Real-Time RFI Processor for the Next Generation Satellite Radiometers

Anthropogenic Radio Frequency Interference (RFI) within radiometer bands is a serious problem in passive microwave remote sensing. Since this problem is ever-increasing, the next generation satellite radiometers will require efficient methods to mitigate the effects of RFI. In this paper, we present one solution: a spaceborne RFI processor to detect and blank the RFI in real time. The processor was designed to be compatible with the Microwave Imager (MWI) instrument, 18.7 GHz channel, onboard the European MetOp Second Generation satellite system. The developed RFI processor applies the following detection algorithms: (1) anomalous amplitude detection, (2) kurtosis, and (3) cross-frequency. In the processing, the data are divided into sub-samples in time and frequency with fine resolution. The RFI processor can detect and filter out RFI with this fine resolution in real time and then integrate the clean (non-contaminated) subsamples over time and frequency. Thus, a cleaned version of the radiometer data can be downlinked at traditional low data rate. The processing is implemented in a reprogrammable FPGA with high processing capacity, which provides high flexibility. The applied processing bandwidth is 200 MHz (+ 25 MHz transition bands at both sides). The measured performance of the RFI processor corresponds to the simulations and good overall detection capability has been achieved for narrow-band RFI. The power consumption of the RFI processor is approx.12 W (at room temperature) and the mass is approx. 1 kg.