SU1330580A2 - 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 oscillographic phase meter contains a sweep generator 1, comm mutator 2, local oscillator 3, mixer 4, intermediate frequency amplifier 5, keys 6 and 20, delay element 7, drive 8, electron-tube tubes 9 and 13, reference generator 10, voltage, phase shifter 11 90, amplifiers 12 and 14, detectors: amplitude 15, frequency 16, differentiation block 17, unipolar gate (L с 14) LV

Description

18 and match element 19. Compared with the known, the proposed phase meter allows to increase the accuracy and uniqueness of the visual assessment of the main parameters of the detected phase-manipulated signal by suppressing a spurious signal received via the image channel. This is achieved by amplitude and frequency

. one ,

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 improve the measurement accuracy and unambiguity of the visual assessment of the main parameters of the phase-shift keyed signal by eliminating reception on the image channel.

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

The oscillographic phase meter contains a oscillator 1 sweep, switch 2, local oscillator 3, mixer 4, intermediate frequency amplifier 5, key 6, delay element 7, accumulator 8, first cathode ray tube 9, reference voltage generator 10, phase shifter 11 on 90, amplifier 12 , the second electron-beam tube 13, the second amplifier 14, the amplitude detector 15, the frequency. a detector 16, a differentiation unit 17, a unipolar gate 18, a coincidence element 19 and a second key 20.

A scan generator 1 is connected to a horizontal deflecting electrode of a first cathode ray tube 9 and through a series-connected switch 2, a local oscillator 3 a mixer 4, an intermediate frequency amplifier 5, a frequency detector 16, a differentiation unit 17, a unipolar gate 18, a second key element 19, a second switch 20 and a storage unit 8 with a second input of the switch 2, a delay element 7, a control input of the first key 6 and a vertical deflecting

detection of a frequency-transformed signal with combined phase shift and linear frequency modulation followed by comparison of the detection results with each other. In this case, the output voltage of the frequency detector is pre-differentiated in time. 1 il.

the electrode of the first cathode ray tube 9. The device input is connected to the second input of the mixer 4. The output of the second key 20 is additionally connected through the first key 6 to the modulating electrode of the second electron beam tube 13. The output of the intermediate frequency amplifier 5 is additionally

through amplitude detector 15 is connected to the second input of coincidence element 19. The output of the delay element 7 is connected to the second input of the accumulator 8. The output of the generator 10 of the reference voltage is connected via a second deflection electrode through a second amplifier 14, and through 90 ° phase shifter 11 through 90 ° and a first amplifier 12 - with a horizontal deflection electrode of a second CRT 13.

The oscillographic phase meter works as follows.

The set frequency range is viewed using a sweep generator 1, which tunes the frequency of the local oscillator 3. At the same time, the sweep generator 1 generates a horizontal sweep of a cathode ray tube (CRT) 9, which is used as a frequency axis, and its length corresponds to the frequency span of the frequency span. Keys 6 and 20 are in their original state closed.

Accepted Phase Manipulated

I

(FMN) signal

U (t) U., t + Cfi.Ct) + H with,

40

and,, Uc, -Рс amplitude, carrying

frequency and initial phase of the signal;

,; | i (t) is the manipulated cokaval yu, and the phases reflecting the law of phase manipulation,

is fed to the input of the mixer 4, to the other input of which the voltage of the local oscillator 3 is applied is linearly changing} to the frequency

Ujt)

SRG),

and cosCcj t + i g t where Ll | -, Pr amplitude, frequency

Aia

TC

ufn

and the initial phase of the heterodyne voltage

rate of change of the local oscillator frequency, frequency deviation.

At the output of the mixer 4, voltage combinations are generated. The intermediate frequency amplifier 5 selects the intermediate frequency voltage

(t) U, - Cp, (t) VytS,

where Unp | KUcUr -,

K - mixer transfer coefficient, (l) .- intermediate frequency,

. -fnp 4 r-4 c.

This voltage is a frequency-transformed signal with combined phase shift keying and linear frequency modulation (FMK-LFM). The voltage Up (t) from the output of the amplifier 5 intermediate frequency simultaneously arrives at the inputs of the amplitude 15 and frequency 16 detectors.

The amplitude detector 15 extracts the signal envelope that is fed to the first input of the coincidence element 19.

From the output of the frequency detector 16, the video signal, whose shape corresponds to the law of frequency variation of the signal, is fed to the input of differentiation unit 17, the output of which is fed to the input of a single-field p. Ventil 18. The latter transmits only positive pulses.

The output pulse of the valve 18 is supplied to the second input of the coincidence element 19. Since the voltages arriving at the two inputs of the coincidence element 19 occupy the same interval on the time axis, the voltage from the output of the coincidence element 19 goes to the control input of the second

0 key 20, open it. Wherein

the voltage U (t) from the output of the intermediate frequency amplifier 5 through the public key 20 is fed to the input of the accumulator 8, where after accumulation

5 and the threshold level in the accumulator 8 acts on the control input of the electronic switch 2, disconnecting the local oscillator 3 from the sweep generator 1, on the control input of the switch 6, opening it, and on the vertical electrode of the CRT 9, the horizontal electrode of which is connected to the second output generator 1 sweep. From this moment on, the process of the search for 5 PSK signals is terminated.

The accumulation time and the threshold level and Q in the accumulator 8 are chosen such that this level is not exceeded by random interference. In this case, a pulse (frequency mark) is formed on the screen of the CRT 9, whose position on the horizontal scan unambiguously determines the carrier frequency CJ of the received QPSK signal.

For a visual assessment of the magnitude of the phase jumps asp and the multiplicity of phase manipulation m of the received FMK signal, CRT 13 is used with a circular scan, and the circular scan is formed using a reference voltage generator 10, whose frequency is equal to the intermediate frequency Upn of the received QPSK signal (SD SOpr) The voltage of the generator 10 is supplied through the amplifier 14 to the vertical electrode, and through the phase shifter 11 and the amplifier 12 to the horizontal electrode of the CRT 13, to the control electrode of which, through the open key 6, receives a QPSK signal The intermediate frequency from the output of the amplifier 5. Therefore, the voltage of the generator 10 is used to form a circular sweep of the CRT beam 13, and the received FMN signal of the 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.

0

five

0

five

0

five

The number of points determines the multiplicity of phase manipulation n, and the angular distance between them is equal to the magnitude of the phase jumps of the received da-n signal. If the frequencies Ue and CJ are unequal, the correct labels will move around the circumference with the difference frequency.

If the QPSK signal is received in the image channel at the frequency f, then the output of the intermediate frequency amplifier 5 produces a voltage

Unp (t) - And Jf t

 Unpcos

.npt,

where is jnp

the frequency of which varies according to the law of a linear falling saw. This voltage simultaneously arrives at the inputs of the amplitude 15 and frequency 16 detectors. Amplitude detector 15 extracts the signal envelope that enters the first input of coincidence element 19. From the output of the frequency detector 16, the video signal, the shape of which corresponds to the law of frequency variation of the signal, is fed to the input of block 17 differentiated

VIA, the output signal of which is fed to the input of a uni-polar valve 18, which does not let it through. Therefore, the signal does not arrive at the second input of the coincident element 19, the latter does not work, the key 20 does not open, and a false signal is received on the image channel at the frequency

f is suppressed. about

Editor A.Lezhnina Order 3579/48

Compiled by V. Shubin

Tehred V.Kadar Proofreader A.Zimokosov

Circulation 730 Subscription VNIIPI USSR State Committee

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

Production and printing company,. Uzhgorod, st. Design, 4.

In case of detection of the next QPSK signal, the phase meter operates in the same way as described.

Thus, the proposed oscillographic phase meter as compared with the prototype improves the accuracy and uniqueness of a visual assessment of the main parameters of the detected phase-shift signal by suppressing a spurious signal received by the ps in the mirror channel, which is achieved5 (amplitude and frequency detection of the frequency-converted signal with combined phase shift and linear frequency modulation followed by comparison of the detection results between each other. frequency detector apr

pre-differentiated in time.

Claims (1)

Invention Formula 25 Oscillographic phase meter on. auth. St. No. 1247778, characterized in that, in order to improve the measurement accuracy and uniqueness of the visual assessment of the main parameters of the phase-shift keyed signal, a frequency detector, a differentiation unit, a unipolar gate, a coincidence unit, are entered into it, and the second input of the KOTojioro is connected to an amplitude of the detector, and the second key, with the amplitude and frequency detector and the second key inputs being combined and connected to the output of the amplifier 40 daily frequency, and the output of the second key is connected to the input of the first key.