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340 results on '"Li, Nianqiang"'

6. An RF-source-free microwave photonic radar with an optically injected semiconductor laser for high-resolution detection and imaging

Author

Zhou, Pei, Zhang, Rengheng, Li, Nianqiang, Jiang, Zhidong, and Pan, Shilong

Subjects
Electrical Engineering and Systems Science - Signal Processing, Physics - Optics
Abstract

This paper presents a novel microwave photonic (MWP) radar scheme that is capable of optically generating and processing broadband linear frequency-modulated (LFM) microwave signals without using any radio-frequency (RF) sources. In the transmitter, a broadband LFM microwave signal is generated by controlling the period-one (P1) oscillation of an optically injected semiconductor laser. After targets reflection, photonic de-chirping is implemented based on a dual-drive Mach-Zehnder modulator (DMZM), which is followed by a low-speed analog-to-digital converter (ADC) and digital signal processer (DSP) to reconstruct target information. Without the limitations of external RF sources, the proposed radar has an ultra-flexible tunability, and the main operating parameters are adjustable, including central frequency, bandwidth, frequency band, and temporal period. In the experiment, a fully photonics-based Ku-band radar with a bandwidth of 4 GHz is established for high-resolution detection and inverse synthetic aperture radar (ISAR) imaging. Results show that a high range resolution reaching ~1.88 cm, and a two-dimensional (2D) imaging resolution as high as ~1.88 cm x ~2.00 cm are achieved with a sampling rate of 100 MSa/s in the receiver. The flexible tunability of the radar is also experimentally investigated. The proposed radar scheme features low cost, simple structure, and high reconfigurability, which, hopefully, is to be used in future multifunction adaptive and miniaturized radars.

Published
2021

8. Improving Apple Detection Using RetinaNet

Author

Ma, Zhen, Li, Nianqiang, Angrisani, Leopoldo, Series Editor, Arteaga, Marco, Series Editor, Panigrahi, Bijaya Ketan, Series Editor, Chakraborty, Samarjit, Series Editor, Chen, Jiming, Series Editor, Chen, Shanben, Series Editor, Chen, Tan Kay, Series Editor, Dillmann, Rüdiger, Series Editor, Duan, Haibin, Series Editor, Ferrari, Gianluigi, Series Editor, Ferre, Manuel, Series Editor, Hirche, Sandra, Series Editor, Jabbari, Faryar, Series Editor, Jia, Limin, Series Editor, Kacprzyk, Janusz, Series Editor, Khamis, Alaa, Series Editor, Kroeger, Torsten, Series Editor, Li, Yong, Series Editor, Liang, Qilian, Series Editor, Martín, Ferran, Series Editor, Ming, Tan Cher, Series Editor, Minker, Wolfgang, Series Editor, Misra, Pradeep, Series Editor, Möller, Sebastian, Series Editor, Mukhopadhyay, Subhas, Series Editor, Ning, Cun-Zheng, Series Editor, Nishida, Toyoaki, Series Editor, Pascucci, Federica, Series Editor, Qin, Yong, Series Editor, Seng, Gan Woon, Series Editor, Speidel, Joachim, Series Editor, Veiga, Germano, Series Editor, Wu, Haitao, Series Editor, Zamboni, Walter, Series Editor, Zhang, Junjie James, Series Editor, Yao, Jian, editor, Xiao, Yang, editor, You, Peng, editor, and Sun, Guang, editor

Published
2022
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14. Microwave Phase Noise Analyzer Based on Photonic Delay-Matched Frequency Translation

Author

Zhou, Pei, Jiang, Zhidong, Tang, Zhigang, Li, Nianqiang, and Pan, Shilong

Abstract

A wideband and high-sensitivity microwave phase noise measurement approach is proposed and experimentally demonstrated based on photonic delay-matched frequency translation. In this scheme, the signal under test (SUT) is down-converted to a lower intermediate frequency (IF) signal using a local oscillator (LO) signal, effectively extending the operation bandwidth beyond the limitations imposed by electrical devices. Additionally, the residual phase noise introduced by the LO signal can be effectively suppressed by matching the time delays of the two down-conversion branches, thus eliminating the need for a high-performance reference source. Consequently, the proposed phase noise measurement technique offers a large operation bandwidth and high sensitivity compared to traditional frequency-discriminator-based method. Our experimental results demonstrate accurate phase noise measurement of SUTs within a large operation bandwidth ranging from 10 to 40 GHz. A high measurement sensitivity of −134.13 dBc/Hz@10 kHz is achieved with a 2-km single-mode fiber, which can be further enhanced by applying a longer fiber. In summary, our proposed approach presents a promising solution for evaluating wideband tunable and ultralow phase noise microwave signals.

Published
2024
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25. A Method of Reducing Output Waveform Distortion in Photovoltaic Converter System

Author

Xu, Huixiang, Li, Nianqiang, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Weikum, Gerhard, Series editor, Huang, De-Shuang, editor, Han, Kyungsook, editor, and Hussain, Abir, editor

Published
2016
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26. A Control Strategy of Depressing the Voltage Spike During Soft-Switch Based on the Method of PI in Photovoltaic Converter System

Author

Xu, Huixiang, Li, Nianqiang, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Weikum, Gerhard, Series editor, Huang, De-Shuang, editor, and Jo, Kang-Hyun, editor

Published
2016
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35. An Enhanced Photonic Spiking Neural Network Based on the VCSEL-SA for Recognition and Classification

Author

Zhang, Yupeng, Huang, Yu, Yang, Yigong, Feng, Yuhang, Zhou, Pei, Xiang, Shuiying, and Li, Nianqiang

Abstract

Neuromorphic computation based on physical devices has attracted wide attention due to its high performance in solving specific tasks. The chosen devices usually imitate the way the brain transmits information and calculates. However, the majority of existing encoding methods for neuromorphic computation rely on either rate or temporal information, resulting in inefficiency in accomplishing computing tasks. Here, we present an efficient and biologically plausible encoding method for a photonic spiking neural network (PSNN) based on vertical-cavity surface-emitting lasers with an embedded saturable absorber (VCSELs-SA). In the proposed method, the date information is encoded into the strength of the injection rectangular pulse and then converted into spikes emitted by VCSELs-SA. We can obtain timing and threshold characteristics by adjusting the injection intensity which is beneficial to process the data in the following steps. The encoding method is verified by recognizing four spiking patterns and four expressions. Furthermore, we classify the Iris data set based on the encoding method with only four pre-neurons and two post-neurons. The encoding method and structure further explore the application of PSNN to pave the way for the hardware implementation.

Published
2024
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