SU1247777A1 - Device for measuring phase difference and damping factor of two signals - Google Patents

Abstract

The invention relates to the field of measurement technology. The purpose of the invention is to improve the measurement accuracy. For this purpose, a device containing a high-frequency generator 1, terminals 2 for connecting the measured quadrupole, phase manipulators 3, 6, frequency divider 8, quadratic detector 11, pulse generator 5, intermediate frequency filter 12, synchronous detector 15, filter 17 low frequency, phase modulator 4, inverter 9, phase manipulator 7, adder 10, intermediate frequency amplifier 13, second frequency divider 14, intermediate frequency phase modulator 16 are introduced. The use of a phase modulator 16 allows the information to be transferred from the measured parameters K and (where Kj is the attenuation coefficient; phase shift) to an intermediate frequency. The use of the third phase manipulator makes it possible to eliminate the parasitic amplitude modulation of the SA. By adjusting the phase modulation index of the IF phase modulator u © K.of, it is possible to compensate for the error in setting the phase shift keying index bb 2 eq. which ultimately increases the measurement accuracy. The measurement accuracy of the proposed device is 1-1.7 ° in phase and 0.2-0.3 dB in amplitude in the dynamic range of 50-55 dB, which distinguishes it from the prototype. 1 il. --Str t I (Л С 1ч9 {H а «h

Description

The invention relates to a measurement technique - and can be used to measure the phase difference and attenuation coefficient of two coherent signals, as well as as part of a complex for the removal of AFR antennas.

 The purpose of the invention is to increase the measurement accuracy.

The drawing shows a structural electrical circuit of the device.

The device consists of a high-frequency generator 1, terminals 2 for connecting the measured quadrupole of the first phase handler 3, phase modulator 4, pulse generator 5, second phase handler 6, third phase handler 7, frequency divider 8, inverter 9, adder 10, a quadratic detector 11, an intermediate frequency filter 12, an intermediate frequency (IF) amplifier 13, a second frequency divider 14, a synchronous detector 15, an intermediate frequency phase modulator 16, a low frequency filter 17. , ..

Generator 1 is connected to the terminals for connecting the measured quadrupole, the output of which is through the first 3, second 6 and third 7 phase handlers connected in series, adder 10, quadratic detector 11, intermediate frequency filter 12, intermediate frequency multiplier 13, synchronous detector 15 and filter 17 low frequency (LF) is connected to the output of the device. The pulse generator 5 is connected simultaneously with the phase modulator 4, the frequency divider 8, the frequency divider 14 and the second intermediate frequency phase modulator 16, the output of which is connected to the second input of the synchronous detector 15, and the output of the frequency divider 14 to K with the second input of the second phase modulator 16 intermediate frequency. The output of the first phase modulator 4 is connected to the second input of the first phase switch 3, the frequency divider code 8 to the inputs of the first phase modulator 4, the second phase switch 6 and through the inverter 9 the third phase switch 7, and the second input of the adder 10 connected to the output of the generator 1 high frequency.

The device works as follows.

477772

The signal at ,, generator 1 output can be described as

a (t)), t, (1)

where A: and uJ, / 2Tr-, respectively

oscillator amplitude and frequency 1.

The signal passes through the measured quadrupole, where it receives a phase shift, or K.

f and damping factor10

a (t) (). (2) The signal at the output of the generator 5 pulses is described as

I P: I siniSZ t ,. (3)

 , J, 5 1

where Si, / 2fT is the frequency of the following direct mono. coal generator pulses 5.

Pass the phase modulator 4, to the modulating input of which a rectangular pulse with a frequency of 5iy2lTn SI 2TV, i.e. , the signal at the output of the phase modulator 4, which creates the index phase manipulation ®i1l (b + Dbko0), can be described by the expression

TsintiQ t + ()

4 1 fe;, 5

.

where 0 is the phase shift index.

(four)

equal to t.

The core characterizes the actual trim & , i.e., you can manually

adjust (adjust), which is easily provided in the region of relatively low frequencies.

Then the signal at the output of the first phase shift key, which creates the phase shift keying (9 + A0),

where 0, -2 U0, is the inaccuracy of the installation (usually 5 - 10%) of the phase shift keying index by microwave, can be described by the expression

) A, K,

uf- .z: ,, t.

 1-1,3,51-

); I sinKSi

i 1,3,5 J

xcos {u} t-fif, + (0, + A0,) | f:

+ (

, co. , -, yes J-, - (6 + 11 j; sinK52 ,, (5)

where m is the value characterizing the difference in the transmission coefficients of the first phase manipulator .3 for different phase states.

Actually - the parasitic index

amplitude manipulation accompanying phase (usually m% 0.1)., and

- - 0) 05 (for a known device

t, dk).

The second and third phase manipulators 6 and 7 create phase shift keying indices, respectively (Q + A6) and - (, where 0, |; U © ,, - inaccuracy of installation on microwave 0.

 g

9. |;

 - inaccuracy of the installation on the microwave frequency of 46j, usually 5 - 10 °, and the indices of parasitic amplitude manipulation

Shg

and

 2

t.

The presence of (-) signs in front of and in front of (9 + 10) characterizes the fact that the third microwave frequency manipulator 7 modulating pulse with a frequency j / 2 n is driven through the inverter, unlike the second phase manipulator 6, to the modulating input of which it falls uninverted.

The signal at the output of the third phase manipulator 7 can be described by live. . .

fSi i

Further, the signal described by the expressions, that 4 1, | ..Mtiji - - -., Uiini annoui vralei-

a (t) A (, K | 1+ j Z Sin {i5J t + em (7), is summed with the signal of the gene, rator 1, described by expression (2)

l 00 1-.1in the adder 10

0., „,) gl sinKft tllx

,four. P-.

CI, 5

a- (t) a, (t) + a (t) A, K, {H | i

lsinKa) .. cos. {4t -.- (e.-bV | g: Jsinti5, t -. (, p) x

X Г1 | sinK5i t cJ t + 4 + (0, -b

,, - ii.K K.., - S

x (1 +

..lsinKa, t- f.K -ti5

.2F, 5 r

 -av,) C: d81p 5, e + (, op) x | , t + (0i + ft0Kop) t4, A5 1.

 .five

I n: sinKa t1 () f | sinKSl -45 xsin A, cos4t. (eight)

4 00 1 square squared detector 11 pin ... 4yet

- (0j + u%) El gsinKS tj. (6) squared signal bend (8)

Usually phase manipulators (or (a, (t)), (.Ml +2 | a, (t) b

controlled discrete phase shifters) 50i | a (t) j-cosif,

made on the basis of diode switches, the leters of which depend on the parameters of the control signal, which opens or closes the diode

where H - the phase difference between a (t)

and a / (t).

Then

(pin). Control signals (some 55 .j i + Sj-, tH the second is the change in the amplitude of the control, bi, i, 6 i

pulses can be equalized with the flow Q, Q for the second and third phase

k.k.

| sinKS, t + A Hl of tori, i.e. t and t, then an expression of the form (6) is rewritten as

a (,. k | | sintiS; t

+ (b ,, ch-lvkor) |

G1 isinK2, X

CMDZ J

), t + 4 .. + () J EI, t +

 J, S 1

+ (0, + d0,) x s: 4sinKS t + (0, -v +. 4 kg l. G

 i 5 J

T5

) j sinK.5.

(7)

and provided that a f

 Denote by 40,, jKi

In fact, the second and third phase handles are equivalent to one phase switch that creates the phase shift keying index - (J, with the amplitude shift keying accompanying the phase key, is compensated here.

Further, the signal described by the expressions Mtiji - -. Lungs, uiini annoui vyralei-

Eat (7) is summed with the signal Gene1

,, - ii.K

K -ti5

 -av,) C: d81p 5, e + (, op) I xf: I sin K $ 2, t - (0 ,,.

 .five

45 xsin A, cos4t. (eight)

 i + Sj- lsin bi, i, 6 i

k.k.

| sinKS, t + A H42A4 / iuf- n:} sinLi ", t + (9, + 49 ,,)

f ZI lsinK a, COS (e + de,), 5

.K - 1L5 K - - -. ...

Tsinti, t + (); one

X-1,5,5

sinKnjt - (Qj + u025K6) G1 sinKSjt.

  . (9)

A signal of the form (9) passes filter 12 and is amplified by the GGCH amplifier 13. Filter 12 and the IF amplifier 13 are tuned to the frequency, and the pass band of the latter and after a number of transformations the signal at the output of the IF amplifier 13 has the form L9xx.-b2: cos cos d0., EkB-81Pye, 5

1st-298

a, o (t) a (t) + ag (t).

° 10 - - 9 - Jj K

0 (t) 4A% cos2A0 ,,, a5-TlltQl

sinfl.t- | -, sinA6, cos4,

(ten)

+ cos (iS2, t + V,) 1.

It can be seen that the first term of expression (10) with increasing K decreases by 30 relative to the measuring term cos ((), so if there is an initial damping K in the measuring channel (- 8 dB, it is less than 3Q dB, which corresponds to the accuracy of measuring 35 зы 1, amplitude 0.3 dB. With increasing KX, the measurement accuracy increases. The second term is in any case less than the measuring term by 40-50 dB, which reduces the measurement accuracy in phase to 40 ° by 0.5 °, and in amplitude - 0.1 dB In the lower part of the amplitude dynamic range, the accuracy decreases due to an increase in the influence of noise. ri - 60 dB accuracy of phase 45 is 1,7 ° and 0.3 dB for growth of the amplitude, then deteriorates with increasing.

Taking into account that the reference input of the synchronous detector 15 receives a signal from the phase modulator 16 in the form of successively following (with a frequency Sy21fK r m) quadrature components of the reference signal with a frequency j, the output signal of the low-pass filter 17

rt proportional to quadrature components

50

55

a ,, (t)

at

T, П1). at,

EFFI1

nosti.

Uh

where C is the proportionality coefficient.

0

(five

five

0 5 0 5

0

55

The phase difference H and the attenuation can be measured directly using a signal of the form (10) from the output; amplifier 13; Measurements are made using standard instruments, for example, an F2-16 IF frequency meter and a B7-28 digital meter.

The equality of the 4 Corner 4®e6 is achieved as follows.

Instead of the product, the measuring channel includes a smooth phase shifter and a fixed attenuator in series with it so that the total attenuation of the smooth phase shifter and attenuator is about 30 dB, i.e. db Then the signal at the output 5Т1Ч 13 can be written as

a (t) (cosAS ,, g, -bsinu02, K6 (cos 4 OKOR + sin) xcos-SJ, t- (cos4e, i, Kb-sin 0.5k6) (cosyv op- -sipl © op) xsin t jjrA2K (+ sin D0., 1) (created 0 dr + 3dp0 p) x xsin () + 2sin (4e, j,) sinV jSinft t., (12)

It can be seen that in expression (12) the first term determines the useful signal, and the second term the interference. With a change in H ;, the total vector in amplitude changes as the useful vector shifts in phase by, and the interference changes in amplitude. Change - the phase shift introduced by a sliding coaxial line, you can observe the change in the amplitude of the signal (12). Now, by changing the phase manipulation index of the phase modulator 4, it is achieved by changing the -fx without changing the signal amplitudes (11), which corresponds to the absence of interference, i.e. The equality Л0, op-y02} k6 is established, after the adjustments made, the output of the amplifier 13 is present

1GaVK o82402 cos (5i ,,).

. Thus, using phase modulator 16 allows converting the quadrature components of a measuring signal - (an algebraic form of recording a signal into a complex), which are transmitted at different points in time, into a normal signal (into an exponential form of a complex number), i.e. transfer information about the measured parameters K and H to the intermediate frequency. In this case, the use of the third phase switch eliminates parasitic amplitude modulation m, and by adjusting the IF modulation of the phase modulation of the IF phase modulator, it is possible to compensate for the error in setting the phase shift index, which will increase the measurement accuracy. The measurement accuracy of the proposed device, as can be seen from the analysis of the signal passage, is t -. 1.7 in phase and 0.2 - 0.3 dB in amplitude in the dynamic range 50 - 55 dB. ..

Claims (1)

Invention Formula A device for measuring the phase difference and attenuation coefficient of two signals, comprising a high-frequency generator, a pulse generator, the first and second phase manipulators in series, the first frequency divider connected by input to the pulse generator, and the output connected to the second input of the second phase manipulator , quadratic detector connected to the intermediate frequency filter input, synchronous detector Editor N.Shvyschka Compiled by A.Shubin Tehred I.Veres. Proof.More.Pojo Order 4810 Circulation. 728 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., d. 4/5 Production and printing company, Uzhgorod, Projecto st., 4 a torus whose output is connected to the input, a low-frequency filter, two terminals for connecting the studied quadrupole, one of which is connected to the output of the high-frequency generator, and the other to the input of the first phase manipulator, in order to increase the measurement accuracy , a phase modulator, an inverter, a third phase manipulator, an adder, an intermediate frequency amplifier, a second frequency divider, an intermediate frequency modulator, and the output of the pulse generator are connected to the inputs of the the first and second frequency dividers and the intermediate frequency phase modulator, the output of the first frequency divider is connected to the inputs of the phase modulator and the inverter, the output of which is connected to the input of the third phase switch, the second input of which is connected to the output of the second phase the manipulator and the output - 5 with the input of the adder, the second input of which is connected to the output of the high-frequency generator, the output of the phase modulator is connected to the second input of the first phase manipulator, the output of the accumulator is connected to the input m quadratic detector, the output of the intermediate frequency filter through the intermediate frequency amplifier connected to the input of the synchronous detector and an output of the second frequency divider coupled to a second input of the phase modulation the intermediate frequency of a torus, whose output is connected to a second input of the synchronous detector.