Single frequency (Doppler) radars cannot be used in target range estimation due to the associated large range ambiguities. An additional frequency can be used to increase the maximum unambiguous range to values adequate for range estimation of moving targets within buildings and enclosed structures. The dual-frequency technique uses phase comparison of the transmitted and received CW signals to provide an estimate of the target range. It offers the benefit of reduced complexity, fast computation, and real time target tracking. However, the dual-frequency approach for range estimation can be compromised due to the presence of drift in frequency, I/Q mismatch, and noise. In this paper, we analyze the effect of I/Q mismatch and noise on the bias and variance of the target range estimate. We consider targets with both linear and simple harmonic motions. Computer simulations are provided for illustrating the performance as a function of signal-to-noise ratio.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.