Pirahna filter

The structure of the “PIRANHA” filter is briefly presented. This structure consists of the use of a cascade of notch filters which, individually, have a small influence on the GPS signal. These cells converge as soon as there is a signal whose power density exceeds that of the noise floor. Each cell will thus attack sequentially and gradually reduce all jammers in the band of the GPS signal.

Each of the PIRANHA Cells has the same behavior. According to its initialization, the cell converges and attacks the jammer closest to its initial conditions. If a jammer is wider and more powerful, several cells will converge on the same jammer while the other cells will seek to eliminate other jammers in the spectrum.

Two other anti-jamming filters have been developed. The first filter relates to a technique using a wavelet decomposition called Wavelength Coefficients Thresholding (WCT) and which has the advantage compared to the sliding Fourier Transform to behave better in the face of unsteady signals. . The limitations of this technique concern rather the computational load and the complexity of the implementation incompatible with our specifications. Finally, a technique already existing but for which there are very few bibliographic elements, the Treatment of the Domain of the Amplitudes is the object of an in-depth study. This is the ADP filter for Amplitude Domain Processing.