Pre-Calibration of the Phase Interpolator of a Precision Time Interval Meter
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PRE-CALIBRATION OF THE PHASE INTERPOLATOR OF A PRECISION TIME INTERVAL METER D. G. Kalinov1 and V. I. Rimlyand2
UDC 531.761
The issues of precision determinations of time intervals for which results are essential, such as to estimate the metrological characteristics of structural systems of space navigational systems, are considered. A precision time-interval measurement unit has been designed. The dependence between observations of the measurement unit and the value under test has been established. A procedure for pre-calibration of a phase interpolator with nonuniform step size of quantization from the composition of the precision time-interval measurement unit has been developed and tested. In the course of creating the procedure, an optimal value was selected for the reference frequency, and the optimal size for the measuring matrix, consisting of sequentially connected logic gates, was studied. The extent of the effect of FPGA crystal temperature (integrated circuit) on the operation of a phase interpolator was determined. Requirements for test signals were developed, and the possibility of applying the reference signals of secondary standards for time and frequency (for example, the State Secondary Standard of units of time and frequency VET 1-7) was evaluated in the process of pre-calibration of the phase interpolator. Special software for determining the subquanta boundaries of the phase interpolator with a resolution of units of picoseconds was developed, and probability density functions of the transient process from one subquantum to the subsequent one were calculated. Requirements for the spectral composition of the frequency of the reference signal were provided, and the frequency detuning of a test signal relative to reference was determined. Verification of the a developed methodology for pre-calibration of the temporal position of the interpolator phase transitions was accomplished by repeated recalibrations and comparison of the obtained results. Keywords: calibration, time interval, phase transition, delay line, hardware-software complex.
Introduction. The precision determination of time intervals is widely used in solving various scientific-technical and applied problems in radiolocation [1], optical communication, and medicine for obtaining a layer-by-layer image [2], as well as for high-precision measurements of various physical quantities. The precision measurement of time intervals is one of the chief methods for evaluating the metrological characteristics of structural complexes of space navigation systems, such as GLONASS, GPS, and others [3]. The serviceability and positioning accuracy of navigational systems is based on the time-frequency measurements of terrestrial infrastructure, of reference complexes of time and frequency scattered in space, which consist of ensembles (3–15 pieces) of frequency and time standards. The working scales of reference complexes are generated based on the results of high-precision time measurements [4]. The proposed development of navigational systems wil
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