Instantaneous frequency analysis of broadband LFM signals by photonics-assisted equivalent frequency sampling

We propose a photonics-assisted equivalent frequency sampling (EFS) method to analyze the instantaneous frequency of broadband linearly frequency modulated (LFM) microwave signals. The proposed EFS method is implemented by a photonic scanning receiver, which is operated with a frequency scanning rate slightly different from the repetition rate of the LFM signals. Compared with the broadband LFM signal analysis based on temporal sampling, the proposed method avoids the use of high-speed analog to digital converters, and the instantaneous frequency acquisition realized by frequency-to-time mapping is also simplified since real-time Fourier transformation is not required. Feasibility of the proposed method is verified through an experiment, in which frequency analysis of Kα-band LFM signals with a bandwidth up to 3 GHz is demonstrated with a moderate sampling rate of 100 MSa/s. The proposed method is highly demanded for analyzing the instantaneous frequency of broadband LFM signals used in radar and electronic warfare systems.

[1]  Xihua Zou,et al.  An Approach to the Measurement of Microwave Frequency Based on Optical Power Monitoring , 2008, IEEE Photonics Technology Letters.

[2]  W. Pan,et al.  Photonics for microwave measurements , 2016 .

[3]  H. G. D. Chatellus,et al.  Optical real-time Fourier transformation with kilohertz resolutions , 2016 .

[4]  Yu Hen Hu,et al.  Enhanced Random Equivalent Sampling Based on Compressed Sensing , 2012, IEEE Transactions on Instrumentation and Measurement.

[5]  Photonic-assisted single system for microwave frequency and phase noise measurement , 2020 .

[6]  Robert A Minasian,et al.  Instantaneous high-resolution multiple-frequency measurement system based on frequency-to-time mapping technique. , 2014, Optics letters.

[7]  S. Pan,et al.  Deep neural network-assisted high-accuracy microwave instantaneous frequency measurement with a photonic scanning receiver. , 2020, Optics letters.

[8]  Ming C. Wu,et al.  Characterization of a coherent optical RF channelizer based on a diffraction grating , 2001 .

[9]  Shilong Pan,et al.  Photonics-based dual-functional system for simultaneous high-resolution radar imaging and fast frequency measurement. , 2019, Optics letters.

[10]  Guoqiang Zhang,et al.  Photonics-based broadband radar for high-resolution and real-time inverse synthetic aperture imaging. , 2017, Optics express.

[11]  Shilong Pan,et al.  Photonics-Based Broadband Microwave Instantaneous Frequency Measurement by Frequency-to-Phase-Slope Mapping , 2019, IEEE Transactions on Microwave Theory and Techniques.

[12]  S. Pan,et al.  Simultaneous Radar Detection and Frequency Measurement by Broadband Microwave Photonic Processing , 2020, Journal of Lightwave Technology.

[13]  P. W. East.  Fifty years of instantaneous frequency measurement , 2012 .

[14]  Daiyin Zhu,et al.  Photonics-based real-time and high-resolution ISAR imaging of non-cooperative target , 2017 .

[15]  Wei Pan,et al.  Photonic-Assisted Microwave Channelizer With Improved Channel Characteristics Based on Spectrum-Controlled Stimulated Brillouin Scattering , 2013, IEEE Transactions on Microwave Theory and Techniques.

[16]  José Azaña,et al.  Experimental demonstration of real-time Fourier transformation using linearly chirped fibre Bragg gratings , 1999 .