A real-time detection method for GPS flex power

Guanlong Meng, Haibo Ge, Bofeng Li

GPS satellites of Block IIR-M and the subsequent Blocks have the capability to redistribute the transmit power of the individual signal components, which is called flex power. This technology is used to prevent enemy jamming by increasing the power of the designed signal. It is of great importance to detect flex power since it has great impacts on differential code biases, phase shifts, and multiple access interference. Based on geodetic stations, stepwise enhancement in their carrier-to-noise density ratios (C/N0) can reflect the power changes caused by flex power. Thus, we propose a real-time detection method for GPS flex power based on C/N0 patterns. The patterns for 100 International GNSS Service stations uniformly distributed around the world are built according to their azimuths and elevations. In order to evaluate the performance of the proposed method, daily data with 30-s sampling in 2020 and real-time data with 1-s sampling in 2023 are adopted to detect flex power with the new method. Results of experiment show that the average false positive rate for real-time detection is around 10^–6, and the true positive rate is 0.999479. The results confirm the effectiveness of our method for real-time flex power detection. Meanwhile, a new flex power mode is discovered in real-time detection experiments, which has the largest coverage area between longitudes 125°W and 180°E.