Measurements of Periodic Signals Phase Shifts with Application of Direct Digital Synthesis

I. V. Gula,I. V. Karpova,K. I. Horiashchenko,O. I. Polikarovskykh,V. M. Melnychuk

doi:10.21122/2220-9506-2019-10-2-169-177

Abstract

The development of new methods and high-bit instruments for measuring phase shifts of high-frequency periodic signals with high speed for radar and radionavigation tasks is an actual task. The purpose of this work is to create a new phase shift meter for high-frequency periodic signals based on the double-matching method using direct digital frequency synthesis.On the basis of the proposed mathematical model of phase shift measurements of periodic signals by the method of double coincidence using the statistical accumulation of pulse coincidences, a functional diagram of a digital phase shift meter of periodic signals using a direct digital frequency synthesizer is developed. This allowed the implementation of an 8-bit converter phase shift signal to the code on the programmed logic integrated circuit EPM240T100C5N firm Altera.The digital phase shift meter of periodic signals based on the double-matching method consists of two comparators, two short-wave pulse generators, a direct digital frequency synthesizer, two pulse counter control circuits, two short pulse coincidence circuits, two pulse counting circuits, four clock counters, four registers, a microcontroller and an indicator. Block diagram of a double-matching digital phase meter using direct digital sintesizer use minimal hardware logic.In the developed phase shift meter, due to the use of the double-matching method, the time delay between signals does not depend on the period of input signals and can be found when changing the frequency of periodic pulses in wide limits. Measurement errors will be determined mainly by the duration of the pulses of coincidence. The use of statistical accumulation of pulse coincidence in the basis of the work allowed eliminating the restrictions on the duration of pulses of known non-ionic meters.On the basis of the obtained results, a high-bit converter of phase shifts of high-frequency periodic signals into a binary code with high speed for problems of industrial tomography, radar and radionavigation can be developed.

Highlights

In modern measuring devices, different methods of phase determination are used, such as: electroncounting method for determining the phase shift of signals without frequency conversion, with frequency conversion, non-linear measurement methods
The main advantages of the double-matching method are to increase the accuracy of the measurement in comparison with the nonius methods due to the almost complete elimination of the sampling error
As a result of the analysis of nonlinear methods for measuring phase shifts of signals, it has been established that the existing methods do not allow to solve the problem of precision increase in the phase meter devices at high frequencies effectively. This is due to the need to reduce the duration of pulses with an increasing frequency of input signals and high requirements for the stability of the formation of periods of input and reference signals

Summary

Introduction

Different methods of phase determination are used, such as: electroncounting method for determining the phase shift of signals without frequency conversion (at frequency up to 1 MHz), with frequency conversion (at frequencies above 1 MHz), non-linear measurement methods (single and multiple). Nonius methods allow increasing the accuracy of measurement of phase shifts of periodic signals using the same elemental base. The nonius method allows for high accuracy of measurement when using reference frequencies close to the input signal frequencies [4]. With the increase in the frequency of input signals, it is necessary to reduce the duration of the pulses of the reference frequency, which makes it difficult to use these methods at high frequencies. In this case, it is necessary to form impulses of nanoseconds and picoseconds duration. To eliminate the restrictions on the duration of impulses of known nonunique methods, a method of measurement is proposed based on a double match with the statistical accumulation of the number of pulses per cycle of measurement

Main part

Pulse duration using the nonius methods

Findings

Conclusion