 il. (Li fie.1 N

Description

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

The purpose of the invention is to increase the measurement accuracy and unambiguity of the visual assessment of the main parameters of the received phase-shift keyed signal by suppressing spurious signals received via the mirror and Raman channels.

FIG. 1 shows the structural scheme of the proposed oscillographic phase meter in FIG. 2 is a block diagram of a storage device; FIG. 3 - timing diagrams explaining the principle of suppression of spurious signals.

The oscillographic phase meter contains a sweep generator 1, an electronic switch 2, a local oscillator 3, a mixer .4, an intermediate frequency amplifier 5, a switch 6, a delay line 7.

15

()

electronic switch 2. Additionally, the output of the amplitude detector 20 is connected to the second input element

22 matches, and the output of the second key

23- with the second input of the multiplier 25. The generator 10 of the reference voltage is connected through a sequentially connected phase shifter 11 and an amplifier 12 with a horizontally deflected YEGZ electrode, and through a second amplifier 14 with a vertically deflecting electrode of the CRT 13. The second electrodes of the vertical and horizontal The deflector plates of the cathode ray tubes 9 and 13 are grounded.

The oscillographic phase meter works as follows.

The set frequency range is viewed with the help of the sweep generator 1, which periodically tunes the heterodyne frequency 3. At the same time, the sweep generator 1 forms a horizontal

drive 8, electron beam tube- jg sweep of the electron beam tube

(CRT) 9, which is used as a frequency axis, and its length corresponds to the frequency span of the frequency range.

the reference voltage is a phase shifter 11 by 90, amp 9, generator 10

NIA,

body 12, the horizontal electrode of the second electron beam tube 13, the second amplifier 14, multiplies spruces 15, -15, frequencies, analyzers 16, -16 c, of the spectrum,

blocks 17) -17 comparisons, threshold elements 18, -18, element, amplitude detector 20, second delay line 21, match element 22, second key 23, third delay line 24, multiplier 25 and filter 26. I. ,

: The output of the sweep generator 1 is connected to the corresponding input of the cathode-ray tube 9 and through the series-connected electronic switch 2, the local oscillator 3, the mixer 4, the second input of which is the device input, the intermediate frequency amplifier 5, the amplitude detector 20, 45 4, the second input of which the second delay line 21 is supplied, the element 22 is the voltage of the local oscillator 3 linearly measuring the match, the second key 23, the third delay line 24, the multiplier 25, the filter 26 and the first key 6 is connected to the vertical deflecting electrode 50 th ray tube 13, the second input of the electronic switch 2 is connected to a vertical tube cathode electrode

55

current frequency

yr (t) Ur.-cos (cOrt + TTj.), where Ur, COr, Hr

9, with the control input of the first key 6 and, through the first delay line 7, with the input of the accumulator 8, the second input of which is connected to the input of the filter 26, and the output of the control input

amplitude, initial frequency, and initial phase of the voltage of the gethe homeland;

the rate of change of the local oscillator frequency. At the output of the mixer 4, voltage combinations are generated. Amplifier 5 intermediate frequency output - -5L (Gg t

five

()

electronic switch 2. Additionally, the output of the amplitude detector 20 is connected to the second input element

22 matches and the output of the second key

23- with the second input of the multiplier 25. The reference voltage generator 10 is connected via a sequentially connected phase shifter 11 and an amplifier 12 with a horizontally deflected YGCim electrode, and through a second amplifier 14 with a vertically deflecting electrode of a CRT 13. The second electrodes are vertical and horizontal deflecting CRT tubes 9 and 13 are grounded.

Oscillographic phase meter works as follows.

Viewing a given frequency range is carried out using a sweep generator 1, which periodically tunes the frequency of the local oscillator 3. At the same time, the sweep generator 1 forms a horizontal

scan tube

(CRT) 9, which is used as a frequency axis, and its length corresponds to the frequency span of the frequency range.

Received phase shift keyed signal (FMN) signal

U (t), t + q (t) + q) J,

About 6 .t T

(one)

where Up, с s, T (., | | .- is the amplitude, the carrier frequency, the duration and the initial phase of the signal,

40 H k) a manipulated phase component representing the law of phase manipulation,

enters the first input of the mixer

4, to the second input of which the voltage of the local oscillator 3 is linearly measured

current frequency

yr (t) Ur.-cos (cOrt + TTj.), where Ur, COr, Hr

amplitude, initial frequency, and initial phase of the heterodyne voltage; .

the rate of change of the local oscillator frequency. At the output of the mixer 4, voltage combinations are generated. The amplifier 5 intermediate frequency output - -5L (Gg t

only the intermediate frequency voltage is made

Upp (t) U „pCos.u„ pt-cp (t); ry, t2 + q, J ,, О t T, where and, p. I,.;

The QPSK signal only over the main channel at frequency a (Fig. 3, d). This impulse goes to the control input key of the key 23, opening it. In the initial state, keys 6 and 23 are always closed. The signal Unp (t) from the output of the amplifier 5 intermediate frequency through the public key 23 is received on the input of the multiplier 25 and the input is

"L vidh neiempizhi1elp j and pl slid li

K is the transfer coefficient of the delay Yu-mixture, at the output of which a signal is formed

.-COj. - intermediate frequency,

 -C with. This voltage represents

a frequency-transformed signal with combined linear frequency modulation and phase shift keying (chirp-FMN).

In the process of rebuilding the local oscillator 3, the continuous QPSK signal falls into the ufp bandwidth of the amplifier 5. The intermediate frequency is four times: in the mirror channel at the frequency Co,., In the main channel at the frequency co, in the first combination channel in the frequency, and in the second combination channel in frequency with (Fig. 3). In this case, at the output of the amplitude detector 20 in each period T of the local oscillator 3, 4 pulses are formed (Fig. 36) with the parameters:

Unp, (t) Unp (,). (T-7rj2 4, (,) + iry, (t- rj,) + q, J,

O t T ,,

20

where o-j is the delay time of line 24 of the hold.

Voltage (t) is fed to the input of multiplier 25. Line 24 for the holder, multiplier 25 and band 25 filter 26 form an autocorrelator, at the output of which (filter 26) a beating signal appears

thirty

U / t) - Ug-cos cOjt + tf t + q g,

where j y, beat signal frequency,

ufn- /

Tg.

fa .. t fi. t - -2% i X ". h - Y2 z5

Ug

If,

De T, T,

.Ta

the duration and time interval between the pulses formed when the signal is received in the main and mirror channels;

the duration and time interval between pulses formed when receiving a signal on the first and second combinational channel 1M.

These pulses are fed to the first input of the coincidence element 22 and to the input of the delay line 21, the delay time of which is chosen to be equal to

T

J- ,. . .

The delayed pulses from the output of the delay line 21 (Fig. 3, b) arrive at the second input of the coincidence element 22, at the output of which one pulse is formed, corresponding to the reception

one .

QPSK signal only on the main channel at frequency a (Fig. 3, d). This impulse arrives at the control input of the key 23, opening it. In the initial state, keys 6 and 23 are always closed. In this case, the signal Unp (t) from the output of the amplifier 5 of the intermediate frequency through the public key 23 is fed to the input of multiplier 25 and to the input of livepower n and j

  delays at the output of which a signal is generated

Unp, (t) Unp (,). (T-7rj2 - 4, (,) + iry, (t- rj,) + q, J,

O t T ,,

where o-j is the delay time of line 24 delay.

Voltage (t) is fed to the input of multiplier 25. Line 24 delay, multiplier 25 and band-pass filter 26 form an autocorrelator, the output of which (filter 26) shows a beating signal

U / t) - Ug-cos cOjt + tf t + q g,

gdeso j y, frequency of the beat signal,, - - 2 i.2 - the initial phase of the signal

beat, C ,, (t) q., () -tf, (t).

This signal is a phase-shift keyed signal at the beat frequency; linear frequency modulation is no longer present. The signal u, (t) from the output of the filter 26 is fed to the input of the accumulator 8, where after accumulating and exceeding the threshold level, it affects the control input of the electronic switch 2, disconnecting the local oscillator 3 from the sweep generator 1, the control input of the key 6 , opening it, and on the vertical electrode of the first pair of CRT 9, 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.

The drive 8 can be made in various ways.

The drive shown in FIG. 2 is three channels connected in parallel, connected to

your input. Each of the channels, for example, the first one, contains a sequence of enabled multipliers 15, a spectrum analyzer 16, j, a comparison unit 17 and a threshold element 18 ,. The second inputs of the threshold elements 18 are connected to the second input of the accumulator, and the outputs of the threshold elements, which are the outputs of each channel, are connected to the inputs of the OR element 19, the output of which is the output of the accumulator. The first input of the drive; through an additional analyzer 16, the spectrum is connected to the second inputs of the comparison units, and the multipliers 15 (, 15 and 15z frequencies have multiplication factors, respectively 2,4,8.

If the input signal of the accumulator 8 receives the FMSN signal tf (t) 0, n J, then at the output of each of the multipliers 15 ,, 15 and 15a frequencies harmonic oscillations are formed, respectively:

. U, (t) Ug.cos (2G5gt + 24 p); U (t). -% cos (4ugt + 4cpnp); U3 (t) Uj.cos (8agt + 8Cf p). 0 t t It .T

Since 2.1 (t) 0.21 t:; , (t) 0.4 ii; Burr, (t) 0.8 ir, .to in these oscillations of manipulation, the phases are already absent. The width of the spectrum of the second harmonic Afj, the fourth bf and the eighth ifg is determined by the duration

signal (l f2 4) - whereas the width of the spectrum of the QPSK signal is determined by the duration of its

mental-parcels. (& (.., i.e.

Ln

the width of the spectrum of these harmonics is N times smaller than the width of the spectrum

input signal:

ufc

 ufj

uf

uf

  N.

Consequently, when multiplying the frequency of the QPSK signal by two, four and eight, the spectrum is folded N times. This circumstance makes it possible to detect a QPSK signal even when its input power is less than the noise power. The width of the input spectrum is measured by the analyzer 16, the spectral width of the second f, fourth 0 f5

0

five

0

five

0

That Uf and eighth Uf of the signal harmonics is measured using analyzers I6j, 16J and 1 spectrum, respectively. The voltages U ,, U, U, proportional, YUd and lfo, respectively, from the outputs of analyzers 16, 16 and 16 of the spectrum are fed to the first inputs of blocks 17 ,, 17 ,, and 17 comparisons, to the second inputs of which voltage U c is applied the output of the analyzer 16, the spectrum is proportional to lf. Since UU ,, UU, UU ,, then at the output of blocks 17,, 17. and 17, there are put-gul impulses that exceed the threshold level Upop in the threshold elements 18,, 18.J, and 18j and through the element OR 19 arrive at the exit.

If the input of the accumulator 8 receives a signal with a double phase control, FMN, cf 1, (t) 0, ir / 2, ir, 3/2 ir, then by: Е Ы The output of the multiplier 15 | frequencies by two. A phase-manipulated signal 4i, (t) 0.1 G, 2, AF is generated, and at the outputs of multipliers 15 and frequencies by four and eight, harmonic oscillations Uj (t) and U (t) are formed, i.e. . in these channels, the input signal is convolved.

If the input of the device receives a signal from a three-time phase money / / / t 4, (t) O, -, -, --- T, / -5 / V. 3G 7 convolution

its spectrum is carried out only at the output of the frequency multiplier 15 by eight, while a positive voltage is generated only at the output of the comparator block 17.

The accumulation time and the threshold level in the accumulator 8 are chosen such that this level does not exceed the random interference. At the same time on the screen CRT i

9, a pulse (frequency tag) is formed, whose position 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 Ds and the multiplicity of the phase manipulation of the received QPSK signal, a second CRT 13 with a circular scan is used, with the circular scan being generated using a generator

10 support voltage whose frequency S3d is equal to the beating frequency Ug of the received QPSK signal (and op). The voltage of the generator 10 goes through the black amplifier 14 to the vertical electrode, and through the phase shifter 11 and the amplifier 12 to the horizontal electrode of the second CRT 13, The QDF signal Ug (t) from the output of the band-pass filter 26 is transmitted through the public key 6. Therefore, the voltage of the generator 10 is used to form a circular scan of the CRT beam 13, the a-received QPSK signal at the beat frequency its pk modulation STI. On the screen of a CRT 13, an image is formed in the form of several bright points located on a circle. The number of points determines the multiplicity of phase manipulation m, and the angular distance between them is equal to the magnitude of the phase jumps of the received QPSK signal. With the inequality of the frequencies of sa and oe g krkost-Hbie marks will move around the circumference with a difference frequency.

The time delay of the delay line 7 is chosen so that the main parameters of the received QPSK signal can be visually assessed, the oscillograms on the CRT screens 9 and 13 are observed. After this time has passed, the voltage from the output of the delay line 7 goes to the reset input of the accumulator 8 and resets it elements 18 ,, .182 and 18J in 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 6 is closed. WITH

five

0

five

0

five

At this moment, the viewing of the specified frequency range and the search for FMK signals is stopped. In the case of detection of the next QPSK signal, the phase meter operates as described.

Thus, the proposed oscillographic phase meter provides an increase in the accuracy and uniqueness of the visual assessment of the main parameters of the received QPSK signal, which is achieved by suppressing spurious signals received on the specular and combinational channels. .

Claims (1)

Invention Formula Oscillographic phase meter on the author. St. No. 1247778, characterized in that, in order to increase the accuracy and uniqueness of the visual assessment of the main parameters of the received phase-shift keyed signal by suppressing spurious signals received through the mirror and combinational channels, the amplitude detector is inserted in series between the output of the intermediate frequency amplifier and the key and accumulator inputs. the second delay line, the coincidence element, the second input of which is connected to the output of the amplitude detector, the second key, the second input of which is connected to the output of the intermediate frequency amplifier, a third delay line, a multiplier, the second input of which is connected to the output of the second key, and a band-pass filter. fir.2 a ± (rig.s