Laser & Optoelectronics Progress, Volume. 58, Issue 23, 2306002(2021)

Undersampling Digital Orthogonal Demodulation Method for Heterodyne Interference System

Jie Ma1, Min Li1, Lü Haifei1, Hongyun Gao1, Xiaoyan Wen1、*, and Kai Su2
Author Affiliations
  • 1School of Science, Wuhan University of Technology, Wuhan , Hubei 430070, China
  • 2School of Water Resources and Hydropower Engineering, Wuhan University, Wuhan , Hubei 430070, China
  • show less

    Optical heterodyne interference systems have high signal frequency. The tranditional oversampling demodulation method has the disadvantages of high cost and large amount of data, so it is inconvenient for real-time demodulation monitoring. In this paper, an undersampling digital orthogonal demodulation method is studied to reduce the sampling frequency of a heterodyne system, so as to meet the demands of fast demodulation and real-time monitoring in vibration sensing. Firstly, the undersampling principle of a heterodyne interference system is analyzed theoretically to obtain the condition that the sampling frequency must meet, that is, the minimum sampling frequency should be more than twice of the signal bandwidth. Then undersampling demodulation is verified experimentally. For a vibration with a 0.5 V piezoe-lectric transducer (PZT) excitation voltage and an 80 MHz heterodymium frequency, the phase could be demodulated with sampling frequency as low as 20 kHz‒10 MHz. The largest demodulation error is 0.3%, and it does not increase with the decrease of sampling frequency. The influence of sampling frequency on measurable PZT excitation voltage range is studied. Higher sampling frequency leads to larger voltage range, and the linear demodulation intervals corresponding to 50, 100, and 200 kHz sampling frequencies are 1‒7, 1‒14, and 1‒20 V, respectively. Undersampling digital orthogonal demodulation is believed to have extensive application prospects in optical heterodyne interference systems due to its low-cost and fast demodulation.

    Tools

    Get Citation

    Copy Citation Text

    Jie Ma, Min Li, Lü Haifei, Hongyun Gao, Xiaoyan Wen, Kai Su. Undersampling Digital Orthogonal Demodulation Method for Heterodyne Interference System[J]. Laser & Optoelectronics Progress, 2021, 58(23): 2306002

    Download Citation

    EndNote(RIS)BibTexPlain Text
    Save article for my favorites
    Paper Information

    Category: Fiber Optics and Optical Communications

    Received: Jan. 7, 2021

    Accepted: Mar. 23, 2021

    Published Online: Nov. 18, 2021

    The Author Email: Wen Xiaoyan (wenxy@whut.edu.cn)

    DOI:10.3788/LOP202158.2306002

    Topics