Wind Speed Estimation Using FRFT-Based Method for mmWave Wind Profiler Radar in Low SNR Conditions

When utilizing mmWave wind profiler radar (WPR) to detect wind speed in low signal-to-noise-ratio (SNR) conditions, increasing the No. of coherent accumulation (COACC) is an effective way to increase the SNR, but will also lead to a longer beam period. In a long period, the velocity of wind or clutters cannot be regarded as constant and the acceleration of targets will cause spectrum overlap. In this paper, we propose a wind speed estimation method based on fractional Fourier transform (FRFT) to solve the spectrum overlap problem, estimate the Doppler shift of received signal in the 2-D FRFT domain, and calculate the wind speed of backscattered turbulent echoes. The proposed FRFT-based method is applied to a 24 GHz wind profiler radar in the Zhangbei wind farm of Hebei province, China. In the local wind farm, the results of the proposed method show good match with the meteorology mast in low SNR conditions.