Simultaneous and unambiguous identification of DFS and AOA without dependence on echo signal power

We present a photonics-based method of estimating Doppler frequency shift (DFS) and angle of arrival (AOA). The pro-posed identification method for the DFS and AOA is simulta-neous and unambiguous. A reference radio frequency signal is introduced to realize the frequency downconversion. By monitoring the frequency of the downconverted signals gen-erated after the photodetection, the direction ambiguity of the DFS is canceled out. The AOA can be instantaneously calculated through two downconverted signals via a Hilbert transform. Experimental results verify that a -77.90 degrees to 77.90 degrees AOA measurement with errors of less than +/- 1 degrees is implemented, and a DFS measurement with errors of no more than +/- 3.1 Hz is also realized. Our proposed method not only removes the direction ambiguities of both DFS and AOA, but also avoids the dependence on echo signal power in AOA measurement, which largely increases the feasibility in realistic applications.(c) 2023 Optica Publishing Group

Automated summary

We propose a photonics-based method for estimating Doppler frequency shift (DFS) and angle of arrival (AOA). The method simultaneously and unambiguously identifies DFS and AOA. By introducing a reference radio frequency signal and monitoring the frequency of the downconverted signals, the direction ambiguity of DFS is canceled out. AOA can be calculated instantaneously through a Hilbert transform. Experimental results demonstrate accurate AOA measurements within -77.90 degrees to 77.90 degrees with errors less than +/- 1 degrees, and DFS measurements with errors no more than +/- 3.1 Hz. This method removes direction ambiguities and avoids dependence on echo signal power, making it highly feasible for realistic applications.