Moving target localization using dual-frequency continuous wave radar for urban sensing applications

The dual-frequency continuous wave radar measures the target range by comparing the signal phases of two single-tone frequencies. Unfortunately, in practical measurements, the range estimation result suffers significantly from direct-path coupling and return signals from other unwanted scatterers. It is also not applicable when multiple targets exist simultaneously. This paper adopts a simple but effective approach that takes the phases of target signals in Doppler domain for comparison. Thus, the range of the moving target can be estimated without the influences of direct-path coupling and other unwanted return signals. Benefiting from the coherent Doppler integration, the range estimation accuracy in noisy environment is improved. Moreover, the adopted technique is also applicable for multiple moving targets if their Doppler frequencies are separable in the Doppler domain.