SU930154A1 - Method of measuring periodic signal phase shift changes - Google Patents

Description

The invention relates to radio electronics and can be used in measurement technology in processing phase-modulated signals, primarily for measuring movement.

A known method for measuring the phase shift between two periodic signals, based on the principle of heterodyne measuring signals with reference frequency signals, comparing the phase of intermediate frequencies using a phase-sensitive detector, which produces pulses arriving at the local oscillator with the aim of achieving phase response at the phase-sensitive detector Cl 3.

The disadvantage of this method is the measurement of the phase mismatch only in the range of 0-2A, moreover, direct measurement of the rate of change of the phase mismatch is impossible.

The closest in technical essence to the present invention is a method of compensatory measurement of the phase shift, based on the control of a constant voltage by a temporary shift of one of the input voltages before the measured phase shift is compensated. The measuring device shows the average for the period value of the compensation voltage, proportional to the measured phase shift t21.

The disadvantage of this method is that it can only be measured in the O-ZSO range, which limits its application to a whole range of measuring devices, where the number of transitions through 2 liters must be taken into account.

Let us assume that it is impossible to control the rate of change of the phase mismatch. The absence of a digital readout makes it difficult to apply the method in digital devices, since the name of a separate analogue (q) is 39

a second converter will result in additional errors.

The circuit of the invention is an extension of the range of registration of changes in phase to, where K is a factor of multiplicity while simultaneously measuring the rate of change of phase.

The goal is achieved by choosing the follow frequency of the reference signals multiple times the follow frequency of the measuring signals, the multiplicity factor is inversely proportional to the discreteness of measuring phase changes, then the auxiliary sequence of signals is formed from the reference sequence with a frequency equal to the average frequency of the measuring signals signals and form, depending on the sign of the phase changes first or second and The pulses, the duration of which is equal to the time interval between the measuring and auxiliary signals, after which the temporary position of the auxiliary signals is changed by an amount equal to the duration of the indicated pulses, the first pulse changing the temporary position in the direction of advance, and the second in the direction of delay, simultaneously evaluate the rate of change of the phase over the duration of the indicated pulses, and the value of the change of phase is determined by integrating the durations of the first pulse with a plus sign, second on - with a minus sign.

FIG. 1 shows a functional diagram of an apparatus for implementing the method; in fig. 2 - time diagrams of the device.

The device includes a source of 1 signals of the reference frequency, a divider of 2 frequencies, including the first binary cascade 3 on the j-K trigger with C and S coincidence elements and combining element 6 and the second cascade 7, pulse phase discrimination discriminator 8 based on two triggers 9 and 10, match items 11-13 and duration doubler 1, as well as a reversible counter 15 with match item 16. The trigger input 9 is connected to the input 17 of the device.

The rate of change of the phase is controlled by the duration of the signals at

4 D

outputs 18 and 19, the resultant shift in the state of the counter bits 15.

The value of the reference frequency fp at the output of the generator 1 and the coefficient. By dividing the frequency divider 2, the choice is made on the basis of the necessary discreteness of measuring changes in the phase of the signals at input 17.

Consider the operation of the device from the point in time when the phase of the measuring signal with a frequency f relative to signals with a frequency fo is constant, the frequencies of the signals f and f on

The output of the divider 2 are equal and are formed synchronously. In this case, the triggers 9 and 10 of the discriminator 8 are set to one state at the same time, after which the signal from the output of the element 13 returns to the initial state. It is obvious that the phase mismatch signals at the outputs of elements 11 and 12 will not form, which corresponds to zero

phase change rates. The elements of coincidence 5 and 1b are closed, therefore the status of the reversible counter types of discharges is unchanged. Since the control signals of the first stage of the divider are not formed (the transfer signals from the first stage are formed by the coincidence element k, the phase of the signals with the frequency f (j is also unchanged, i.e. the state of the circuit is stable 5).

When the temporal position of the signals at input 17 changes, for example, in the direction of delay, the temporal position of signals with frequencies f

and fo will become as shown in FIG. 2p, 6. Since the trigger 10 is set to the first state first, then the output of the element 12 will form a pulse (Fig. 2, c) of the phase error signal, the duration of which is equal to the phase shift in one period. In order to determine the magnitude of the phase shift, the equilibrium is subsequently restored by shifting the signal with the frequency fy in time. For this, the divider input is blocked for a time equal to the duration of the phase difference signal.

The signal from the output of the element 12 is fed to the input j and K of the trigger 3, blocking its work in the counting mode. Trigger state 3, fixed at the rising edge of the signal at

the output of element 12 remains unchanged throughout the entire misalignment pulse. In order to eliminate the transfer signal, the coincidence element j is also blocked .5

The counter 15 and the coincidence element 16 provide simultaneous measurement of the magnitude of the phase shift as the number of periods of the reference frequency from the output of the oscillator 1 during a time equal to the duration of the error signal.

It is obvious that the measurement of a single shift is carried out for one period of the signals with a frequency of that fX.

In the case of a uniform change in the phase of the input signals, a corresponding error signal is generated in each period of the input signals. 2o Its duration is information about the rate of change of the phase and is determined by the number of pulses with a frequency fQ in the packet at the output of the coincidence element 16 "The result of the accumulation (integration) of the number of pulses in the counter 15 is the value of the phase shift.

The shift for each period of the signal with frequency fj will be compensated by a corresponding change in the temporal position of signals with frequency f, therefore the total value of the phase change may exceed jj 2 l and is limited only by the counter volume.

When the signal is shifted in time with the frequency fx in the direction of advance (Fig. 2, a, d), the trigger 9 first overturns and the phase error signal (Fig. 2, e) is formed at the output of the coincidence element 11. This signal goes through the doubler C of duration to the inputs j and K j of blocking the trigger 3 of the first cascade divider, and, in addition, the doubling element of the transfer signals at the input of the second cascade 7 divider 2. This provides a change in the time position of the signals with the frequency fo in the direction of advance, with the shift value equal to the duration of the control signal.

Since the formation of the error signal at the output of the element P and the shift of the signal with the frequency f occurs simultaneously, and the termination of the signal at the output of the element P is determined by the moment of formation of the signal with the frequency fp (Fig. 2, i-), the duration of the signal at the output of the element 11 will be doubled less actual mismatch. To compensate for this reduction, a doubler is used, which forms a signal (Fig. 2,), the duration of which is equal to the actual error at the time of arrival of the input signal with a frequency f.

The number of periods of the reference frequency, f, determined by the duration of the control signal (element 5), is counted by counter 15 at another input.

As in the previous case, the total phase shift can exceed 2-5 G and is determined by the volume of the counter.

At the initial moment of time or during transients when the power is turned on, the discharge of the reversible counter must be set to the state corresponding to the initial count, and the phase mismatch of the signals with the frequencies fo and f will be automatically processed.

As can be seen, the device implemented by the proposed method is characterized by substantial simplicity, is not associated with performing any mathematical operations and extracting the time points of the phase change from 2J to O and vice versa, it works in real time. At the same time, both the magnitude of the change in the phase of the periodic signals and the rate of its change are determined at the same time.

Claims (2)

Invention Formula A method of measuring changes in the phase shift of periodic signals based on comparing the temporal position of the measurement and reference signals, characterized in that, in order to extend the range of recording changes in phase to + 360 ° K, where K is the multiplicity factor, the reference frequency is chosen repeatedly greater frequency of the measurement signals, the multiplicity factor is inversely proportional to the discreteness of measuring phase changes, then an auxiliary sequence is formed from the reference sequence after Depending on the sign of the phase changes, the first or second pulses, the duration of which is equal to the time interval between the measuring and auxiliary signals, then change the temporal position of the auxiliary signals. signals by an amount equal to the duration of the specified pulses, with the first pulse changing the time position towards the front, and the second 8 in the direction Well lag simultaneously estimate the rate of change of phase, the duration of said pulses and the phase changes are determined by integrating a duration of a first pulse with a positive sign, the second - with a negative sign. Sources of information taken into account in the examination 1.SMIR.NOV PG Digital phase meters. L., Energie, 197, p. 7-8. 2. USSR author's certificate ff 387301, cl. G 01 R 25/00, 1970,