Determination of phase difference of backscatter signals from coherent-on-receive microwave marine radar for wave measurement

In present study, a X-band marine radar was installed at the northwestern coast of Taiwan. The IF signal from the super-heterodyne receiver of the marine radar was retrieved, amplified, band-pass filtered and digitized to be the raw dataset, from which the phase of transmitted and echo radar EM wave could be determined. Based on Doppler theory, the time rate change of the phases between succeeding pulses could be used for estimating the water particle velocity of wave orbital motion. Due to the fact that the magnetron in the marine radar produces random frequency jump, and leading to mis-estimate of the phase differences. We adopted the Ensemble Empirical Mode Decomposition method as a filter to exclude the effects of frequency jump. The results demonstrated the improved capability of coherent-on-receive marine radar for surface wave measurement.