Patent ID: 8643542
Filing Date: 2014-02-04
Classification: G01S

Abstract:
1. A method for self-calibration of frequency offsets in measurement equipment of an interference monitoring system, wherein the measurement equipment has a measurement antenna of a known position, the method comprising the steps of: a) sampling I/Q data using the interference monitoring system measurement equipment; b) acquiring a satellite navigation signal from the I/Q data by correlating the sampled I/Q data with replica signals of different code phases and different carrier frequencies; c) said acquisition of step b) providing an estimate of a carrier frequency of the satellite navigation signal of a satellite; d) calculating visibility of the satellite from ephemeris or almanac data and determining an expected carrier frequency of the satellite navigation signal from satellite orbit data and the known position of the measurement antenna; e) comparing the expected carrier frequency of the satellite navigation signal with the estimated carrier frequency of the satellite navigation signal and calculating a frequency offset value as the difference between the expected and estimated carrier frequencies of the satellite navigation signal; f) storing the frequency offset value in a memory; and g) using the stored frequency offset value to compensate the frequency offset of at least one subsequent measurement wherein steps a)-g) are performed in alphabetical order.