A method of same frequency interference suppression based on QRD-LS algorithm

The same frequency interference (including direct coupling wave of receiving and transmitting antennas, direct surface reflection wave), because of its strong energy, has great effect for the target signal of a near field transient active electromagnetic detection system. This interference has the same frequency as target signal, and is generally bigger than the target signal, so, it is of great harm to the detection system´s normal operation. In this paper, the traditional methods of same frequency interference elimination are analyzed, and the working principle of adaptive RLS(Recursive Least Square) filter is presented, then a new method of same frequency interference suppression which is based on recursive QRD-LS algorithm is put forward. The method has fast convergence speed; low operation amount and can realize real-time processing. The simulation results show that this method can effectively suppress the same frequency interference, and improve the SIR (Signal to Interference Radio) of the target signal. Moreover, the method has a good applicability for the local aberration of the same frequency interference and the changes of its amplitude and time-delay.