SU1569740A1 - Method of measuring statistical characteristics of fluctuations of signal phase - Google Patents

Abstract

The invention relates to a radio metering technique and can be used to measure the statistical characteristics of signal phase fluctuations. The aim of the invention is to increase the statistical accuracy of measuring the probable characteristics of signal phase fluctuations. The method is based on the multiplication of phase shifts between signals, when they are subjected to a time compression - compression. The device implementing the method contains modulators 1 and 2, generators 3 and 4 signals with linear frequency modulation, dispersion lines 5 and 6 delays, demodulators 7 and 8, phase shifter 9, multipliers 10 and 11, integrators 12 and 13 and recorders 14 and 15. The use of temporal compression of signals in this method increases the statistical accuracy of the analysis in comparison with the known method, since the real parameter can reach hundreds and thousands of hours. 3 Il.

Description

SP

OE

with

sl

4b

1

3156

The invention relates to a radio metering technique and can be used to measure the statistical characteristics of signal phase fluctuations.

In the analysis of random processes using a statistical average of the form

Jw

Jvm4w

QCVnO-m, -41). ) eJ-n% lVi (1

 I

called the characteristic function,

where u (t) is a random process (fluctuation of the signal phase)} is the sign of the mathematical expectation;

real parameter of the characteristic function; P (t) probability density

signal phase fluctuations. The transformation of the expression () brings it to the form

e (Vm), {cosVmif (t)) + jmJsinVmcKt) A (Vn) + jB (Vm), (2)

ha

where A (Vm)

and B (Vm) is the real and imaginary part of the characteristic function.

According to the measured estimates of the parts of the characteristic function for various values of the parameter Vm, the probability characteristics of the random phase of the signal are determined.

The aim of the invention is to increase the statistical accuracy by using large values of the real parameter of the characteristic function,

The method is based on the multiplication of phase shifts between signals when they are subjected to temporary compression (compression). When using a dispersive delay line, the temporal compression ratio of the LFM radio pulse to 10 can be obtained. The envelope frequency (in the case of amplitude modulation of the chirp pulse) and, accordingly, the phase shift between the reference and studied signals are multiplied as many times.

A method for measuring the statistical characteristics of phase fluctuations is based on the transmission of chirp radio pulses,

five

0

amplitude-modulated input signals through the dispersion delay lines} and is as follows.

From the studied Uh (t) Uhisin (Jo t-cp) and the reference Ue (t) Umsin (coct-t) signals containing phase fluctuations (f and h at the moments of phase equality, for example, when , they form rectangular radio pulses of duration f equal to the dispersion time t3 of the dispersion delay line used.

Formed square radio pulses are subjected to linear frequency modulation with frequency variation according to the law

. . ai) w, (t) we + t- (t5

0

five

. . ШШ. w / t) yuo + -p (CUt P. We

;),),

(3)

 - initial

(four)

where (jjc is the frequency of the test and reference signals;

instantaneous frequency of chirp radio pulse; (and t - random initial phases

test and reference signals;

TO) - the deviation of the frequency of the chirp radio pulse, the maximum value of which is chosen in accordance with the required value of the real parameter, equal to

4Y

ysh,

 lt

(five)

where Vm is a real parameter;

yi) l is the bandwidth of the working linear portion of the dispersive delay line. The obtained frequency-modulated signals are subjected to amplitude modulation by the test and reference signals and receive modulated signals of the form

0

Urn, (t) u l + sin t4t- 7cosr4t +

+ i / ti Jft.

 (2uTc; JJ

Umj (t) uЈl + sin u ct-ijcos t +

(6)

(-J

It

iOc / JJ

Sh.

(7)

five

/ Ju)

+ T 4

The signals thus generated are passed through the dispersion delay lines, in which, taking into account (3) - (5), the dependences of the delay time on the instantaneous frequency are

t3, (Wi, t) t0- (W3;

J l, - W.

(8) (9)

t3, (, t) te- (Vt3.

The signals obtained at the output of the two dispersive delay lines are detected by selecting the envelopes, and the instantaneous values of these envelopes are determined. Taking into account expressions (8), (9) and (5), as well as fulfilling the condition), it is obtained that the predicted signals are equal to

(t) sinu) (t- Ј-) (Yu)

one

Uj

-fcoj,

(YU

where the coefficient of measurement is not the scale of time.

Thus, after the delay line, a new frequency occurs.

  .ABOUT )

Since it should be considered, taking into account (5) receive

 13)

The oscillations (10) and (11) thus transformed are multiplied with each other; moreover, the reference oscillation (11) is subjected to an additional transformation by rotating its phase by 90 ° and again multiplying it with the oscillation under study (10). The results of the multiplication are averaged and two electric signals are obtained that are proportional to the estimated real and imaginary parts of the characteristic function of the fluctuations of the phase of the signals.

FIG. 1 shows a block diagram of an analyzer that implements the proposed method; in fig. 2 is a signal generator circuit with linear frequency modulation; on fig.Z - timing charts of the analyzer.

The analyzer contains the first 1 and second 2 modulators, generators 3 and

4 signals with linear frequency modulation (VLFM), dispersion lines

5 and 6 delays, demodulators 7 and 8, phase shifter 9, first 10 and second

11 multipliers, integrators 12 and 13, and recorders 14 and 15.

-

ten

15

20

25

5697406

The inputs of the analyzed and reference signals of the statistical analyzer are the low-frequency inputs of modulators 1 and 2, also connected to the first inputs of the LPGM 3 and 4, the second inputs of which are combined and are the input of the real parameter V, and the outputs are connected to the high-frequency inputs of the modulators 1 and 2, the outputs of which are connected respectively to the inputs of the dispersion lines 5 and 6 delays, the outputs of which are connected respectively to the inputs of the demodulators 7 and 8, the output of the second demodulator 8 is connected to the second input of the second converter knives 11 and through the phase shifter 9 to the second input of the first multiplier 10, and the output of the first demodulator 7 to the first inputs of the multipliers 10 and 11, the outputs of which are connected via integrators 12 and 13 to the inputs of the recorders 14 and 15, respectively.

Modulators 1 and 2 are amplitude modulators and serve for amplitude modulation of chirp pulses and can be performed by any known method. Dispersion delay lines 5 and 6 are delay devices whose delay time depends on the frequency of the signal and is usually made of a piezoelectric material. The comodulators 7 and 8 are amplitude detectors and are designed to pick out the envelope of the amplitude modulated signal.

SLCP 3 and 4 are used to form chirp pulses synchronized by input signals and contain (Fig.2) serially connected driver I6, a linearly varying voltage generator 17 with controlled voltage rise rate, and a frequency-modulated generator 18.

The imaging unit 16 serves to start the generator 17 at the times corresponding to the transition times by the output signals of zero level. The rate of change of the generator voltage is proportional to the desired value of the real parameter. Generator 18 is a voltage to frequency converter.

The analyzer works as follows.

35

50

55

Measurements of the estimates of the characteristic function are performed sequentially with the selected value of the parameter Vm. The values of the parameter V are selected by integers. When the control input is selected, the rate of change of the linearly varying voltage is chosen so that the maximum frequency deviation of the frequency-modulated signal from the HLFC outputs is determined by the expression (5)

In this case, the compression ratio of the signals takes integer values that are proportional to V. Voltages (FIGS. 3a, 2b) with random phases (and applied to amplitude modulators I and 2. At the time when the signals go through the zero level, the LFCF is triggered by time Ј equal to Ut3) so that SLTMs operate with voltages whose instantaneous frequency varies as shown in Fig. 3c, d.

Pulses of duration with linear frequency modulation (fig. 3d, e) are subjected to amplitude modulation in modulators 1 and 2 by input signals so that the voltages (fig.) Described by expressions (6) and (7 ) "Voltages modulated in this manner are applied to the dispersion lines 5 and b of the delay, whose delay time depends on the instantaneous frequency of the signals at their inputs. The voltages from the outputs of the delay lines (Figs. 3i, k) are fed to the inputs of the amplitude detectors 7 and 8, which isolate the voltage envelopes. Then, at the outputs of the amplitude voltage detectors (Fig. Zl, m), which, if provided, are described by expressions (10) and (11). These voltages are multiplied in multiplier 11, and the result of multiplication is integrated in integrator 13, after which the recorder 15 registers the voltage proportional to the estimate of the real part of the characteristic function

 I cosv cr-Odt.

The reference oscillation after the phase rotates by 90 ° in the phase shifter 9 multiplies with the oscillation under study in the multiplier 10, the result of the multiplication is integrated integrato

0

five

0

five

0

five

0

12, and the recorder 14 registers a voltage proportional to the estimate of the imaginary part of the characteristic function

BOU- | J sinVm () dt.

about

Thus, the use of temporal compression of signals in the proposed measurement method makes it possible to increase the statistical accuracy of the analysis of the probabilistic characteristics of the signal phase fluctuations compared to the known one, since the real parameter can reach hundreds or thousands of hours.

Claims (1)

Invention Formula A method of measuring the statistical characteristics of the phase fluctuation of a signal, based on multiplying the phase fluctuations by converting the spectrum of the input (test and reference) signals, multiplying the transform of the selected test signal by the transformed reference signal and the transformed reference signal, which is additionally out of phase shifted by 90 °, averaged the results of multiplying, indicating two averaged signals, as the values of the real and imaginary parts of the characteristic function, characterized in that, in order to increase statistical accuracy due to the use of large values of the real parameter of the characteristic function, transform the spectrum of input signals using dispersive delay lines, at the input of which form radio pulses at the moment of transition of input signals through a predetermined phase value, and the frequency of filling of radio pulses is set linearly. variable within the frequency band of the dispersive delay line in accordance with the expression C) H + | (and) V vmdt uv de CO is the initial instantaneous frequency of filling in frequency-modulated radio pulses; Vm is the real parameter of the characteristic function; 4 (dispersion delay bandwidth; / it3 time dispersion dispersive delay line; Wc- frequency of the investigated signal; t is the current time; ty is the initial phase of the signal, and the amplitude of the received radio pulses is modulated accordingly. FROM and reference signals, the signals obtained at the output of the dispersive delay lines are detected, and the selected envelopes are used as transformed signals to measure the values of the real and imaginary parts of the characteristic (function. . FIG. 2