Author Affiliations
Abstract
School of Artificial Intelligence, Hebei University of Technology, Tianjin, 300130, China
In order to solve the problem that blade fixing bolt cannot be detected quickly and conveniently in the field in actual production, this paper proposed a field rapid detection method of wind turbine blade fixing bolt defects based on field programmable gate array (FPGA), and Yolov4-tiny is selected as the basic algorithm. Nonetheless, the original Yolov4-tiny was not suitable for detecting small defects, so this paper improved the Yolov4-tiny to enhance the detection effect. Next, the convolutional operations in the algorithm were encapsulated into intellectual property (IP) cores by high-level synthesis (HLS) and Vivado, and parallel computation was realized using FPGA features. In the end, using Python to call the IP core and the FPGA hardware library, this paper achieved the purpose of rapid detection. Compared with traditional detection methods and other algorithms, the accuracy and speed of this method are significantly improved, which has a good application value.
光电子快报（英文版）
2022, 18(9): 541
Author Affiliations
Abstract
Department of Communication Science and Engineering, and Key Laboratory for Information Science of Electromagnetic Waves (MoE), Fudan University, Shanghai 200433, China
Asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM) has been a promising candidate in visible light communications (VLC) due to its improvement in power efficiency and reduction of nonlinearity based on previous simulation analysis. In this paper, for the first time as far as we know, we experimentally verify that ACO-OFDM would be an efficient scheme to improve the performance of a gigabit wavelength division multiplexing VLC system. Our theoretical investigations reveal that the advantages of ACO-OFDM can be attributed to the reduction of inter-carrier interference caused by signal–signal beating noise. An aggregate data rate of 1.05 Gb∕s is successfully achieved over 30 cm transmission below the 7% forwarderror-correction threshold of 3.8 × 10 -3. The experimental results show that ACO-OFDM can outperform DC-biased optical OFDM by BER performance of 1.5 dB at the same data rate and 4 dB at the same bandwidth, which clearly demonstrates the benefit and feasibility of ACO-OFDM.
Free-space optical communication Optical communications Light-emitting diodes Photonics Research
2014, 2(5): 05000138
Author Affiliations
Abstract
Key Laboratory for Information Science of Electromagnetic Waves (MoE), Department of Communication Science and Engineering, Fudan University, Shanghai 200433, China
We propose and experimentally demonstrate a 2 × 2 imaging multiple-input–multiple-output (MIMO) Nyquist single carrier visible light communication (VLC) system based on spectral efficient 64/32-ary quadrature amplitude modulation, as well as pre- and post-equalizations. Two commercially available red–green–blue light-emitting diodes (LEDs) with 3 dB bandwidth of 10 MHz and two avalanche photodiodes with 3 dB bandwidth of 100 MHz are employed. Due to the limited experiment condition, three different colors/wavelengths are transmitted separately. The achieved data rates of red, green, and blue LED chips are 1.5, 1.25, and 1.25 Gb/s, respectively. The resulting bit error ratios are below the 7% pre-forward error correction limit of 3.8 × 10-3 after 75 cm indoor transmission. To the best of our knowledge, this is the first experimental investigation of imaging MIMO system, and it is the highest data rate ever achieved in MIMO VLC system.
060.2605 Free-space optical communication 060.4080 Modulation 060.4510 Optical communications Chinese Optics Letters
2014, 12(10): 100603
复旦大学 通信科学与工程系,电磁波信息科学教育部重点实验室,上海200433
W波段(75~110 GHz)作为一个新的RF(射频)波段，相比于其他波段有着更宽的带宽和更高的频率，在这个波段能够为移动数据通信提供千兆的无线链路，这已经成为下一代无线通信系统的一个热点话题。实现W波段大容量通信系统有多种方法，如高阶调制、天线复用和多频带调制等，目前这些技术从调制效率、频带利用率和带宽宽度等多方面已实现了系统的优化。文章深入介绍了W波段大容量光纤无线融合系统的背景、研究成果及技术支持, 以期为未来的研究提供参考。
W波段 天线偏振复用 多频段复用 大容量光纤无线融合 射频波段 Wband antenna polarization multiplexing multiband multiplexing largecapacity converged fiberwireless system RF band
Author Affiliations
Abstract
We report a 3.75-Gb/s visible light communication (VLC) system thatusessingle-carrier frequency-domain equalization (SC-FDE) based on a single red–green–blue (RGB) light-emitting diode (LED), with the measured bit error rates (BERs) under a pre-forward-error-correction threshold of 3.8 \times 10-3. The fundamental characteristics of an RGB-LED-based VLC system are measured. We also compare SC-FDE with OFDM in terms of peak-to-average power ratio and BER performance, which shows that SC-FDE outperforms the OFDM modulation scheme.
060.0060 Fiber optics and optical communications 060.4080 Modulation 060.2605 Free-space optical communication Chinese Optics Letters
2014, 12(1): 010605
复旦大学通信科学与工程系 专用集成电路与系统国家重点实验室, 上海 200433
LED替代白炽灯和日光灯用于照明已经成为明显的趋势。LED可以同时用于照明与通信的特点，使得可见光通信(VLC)成为了近年来研究的热点。随着计算机和智能设备的迅速普及，接入网的速率和覆盖面需要进一步提高，VLC技术有望成为突破瓶颈的高速数据传输技术。VLC技术发展的主要挑战在于白光LED有限的调制带宽，研究者们已经提出了多种技术，如均衡技术、蓝光过滤、高阶调制格式、离散多音调调制、波分复用技术和多输入多输出(MIMO)技术等，以扩展调制带宽、提高传输速率。对这些技术的原理和性能进行了分析与讨论，以期为未来的研究提供一些参考。
光通信 可见光通信 白光LED 蓝光过滤 均衡技术 离散多音频调制 多输入多输出技术 波分复用技术 激光与光电子学进展
2013, 50(5): 050003
1 复旦大学 通信科学与工程系，上海200433
2 武汉理工大学 信息工程学院，湖北 武汉430070
VLC（可见光通信）是一种新兴的无线光通信技术，它兼具照明和通信，具有多项优势和广阔的应用前景，已成为近年来研究的热点，结合MIMO（多输入多输出）等技术，可以大大提高其通信速率。研究人员已经提出了多种可用于 VLC的MIMO模型和技术，国际上基于MIMO的光通信系统的研究有多点漫射MIMO系统、像素化MIMO系统、非成像MIMO系统和成像MIMO系统。文章对这些系统进行了探讨，总结了各种光MIMO通信模型的优缺点，可作为深入理解和进一步研究可见光MIMO通信技术的基础。
可见光通信 多输入多输出 多点漫射 像素化 非成像可见光通信 成像可见光通信 VLC MIMO multispot diffuse pixilated nonimaging VLC imaging VLC
Author Affiliations
Abstract
We propose a configuration of a wavelength division multiplexing (WDM)-visible light communication (VLC) system using orthogonal frequency division multiplexing (OFDM) modulation and an adaptive Nyquist windowing of the OFDM signal in the receiver. Based on this configuration, we demonstrate a 750-Mb/s WDM-VLC transmission based on RGB light-emitting diode (LED) with a distance of 70 cm. The measured bit error rate (BER) for all channels are under the pre-forward error correction limit of 3.8 \times 10-3. The BER performances of all the channels of the proposed WDM-VLC system show considerable improvement compared with those of the system without Nyquist windowing.
060.2605 Free-space optical communication 140.7300 Visible lasers 070.2025 Discrete optical signal processing Chinese Optics Letters
2013, 11(8): 080605
提出了一种基于副载波复用的新型的多输入单输出(MISO)正交频分复用可见光通信(OFDM-VLC)系统构架，并且实验验证了2×1和3×1的MISO OFDM-VLC系统传输。分别测量了2×1和3×1的实验系统的误差矢量幅度(EVM)随输入电压变化的曲线图，找出了两个系统各自的最佳偏置范围。在将输入电压设置在最佳偏置范围之内的情况下，改变传输距离，对2×1系统，给出了系统EVM性能变化的曲线图；对3×1系统，给出了系统EVM和误码率(BER)性能变化的曲线图。在没有任何均衡的情况下，两个系统的传输距离都可以长达140 cm。
光通信 可见光通信 正交频分复用 副载波复用 多输入单输出 白光LED 中国激光
2012, 39(11): 1105001
复旦大学通信科学与工程系专用集成电路与系统国家重点实验室， 上海 200433
随着波分复用(WDM)、偏振复用(PDM)和高阶调制等技术的使用，单模光纤的传输容量已经快速接近其香农极限。目前有望突破该极限的方法是空分复用(SDM)，这使得多模光纤重新受到关注。基于多模光纤的多输入多输出(MIMO)技术是解决信息爆炸式增长的新领域。研究并比较了光MIMO系统的各种实现方式，其中重点介绍了模群分集复用(MGDM)技术；同时也阐述了相干多输入多输出系统(COMIMO)相应的内容。最后指出多模光纤MIMO系统中存在的问题，以期对以后的研究有所裨益。
光通信 多模光纤 多输入多输出 波分复用 正交频分复用 模群分集复用 激光与光电子学进展
2011, 48(10): 100601
