Simple photonics-based system for Doppler frequency shift and angle of arrival measurement

Area of Science:

• Photonics
• Radar Systems
• Signal Processing

Background:

• Accurate measurement of Doppler frequency shift (DFS) and angle of arrival (AOA) is crucial for radar system performance.
• Existing methods may be complex or costly, limiting their widespread application.

Purpose of the Study:

• To present a novel, simple, and low-cost photonic approach for simultaneous DFS and AOA measurement in microwave radar signals.
• To demonstrate the system's wide operating frequency range and robust performance.

Main Methods:

• Utilized a fiber optic link structure comprising a laser, optical modulator, and photodetector.
• Applied the incoming microwave radar signal and a reference signal to the optical modulator.
• Analyzed the low-frequency electrical signal generated by the beating of echo and reference signal sidebands at the photodetector using an electrical spectrum analyzer.

Main Results:

• Successfully measured DFS around 15 GHz with errors under ±0.2 Hz.
• Achieved AOA measurement from 0° to 90° with errors less than ±1°.
• The system demonstrated a simple structure, low cost, wide operating frequency range, and robust performance.

Conclusions:

• The proposed photonic approach offers an effective and efficient solution for simultaneous DFS and AOA measurement in radar systems.
• The system's simplicity, low cost, and high accuracy make it a promising technology for advanced radar applications.