Experimental evaluation of an FPGA based Real-Time Doppler estimator

The performance of a coherent receiver depends on accurate Doppler estimation. This paper presents a Doppler estimator intended for single-carrier data streaming. It is based on a coarse estimate found via a small bank of shifted replicas, followed by a correction step. The cross-ambiguity function phase difference between two binary pseudo-noise training sequences, embedded in the start of the frame, is used to find the correction factor. The Doppler estimator was implemented in an FPGA and evaluated in three horizontal very high frequency (250 kHz) shallow water channels. The results show satisfactory real-time performance in the range of $\pm 2$ m/s.