A Technique of Interference Monitoring in GNSS Applications, Based on ACF and Prony Methods

The interference monitoring plays a fundamental role in different satellite navigation applications that require a very high level of precision and accuracy. In fact, as the received signal is characterized by a very low power level, it can be very sensitive to other electromagnetic sources that can affect the correct working of the receiver [1] [2]. The detection of the presence of undesired sources into the received signal is only the first step of the interference monitoring; it is fundamental to try to recognize the type of interference in order to possibly localize the source and eventually apply some mitigation techniques [5] [6]. The technique presented here can be defined as a hybrid technique between detection and jam source characterization. The algorithm in fact provides the detection of the presence of the undesired source in the received signal allowing at the same time to estimate its time characteristic and its power. In particular, the paper has the aim to describe an algorithm able to estimate the time and frequency characteristics of a pulsed signal that transmits within the Global Navigation Satellite System (GNSS) bands. The post-processing of the Auto-Correlation Function (ACF) of the received signal allows to detect the presence of the interference source, defining its characteristics [4]. The method takes advantage of the characteristics of the ACF of the GNSS signals and the noise and it is able to estimate the time characteristics of the interference signal with a certain level of accuracy. The paper is focused on an augmentation of the algorithm described in [4], that is the introduction of the Prony’s method during the interferer frequency carrier estimation, which leads to a significant improvement of the technique performance. The presented case study deals with the interference from surveillance radar that share portion of bands with GNSS systems, but it is important to emphasize that the technique can be adapted to different undesired signal and different interference scenarios. Simulation results will be presented.