Detection and Analysis of GPS L1-Band Radio Frequency Interference Using Spaceborne Global Navigation Satellite System Reflectometry Receivers

We report a study of radio frequency interference (RFI) in the GPS L1-band ( $1575.42~\pm ~2$ MHz) using spaceborne global navigation satellite system reflectometry (GNSS-R) data. An examination of the “noise” levels reported by both Spire, Inc. and Cyclone GNSS (CYGNSS) standard Level 1 products is first presented, which shows clear evidence of RFI contributions. Data from 498 acquisitions in CYGNSS’s special raw intermediate frequency (I/F) mode are then used to examine RFI source properties in greater detail. Both kurtosis and cross-frequency algorithms are applied with the raw I/F data to detect the presence of RFI. The results suggest that up to 25% of the acquisitions considered contain RFI, with both “narrow” and “wideband” sources of varying amplitudes observed. The results provide insights into RFI source properties in the GPS L1-band as well as methods by which the RFI can be detected.