Enhanced Velocity Estimation Based on Joint Doppler Frequency and Range Rate Measurements

Modern commercial radars estimate the velocity of target by measuring its Doppler frequency. However, there is a fundamental limit in the detectable Doppler frequency due to Nyquist sampling theorem. The velocity exceeding the maximum detectable velocity is aliased and folded back into the unambiguous detection region, which is known as velocity ambiguity. To address this issue, we propose a novel velocity disambiguation method which combines two velocity estimates with different properties. The first estimate is based on conventional Doppler frequency estimation method which is ambiguous but has high accuracy. The second estimate utilizes the range rate measured for multiple frames which is less accurate but unambiguous. These two estimates are combined to produce a single estimate that is accurate and unambiguous. Simulation results verified that the proposed method can successfully resolve the velocity ambiguity for every velocity values of interest.