Suppression Of Narrow-band Interference In Wideband HF Communication Based On OFDM

NBI notch suppressing technology used in this paper consists of transform-domain notch suppressing and time-domain ones. A predigested LMS algorithm is given in transform-domain notch suppressing, improving the performance by using a kind of window technique. The algorithms based on direct-form IIR filter and lattice -form IIR filter are given in time-domain notch suppressing. As the adaptive algorithm of time-domain IIR notch filter is sensitive to initial conditions, forgotten factor and smooth factors, it is not effective against NBI. Combining the excellences of time-domain and transform-domain notch suppressing, and according to the demand of the HF communication, we design a modified method based on FFT frequency estimation.The method is designed according as the characteristic of NBI in frequency-domain. NBI has great peak value in frequency-domain, the positions of the peak value can be fined in frequency domain data, then the estimators of NBI frequencies is obtained. At last it is passed to frequency parameter of IIR notch filter. Simulation results show that the modified method has better performance than former ones.