Photonic approach for simultaneous measurement of microwave DFS and AOA

A photonic scheme that can simultaneously estimate the microwave Doppler-frequency shift (DFS) and angle-of-arrive (AOA) is demonstrated. In the proposed system, the transmitted signal is independently mixed with two echo signals by a dual-channel microwave photonic mixer. By measuring the frequency of the intermediate frequency (IF) signal output from the two channels and the phase difference between them, the DFS (with direction identification) and AOA parameters can be obtained. In a proof-of-concept experiment, the errors are less than ${{\pm}}\;{0.08}\;{\rm{Hz}}$ for the DFS measurement within a range of ${\rm{\pm 100}}\;{\rm{kHz}}$ and less than ${\rm{\pm 1}.{3}}\deg$ for the AOA measurement ranging from 0° to 90°, respectively.