An Analysis of short pulse and dual frequency radar techniques for measuring ocean wave spectra from satellites


  • Frederick C. Jackson


A four-frequency moment characterization of backscatter from the near-vertical is applied to an analysis of the short pulse (SP) and dual frequency (DF) microwave techniques. It is found that (1) the range reflectivity modulation spectrum closely approximates the directional wave slope spectrum. Harmonic distortion is small and is a minimum near 10° incidence. (2) The SP measurement SNR (signal-to-noise ratio) is typically 20–30 dB greater than the narrowband DF SNR. The difference in SNR is the ratio of the range beam extent to pulse length, minus the ratio of beam-limited to pulse-limited Doppler spreads. It is concluded that narrowband DF measurements are basically impractical. To be practical, the DF technique must be ‘widebanded.’ SP measurements on the other hand are found to be practical, using existing space-qualified microwave hardware.