چكيده به لاتين
The Global Positioning System (GPS) is a satellite navigation system used for precise location determination. Due to the low power on the surface of Earth, received GPS signals are easily affected by noises and disturbances, the most common of which is jamming. To deal with this problem, a notch filter was designed which effectively removes continuous jamming. Along anti-jamming design, two IIR filters with narrow bandwidth were designed to remove jamming signals at 3.905 and 4.105 MHz frequencies. In the next step, these filters were implemented on the ARM hardware platform using the STM32F746G-DISCO board, which with the Cortex-M7 processor provides the ability to quickly process signals and eliminate jamming interferences. IIR notch filters are implemented with coefficients calculated in MATLAB on STM32F7 platform. The performance of the filter was evaluated based on various criteria.
By applying the filter to the single-tone jamming with a sampling frequency of 50 MHz to the received signal, the MAE is reduced by about 10.2% and the RMSE is reduced by about 11.1%, while the SNR is increased to an average of about 5.3% by applying the filter. On multi-tone jamming, the MAE after filtering is reduced by an average of 64.3% and the RMSE is also reduced by about 67%, also the SNR is increased by an average of about 60.5% with the application of the filter. To evaluate the improvement of the implemented signal compared to the simulated signal, experiments were performed with two sampling frequencies of 50 and 150 MHz and different number of samples (500, 1000, 2000 and 3000). evaluating on single- tone jamming shows that with the increase in the number of samples, the SNR measures increase by about 1.25% and 0.72%, RMSE decreases by about 8.33% and 4.61%, MAE decreases by about 10.37% and 7.29% respectively, and SHCD improves by about 61.4% and 70.6%, and PNDI show about 8.3% and 4.4% improvement. This evaluation has also been performed on multi-tone jamming, which shows that with the increase in the number of samples, SNR measures increase by about 0.24% and 0.84%, RMSE decreases by about 11.39% and 10.82%, MAE decreases by about 11.94% and 10.78%, SHCD by about 56.9% and 79.97% improvement, and PNDI shows about 0.6% and 1.3% improvement.
