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14th IEEE International Conference on Solid-State and Integrated Circuit Technology (ICSICT)

作者： Sun, Yi-Fei Kobori, Yasunori Kobayashi, Haruo Gunma Univ Div Elect & Informat Kiryu Gunma 3768515 Japan

ISBN: (纸本)9781538644416

This paper proposes an EMI spread spectrum technology with automatic setting the notch frequency using the pulse coding controlled method of the DC -DC switching converter for the communication equipment. This proposed EMI spread spectrum technique does not distribute the switching noise into some specified frequency bands. The notch in the spectrum of the switching pulses is represented by the pulse Width coding (PWC) method. Notch frequency F-n is automatically set to the frequency of the received signal by adjusting the clock frequency F-ck using the equation F-n = (N + 0.5)F-ck. Here N is an integer. We have confirmed with ulation that the proposed technique is effective for EMI eduction and notch generation.

关键词： Switching converter Spread spectrum EMI reduction Notch frequency pulse coding

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Full Automatic Notch Generation in Noise Spectrum of pulse coding Controlled Switching Converter

Full Automatic Notch Generation in Noise Spectrum of Pulse C...

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IEEE International Conference on Solid-State and Integrated Circuit Technology

作者： Yi-Fei Sun Yasunori Kobori Haruo Kobayashi Division of Electronics and Informatics Gunma University Kiryu Japan

This paper proposes an EMI spread spectrum technology with automatic setting the notch frequency using the pulse coding controlled method of the DC-DC switching converter for the communication equipment. This proposed EMI spread spectrum technique does not distribute the switching noise into some specified frequency bands. The notch in the spectrum of the switching pulses is represented by the pulse Width coding (PWC) method. Notch frequency F_n is automatically set to the frequency of the received signal by adjusting the clock frequency F_(ck) using the equation F_n = (N + 0.5)F_(ck). Here N is an integer. We have confirmed with simulation that the proposed technique is effective for EMI reduction and notch generation.

关键词： Switching converter Spread spectrum EMI reduction Notch frequency pulse coding

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157km BOTDA with pulse coding and image processing 6

157km BOTDA with pulse coding and image processing

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6th European Workshop on Optical Fibre Sensors

作者： Qian, Xianyang Wang, Zinan Wang, Song Xue, Naitian Sun, Wei Zhang, Li Zhang, Bin Rao, Yunjiang Univ Elect Sci & Technol China Educ Minist China Key Lab Opt Fiber Sensing & Commun Chengdu 611731 Peoples R China

ISBN: (纸本)9781510602199

A repeater-less Brillouin optical time-domain analyzer (BOTDA) with 157.68km sensing range is demonstrated, using the combination of random fiber laser Raman pumping and low-noise laser-diode-Raman pumping. With optical pulse coding (OPC) and Non Local Means (NLM) image processing, temperature sensing with +/- 0.70C uncertainty and 8m spatial resolution is experimentally demonstrated. The image processing approach has been proved to be compatible with OPC, and it further increases the figure-of-merit (FoM) of the system by 57%.

关键词： Fiber optics sensors pulse coding distributed amplification Brillouin optical time domain analyzer image processing

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Pre-frequency-shift method for random number coding Phi-OTDR lightweight demodulation

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OPTICS AND LASERS IN ENGINEERING 2025年 192卷

作者： Li, Peihong Liu, Kaixin Li, Junchan Wu, Yangxu Zhao, Xiaojie Chen, Ping North Univ China State key Lab Extreme Environm Optoelect Dynam Tes Shanxi Key Lab Intelligent Detect Technol & Equipm Taiyuan 030051 Shanxi Peoples R China North Univ China Sch Software Taiyuan 030051 Peoples R China

pulse coding technology can effectively improve the performance of the phase-sensitive optical time domain reflectometry (Phi-OTDR) system, but the cross-correlation decoding for mass data along a long sensing distance brings a lengthy extra time cost. In this paper, a pre-frequency-shift method is proposed for the lightweight demodulation in the random number coding Phi-OTDR system. By using the first-order sideband generated by the phase modulation, this method can effectively reduce the frequency of the beating signal, thus reducing the requirement of the data sampling rate. The principle of the cross-correlation decoding algorithm based on sequence interpolation is studied, and the extra computation caused by the cross-correlation operation is analyzed theoretically. In the experiment, the validity of the pre-frequency-shift scheme is verified, and the sampling rate of the system is reduced from 500 MSps to 100 MSps. Comparative experiments using conventional down-sampling techniques with sampling rates of 250 MSps, 125 MSps, and 60 MSps validate the superiority of the proposed method. Finally, the vibrations of different frequencies are successfully located at 62.24 km with a spatial resolution of 5 m. At this distance, the algorithmic time cost of the proposed method is only 13.28 % of that of the traditional scheme.

关键词： Phase-sensitive optical time domain reflectometry pulse coding Random number coding pulse Pre-frequency-shift Lightweight demodulation

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Long-Range and High Spatial Resolution Brillouin Time Domain Sensor Using Oversampling coding and Deconvolution Algorithm

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IEEE SENSORS JOURNAL 2022年第15期22卷 14883-14891页

作者： Li, Yiqi Zhao, Can Wu, Hao Tang, Ming Huazhong Univ Sci & Technol Sch Opt & Elect Informat Wuhan Natl Lab Optoelect WNLO Wuhan 430074 Peoples R China Huazhong Univ Sci & Technol Natl Engn Lab Next Generat Internet Access Syst Sch Opt & Elect Informat Wuhan 430074 Peoples R China

Brillouin optical time domain reflectometer is widely used due to the advantage of single-ended input, but facing the trade-off between sensing distance, spatial resolution, and measurement time in long range application. Harnessing the co-propagating Raman amplification, we introduce Golay code under oversampling conditions to enhance the performance of the sensor. The relationship between the coding gain and the oversampling rate is investigated to determine the optimal sampling rate. At the sampling rate of 250 MSa/s, long distance experiments are conducted over a 100 km sensing fiber with 64-bit return to zero Golay coding using 100 ns optical pulses, yielding a BFS uncertainty of about 1 MHz along the fiber and complete rising edge of 20 m. At the same time, the total variation regularization-based deconvolution algorithm is proposed to resolve the deterioration of spatial resolution due to direct decoding. The robustness of the algorithm over different signal-to-noise ratio, temperature gradients, and sampling rates is investigated through simulations and experiments. Finally, the spatial resolution of the experimental results is improved to be higher than 6 m, which is one third of the original result. These methods greatly facilitate optical pulse coding in long range and high-resolution sensing.

关键词： Encoding Signal to noise ratio Optical fiber sensors Spatial resolution Optical pulses Deconvolution Decoding Optical fiber sensors Brillouin scattering pulse coding deconvolution

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Balanced Detection for Performance Enhancement in a pulse-Coded Brillouin Optical Time Domain Analyzer

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IEEE SENSORS JOURNAL 2023年第2期23卷 1166-1171页

作者： Li, Zonglei Zhou, Yin Hua, Zexi Yan, Lianshan Southwest Jiaotong Univ Lab Intelligent Percept & Smart Operat & Maintena Chengdu 611756 Peoples R China Southwest Jiaotong Univ Ctr Informat Photon & Commun Sch Informat Sci & Technol Chengdu 611756 Peoples R China

A pulse-coded Brillouin optical time domain analyzer (BOTDA) so far uses the single-sideband photo detection. Here, thanks to a specially designed Brillouin gain extraction scheme, the dual-sideband balanced photo detection is successfully employed in a pulse-coded BOTDA. Compared with the single-sideband detection, the balanced detection can effectively eliminate common-mode noises existing in the two sidebands of the commonly used dual-sideband probe. In addition, the signal-to-noise ratio (SNR) at the far fiber end can be enhanced by 1.5 dB. The two benefits are experimentally demonstrated in a 117.46-km Golay-coded BOTDA, resulting in the reduction of the Brillouin frequency shift (BFS) measurement uncertainty from 30 km to the far fiber end.

关键词： Balanced detection Brillouin optical time domain analyzer (BOTDA) distributed optical fiber sensor pulse coding stimulated Brillouin scattering

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Random coding method for coherent detection ?-OTDR without optical amplifier

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OPTICS AND LASERS IN ENGINEERING 2023年 161卷

作者： Li, Peihong Wang, Yu Yin, Kang Liu, Xin Bai, Qing Zhang, Hongjuan Gao, Yan Jin, Baoquan Taiyuan Univ Technol Coll Phys & Optoelect Key Lab Adv Transducers & Intelligent Control Syst Minist Educ & Shanxi Prov Taiyuan 030024 Peoples R China Taiyuan Univ Technol Coll Elect & Power Engn Taiyuan 030024 Peoples R China

In this article, a coherent detection phase-sensitive optical time-domain reflectometry (T-OTDR) without optical amplifier using random coding method is proposed. A series of pulses modulated by random codes are injected into the optical fiber to enhance the signal-to-noise ratio (SNR) and extend the sensing distance. The code only needs one sequence for decoding, which maintains the original sensing bandwidth. Simultaneously, the coding probe pulse does not pass through any optical amplifier to avoid the transient effect. Experimental results show that the SNR of the demodulated signal is improved 14.19 dB by using 128-bit random coding pulse. In the traditional single pulse scheme with erbium doped fiber amplifier (EDFA), the intensity SNR at 25.521 km is only 5.39 dB with a 40 ns pulse width, and the vibration signal cannot be effectively demodulated. In the proposed system with the same pulse width, the external disturbance can be located successfully at 42.338 km, and the SNR of the demodulated signal is 21.5 dB.

关键词： Distributed optical fiber vibration sensor Phase-sensitive optical time domain reflectometry pulse coding Random coding pulse

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Dead-time-based sequence coding method for single-photon lidar ranging

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OPTICS COMMUNICATIONS 2022年 517卷

作者： Li, Zhijian Lai, Jiancheng Wu, Zhixiang Wang, Chunyong Yan, Wei Li, Zhenhua Nanjing Univ Sci & Technol Dept Informat Phys & Engn Nanjing Peoples R China

Sequence coding is beneficial for reducing range ambiguity and acquisition time in single-photon lidar (SPL) ranging. In SPL data acquisition, dead time is usually regarded as an adverse condition. However, properly utilizing echo-induced dead time in sequence coding may allow it to be useful. In this study, we propose a dead-time-based sequence coding method. We set the time intervals of the subpulses to be slightly longer than the dead time, such that the detection of a subpulse can 'block' incoming noise detections until the arrival of the next subpulse. Starting with a sequence of three subpulses, we determined the optimal pulse-interval criteria of 'alpha dead time + pulse width' when the subpulses are identical in shape and intensity. A method to extract the range with few accumulations was proposed (FARE method), incorporating the maximum cross-correlation and threshold filtering. Simulation and experiment results demonstrated that our 'optimal interval + FARE' method is more efficient and less ambiguous than the sequence coding method without the merit of dead time, and the conventional 'single laser pulse' method. Our method is promising for low range ambiguity and fast ranging, and helps reduce laser energy consumption without wasting transmitting pulses.

关键词： Dead time pulse coding Photon-counting Single-photon lidar

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Synchronous cascade using random number modulation in Phi-OTDR systems

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OPTICS AND LASER TECHNOLOGY 2023年第1期167卷

作者： Li, Peihong Wang, Yu Liu, Xin Bai, Qing Jin, Baoquan Taiyuan Univ Technol Coll Phys & Optoelect Key Lab Adv Transducers & Intelligent Control Syst Minist Educ & Shanxi Prov Taiyuan 030024 Peoples R China

In this paper, a synchronous cascade scheme using random number modulation is proposed for signal-to-noise ratio (SNR) enhancement in phase-sensitive optical time-domain reflectometry (tp-OTDR) systems. The SNR gain is obtained by the random number codes, the effects of the pulse extinction ratio and the rising edge on coding gain are investigated, and the coding quality is improved by the synchronous cascade modulation (SCM) structure. The theoretical simulation and experimental results show that the scheme can improve the pulse extinction ratio and shorten the pulse rising edge, so as to optimize the coding gain and enhance the SNR. Compared with the traditional coding modulation scheme, the extinction ratio is improved by 21.9 dB, the rising edge is shortened from 10.12 ns to 3.31 ns, and the coding gain is improved by 1.1 dB. In the equivalent experiments, the results along a 42.240 km fiber under test (FUT) show that the phase signal demodulated is more stable under a static environment, and the SNR of the demodulated vibration signal is increased by 7.82 dB. Benefitting from the SNR enhancement, the sensing distance can be extended to 62.440 km with a 4.4 m spatial resolution, and the SNR of the demodulated signal under 100 Hz vibration is up to 28.4 dB.

关键词： Phase-sensitive optical time-domain reflectometry pulse coding Signal-to-noise ratio improvement Random number coding pulse Synchronous cascade modulation

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Latest research on long-range Brillouin distributed sensing

Latest research on long-range Brillouin distributed sensing

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Conference on Optical, Opto-Atomic, and Entanglement-Enhanced Precision Metrology

作者： Loayssa, Alayn Urricelqui, Javier Iribas, Haritz Marinelarena, Jon Jose Mompo, Juan Univ Publ Navarra Inst Smart Cities Pamplona 31006 Spain

ISBN: (纸本)9781510625112

We review the latest developments in long-range Brillouin optical time-domain analysis sensors. The factors that impair the performance of these sensors, particularly in terms of their distance range, are discussed together with the latest methods to overcome them. We focus on our recent contributions based on the application of the probe dithering method, which is based on introducing a wavelength modulation to the probe wave. This technique is shown to effectively compensate nonlocal effects originated in the depletion of the pump pulse as well as of its pedestal. In addition, it can provide amplification to the pump wave with a slight modification of the setup. Furthermore, this method can be combined with pump pulse coding and a new technique for coding linearization that we have devised to further extend the sensing length into the hundreds of kilometers range.

关键词： stimulated Brillouin scattering Brillouin optical time-domain analysis non-local effects pulse coding

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