Pre-Despreading Authenticity Verification for GPS L1 C/A Signals

The performance of GNSS receivers can be highly affected by structural interference signals such as spoofing and meaconing. The structure and power level of these signals are very similar to those of the authentic GNSS signals and as such they cannot be easily detected in the received signal set. This paper proposes a low complexity authenticity verification technique that takes advantage of the GPS signal structure in order to detect the presence of undesired structural interferences in the received signal samples. The proposed technique operates on the raw signal samples and can detect the overpowered GPS spectrum prior to signal de-spreading. This method does not need any information regarding the AGC gain and operates on digitized signal samples only. The simulation results and real data processing verify the desired performance of the proposed method even when the received signal strength (RSS) of the spoofing and authentic signals are very close to each other. Copyright © 2014 Institute of Navigation.