A phase-based ranging method for fast frequency hopping system

Alternative Position, Navigation, Time (APNT) service is gradually on the rise to maintain safety, and minimize economic impacts from GNSS interference outages within the airspace system. As a result, anti-interference ranging methods are urgently needed in APNT systems. Fast frequency hopping technology can provide strong resistance to radio interference for APNT systems. However, it is hard to get accurate range estimate from measurements of one hop because the residence time and the baseband width are limited in fast frequency hopping systems. In this paper, we propose a new phase-based ranging method for fast frequency hopping system, which is called Time-Frequency Matrix Ranging (TFMR). By TFMR, we can combine measurements of multi-hops to achieve high accuracy of range estimate. We present DFT-based and FFT-based estimators for different scenarios respectively. Different estimate accuracies are achieved by using matrices in different sizes. We calculate the Cramer Rao lower bounds (CRLB), which can provide a benchmark for selecting matrices with different signal-to-noise ratio.