Use of Adaptive Filtering Techniques and Deconvolution to Obtain Low Sidelobe Range Samples in NASA D3R Radar

Title: Use of Adaptive filtering techniques and deconvolution to obtain low sidelobe range samples in NASA D3R Radar.

 Mohit Kumar, and V Chandrasekar

1373, Campus Delivery, Colorado State University

Fort Collins, CO 80523-1373

The NASA dual-frequency, dual-polarization, Doppler radar (D3R) is an important ground validation tool for the global precipitation measurement (GPM) mission’s dual-frequency precipitation radar (DPR). The use of mismatched filtering have brought down the integrated sidelobe levels successfully, but often this can result in long filters. Long filters can mask weak echoes at short as well as long range because of sidelobe energy spreading to a much larger range domain. Thus for long pulse compression filters, the sidelobe energy needs to be contained. In this paper, two methods are discussed to contain sidelobes. The sidelobe effects of these long pulse compression filters can be mitigated with adaptive filtering techniques by tailoring the desired response to suit our requirements of high sensitivity near to precipitation regime or far away. The use of clean algorithms, as post processing option, is also discussed.

The major advantage of using adaptive filter techniques is that we can tailor the shape of the sidelobe response by using appropriate desired response. Combined with clean deconvolution, this will be used to detect low SNR targets at far ranges in the presence of strong meteorological events happening near the radar. For an RHI processing, the filters with enhanced performance in near range can be synthesized. We present data from NASA D3R radar demonstrating the performance of both of these algorithms presented in this paper.