SU779903A1 - Digital phase meter - Google Patents

Description

one

: The invention relates to digital measurement technology, in particular, for measuring in electrical and radio engineering installations for various purposes, the phase difference of a path by a reference signal and a phase-modulated signal, whose amplitude varies in a wide dynamic range.

Phase meters are known that contain a time interval shaping unit, one input is connected through the first limiting amplifier to the output of a reference signal source, another input through a second amplifier the limiter is connected to the output of a phase modulated signal source, the output of the time interval shaping unit is connected to control key input 1, the other input of which is connected to the output of the pulse generator, and the output is connected to the counting input of the counter of the indicator deviceTBa lj.

In this digital phase meter in the amplifier limiter, the asymmetry of the limitation (the inequality of the maximum and minimum value of the output voltage) is inevitably observed. Which leads to a mixing of the zero signal level and, accordingly,

the shift of the fronts of the output voltage of a rectangular shape relative to the moments of the transition of the input sinusoidal signal through zero.

S Reducing the magnitude of this error by balancing the limitation thresholds or using the full-wave digital phase meter circuit is quite difficult in technical terms.

10 implementation.

The aim of the invention is to increase accuracy and measurement.

The goal is achieved by the fact that in a digital phase meter containing

"With a time interval shaping unit, in which one input through the first amplifier-limiter is connected to the output of a reference source, another input through the second amplifier20; limiter is connected to a source of a phase-modulated signal, the output of the time interval shaping unit of the connection with the first input of the key, which has a second input connected to a pulse generator, and the output - with

2S counting input counter indicator device, introduced a frequency divider by four and a reversible counter, in which the first input through the divider

30 frequency to four connected to the output

pulse generator, the second input is connected to the output of the second amplifier of the limiter, and the outputs of the reversible counter are connected to the tires of the initial installation of the counter indicator device. .

FIG. 1 shows the structural scheme of the proposed phase meter in FIG. 2 - timing diagrams, showing the operation of the phase meter.

Zyf 5 phase meter contains the first amplifier-limiter 1, the second amplifier-limiter 2, the block forming the time interval 3, the pulse generator 4, the key 5, the frequency divider by four b, the reversible counter 7, the counter indicator device 8. The device works as follows.

The reference and phase-modulated signals are transformed by the amplifiers-constraints by readers 1 and 2 into the corresponding sequence of rectangular pulses, which arrive at the time interval 3 shaping unit. the input of the counter of the indicator device 8 receives pulses from the output of the generator 4. The counting input of the reversible counter 7 receives pulses from the output of the frequency divider by four 6, the frequency of which is four times It is higher than the output of the pulse generator 4. The control input, the input of the reversible counter, receives a signal from the output of amplifier limiter 1, and if this signal is symmetrically limited (i.e. there is no offset from the amplifier of limiter 1), then the time interval in which the reversible counter 7 operates in the summation mode, arriving at the counting input of pulses, is equal to the time interval at which the reversible counter 7 operates in the subtraction mode. At the same time, at the end of the measurement cycle, the resulting difference is zero, which is fed to the tires of the initial installation of the meter indicator device 8.

 When a phase-modulated-signal zero displacement appears, an error in measuring the phase shift UQ (Fig. 1) occurs. Now the resulting difference in the output of the reversing counter 7 is already different from zero and numerically equal to the phase error caused by the zero offset level. limiter 1. The implementation of this equality is ensured by introducing a frequency divider of four b. Since, for any measurement cycle, the value of the compensating number is determined during the previous measurement cycle, the condition for complete compensation of the phase error is.

the rate of change of the voltage is relatively small; :: the displacement of the zero level per measuring cycle. In real amplifiers of the limiters, the voltage of the zero level changes over time much longer than the duration of the measurement cycle, which makes it possible to fully compensate for the error of this type.

o The operation of the proposed phase meter is illustrated by the timing diagrams in FIG. 2, where the plot 2a shows the input sinusoidal phase-modulated signal (Ug) and that

 the same Ug signal when there is a UCM zero level offset. as well as the signal and at the output of the amplifier are limited: bodies 1; plot 26 shows the number of pulses corresponding to the phase error in the presence of a zero-level bias of amplifier-limiter 1; on plot 2b and 2d is the number of pulses arriving at the counting input of the reversible counter 7 when it is operating in the subtraction and addition mode corresponding to the diagram of the plot 26, the number of pulses whose code is numerically equal to the value of the compensated error device. the beginning of the measuring cycle.

The introduction of new elements and connections favorably distinguishes the proposed digital phase meter from the prototype, since the component error has significantly decreased due to the presence of a zero-level offset of the input phase-modulated signal. This allows for more. accurate data on the phase of the signal that 0 will increase the application of this phase meter.

Claims (1)

Invention Formula A digital phase meter containing a time interval shaping unit, in which one input through the first limiting amplifier is connected to the output of the reference source signal, another input through the second limiting amplifier is connected to a phase-modulated signal source, the output of the time interval shaping unit is connected to the first 5 key entry, which has a second the input is connected to the pulse generator, and the output is connected to the counting input of the indicator of the indicator device, characterized in that 0 in order to improve the measurement accuracy, a frequency divider by four and a reversible counter is entered in it, in which the first input is connected via the frequency divider to the output of the pulse generator, the second input is connected to the output of the second amplifier-limiter, and the outputs of the reversible counter are connected indicator device; Sources of information taken into account in the examination 1. Infrared frequency phasemeter frequency meter NF-3, Technical Description,. Kazan, 1963. fig