Receiver-independent GNSS Smart Antenna for Interference Mitigation

Abstract

The presence of unintentional or intentional Radio Frequency Interference (RFI) signals in the Global Navigation Satellite Systems (GNSS) frequency bands is by far one of the main vulnerabilities of every GNSS receiver. This known threat can cause severe positioning performance degradation and even a complete service unavailability. Complementary to time and frequency-domain mitigation techniques, it is well known that antenna-array based receivers can benefit from spatial domain processing. By exploiting spatial diversity, an array-based smart antenna can selectively attenuate the RFIs Direction of Arrival (DOA) and provide high gain towards the legitimate GNSS signals. In this work, we propose a receiver-independent GNSS smart antenna architecture that implements a real-time automatic and autonomous null-steering spatial filtering for GNSS bands. The platform uses Commercial Off The Shelf (COTS) components including a multichannel receiver front-end, a System on Chip (SoC) hybrid FPGA/CPU digital signal processor, and an up-converter to shift the spatially filtered GNSS signal back to its carrier frequency. In this way, the proposed smart antenna can be connected to any conventional single-antenna GNSS receiver. The paper includes both the theory of operation, the implementation details, and the prototype performance in a real-life open field scenario.