Frequency Agile Dual-Band RF Front-End for GNSS Receivers

Abstract

Global Navigation Satellite System (GNSS) is a navigation system used for geo-spatial positioning across the globe and encompasses GPS, GLONASS, Galileo, Beidou and other regional systems. The signals received by GNSS receivers are relatively weak and thus intentional and unintentional interference or jamming can overwhelm the GNSS reception which can lead to erroneous or in worst case no navigation at all. This can become a major issue in case of upcoming autonomous vehicles. Therefore, this thesis focuses on design of dual-band RF front-end for single antenna based GNSS receivers with the capability of having frequency agility in order to mitigate jamming and interference in the GNSS bands. Active smart filtering is used to protect the receiver from interferences and/or to generate appropriate notifications. Lower and higher bands are separated inside front-end, thus making it ideal for single antenna-based applications. Front-end is capable of detecting the in-band interference signals both in GNSS lower and higher bands independently, therefore, only a lower band will be switched if interference is in lower band, keeping higher band intact and vice-versa. High rejection is provided by SAW (Surface Acoustic Wave) filters so that only interference signals are rejected. For the worst-case scenario, when complete GNSS band is jammed, and interference can’t be mitigated, an appropriate notification indicates that the received signals are erroneous