Short Kernel Phase Codes for Mitigation of Range-Velocity Ambiguities

Quadratic phase codes with 5 and 7 samples kernel lengths (L) had been proposed for mitigating ambiguities in range and velocity inherent in pulse Doppler radars. These codes are advantageous for protecting first trip returns from the 6^th (in case of L=5) and 8^th (in case of L=7) trip returns. Compared to the currently used SZ(8/64) codes on the WSR-88D (operating at 10 cm wavelength) the proposed ones are better suited for shorter wavelength (i.e., 5 and 3 cm) weather surveillance radars. This advantage and other specifics of the codes will be presented. Herein included is a figure where the envelopes of the recovery region in the space of second trip SNR and spectrum width of the first trip signal is presented. The envelops are for the SZ(8/64) code and the L7 codes of length 63 and 64. The codes have been implemented on a 3 cm wavelength radar for initial evaluation. The radar has a solid-state transmitter and built -in features facilitating phase coding. Coded pulse sequences have been transmitted and data (in phase and quadrature phase components) from precipitation have been collected. To our knowledge this is the first implementation of the codes and demonstration of data collected in that mode. Although the initial analysis indicates expected performance further study and evaluations are needed before recommending implementation for operational applications.