Photonic-Assisted Approach to Simultaneous Measurement of Frequency and Angle-of-Arrival

A microwave photonic system that can simultaneously measure the frequency and angle-of-arrival (AOA) of the received signal is conceived and practically demonstrated. Parallel dual-polarization Mach–Zehnder modulators are used to construct multiple optical subsampling links. Different relative phase shifts are introduced to different subsampled intermediate frequency signals by an optical delay line and the distances between different antennas. A phase comparison scheme with multi-baseline ensures that there is no ambiguity in the measurement of AOA in a large frequency range. The frequency and AOA can be determined through the phase shift analysis of the intermediate frequency signal. In a proof-of-concept experiment, a 0.6–31 GHz frequency measurement range with an error of 80 kHz and high-precision AOA measurement of less than 1° in the range of ±80° can be achieved. The proposed system also has the capability for multi-tone signal and broadband signal detection.