Photonics-Based Instantaneous Multi-Parameter Measurement of a Linear Frequency Modulation Microwave Signal

A novel approach for simultaneous and instantaneous measurement of the center frequency (CF), bandwidth (BW), pulse width (PW), pulse amplitude (PA), and time of arrival (TOA) of a linear frequency modulation (LFM) pulse signal is proposed and experimentally demonstrated. The approach is based on a linear amplitude comparison function (ACF) obtained by intensity modulation and first-order differentiated phase modulation, which are realized using a polarization modulator, two polarizers, and an optical linear filter. The linearity characteristic of the ACF ensures the ability of the proposed system to measure multiple parameters of an LFM pulse signal. In a proof-of-concept experiment, the measurement errors for CF, BW, PW, PA, and TOA of an LFM pulse are within ±0.3 GHz, ±0.4 GHz, ±120 ps, ±50 mV, and ±15 ps, respectively. Factors affecting the performance of the measurement system, such as the shape, slope, and resolution of the ACF, are discussed.