Use of Agc in Mitigation of Continous-wave Interference in Gnss Receivers

This work investigates the ways that Automatic Gain Control (AGC) operation can be modified to minimise the Signal-to-Noise Ratio (SNR) losses in the presence of a Continuous-Wave (CW) interferer for Global Navigation Satellite System (GNSS) receivers. It was found that the recommendations based on analysis of a probabilistic model of a Direct Sequence Pseudorandom Noise (DSPN) receiver reported in the literature work to minimise the magnitude of the CW relative to the amount of GNSS signal captured. This however, comes at the cost of increased Total Harmonic Distortion (THD) which degrades the system performance. It was found that the level of THD could be minimised by taking advantage of higher thresholds in the Analogue-to-Digital Converter (ADC) (if available, such as 4-bits) while still adequately capturing the underlying GNSS signal. This operation is ideal if further processing is to be performed on the samples to mitigate the effects of Radio-frequency Interference (RFI).