Range sidelobe suppression by locally weighting filter

One of the important technologies in the pulsed radar is the pulse compression by means of chirp signals. This technology simultaneously satisfies the contradicting requirements of increased search distance, or the increase of the average transmission power, and of range resolution. However, the waveform after pulse compression has a range sidelobe in the range direction and a small object existing near an object with a large radar cross section is hidden in the range sidelobe so that its detection becomes difficult. To suppress the range sidelobes, a method has been considered to provide weights to the frequency characteristics of the pulse compression radar. In this paper, the wavelet transform as a tool for time frequency analysis is used for the analysis of pulse compression waveform. A range sidelobe suppression method in which a filter with a wavelet localized on the time and frequency axis as an impulse response is placed behind the compression filter is proposed since the frequency components near the main lobe and near the sidelobes are different. In this method, the local weighting is carried out. As a result of the convolution of the pulse compressed waveform with the wavelet with a scale corresponding to the frequency components near the main lobe, i.e., the filtering, it is shown by computer simulation that the correlation is reduced in the range sidelobe region and the maximum sidelobe level is reduced by about 10 dB. The proposed method can be combined with the weighting of the frequency characteristics of the pulse compression filter. Further, the dc offset of the I/Q signal can be eliminated.