Enhanced radar data acquisition system and signal processing algorithms for the Terminal Doppler Weather Radar

An improved prototype of the radar data acquisition (RDA) system has been developed for the Terminal Doppler Weather Radar (TDWR). A quad-processor server running Linux performs both the signal processing and system control functions. A digital receiver with dual-offset channels yields an instantaneous dynamic range of 105 dB. This feature eliminates the need for an automatic gain control (AGC) function used in the legacy RDA. The overall radar phase stability has been improved over the legacy system, with clutter suppression to 65 dB possible. New signal processing algorithms have been developed to take advantage of the increased data fidelity and computing power. The initial focus has been on improving data quality through range-velocity (RV) ambiguity mitigation for near-surface scans. An adaptive transmission/processing scheme has been devised such that unambiguous-range data from an initial long pulse repetition interval (PRI) scan are used to select from a menu of multi-PRI and phase-coded pulse sequences on a radial-by-radial basis. Because multi-PRI and phase-code processing have complementary strengths in range-overlay protection, this scheme allows better first-trip protection over all ranges and azimuths compared to having only one type or the other available for the entire scan. A combination of interrupt-driven software and field programmable gate array (FPGA) code in the new prototype RDA allows the radar to change PRI and phase coding every radial.

This work was sponsored by the Federal Aviation Administration under Air Force Contract FA8721-05-C-0002. The views expressed are those of the authors and do not reflect the official policy or position of the U.S. Government. Opinions, interpretations, conclusions, and recommendations are those of the authors and are not necessarily endorsed by the U.S. Government.