A method for self-calibration of frequency offsets in a measurement equipment of an interference monitoring system is provided. The method involves sampling I/Q data using the interference monitoring system measurement equipment and acquiring satellite navigation signals from the I/Q data. A carrier frequency of the satellite navigation signal is estimated and an expected carrier frequency of the satellite navigation signal is calculated. The expected carrier frequency of the satellite navigation signal is compared with the estimated carrier frequency of the satellite navigation signal and a frequency offset value is calculated as the difference between the expected and estimated carrier frequencies of the satellite navigation signal. The frequency offset value is stored in a memory and used to compensate the frequency offset of at least one subsequent measurement.