Radio Frequency Interference (RFI) is a growing concern for Global Navigation Satellite System (GNSS) reliability. The Cyclone GNSS (CYGNSS) constellation, designed for ocean wind retrieval via GNSS reflectometry (GNSS-R), provides Delay-Doppler Maps (DDMs) with noise floor metrics exploitable for spaceborne RFI detection. This study proposes a maximum-based DDM noise floor strategy that selects the highest noise floor value among four simultaneous GNSS reflections at each 0.5-second epoch, rather than their mean, preventing dilution of anomalous signals by unaffected channels. To suppress false alarms, a two-tier verification framework is introduced: (1) multi-satellite concurrent detection, confirming RFI when two or more CYGNSS satellites independently flag the same geographic region, and (2) temporal persistence verification, confirming a single-satellite detection only if threshold exceedance persists over a 10-second window. The physical basis for this criterion is established through slant-range geometry analysis between a ground-based jammer and the orbiting satellite.
Detection of GNSS Interference Using Reflected Signal Observations from the LEO Satellite Constellation
