Pre-Calibration of the Phase Interpolator of a Precision Time Interval Meter

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.