The Range-Overlaid Staggered PRT Algorithm

A well-understood limitation of sampling the environment with weather radars is the Doppler dilemma. That is, if a uniform sampling period or pulse repetition time (PRT) is made large for extended range coverage, no overlaid conditions occur, but Doppler velocity measurements become ambiguously aliased. Conversely, if the PRT is made small to unambiguously resolve velocities, range-overlaid signals become more likely. The staggered PRT (SPRT) algorithm has been shown to mitigate range and velocity ambiguities by decreasing velocity aliasing while extending the radar coverage. However, the performance of the SPRT algorithm to accurately dealias Doppler velocities deteriorates as the spectrum width of the weather signal increases in relation to the Nyquist interval, an issue that is exacerbated for longer PRTs. In this work, we demonstrate that the SPRT algorithm can tolerate overlaid echoes better than with uniform sampling. By allowing some overlaid signals to occur, shorter PRTs can be used to increase the SPRT dealiasing performance. The reduced range coverage associated with the use of shorter PRTs is offset by providing a means to recover Doppler velocities and spectrum widths beyond the unambiguous range of the standard SPRT algorithm. This variation of the standard technique is referred to as the range-overlaid SPRT algorithm.

The performance of this novel technique is evaluated with simulations and real weather examples. The significant improvement with respect to more traditional signal processing techniques makes the range-overlaid SPRT algorithm a solid candidate to improve the mitigation of range and velocity ambiguities on operational weather radars.