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第十四届中国卫星导航年会

作者： Qiongqiong Jia Weipeng Li Tianjin Key Lab for Advanced Signal Processing Civil Aviation University of China

The Popular of Global Navigation Satellite System(GNSS) is attributed to its good ***,the performance of a conventional GNSS receiver is severely degraded or even failed to provide services in complex *** Position Estimation(DPE) combines all the visible satellite signals for energy accumulation in the navigation domain first,and then the navigation solution is estimated directly from the accumulation *** the navigation performance of GNSS can be effectively improved in complex environments by ***,the signal accumulation of DPE requires calculating the correlation values of all the visible satellite signals at each candidate grid in the navigation domain,the computation load of which limits its *** alleviate this problem,a GPU-based parallel implementation of the DPE receiver is designed,which decomposes the operations involved in the joint accumulation into three levels of parallel *** effectiveness of the designed parallel implementation of the DPE receiver is verified by experiment *** the available hardware in our laboratory,the designed DPE implementation improves the efficiency to approximately 146 times on average over the conventional DPE implementation.

关键词： Direct position estimation Complex environments GPU Parallel processing Joint accumulation

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DACNet: Single image Dehazing Network Based on Attention Mechanism

DACNet: Single Image Dehazing Network Based on Attention Mec...

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Intelligent Communications and Computing (ICC), International Conference on

作者： Yongling Liu Ping Han Wanwei Wang Tianjin Key Lab for Advanced Signal Processing Civil Aviation University of China Tianjin China

Aiming at the problem that atmospheric scattering model-based haze removal methods are prone to degradation of haze removal performance due to inaccurate parameter estimation, a single-image haze removal network based on the attention mechanism is proposed for direct restoration of haze-free images. The network consists of encoder and decoder, where the traditional convolution is replaced by combining dilated convolutions with different dilated rates for acquiring and processing haze-related image features. Due to the different weighted information contained in different channel features, an increased attention mechanism is used to enhance the feature representation of important channels through adaptive learning channel features, thereby enabling the encoder to pay more attention to channel information in the haze region. In the encoding and decoding structure, dilated convolution and attention mechanism are used in combination for image dehazing for the first time. By targeting the network to pay attention to the regions with high fog distribution while increasing the sensory field to obtain global information. The method presented in this paper improves the ability of network to process hazy images and brings a new breakthrough in the field of hazy image processing. Experiments show that the algorithm proposed in this paper achieves significant improvements in both subjective and objective indicators comparing with many state-of-the-art methods.

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Infrared Small Target Detection Algorithm Based on Improved DeeplabV3+

Infrared Small Target Detection Algorithm Based on Improved ...

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6th International Conference on Intelligent Computing and signal processing (ICSP)

作者： Mengfei Qi Guimin Jia Tianjin Key Lab for Advanced Signal Processing Civil Aviation University of China Tianjin China

Infrared small target detection aims to segment small targets from the infrared images. Aiming at the problem of infrared small target detection, an improved algorithm is proposed based on DeeplabV3+ network. For the encoding part of DeeplabV3+, considering the small size of infrared small targets, the dilation rate of ASPP module is adjusted to capture the features of small targets more effectively. For the small targets are prone to lose spatial information during feature extraction, a location enhancement module is introduced to supplement accurate location information and to improve the accuracy of detection. In order to preserve detail information, an additional feature map is added from the backbone network to fuse detail information and semantic information for the decoding part of DeeplabV3+. Experimental results have demonstrated that the proposed algorithm is capable of enhancing the detection performance of DeeplabV3+ network in the infrared small target detection task.

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Navigation domain multipath characterization using GNSS direct position estimation in urban canyon environment 35

Navigation domain multipath characterization using GNSS dire...

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35th International Technical Meeting of the Satellite Division of the Institute of Navigation, ION GNSS+ 2022

作者： Huang, Jihong Sun, Rui Yang, Rong Zhan, Xingqun Chen, Wantong School of Aeronautics and Astronautics Shanghai Jiao Tong University Shanghai China Tianjin Key Lab for Advanced Signal Processing Civil Aviation University of China Tianjin China

ISBN: (纸本)9781713871361

Multipath is a common factor that degrade the performance of Global Navigation Satellite System (GNSS), especially in urban canyon and indoor environments. Due to the reflection of surrounding buildings, multiple Non-Line of Sight (NLOS) signals will arrive receiver antenna with various paths, and the Line of Sight (LOS) signals parameters such as the amplitude and phase will suffer significant distortions and fluctuation. However, due to the random feature of temporal, spatial and frequency diversity across the signal bands, it is difficult to accurately characterize the multipath effect. In this paper, a new attempt has been made to characterize the multipath fading in navigation domain using GNSS direct position estimation (DPE) algorithm. Live tests were conducted in viaduct and urban environments in Shanghai with both traditional two-step and DPE algorithm. The results show the robust of DPE no matter the receiver is moving or static. And the navigation domain manifolds for viaduct and urban scenarios are compared to characterize the multipath fading. The results demonstrate the feasibility of navigation domain multipath characterization using GNSS direct position estimation in urban canyon environment. © 2022 by Institute of Navigation. All rights reserved.

关键词： Navigation

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Speech Recognition Model of Civil Aviation Radiotelephony Communication Based on Improved Conformer

Speech Recognition Model of Civil Aviation Radiotelephony Co...

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2022 International Conference on Automation, Robotics and Computer Engineering, ICARCE 2022

作者： Xiao, Zewei Jia, Guimin Shi, Bo Civil Aviation University of China Tianjin Key Lab for Advanced Signal Processing China Civil Aviation University of China College of Electronic Information and Automation Tianjin China

ISBN: (纸本)9781665475488

Radiotelephony communication has a special grammatical structure and pronunciation, and it is difficult to apply the model of generic speech recognition directly to the field of radiotelephony communication. We propose a Conv1DSlide-Conformer model for speech recognition of radiotelephony communication. The sliding-window attention mechanism is used instead of the self-attention mechanism to improve the decoding speed of the model and increase the adaptability of the model to radiotelephony communication. The convolutional module is used instead of the feedforward neural network module to make the encoder focus more on local information. The improved Conformer model processes the FBANK features of radiotelephony communication and can extract high-dimensional features that better fit the characteristics of radiotelephony communication. The use of concatenated temporal classification (CTC) combined with a data augmentation strategy assists training to speed up convergence during model training and reduce the complexity of model training. Decoding is assisted by CTC and language models to improve the performance of speech recognition. The experimental results show that the improved Conformer speech recognition model in this paper reduces the word error rate to 8.1% and 7.8% on the actual Chinese radiotelephony communication speech dataset. © 2022 IEEE.

关键词： Radio telephone

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Modeling of the Multipath Effect on the Vector Tracking Loop

SSRN

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SSRN 2023年

作者： Jia, Qiongqiong Wu, Renbiao Tianjin Key Lab for Advanced Signal Processing Civil Aviation University of China Tianjin300300 China

The vector tracking loop (VTL), where the internal aiding is achieved with multi-channel information sharing, is generally superior to the traditional scalar tracking loop (STL). Multipath effect on the VTL is illustrated and theoretical models of multipath induced tracking bias to the VTL, for both the coherent and non-coherent discriminators, are established. Correctness of the established models are validated by numerical simulations. It is revealed that the multipath induced tracking bias to the VTL is dependent on the code phase offset, which is originated from its internal aiding nature. Conclusions are drawn based on the established models: multipath induced tracking bias to the VTL is not greater than it to the STL in constructive multipath case, while in destructive multipath case, the bias envelop of VTL is not superior to STL. We finally define the positive and negative maximum biases as the maximum VTL bias envelop to stand for the worst case performance. Abnormal phenomenon appears in the maximum VTL bias envelop is also analyzed in detail, with the conclusion that the discriminate curve distortion becomes more severe as the correlator spacing and the relative amplitude of the multipath signal increase. © 2023, The Authors. All rights reserved.

关键词： Global positioning system

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Clutter Suppression of Wind Farm for Airborne Radar Based on EFA

Clutter Suppression of Wind Farm for Airborne Radar Based on...

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2021 CIE International Conference on Radar, Radar 2021

作者： Zhang, Ying Zhang, Xinyun He, Weikun Wang, Xiaoliang Civil Aviation University of China Tianjin Key Lab for Advanced Signal Processing Tianjin China

ISBN: (纸本)9781665498142

With the rapid development of wind power generation, the clutter generated by wind farms may lead to the problems such as decreased detection probability, increased false alarm rate, and target track divergence. Research on the wind farm clutter mitigation technology for airborne radar is vital. Considering the special problems of the wind farm clutter mitigation for airborne radar, such as the less prior information and the more complicated spectrum of the echoes, it is difficult to suppress the wind farm clutter with non-Gaussian and dynamic characteristics. In this paper, the extended factored approach (EFA) algorithm is used to suppress the wind farm clutter through space-time adaptive processing of airborne array radar echoes. The EFA algorithm does not need the prior information of wind farm clutter or a large number of training data and can adaptively form null with a certain width in the Doppler domain. The null is used to suppress the wind farm clutter, which can avoid the interference of the wind farm clutter on the detection of aircraft targets and improve the detection probability of airborne radar. The experiment results verify the effectiveness of the proposed method. © 2021 IEEE.

关键词： airborne radar clutter suppression extended factored approach wind farms

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Path planning based on fuzzy-control Dynamic Window Approach 3

Path planning based on fuzzy-control Dynamic Window Approach

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3rd International Conference on Control and Intelligent Robotics, ICCIR 2023

作者： Chen, Wantong Yang, Qianqian Chen, Min Li, Xiaoqiang Liu, Zhuo Tianjin Key Lab for Advanced Signal Processing Civil Aviation University of China Tianjin China School of Electronic Information and Automation Civil Aviation University of China Tianjin China Beijing Sky Aviation Co. Ltd China Sichuan Jiuzhou Aerocont Technologies Co. Ltd China

ISBN: (纸本)9781510671867

A method integrating rapidly-exploring random tree (RRT) and improved dynamic window approach (DWA) is proposed to realize obstacle avoidance of mobile robots in complex dynamic obstacle environments. Based on the known environment information, the global optimal safe path is generated using the improved RRT algorithm. To address the problem of too many invalid nodes in the expansion of the RRT algorithm, the efficiency of the algorithm is improved by introducing a bidirectional alternating search (BAS) strategy;the forward search tree and the backward search tree alternate searching paths with new nodes as the target nodes until the paths meet;and the redundant nodes in the paths are removed using path node filtering to shorten the path. Secondly, the DWA algorithm is used to track the improved RRT algorithm to plan the path. When unknown obstacles appear in the environment, the weights of the DWA algorithm evaluation function are dynamically adjusted by fuzzy control to avoid the obstacles and return to the original route in time. Finally, the simulation experiments verify that the proposed improved fusion algorithm in complex dynamic environment has short running time, small path cost, and always keeps a safe distance from the obstacles to ensure the optimal path is tracked while safely avoiding the dynamic obstacles. © 2023 SPIE.

关键词： Fuzzy control

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ESA-Net: A network for enhancing small target detection performance in SAR imagery aircraft

ESA-Net: A network for enhancing small target detection perf...

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IET International Radar Conference (IRC 2023)

作者： Ping Han Han Zhao Tianjin Key Lab for Advanced Signal Processing Civil Aviation University of China Tianjin People's Republic of China

ISBN: (数字)9781837240982

In synthetic aperture radar (SAR) image aircraft target detection, aircraft small targets have a lower AP than aircraft targets and large targets due to the small number of pixel points they occupy and background clutter interference. To solve this problem, this paper proposes a network for enhancing the performance of aircraft small target detection for SAR images(ESA-Net). The network is designed based on yolov5s with a backbone network BH-CSPDarknet and a detection head ***-CSPDarknet allocates more computational resources in the shallow layer of the network to process high-resolution feature maps, which effectively extracts richer feature information of aircraft small ***-Head provides appropriate feature preferences for classification and localisation tasks to provide TFA-Head provides appropriate feature information for classification and positioning task feature preferences, which can effectively suppress the background clutter interference while enhancing the aircraft small target features. The experimental results using the SAR-ADRD dataset show that the method improves the average accuracy of YOLOv5s by 1.9% and the average accuracy of aircraft small targets by 15.6%.

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Autonomous Path Planning via Sand Cat Swarm Optimization With Multi-Strategy Mechanism for Unmanned Aerial Vehicles in Dynamic Environment

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IEEE Internet of Things Journal 2025年

作者： Deng, Wu Feng, Jiayi Zhao, Huimin Civil Aviation University of China College of Electronic Information and Automation Tianjin300300 China Civil Aviation University of China Tianjin Key Lab Intelligent Signal and Image Processing Tianjin300300 China State Key Laboratory of Rail Transit Vehicle System of Southwest Jiaotong University Chengdu610031 China

Unmanned Aerial Vehicles (UAVs) face critical challenges in path planning in dynamic environment. Sand Cat Swarm Optimization (SCSO) algorithm has demonstrated promise in addressing complex optimization challenges. However, SCSO is limited by slow convergence, susceptibility to local optima, and insufficient adaptability. To overcome these shortcomings, an enhanced SCSO with the spiral search, Livy flight, tent chaotic mapping, and adaptive sparrow alert mechanism, namely TSLS-SCSO is developed to propose an autonomous path planning method for UAVs in dynamic environment. In TSLS-SCSO, a new population initialization strategy with tent chaotic mapping is designed to achieve a large dynamic range and coverage capability. Then a new spiral search strategy is designed to broaden the search range in the search phase. And a new Livy flight strategy is employed to enrich the diversity of population in the attacking prey phase. A new sparrow alert mechanism with integrating the sand cat group with the sparrow alert is designed to obtain faster convergence speed and accuracy. The experiment results on CEC 2017 and CEC 2022 show that the TSLS-SCSO obtains higher accuracy and more stable solutions and exhibits better competitiveness. Furthermore, the proposed UAV path planning method successfully found effective paths with an obstacle avoidance effectiveness of 95.5%. The obtained results validate the effectiveness and competitiveness of TSLS-SCSO in UAV path planning in the dynamic environment. © 2014 IEEE.

关键词： Unmanned aerial vehicles (UAV)

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