RADAR BACKSCATTER MEASUREMENT ACCURACY FOR A SPACEBORNE PENCIL-BEAM WIND SCATTEROMETER WITH TRANSMIT MODULATION

Scatterometers are remote sensing radars designed to measure near-surf ace winds over the ocean. The difficulties of accommodating traditiona l fan-beam scatterometers on spacecraft has lead to the development of a scanning pencil-beam instrument known as SeaWinds, SeaWinds will be part of the Japanese Advanced Earth Observing Satellite II (ADEOS-II) to be launched in 1999. To analyze the performance of the SeaWinds de sign, a new expression for the measurement accuracy of a pencil-beam s ystem is required. In this paper we derive a general expression for th e backscatter measurement accuracy for a pencil-beam scatterometer whi ch includes the effects of transmit signal modulation with simple powe r detection. Both separate and simultaneous signal+noise and noise-onl y measurements are considered. The utility of the new expression for s catterometer design tradeoffs is demonstrated using a simplified geome try, A separate paper [8] describes detailed tradeoffs made to develop the SeaWinds design.