An improved phase generated carrier demodulation algorithm of fiber optic fabry-perot sensor
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摘要:
为解决相位生成载波-反正切解调算法(PGC-Atan)的非线性失真问题,搭建了基于改进型PGC-Atan算法的非本征型法珀传感器(EFPI)解调系统。首先,理论分析载波相位调制深度(C)偏离最优值、伴生调幅、载波相位延迟等非线性因素对经典PGC-Atan算法中参与反正切运算的正弦与余弦两路信号的影响。然后,针对外调制或伴生调幅较小的情况,提出了一种基于系数补偿的改进型PGC-Atan算法(PGC-CC-Atan)。该算法通过构造与C值和载波相位延迟有关的系数,消除反正切运算中的非线性参数。针对内调制情况,提出了一种基于椭圆拟合的改进型PGC-Atan算法(PGC-EF-Atan)。该算法通过基于分块矩阵的最小二乘法拟合椭圆并提取3个椭圆参数,进而将受非线性因素影响的正弦与余弦两路信号校正为正交信号。最后,通过仿真验证了改进型算法的正确性,并采用高调制特性的垂直腔面发射 器(VCSEL)和常规腔长的EFPI传感器等搭建PGC解调系统,对比经典PGC-Atan算法与两种改进型算法的解调性能,证实了改进型算法抑制非线性失真的有效性。实验结果表明:一定C值范围内,两种改进型算法可在非线性因素影响下有效解调。PGC-EF-Atan算法相较于PGC-CC-Atan算法,解调信纳比提升了11.602 dB,总谐波失真降低了10.951%。两种改进型算法中,PGC-EF-Atan算法对非线性失真的抑制效果更好,且解调线性度良好,准确度高。
Abstract:To address the issue of non-linear distortion in the Phase Generated Carrier (PGC) demodulation algorithm, we have developed an extrinsic Fabry-Perot Interferometer (EFPI) sensor demodulation system that is based on an improved PGC-Atan algorithm. The theoretical analysis focuses on the nonlinear factors affecting sine and cosine signals used in arctangent operation of the PGC-Atan algorithm. Such factors include deviations from optimal values of the phase modulation depth (C), companion amplitude modulation, and carrier phase delay. As a solution, we propose an improved PGC-Atan algorithm based on a correction coefficient (PGC-CC-Atan) suitable for external modulation or the case of low companion amplitude modulation scenarios. The PGC-CC-Atan algorithm generates a coefficient relating to C and carrier phase delay while excluding nonlinear parameters in the arctangent operation. Furthermore, an improved PGC-Atan algorithm that utilizes an elliptic fitting algorithm (PGC-EF-Atan) is proposed for internal modulation. The ellipse fitting technique is employed to fit the eclipse using the least squares method based on a matrix block decomposition. The pair of signals that are influenced by nonlinear factors are corrected and transformed into orthogonal signals utilizing three parameters of the ellipse. Finally, the correctness of the two improved algorithms is verified through simulations and experiments. The PGC demodulation system comprises a high dv/di VCSEL laser and a conventional cavity length F-P sensor. By comparing the demodulation performance of the PGC-Atan algorithm with that of the two improved algorithms, their effectiveness in suppressing nonlinear distortion is verified. Experimental results indicate that the two improved algorithms exhibit effective demodulation in the presence of nonlinear factors within a specific range of C values. The signal-to-noise and distortion ratio (SINAD) of demodulation result obtained from PGC-EF-Atan algorithm surpasses that of the PGC-CC-Atan algorithm by 11.602 dB, while the THD is reduced by 10.951%. Between the two improved algorithms, the PGC-EF-Atan algorithm possesses superior demodulation linearity, accuracy, and nonlinear distortion suppression performance.
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表 1三种解调算法的性能对比
Table 1.Performance comparison of the three demodulation algorithms
解调方法 幅值/rad SINAD/dB THD PGC-Atan 1.494 13.063 21.276% PGC-CC-Atan 0.947 15.189 12.562% PGC-EF-Atan 0.910 26.791 1.611% -
[1] PINET É. Fabry-Perot fiber-optic sensors for physical parameters measurement in challenging conditions[J].Journal of Sensors, 2009, 2009: 720980. [2] 李爱武, 单天奇, 国旗, 等. 光纤法布里-珀罗干涉仪高温传感器研究进展[J]. 中国光学(中英文),2022,15(4):609-624.LI A W, SHAN T Q, GUO Q,et al. Research progress of optical fiber Fabry-Perot interferometer high temperature sensors[J].Chinese Optics, 2022, 15(4): 609-624. (in Chinese). [3] YU L, LANG J J, PAN Y,et al. A hybrid demodulation method of fiber-optic Fabry-Perot pressure sensor[J].Proceedings of SPIE, 2013, 9044: 90441A. [4] 张天鹏. 基于冠脉血流储备分数检测的光纤法布里-珀罗传感器研究[D]. 济南: 山东大学, 2019.ZHANG T P.Research of fiber Fabry-Perot sensor based on coronary fractional flow reserve detection[D]. Ji’nan: Shandong University, 2019. (in Chinese). [5] 张知先, 雷嘉丽, 陈伟根, 等. 基于多参量光纤F-P传感的变压器局部放电与油温传感方法[J]. 高电压技术,2022,48(1):58-65.ZHANG ZH X, LEI J L, CHEN W G,et al. Transformer’s partial discharge and oil temperature sensing method based on multi-parameter fiber optic F-P Sensing[J].High Voltage Engineering, 2022, 48(1): 58-65. (in Chinese). [6] LIU W, YANG T Y, SHI Y J,et al. White light interference demodulation of optical fiber Fabry-Perot micro-pressure sensors based on the Karhunen-Loeve transform and singular value decomposition[J].Optics Express, 2022, 30(4): 5618-5633.doi:10.1364/OE.450548 [7] HUANG Y, WANG SH, JIANG J F,et al. Orthogonal phase demodulation of optical fiber Fabry-Perot interferometer based on birefringent crystals and polarization technology[J].IEEE Photonics Journal, 2020, 12(3): 7101209. [8] 江毅, 江树桓. 光纤 干涉测量技术在EFPI传感器信号解调中的研究进展[J]. 与光电子学进展,2021,58(13):1306017.JIANG Y, JIANG SH H. Research progress on fiber optical laser interferometry in signal demodulation of EFPI sensor[J].Laser & Optoelectronics Progress, 2021, 58(13): 1306017. (in Chinese). [9] WANG F Y, XIE J H, HU ZH L,et al. Interrogation of extrinsic Fabry-Perot sensors using path-matched differential interferometry and phase generated carrier technique[J].Journal of Lightwave Technology, 2015, 33(12): 2392-2397.doi:10.1109/JLT.2014.2379943 [10] 符浩. F-P声压传感器的PGC解调及复用技术研究[D]. 哈尔滨: 哈尔滨工业大学, 2018.FU H. PGC demodulation and multiplexing research based on Fabry-Perot fiber acoustic sensor[D]. Harbin: Harbin Institute of Technology, 2018. (in Chinese). [11] 孙韦, 于淼, 常天英, 等. 相位生成载波解调方法的研究[J]. 光子学报,2018,47(8):0806004.doi:10.3788/gzxb20184708.0806004SUN W, YU M, CHANG T Y,et al. Research and improvement based on PGC demodulation method[J].Acta Photonica Sinica, 2018, 47(8): 0806004. (in Chinese).doi:10.3788/gzxb20184708.0806004 [12] 施清平, 王利威, 张敏, 等. 一种消除伴生调幅的光源调频型相位生成载波解调方法[J]. 光电子· ,2011,22(2):180-184.doi:10.16136/j.joel.2011.02.032SHI Q P, WANG L W, ZHANG M,et al. Frequency-modulated phase generated carrier demodulation for eliminating companion amplitude modulation[J].Journal of Optoelectronics·Laser, 2011, 22(2): 180-184. (in Chinese).doi:10.16136/j.joel.2011.02.032 [13] VOLKOV A V, PLOTNIKOV M Y, MEKHRENGIN M V,et al. Phase modulation depth evaluation and correction technique for the PGC demodulation scheme in fiber-optic interferometric sensors[J].IEEE Sensors Journal, 2017, 17(13): 4143-4150.doi:10.1109/JSEN.2017.2704287 [14] HOU CH B, GUO SH. Automatic carrier phase delay synchronization of PGC demodulation algorithm in fiber-optic interferometric sensors[J].KSII Transactions on Internet and Information System, 2020, 14(7): 2891-2903. [15] 胡雨润, 王目光, 孙春然, 等. 光纤干涉传感器相位生成载波解调算法研究[J]. 技术,2022,46(2):213-219.doi:10.7510/jgjs.issn.1001-3806.2022.02.011HU Y R, WANG M G, SUN CH R,et al. Research on improvement of phase generated carrier demodulation algorithm for fiber optic interferometric sensor[J].Laser Technology, 2022, 46(2): 213-219. (in Chinese).doi:10.7510/jgjs.issn.1001-3806.2022.02.011 [16] QU ZH Y, GUO SH, HOU CH B,et al. Real-time self-calibration PGC-Arctan demodulation algorithm in fiber-optic interferometric sensors[J].Optics Express, 2019, 27(16): 23593-23609.doi:10.1364/OE.27.023593 [17] HOU CH B, LIU G W, GUO SH,et al. Large dynamic range and high sensitivity PGC demodulation technique for tri-component fiber optic seismometer[J].IEEE Access, 2020, 8: 15085-15092.doi:10.1109/ACCESS.2020.2966280 [18] 严利平, 周春宇, 谢建东, 等. 基于卡尔曼滤波的PGC解调非线性误差补偿方法[J]. 中国 ,2020,47(9):0904002.doi:10.3788/CJL202047.0904002YAN L P, ZHOU CH Y, XIE J D,et al. Nonlinear error compensation method for PGC demodulation based on Kalman filtering[J].Chinese Journal of Lasers, 2020, 47(9): 0904002. (in Chinese).doi:10.3788/CJL202047.0904002 [19] 畅楠琪, 黄晓砥, 王海斌. 基于EKF参数估计的光纤水听器PGC解调方法研究[J]. 中国 ,2022,49(17):1709001.CHANG N Q, HUANG X D, WANG H B. Phase generated carrier demodulation approach in fiber-optic hydrophone based on extended Kalman filter parameter estimation[J].Chinese Journal of Lasers, 2022, 49(17): 1709001. (in Chinese). [20] FITZGIBBON A, PILU M, FISHER R B. Direct least square fitting of ellipses[J].IEEE Transactions on Pattern Analysis and Machine Intelligence, 1999, 21(5): 476-480.doi:10.1109/34.765658 [21] HALÍŘ R, FLUSSER J. Numerically stable direct least squares fitting of ellipses[C].Proceedings of the 6th International Conference in Central Europe on Computer Graphics and Visualization, 1998.(查阅网上资料, 未找到本条文献出版社信息, 请确认).HALÍŘ R, FLUSSER J. Numerically stable direct least squares fitting of ellipses[C].Proceedings of the 6th International Conference in Central Europe on Computer Graphics and Visualization, 1998.(查阅网上资料, 未找到本条文献出版社信息, 请确认).