Estimation of the Influence of the External Generator Frequency on the Relative Phase Measurements of the GLONASS Signals

V. B. Pudlovskiy, D. S. Pecheritsa, A. A. Karaush

Transactions of IAA RAS, issue 52, 40–45 (2020)

DOI: 10.32876/ApplAstron.52.40-45

Keywords: GNSS, phase measurements, GLONASS, navigation signals

Abstract

The correct interpretation of carrier phase measurements obtained with user navigation equipment or GNSS receivers from different manufacturers is one of the key conditions for the successful implementation of various modes of precise relative and / or absolute positioning. It is widely accepted that carrier phase measurements of the GLONASS satellite may depend upon its frequency channel and may be manufacturer-dependent. However, the issue of the agreement between reference oscillator frequency estimates obtained with the receiver by GNSS signals with code (GPS) and frequency division (GLONASS) has not been completely studied yet. To solve this problem, the goal of this work may be stated as: to investigate whether the carrier phase increments for GNSS signals with frequency and code division change equally in the receiver when the frequency of the reference oscillator changes. To achieve this goal, a method is proposed for assessing the influence of the GNSS receiver reference frequency on the measurement of the GNSS signals carrier phase. The method is based on processing the single differences of carrier range measurements separately for each satellite. An estimate of the relative bias of phase measurements separately for each of the real signals of the satellite of any GNSS can be obtained as a single difference of carrier range measurements between two receivers connected to a common antenna and to different external high-stable oscillators. By measuring the difference in the external reference frequencies of these receivers using GNSS signals, it is possible to assess how much the carrier range increments for signals with frequency and code division change with a variation of the external oscillator relative frequencies. The results of an experiment with simulated reference frequency change for one of the GNSS receivers using the HROG-5 frequency offset generator were used in processing the single-differences in carrier phase measurements for each satellite. According to the results of the experiment, the following was stated: – increments of carrier phases for the signals of the spacecraft with frequency and code division change similarly when changing the frequency of the reference oscillator; – the influence of the frequency channel of the GLONASS satellite on the estimate of the external reference frequency difference using the carrier phase measurements was not detected; – the results obtained are valid for the type of GNSS receiver used in the experiment and require additional verification for receivers of other manufacturers.

Citation