Design and performance of interference cancellation circuit

Abstract

This paper presents an interference cancellation circuit based on a side-lobe canceller. A new interference canceller is investigated in which the receiving interference signal of the auxilary antenna is modulated by a low-frequency signal. When this signal is combined with the main antenna receiving signal, envelope detection is used and the error voltage of the interference canceller will be obtained from the detection of the low-frequency signal and the phase. The interference cancellation effect is measured. The results show that above suppression ratio above 40 dB over a bandwith of 50 MHz can be achieved regardless of whether the signal is CW, FM or PSK or the undesired and desired signals are co-channel signals. For a PSK signal even with D/U = -10 dB prior to cancellation, the bit error rate after cancellation can still be maintained equal to that without interference at all. Also a good suppression ratio can even be achieved in outdoor situations and the circuit presented here has obvious practical value.