Effect of radio frequency interference (RFI) on the Global Positioning System (GPS) signals

The effect of radio frequency interference (RFI) on Global Positioning System (GPS) signals needs to be investigated because of the increasing demand for accuracy and precision in positioning, navigation, and timing (PNT) applications. In order to investigate the effect of RFI on the high precision GPS applications (e.g., surveying works), this study was conducted on single- and dual-frequency GPS receivers in differential GPS (DGPS) mode via static observations. All the tests were focused on in-band interference at the GPS L1 and L2 frequency bands with the interference signal power levels being increased from -140 dB until the accuracy of GPS was affected. The use of dilution of precision (DOP) alone to quantify the quality of GPS was found to be insufficient, and hence, residual positions have been used to study this effect. The findings from all the tests show that RFI can degrade the accuracy of GPS measurement, and, in some cases, completely disrupt GPS signals (e.g., loss of tracking of GPS signals). Hence, the presence of RFI sources, both intentional and unintentional, should be an important consideration in planning high precision GPS application.