Multistage FPGA Least Mean Squares Filters Suppressing Multiple Narrowband Radio-Frequency Interferences in the Radio Detection of Cosmic Rays

The article presents the FPGA implementation of 256- and 768-stage Least Mean Squares filters with rectangular, Hamming and Kaiser windows to suppress at least ten narrowbands RFIs. The analysis shows extremely high-efficiency Radio Frequency Interference (RFI) elimination. For a proof of concept study, we used 9-bit real cosmic ray data from the Auger Engineering Radio Array (AERA) as patterns and mixed with 14-bit multiple narrow-band RFIs. They were hidden deep within RFI’s background. After the cleaning process, the patterns were brought out and have shown practically without contamination.