SU864238A1 - Method of measuring phase delay time of signals - Google Patents

Description

(54) METHOD FOR MANAGING PHASE TIME SIGNAL DELAY

I

The invention relates to the field of radio metering technology and can be used to measure the phase delay time of signals in communication lines, in delay lines and some other broadband quadripoles.

There is a known method for measuring the delay time of signals in quadrupoles, based on measuring the frequency of repeated radio pulses when the delayed radio pulse coincides with the next radio pulse received at the input of the delay line D

However, when determining the phase delay time using the specified method, due to the dispersion properties of the studied quadrupoles, a significant error occurs.

There is also known a method in which the phase delay time is measured by comparing the phase of the output signal of a quadrupole with its phase

the input when the input signal frequency changes and the number of points is counted at which the phase difference between the input and output signals is H (1C / 2) 4w7t, where m is an integer from the series 0,1,2 ... 2.

However, this method has a low accuracy of measuring the phase time of the holding of dispersive two-port networks in the range, since

to allows you to determine the delay time only at a few fixed frequencies (minimum points) at which the value of the phase shift of the input output signal is

15 1 "TS | 2CH Wilt. At other values, often the phase delay time can be found only when using the interpolation method, which leads to significant latency measurement errors. In addition, this method has low speed; due to the use of the interpolation method, as well as due to the fact that it is necessary to very precisely fix the frequency of the signal at the minimum points, which inevitably leads to a limitation of the frequency tuning frequency in the vicinity of these points, and consequently, to an increase in the measurement time. The aim of the invention is to improve the accuracy and speed of measurements of the phase time delay of signals in dispersive quadrupoles (such as communication lines and delay lines). This goal is achieved by the fact that in the method of measuring the phase delay time of signals by comparing the phase of the output signal of a quadrupole with the phase of the signal at its input, the frequency of the input signal is changed from a value at which the phase shift introduced by the quadrupole is obviously less than 2 fT to a given frequency value, where it is necessary for the MO to determine the phase delay time or vice versa, while counting an integer number of cycles of changing the phase difference, and after reaching a given frequency of the signal at the output of the quadrupole, ;: Fraction used to read phase-cycle and IS1: omm result determined from expression 2tt (H4oL) where n - the number of integer cycles varying phase difference; оС - phase phase cycle; UJi is the set frequency at which the phase delay of the signal must be determined. FIG. 1 image1 of the device, the implementation of this method; Fig. 2 is a timing diagram of the frequent change of the input signal. In the simplest device (Fig. 1}, the output of the tunable generator 1 is connected to the input of a quadrupole under study 2. Between the output and the input of the quadrupole 2 under study, a parallel device for counting whole cycles of phase difference 3 and phase meter 4 is connected to the input of the four-pole 2 under study the signal of generator 1 with frequency equal to Шц, where the value of Шц is chosen from the condition of the delay time of the signal at where frequency 4 Then the frequency of the input signal could be changed to a predetermined value 1) a. During this frequency change (time t., 1L (Fig. 2), and also at time t ,, t- (where is the time at which the frequency of the output signal is compared with the frequency) using the whole cycle counting device 3 by continuously comparing the phases of the input and output signals, read the number of whole cycles Jl of the change in the phase difference. After the signal frequency at the output of the quadrupole 2 under study is compared with the specified frequency of the input signal (time moment C (.2) during time L - L, With a phase meter A, a measurement is taken Phase delay time is determined from the expression t -) F) If an automatic phase delay meter is created, the frequency of the input signal should vary from (1) to UJg according to the cyclic law, as shown in .2, where ttg is OTpe30K time, for which the transient processes at the output of the input signal (Wi. The law of frequency change in the time interval t) terminate at the output of the studied four-floor / Sikka. It must necessarily be linear, as long as the derivative at the point of maximum steepness of this curve does not exceed the value of the maximum possible counting rate of a n device with an account device. that whole cycles. The sequence of determining the phase time can be changed, i.e. first determine the fraction of the phase cycle ci at the frequency of the CU, and then, changing monotonically the frequency of the input signal from tJtL to the help of the counting device of the entire cycles, determine the number And. The invention compared with the proto. type allows to increase the accuracy and speed of measurements. In the proposed method, the rate of change of frequency can be several tens of times higher than the rate of change of frequency in the prototype, since there is no need for accurate recording of the values of the frequency at which the raid

phase in the studied quadrupole is equal to

- + vy, lt :.

where wea is an integer 1,2,3 ...

Practically, the speed of this method is determined by the maximum possible rate of change of the frequency of the input signal. The measurement of the fractions of the phase cycle cL needs to be performed only at one point at a given 4x frequency ui, which simplifies the possibility of automating the measurement process as compared to the prototype. When achievable at the present time. high (- and accuracy of measurement of phase difference (error .I) at a frequency of 10 MHz; error of measurement of the delay time can be obtained no more than

M

ut-Ш 36o ° .fO (ru,)

0 ,.

Claims (2)

1. USSR author's certificate number 169144, cl. MKIZ GOl R 25/00. from 1965 2. USSR author's certificate number 163221, cl. MKIZ G04 € 10/06. 1965 / pU9.1