An optimization design scheme for multiple PRT and multi-frequency coherent Doppler velometry

摘要

The pulse-to-pulse coherent Doppler method is widely applied to estimate current velocity for its advantages of noninvasive, quick response, and high resolution. However, due to the ambiguities of range and velocity, the application of the pulse-to-pulse coherent Doppler method is limited. Some techniques such as multiple acoustic frequencies, staggered pulse repetition time (PRT), and dual-pulse repetition frequency (PRF) have been proposed to do dealiasing of velocity ambiguity by using multiple carrier frequencies or pulse repetition times. The key to these techniques is the optimal ratios of pulse repetition times or carrier frequencies. Unfortunately, until now, there have been few works giving a guideline for designing the optimal ratios of pulse repetition times or carrier frequencies to achieve the best dealiasing performance. In this research, based on the influence of velocity difference and interval number on dealiasing performance, a formular criterion is deduced to guide the optimization of above mentioned ratios. By adding perturbance to preset velocities with different levels of standard deviations, simulations are conducted evaluating the velocity errors to verify the optimizing criterion. The simulation results show that the closer the value to the formular one, the more similar the dealiasing performance to the optimized one. In addition, some methods for dealiasing are proposed, including the table lookup method and the equation solving method.