Incoherent multibeam Doppler current profiler performance: Part I--Estimate variance

We derive statistical lower bounds on the velocity and shear profile estimation accuracies (variances) achievable with both four-beam and three-beam Doppler current profilers. We find that performance (estimate variance) is asymptotic to a constant as SNR increases; this is evidently due to the assumed incoherent scattering properties of the medium. Curves and expressions are developed which define the tradeoffs between accuracy and resolution for two systems manufactured by AMETEK-Straza. The spatial response properties of the systems are addressed in a companion paper [3].