Adaptive Interference Mitigation Using Frequency-Selective Limiters over GPS Band for Automotive Applications

In this work, we address the challenges associated with the necessity to protect Global Positioning system (GPS) receivers from various types of electromagnetic interference (EMI) generated by internal or external sources. We have developed a compact, lightweight, and passive frequency selective limiter (FSL) technology that automatically and adaptively protects vulnerable input circuits of a GPS receiver from unwanted emissions and prevents a GPS receiver from going into saturation. This technology is based on using magnetostatic surface waves in a magnetically biased ferrite film. The nonlinear processes in ferrite films enable discrimination of signals based on their power levels. In these devices, the frequency-selective transmission response adjusts rapidly and automatically, in real time, such that no portion of the output spectrum exceeds a designated power threshold. FSLs are capable of mitigating multiple interfering signals without prior knowledge of the timing or the frequency content of the interferers. A few examples of FSL design and measured characteristics are provided for GPS L1 band.