Potential Accuracy of Echo-Signal Delay Measurement by Space-Based Radar Altimeter

Abstract

Satellite radar altimetry is a universal tool for global all-weather monitoring of the surface of the Earth. Substantial contribution to the satellite altimeter error is made by a component associated with noise and random nature of the echo-signal itself. When simulating a scattering surface with an array of specular points the altimeter echo-signal represents Gaussian process waveform received against AWGN. In such a case, the conventional statistical design produces an optimal echo-signal delay estimator in the form of the bank of identical energy receivers where decision is made according to maximal response. The Cramer-Rao bound defines the dependence of potential delay estimate accuracy on power and spectral resources used by altimeter, and the form of received power profile. The validity of analytical results obtained is confirmed by MATLAB simulation. It is also shown that the routine method of delay estimate based on threshold crossing yields manifold to the optimal one in measuring accuracy.

Keywords

• спутниковый высотомер
• измерение запаздывания
• оценка по максимуму правдоподобия
• граница крамера-рао