Mitigation of Interference From Iridium Satellites by Parametric Estimation and Subtraction

Abstract

Radio astronomy is the science of observing the universe at radio frequencies. In recent years, radio astronomy has faced a growing interference problem as radio frequency (RF) bandwidth has become an increasingly scarce commodity. Communication systems such as Earth orbiting communication satellites creates severe interference to the radio telescopes. This thesis proposes an algorithm to mitigate the radio frequency interference (RFI) from the Iridium satellite system. A technique is presented here to detect the downlink signal of Iridium, estimate the parameters of the signal, synthesize the noise-free version of the signal and finally subtract the recreated signal from the radio telescope output. Using both simulated and real data captured by a radio telescope testbed, we demonstrate that for Iridium bursts with 20 dB signal to noise power ratio (SNR), the proposed algorithm achieves more than 15 dB cancellation. The method proposed here can be implemented using present-day digital signal processing hardware and software. A performance analysis of this proposed cancellation scheme in the radio astronomy RFI mitigation regime is presented.