Effects of Sampling Rate on STAP-Based RFI Suppression Systems

In this paper, the effects of sampling rate on the performance of the space-time adaptive processing (STAP)-based RFI suppression system is studied when the performance metric consists of pre-correlator performance (output SNR) as well as the post-correlator performance (peak-to-peak ratio and distortion of the cross-correlation function). It is shown that for good performance, the sampling rate should be selected below or equal to the system bandwidth (front end of the antenna electronics). In general, the sampling rate is greater than the system bandwidth which leads to performance degradation. For these situations, a resampling procedure is presented which can be used effectively to reduce the sampling rate to below or equal to the system bandwidth. It is shown that when the resampled data is used in STAP, one obtains good performance. The resampling procedure consists of two steps. First, a low-pass filter is applied to the data. The bandwidth of the low-pass filter is selected to be between the desired signal bandwidth and the system bandwidth. Next, the signals are resampled to match the low-pass filter bandwidth. The antenna array and the signal scenario used in the study is described next