Doppler Frequency Shift and SNR Estimation using Improved STFT-based method for mmWave Wind Profiler Radar

When utilizing mmWave wind profiler radar (WPR) to estimate Doppler frequency shift and wind speed of the backscattered signals, the speed and power of wind turbulence are always inhomogeneous. During the interval of fast Fourier transform (FFT), multiple signals and noise may be received in a single FFT spectrum. The short time Fourier transform (STFT) can partially increase the temporal resolution and select signals by constant false alarm rate (CFAR), but will also lower the frequency resolution. To address that issue, an improved STFT-based method is proposed in this paper, which combines the STFT, interpolation, wavelet transform, and coherent accumulation to improve both temporal resolution and frequency resolution, and accurately estimate Doppler frequency shift and SNR. The proposed STFT-based method is applied to a 24 GHz wind profiler radar, and tested in the actual wind farm in Zhangbei, Hebei province, China. Compared to the FFT and STFT, the proposed method can estimate the Doppler frequency shift and wind speed more accurately.