15b.3 Range Oversampling Techniques on the National Weather Radar Testbed

Faster observation of severe weather is a primary need of radar users. However, modifying scanning strategies to provide faster updates usually leads to trade-offs such as losses in data quality and/or spatial resolution. Range oversampling techniques can lead to faster updates and/or lower estimation errors without increasing the transmit bandwidth and with minimal degradation of the spatial resolution. The National Weather Radar Testbed (NWRT) is a natural platform for range oversampling research because, by default, the system oversamples in range by a factor of 4, 8, or 16. A simple pseudowhitening strategy has already been implemented and tested on the NWRT using a fixed transformation matrix. To better deal with varying conditions, an adaptive strategy is introduced that utilizes different pseudowhitening matrices based on the measured signal-to-noise ratio (SNR) and spectrum width at each range gate. Replicating the behavior of matched filtering at low SNR values is also considered. Adaptive pseudowhitening is a step towards establishing range oversampling techniques as operationally viable on weather surveillance radars. In this paper, a short background describing range oversampling techniques and the associated noise enhancement is provided. Several methods for mitigating the effects of noise enhancement are then presented and compared. Finally, some results applying adaptive pseudowhitening to NWRT data are shown.