SU1370594A2 - Oscillographic phase meter - Google Patents

Abstract

The invention relates to a radio measuring technique and can be used in radiolocation and communication. The aim of the invention is to increase the reliability of the visual assessment of the parameters of the received phase-shift keyed signal. This is achieved using the phase-matching system of the intermediate frequency of the received signal, which ensures the formation of a stable waveform on the CRT screen. For this, a second switch 20, a frequency divider 21 by eight, a narrowband filter 22, a phase detector 23 and a control unit 24 are additionally introduced into the device. The device also includes a sweep generator 1, an electronic switch 2, a local oscillator 3, a mixer 4, an intermediate frequency amplifier 5 , key 6, delay line 7, signal processing channels, accumulator 8, CRT 9 and 13, reference voltage generator 10, phase shifter II 90, amplifiers 12 and 14. In addition, the three signal processing channels consist of serially connected frequency multipliers 15.1 by two, 1 5.2 into four, 15.3 into eight, analyzers 16.1, 16.2, 16.3 of the spectrum, blocks 17.1, 17.2, 17.3 comparisons, threshold elements 18.1, 18.2, 18.3, the element OR 19. 2 Il. S S (L

Description

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The invention relates to a radio measuring technique and can be used in radiolocation and communication, where phase manipulation (FM) signals are widely used, for example, single (OFM), double (DFM) and triple (TFM), and is an improvement of the oscillographic phase meter. av.ev, 1247778.

The aim of the invention is to increase the reliability of the visual assessment of the parameters of the received phase-shift keyed signal due to

vertical deviation to the device through the amplifier 14 is connected to the output of the generator 10 of the reference voltage, and the CRT electrode 13, which controls the brightness, through the switch 6 is connected to the output of the intermediate frequency amplifier 5. The key 20, the frequency divider 21 by eight, the narrowband filter 22, the phase detector 23, the second input of which is connected to the output of the reference voltage generator 10, and the control unit are connected in series with the output of the multiplier 15.3 frequency by eight.

nor a stable waveform in the case of IT 24, the output of which is connected to the second one when the frequency of the reference oscillator is not equal to the intermediate frequency.

Figure 1 shows the structural diagram of the oscillographic phase meter; Fig. 2 shows a waveform view on a cathode ray tube (CRT) screen 2o for signals with different phase shift keying.

The phase meter contains a series-connected sweep generator 1, 25 electronic switch 2, local oscillator 3, mixer 4, the second input of which is connected to the input terminal of the phase meter, intermediate frequency amplifier 5, key 6, delay line 7, signal processing channels (drive 8) , cathode ray tube (CRT) 9, reference voltage generator 10, phase shifter 11 by 90 °, amplifier 12, CRT 13, amplifier 14, with three signal processing channels consisting of series-connected multiplier 15.1 frequencies by two (15.2 on four, 15.3 on eight), analysis torus 16.1

the input of the local oscillator 3. The multipliers 15.1,

15.2,15.3, analyzers 16.1, 16.2,

16.3, comparison blocks 17.1, 17.2, 17.3, threshold elements 18.1, 18.2, 18.3 and the element OR 19 form the accumulator 8.

The principle of operation of the phase meter is based on a search in a given frequency range of the phase-manipulated signal and a visual assessment of its main parameters (carrier frequency and), the magnitude of phase jumps с s / and the multiplicity m of phase manipulation) on the screen of two CRTs. In this case, the intermediate-frequency phase-locked loop system of the received FM signal is used to form a stable waveform.

Phase meter works as follows.

Viewing a given frequency range D is carried out using a sweep generator 1, which periodically, with a period T, ramps the frequency of the heterospectrum (16.2, 16.3), block 17.1 craw-4o Dyne 3. Simultaneously, the generator 1 is (17.2, 17.3), the second input of the screwdriver forms a horizontal bit through the analyzer 16 of the fourth channel spectrum is connected to the output of the intermediate frequency amplifier 5, the threshold element 18.1 (18.2,18.3), the second input of which is connected to the output L1SHI 7 of the delay, and the OR 19 element, whose output It is provided with control inputs of keys 6 and 20, an input to a delay line 7, a control input for an electronic switch 2, and an input for vertical deflection of a CRT 9, whose horizontal deflection input is connected to the second output of the sweep generator 1. A phase shifter 11 on 90, an amplifier 12 and a horizontal deflection input CRT 13, an input

24, the output of which is connected to the second

the input of the local oscillator 3. The multipliers 15.1,

15.2,15.3, analyzers 16.1, 16.2,

16.3, comparison blocks 17.1, 17.2, 17.3, threshold elements 18.1, 18.2, 18.3 and the element OR 19 form the accumulator 8.

The principle of operation of the phase meter is based on a search in a given frequency range of the phase-manipulated signal and a visual assessment of its main parameters (carrier frequency and), the magnitude of phase jumps с s / and the multiplicity m of phase manipulation) on the screen of two CRTs. In this case, the intermediate-frequency phase-locked loop system of the received FM signal is used to form a stable waveform.

Phase meter works as follows.

Viewing a given frequency range D is carried out using a sweep generator 1, which periodically, with a period T, ramps the frequency of the hetero 5 according to the sawtooth law

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five

A CRT 9 coil that is used as a frequency axis, and its length corresponds to the frequency span of the frequency range. Keys 6 and 20 in their original state are always closed.

The received FM signal can be represented as

 U (t) U.), T + Lf (t) + u J,

about i t - t,

where lJ, ui (,, Tj., t / is the amplitude, the carrier frequency, the duration and the initial phase of the signal;

(/ (t) is the manipulated component of the phase, representing the law of phase manipulation -

31370594

tion, and (/ Ct)

N

const at Kf it (K + 1) Op and may be varied by a jump d (e at C, i.e., at the boundaries between the elementary premises (, 2,3, .... N);

the duration and the number of elementary parcels from which the signal is composed of duration T (0). This signal is supplied to the first stroke of the mixer 4, and the voltage of the heterodyne 3 is applied to the second input of the coordinator.

Ur (t) U, .cos (u) ,,), de and, u) |., 1 / are the amplitude, frequency, and initial phase of the heterodyne voltage. At the output of the mixer 4, arrays of combination frequencies are formed. with silica gel 5 the voltage of only intermediate frequency is released

(t) U, p-, t + (f (t} + t /, p,

about t. t

20

25

thirty

with

ABOUT

h

10 l with t

15 M in

then in with on shu si to ro / s mo uj co ro pa | 17

Where

and „p I KU, U ,;

K - transfer coefficient

mixer;

i) intermediate frequency; - LP - its initial phase. The voltage U p (t) after accumulation and exceeding the threshold level U, in

Wnp

drive 8 acts on the control input of the electronic switch 2, disconnecting the local oscillator 3 from the sweep generator 1, and on the control inputs. keys 6 and 20, opening them, as well as to the input of the vertical deflection of the CRT 9, the horizontal deflection input of which is connected to the second output of the sweep generator 1. From this point on, the search for FM signals ceases. The drive 8 contains three channels of signal processing.

If a single OFM-signal ij (t) 0, v arrives at the input of accumulator 8, then at the output of multipliers 15.1, 15.2, 15.3 frequencies the following harmonic oscillations are formed, respectively;

U, (t) U, p. C08 (2iz ", + 2h" p);

UjCt) u, (t)

 and

IP

cos (4uVp + 4);

Upp. so8 (8s „p-8s„ p) About t. T. Since 2i (t) 0, 41 / rt) 0,4s

c

8) 0.8, then in the indicated oscillations the phase manipulation is absent. The width of the spectrum of the second harmonic Af, the fourth df and the eighth dfg are determined by

It is the duration of the signal T. (ffj uf 4 ff 1 / T (.), while the width of the spectrum of the OFM signal is determined by the duration of its elementary sprinkling, i.e. the spectrum of the specified harmonics is N times smaller than the width of the spectrum of the input signal

N.

fc

Jf jf fj

Therefore, when the frequency of the OFM signal is multiplied by two, four and eight, its spectrum is folded N times. This makes it possible to detect an OFM signal even when its input power is more than the noise power. The spectral width f, - of the input signal is measured using a spectrum analyzer 16, the spectrum width of the second Af., The fourth i f and the eighth / sfj, the signal harmonics is measured using the spectrum analyzers 16.1, 16.2 and 16.3. The voltages U,, U and Uj, proportional to fj 4 and Afj, respectively, from the outputs of analyzers 16.1, 16.2 and 16.3 of the spectrum are fed to the first inputs of blocks 17.1, | 17.2 and 17.3 comparisons, to the second inputs of which the voltage U is applied spectrum proportional to 4fc. Since U U, and J Uj, and 7, and then, the outputs of blocks 17.1, 17.2 and 17.3 produce positive pulses that exceed the threshold level Uthr in the threshold elements 18.1, 18.2, 18.3 and through the element OR 19 arrive at the output.

If the input of the accumulator 8 receives a signal with double phase shift keying)

° -i

 3,

 - what

at the output of the multiplier 15.1 frequencies, a phase-managed signal V (t) O, T, 2 / f, is produced by two, and at the output of the frequency multipliers by four 15.2 and eight 15.3, harmonic oscillations are generated and U, (t), respectively. in these channels, the input signal is convolved.

If the input of the device receives a signal with a threefold phase manipulator3

l m rtf (t) 0,, A

3 2

In

then the convolution of its spectrum is osutzest

is only at the output of the multiplier 15.3 frequency by eight. In this case, a positive voltage is generated only at the output of the comparison unit 17.3.

The accumulation time and the threshold level of the UPP in the drive 8 are chosen so that this level does not exceed

shawls are random clutter. In this case, a pulse (frequency mark) is formed on the screen of the CRT 9, whose position on the horizontal scan determines the carrier frequency (of the received FM signal (Fig. 2a).

For a visual assessment of the magnitude of the phase jumps l i; and the multiplicity m of the phase manipulation of the received FM signal is used by a CRT 13 with a circular scan. Moreover, the circular scan is formed using the reference voltage generator 10, whose frequency ы is chosen to be approximately equal to the intermediate frequency of the received FM signal. The voltage of the generator 10 is fed through the amplifier 14 to the vertical deflection input, and through the phase shifter 11 to 90 and the amplifier 12 to the horizontal deflection input of the CRT 13, to the CRT electrode 13, which controls the brightness, the public key 6 receives the FM signal Unp (t a) intermediate frequency output from the amplifier 5.

Consequently, the voltage of the generator 1 is used to form a circular scan of the beam of a CRT 13, and the received FM signal of an intermediate frequency modulates its luminance. On the screen of a CRT 13 an image is formed in the form of several bright points located on a circle (Fig. 2b, c, d). The number of points determines the multiplicity of phase manipulation, m, and the angular distance between H1 and mi is equal to the magnitude of the phase jumps l u of the received FM signal. However, in real conditions under the influence of various destabilizing factors, the equality of frequencies and u) p is not observed. If the frequencies are unequal, the velocity labels on the CRT screen 13 move in a circle with the difference frequency and up to

five

ten

15

20

The reliability of the visual assessment of the main parameters of the received FM signal decreases sharply.

To form a stable waveform on the screen of a CRT 13, an intermediate frequency phase locked loop and is used; received signal, consisting of a multiplier 15.3 frequency by eight, a key 20, a divider 21 frequencies by eight, a narrowband filter 22, a phase detector 23 and a control unit 24.

As a control unit 24, there can be a jet lamp, when subjected to a control voltage, the frequency of the local oscillator 3 changes.

The voltage U (t) from the output of the multiplier 15.3 frequency by eight through open the key 20 is fed to the input of the frequency divider 21 by eight, the output of which is the voltage

and.

COS (Unp +

oh, o.t t,

H 4 (t) - „p, h - PR - - - (;

which is provided by the narrowband filter 22 and fed to the first input of the phase detector 23. To the second input of the phase detector 23, the voltage of the generator 10 of the reference voltage is applied. If the indicated voltages differ in phase from each other, then the output voltage of the phase detector 23 is controlled, and the amplitude and polarity of this voltage depend on the degree and direction of the intermediate frequency deviation, UproP u, of the frequency 10 of the reference voltage generator. The control voltage through the control unit 24 acts on the second input of the local oscillator 3, adjusting its frequency so that the frequencies are equal

(10 pr U) (,).

0

five

Time C, the delay of line 7 is chosen so that the main parameters of the received FM 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 is fed to the reset input of the accumulator 8, brings its elements 18,1, 18.2, 18.3 into the initial state. In this case, the electronic switch 2 is brought to its initial state, in which the local oscillator 3 is connected to

the output of the sweep generator 1, and the keys 6 and 20 are closed, i.e. reset. From this moment on, the review of the specified frequency range and the search for the “H-signals” is continued. In the case of detection of the next FM signal, the phase meter operates in a similar way.

Thus, the proposed phase meter as compared with the known one allows to increase the reliability of the visual assessment of the parameters of the received phase-amplified signal. This is achieved by using the phase-locked loop system of the intermediate frequency of the received signal, which ensures the formation of a stable waveform on a CRT screen.

7G

LTD

6 b

FIG. 2

Claims (1)

Invention Formula Oscillographic phase meter on the auth.St. No. 1247778, which is so that, in order to increase the reliability of the visual evaluation of the parameters of the received phase-shifting signal, a second key connected in series, a frequency divider by eight, a narrowband filter, phase detector and control unit, the output of which is connected to the second input of the local oscillator, the first input of the second key is connected to the output of the frequency multiplier eight, and the second input is connected to the output of the OR element, the second input of the phase detector is connected to the output of the reference voltage generator. J / 2 J / 2 (