The application of reflected signals of global navigation satellite system (GNSS) has emerged in the last two decades as a feasible remote sensing scheme in retrieving various geophysical parameters of the Earth’s surface including ice layer, land, and sea. In this paper, the GPS signals reflected off the sea sur-face are considered. To ensure the signals received by the antenna are reflected signals from the sea sur-face, a procedure is proposed to detect the reflected signals. The procedure is composed of two parts. One is delay prediction and the other is delay estimation between line-of-sight signal and reflected sig-nal. In the procedure for delay estimation, a threshold is set to identify candidate reflected signals from sea surface. Furthermore, the predicted delay and the delay estimation of candidate reflected signals are compared. If the difference between the predicted delay and the delay estimation is within a certain cho-sen threshold, the reflected signals are successfully identified. Several experiments are conducted and the received data are processed. Thresholds about standard deviation of C/N0 and delay error set in the procedure are determined from this experiment analysis. The results in this paper contain one experiment whose wind speed information is measured by an anemome-ter. In this case, the GPS reflected signals from sea surface are identified using the proposed procedure. To correct the results, the simulations of link-budget analysis and delay-Doppler map are made. The link-budget analysis provides the predicted C/N0 information. Thereafter, both simulation results are compared with the C/N0 estimation and delay-Doppler map extracted from experiment to further verify the detected signals are indeed reflected signals.

Keywords: GNSS, remote sensing, LHCP antenna, reflected signal, link-budget analysis, delay-doppler map