Optimal Parameter Estimation Method of Internal Solitary Waves in SAR Images and the Cramér–Rao Bound

摘要

Parameter estimation of internal solitary waves (ISWs) is an important application of oceanic synthetic aperture radar (SAR) images. Several methods have been widely applied for estimating the parameters of ISWs. Most of these methods assume that the ISW signals are corrupted by additive receiver noise. However, the ISW signals in SAR images suffer from both additive (thermal) and multiplicative (speckle) noises. Therefore, the estimation accuracy of previously proposed methods could not reach the Cramér–Rao bound (CRB). This paper proposes an optimal parameter estimation method of ISWs and derives the CRB for parameter estimation of ISWs. The variances of the estimated ISW parameters are shown to reach the CRB. This optimum estimator is validated using ISW SAR signals taken from simulation data and European Remote Sensing 2 (ERS-2) images. The results show that the proposed method is more accurate and effective than other methods. In addition, it should be noted that this optimality could also refer to parameter estimation of other SAR extended targets with an analytical expression.