Cancelling Satellite Interference at the Rapid Prototyping Array. A Comparison of Voltage and Power Domain Techniques

We present results of adaptive canceller experiments at the Rapid Prototyping Array which compare the quality of interference suppression achieved in the voltage and power domains. It is shown that if the optimal complex weights used to model the interference are stationary over the length of the time average, then the same level of suppression is achieved. A limitation of both methods is that the system noise in the reference voltage leads to an attenuation of the interference estimate. Using two reference signals with uncorrelated system noise improves the result, especially in the case where the reference signal has a low interference-to-noise ratio. For GLONASS and GPS interference on a baseline of a few tens of metres, it is shown that the complex weights are stable for several hundred milliseconds. A reduction of at least 36 dB of RFI power was achieved, this number limited by the amount of data available.