In over-the-horizon radar (OTHR)

the selection of transmitted bandwidth is limited by lots of crowded and powerful interference.It is difficult to find a broad and uncontaminated frequency band which results in low range resolution and signal-to-interference and noise ratio(SINR).A desired method is suppressing interference within a definite bandwidth.Considering the poor sidelobe of notch filtering method

in which target signal is masked in the sidelobes of interference

the projection algorithm(PA) and adaptive cancellation algorithm(ACA)are introduced.It follows that PA has the advantage of low complexity of computation and low sidelobe by designing sub band filter group though the temporal response will be introduced.By adjusting the weights

ACA can eliminate sidelobe interference effectively at the cost of heavy burden of computation.The sidelobe level of pulse compression was reduced greatly which will increase target detection probability effectively.