Remote assessment of sea wave height by radar - uses analysis of doppler frequency spectrum of back-scattered rays to indicate wave height

摘要

A pulsed radar beam is directed towards the surface of the sea; and the back-scattered rays are collected in a receiver for analysis of their Doppler frequency spectrum. In the spectrum, the amplitude of the stronger of the two Bragg rays is measured, together with the amplitude of a second order reflection. The ratio of the two amplitudes represents the height of the waves on the surface of the sea being examined. Instead of using the max. amplitudes of the back-scattered rays, their areas can be used in calculating wave height. Two Bragg ray peaks are obtd. (A1-;A1+), which are symmetrical w.r.t. the original frequency; and second order peaks (A2-;A2+) are obtd. with frequencies which equal 1.414 times the frequency of the Bragg rays. The ratio A2+/A1+ or A1-/A2- indicates the wave height.