A Disambiguation Method for Dual-Comb Sampling Frequency Measurement Based on Phase Analysis

A disambiguation method for dual-comb sampling frequency measurement is proposed and experimentally demonstrated. For dual-comb sampling frequency measurement, multiple solutions may exist if only the frequency information of the output signal is employed for disambiguation. By further exploiting the phase relationship between the intermediate frequencies and the first harmonics of the two sampling rates, most of the ambiguous frequencies can be distinguished in our experiment. The experiment results also indicate that nonideal phase response of the devices will reduce the performance of the method especially in high frequencies. To solve the problem, an improved method, in which the variations of the phases are observed and used to solve the ambiguity, is given so that the method is free from the calibration of the nonideal phase response.

I. Introduction

Radio signal spectrum sensing technology is of great importance in electronic warfare (EW), radar and wireless communications [1]–[3]. The frequency information can be used for emitter de-interleaving, signal-recognition and adaptive transmission. However, conventional electronic frequency measurement receivers have a limited operation range due to electronic bottleneck. Featuring broad bandwidth, high flexibility and immunity to electromagnetic interference [4], [5], microwave photonic frequency measurement provides an effective solution to meet future demands of multi-tone signal detection, real-time processing and large bandwidth.