A Study of Signal-to-Clutter Ratio for a Multifrequency Δ K Radar

Abstract

It has been proposed that dual frequency Ak niicrowave radar can be used to measure ocean surface currents and wave spectra. The signal-to-clulter ratio, x, for the Ak technique has been derived in the literature. In general it represents: To assess the feasibility of using information from Ak peak, it is important to investigate its detectability for various ocean surface conditions. Previous work determined that )I’ is inversely proportional to the illiiminated area. In those deriva6ions the ocean wave spectrum is approximated by a theoretical spectrum for a fully developed sea (e.g. Phillip’s spectrum). In this study we have investigated the relationship between experimentally determined x and measured ocean spectrum. For the purpose of the experiment we have used a Stepped Frequency Ak Radarr (SFAKR) developed by the Microwave Remote Sensing Laboratory at the University of Massachusetts. SFAKR is a pulsed C-band, coherent, Doppler radar. It is equipped with a real time signal processor to compress the data, so long records can be gathered. The experiment was conducted at Field Research Facilities at Duck,NC. Various meterological and oceanographic data were obtained simultaneously with our nieasurenients. In this paper we show that x ( and therefore the detectability of the Ak resonmt peak) is highly dependent on the shape of the ocean wave spectra. The dependence of x on the ratio of the energy in the dominant wave of the wave field to the energy of the chosen resonant ocean wave is shown in Figure 1, for a 30 hours period. We note that x increases with thiis ratio. We have also measured the dependence of x on other physical parameters and its connlection with modulation transfer funclion. We will also show how the accuracy of the ocean sudace current nieasureinent also depends strongly on x.