Hardware-Efficient Phase Demodulation for Digital <i>ϕ</i>-OTDR Receivers with Baseband and Analytic Signal Processing
This paper presents hardware-efficient phase demodulation schemes for FPGA-based digital phase-sensitive optical time-domain reflectometry (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>ϕ</mi></se...
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2025-05-01
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| author | Shangming Du Tianwei Chen Can Guo Yuxing Duan Song Wu Lei Liang |
| author_facet | Shangming Du Tianwei Chen Can Guo Yuxing Duan Song Wu Lei Liang |
| author_sort | Shangming Du |
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| description | This paper presents hardware-efficient phase demodulation schemes for FPGA-based digital phase-sensitive optical time-domain reflectometry (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>ϕ</mi></semantics></math></inline-formula>-OTDR) receivers. We first derive a signal model for the heterodyne <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>ϕ</mi></semantics></math></inline-formula>-OTDR frontend, then propose and analyze three demodulation methods: (1) a baseband reconstruction approach via zero-IF downconversion, (2) an analytic signal generation technique using the Hilbert transform (HT), and (3) a wavelet transform (WT)-based alternative for analytic signal extraction. Algorithm-hardware co-design implementations are detailed for both RFSoC and conventional FPGA platforms, with resource utilization comparisons. Additionally, we introduce an incremental DC-rejected phase unwrapper (IDRPU) algorithm to jointly address phase unwrapping and DC drift removal, minimizing computational overhead while avoiding numerical overflow. Experiments on simulated and real-world <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>ϕ</mi></semantics></math></inline-formula>-OTDR data show that the HT method matches the performance of zero-IF demodulation with simpler hardware and lower resource usage, while the WT method offers enhanced robustness against fading noise (3.35–22.47 dB SNR improvement in fading conditions), albeit with slightly ambiguous event boundaries and higher hardware utilization. These findings provide actionable insights for demodulator design in distributed acoustic sensing (DAS) applications and advance the development of single-chip DAS systems. |
| format | Article |
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| language | English |
| publishDate | 2025-05-01 |
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| spelling | doaj-art-ee0ce9583bce4f7c826269659a7414562025-08-20T01:56:45ZengMDPI AGSensors1424-82202025-05-012510321810.3390/s25103218Hardware-Efficient Phase Demodulation for Digital <i>ϕ</i>-OTDR Receivers with Baseband and Analytic Signal ProcessingShangming Du0Tianwei Chen1Can Guo2Yuxing Duan3Song Wu4Lei Liang5Sanya Science and Education Innovation Park of Wuhan University of Technology, Sanya 572000, ChinaSchool of Safety Science and Emergency Management, Wuhan University of Technology, Wuhan 430070, ChinaSanya Science and Education Innovation Park of Wuhan University of Technology, Sanya 572000, ChinaSanya Science and Education Innovation Park of Wuhan University of Technology, Sanya 572000, ChinaSanya Science and Education Innovation Park of Wuhan University of Technology, Sanya 572000, ChinaSanya Science and Education Innovation Park of Wuhan University of Technology, Sanya 572000, ChinaThis paper presents hardware-efficient phase demodulation schemes for FPGA-based digital phase-sensitive optical time-domain reflectometry (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>ϕ</mi></semantics></math></inline-formula>-OTDR) receivers. We first derive a signal model for the heterodyne <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>ϕ</mi></semantics></math></inline-formula>-OTDR frontend, then propose and analyze three demodulation methods: (1) a baseband reconstruction approach via zero-IF downconversion, (2) an analytic signal generation technique using the Hilbert transform (HT), and (3) a wavelet transform (WT)-based alternative for analytic signal extraction. Algorithm-hardware co-design implementations are detailed for both RFSoC and conventional FPGA platforms, with resource utilization comparisons. Additionally, we introduce an incremental DC-rejected phase unwrapper (IDRPU) algorithm to jointly address phase unwrapping and DC drift removal, minimizing computational overhead while avoiding numerical overflow. Experiments on simulated and real-world <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>ϕ</mi></semantics></math></inline-formula>-OTDR data show that the HT method matches the performance of zero-IF demodulation with simpler hardware and lower resource usage, while the WT method offers enhanced robustness against fading noise (3.35–22.47 dB SNR improvement in fading conditions), albeit with slightly ambiguous event boundaries and higher hardware utilization. These findings provide actionable insights for demodulator design in distributed acoustic sensing (DAS) applications and advance the development of single-chip DAS systems.https://www.mdpi.com/1424-8220/25/10/3218distributed acoustic sensingFPGARFSoC<i>ϕ</i>-OTDRheterodyne detectionphase demodulation |
| spellingShingle | Shangming Du Tianwei Chen Can Guo Yuxing Duan Song Wu Lei Liang Hardware-Efficient Phase Demodulation for Digital <i>ϕ</i>-OTDR Receivers with Baseband and Analytic Signal Processing Sensors distributed acoustic sensing FPGA RFSoC <i>ϕ</i>-OTDR heterodyne detection phase demodulation |
| title | Hardware-Efficient Phase Demodulation for Digital <i>ϕ</i>-OTDR Receivers with Baseband and Analytic Signal Processing |
| title_full | Hardware-Efficient Phase Demodulation for Digital <i>ϕ</i>-OTDR Receivers with Baseband and Analytic Signal Processing |
| title_fullStr | Hardware-Efficient Phase Demodulation for Digital <i>ϕ</i>-OTDR Receivers with Baseband and Analytic Signal Processing |
| title_full_unstemmed | Hardware-Efficient Phase Demodulation for Digital <i>ϕ</i>-OTDR Receivers with Baseband and Analytic Signal Processing |
| title_short | Hardware-Efficient Phase Demodulation for Digital <i>ϕ</i>-OTDR Receivers with Baseband and Analytic Signal Processing |
| title_sort | hardware efficient phase demodulation for digital i ϕ i otdr receivers with baseband and analytic signal processing |
| topic | distributed acoustic sensing FPGA RFSoC <i>ϕ</i>-OTDR heterodyne detection phase demodulation |
| url | https://www.mdpi.com/1424-8220/25/10/3218 |
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