Velocity bias and fluctuation in the standard dual beam Doppler reconstruction algorithm

Bias and fluctuation of the standard velocity reconstruction algorithm for dual beam vector Doppler velocity estimation systems are analyzed; both magnitude and angle properties are considered. Bias can arise from any of the error sources known to affect single beam systems in addition to both translation and angle misregistration between the two sample volumes; standard deviation is the result of random temporal fluctuations in Doppler frequency estimates in each beam. Approximate closed-form expressions for both biases and standard deviations of the velocity estimates are derived, and the performance of a typical practical dual beam system is discussed as an illustration of the theory.