{"title":"High-Precision Time Delay Calibration for Radio Astronomy Radars Based on Maximum Likelihood Iteration","authors":"Quanhua Liu;Bowen Cai;Xinliang Chen;Rui Zhu;Zhennan Liang","doi":"10.1109/LGRS.2025.3549788","DOIUrl":"https://doi.org/10.1109/LGRS.2025.3549788","url":null,"abstract":"In the calibration of distributed radar for radio astronomy, deep space radio sources are commonly used as calibration sources to correct interarray delay errors, and accurate delay estimation is critical. Traditional correlation methods are limited by sampling frequency, achieving accuracy only at the sampling interval level. To achieve higher accuracy, subsample estimation is necessary. This letter proposes a precise delay calibration method using maximum likelihood iteration for subsample delay estimation. The proposed algorithm starts with the frequency domain features, first transforming the delay estimation problem into a phase estimation problem, and then calculating the likelihood function of the phase difference. A cost function is established based on the maximum likelihood criterion, and the optimal solution is obtained using the Newton iteration method. Compared to other algorithms, the proposed algorithm achieves superior accuracy in subsample delay estimation, meeting stringent calibration requirements in radio astronomy. Simulation and experimental results verify the validation of the algorithm.","PeriodicalId":91017,"journal":{"name":"IEEE geoscience and remote sensing letters : a publication of the IEEE Geoscience and Remote Sensing Society","volume":"22 ","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143706708","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Learnable Gabor Filters in Attention Unet for Prestack Seismic Inversion","authors":"Yizhen Shan;Yueming Ye;Bangyu Wu","doi":"10.1109/LGRS.2025.3548983","DOIUrl":"https://doi.org/10.1109/LGRS.2025.3548983","url":null,"abstract":"Amplitude variation with angle (AVA) prestack seismic inversion plays a critical role in oil and gas exploration and mineral resource assessment. Recently, deep learning methods, particularly convolutional neural networks (CNNs), have been widely adopted for seismic inversion. However, many of these methods, especially supervised learning, struggle with poor generalization and noise resistance. Seismic data contains rich texture information that can be used as prior to constrain the convolutional kernels of the network. Gabor functions have long been used for seismic data representation, and learnable Gabor filters improve upon this by dynamically extracting latent seismic data information via adaptively updating Gabor filter parameters. In this letter, we propose a multitask AVA inversion method using learnable Gabor filters within a 2-D multitask attention U-Net. We equip the network’s first layer with learnable Gabor filters for latent seismic data feature extraction to enhance both generalization and noise resistance. An adaptive weight update method (AWUM) is employed to balance multitask learning efficiency and generalization performance. By creating a training dataset that combines synthetic and field seismic data with corresponding labels, we integrate field samples into the network training. Experiments for both synthetic and field datasets demonstrate that the proposed method exhibits superior generalization and stability compared to several existing approaches.","PeriodicalId":91017,"journal":{"name":"IEEE geoscience and remote sensing letters : a publication of the IEEE Geoscience and Remote Sensing Society","volume":"22 ","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143716497","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Deep Spiking Neural Network for Energy-Efficient SAR Ship Detection","authors":"Minjung Yoo;Juhyeon Han;Sunok Kim","doi":"10.1109/LGRS.2025.3549108","DOIUrl":"https://doi.org/10.1109/LGRS.2025.3549108","url":null,"abstract":"In this letter, we introduce the first spiking-based network optimized for synthetic aperture radar (SAR) ship detection and compare its performance with conventional neural networks (CNNs). Spiking neural networks (SNNs) offer significant advantages over traditional artificial neural networks (ANNs) by resulting in highly efficient computation. Unlike ANNs, SNNs only perform calculations when spikes occur, leading to lower power consumption and reduced computational costs, making them ideal for energy-constrained and onboard applications. Furthermore, we conduct experiments to analyze the power differences between the SNN and traditional ANN-based detection models. The results demonstrate the potential advantages of SNNs in terms of power efficiency and computational load in satellite-based target detection.","PeriodicalId":91017,"journal":{"name":"IEEE geoscience and remote sensing letters : a publication of the IEEE Geoscience and Remote Sensing Society","volume":"22 ","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143716483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Unsupervised Diffusion Model for Seismic Deconvolution","authors":"Hongzhi Yu;Wenchao Chen;Xiaokai Wang;Dawei Liu","doi":"10.1109/LGRS.2025.3549055","DOIUrl":"https://doi.org/10.1109/LGRS.2025.3549055","url":null,"abstract":"Seismic data deconvolution is vital for enhancing resolution and accurate subsurface interpretation. Traditional methods heavily rely on predefined assumptions that limit their robustness to noisy data. As state-of-the-art generative models, diffusion models excel in capturing accurate prior distributions, which are beneficial to inversion. Moreover, diffusion models inherently resist noise due to their training in reverse noisy processes. Building on this foundation, we introduce an unsupervised diffusion model for seismic deconvolution, leveraging diffusion posterior sampling (DPS) to incorporate observed seismic data into the sampling process to guide high-accuracy reflectivity generation. Unlike traditional single-trace approaches, our method performs deconvolution across entire 2-D profiles, effectively capturing spatial continuity. Though solely trained on synthetic data, our method exhibits satisfactory performance when applied to synthetic and field datasets, demonstrating strong noise resistance and remarkable generalization capabilities.","PeriodicalId":91017,"journal":{"name":"IEEE geoscience and remote sensing letters : a publication of the IEEE Geoscience and Remote Sensing Society","volume":"22 ","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143748771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Qianru Hou;Zhiwen Duan;Jianping Zong;Jianda Han;Hongpeng Wang
{"title":"BKD-CL: Balanced Knowledge Distillation-Contrastive Learning for Distribution-Unknown Generalized Category Discovery in SAR ATR","authors":"Qianru Hou;Zhiwen Duan;Jianping Zong;Jianda Han;Hongpeng Wang","doi":"10.1109/LGRS.2025.3548978","DOIUrl":"https://doi.org/10.1109/LGRS.2025.3548978","url":null,"abstract":"Open-environment machine learning is crucial for category discovery in synthetic aperture radar automatic target recognition (SAR ATR). However, SAR ATR toward intelligent applications requires addressing not only open-world distributions but also data imbalance. In this letter, we first propose the distribution-unknown generalized category discovery (DUGCD) problem and introduce the balanced knowledge distillation-contrastive learning (BKD-CL) framework, which includes the frequency attention ViT (FAViT) module and a multilayer perceptron (MLP) projection head. Second, we optimize the loss function using both supervised and self-supervised contrastive learning methods to learn feature representations from labeled and unlabeled data. We also implement self-distillation and entropy regularization to facilitate knowledge training for a parameterized classifier aimed at classification learning. Finally, to tackle the issue of data imbalance, we introduce balanced knowledge distillation, which selectively transfers knowledge using weighted coefficients to address the poor recognition performance caused by imbalanced data distributions. Extensive experiments conducted on the MSTAR dataset demonstrate the superiority of our proposed method.","PeriodicalId":91017,"journal":{"name":"IEEE geoscience and remote sensing letters : a publication of the IEEE Geoscience and Remote Sensing Society","volume":"22 ","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143667473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Azimuth Multichannel SAR Signal Recovery for One Channel Data Completely Missing","authors":"Zonglin Yang;Zhimin Zhang;Huaitao Fan;Chen Zhen;Yongwei Zhang","doi":"10.1109/LGRS.2025.3548989","DOIUrl":"https://doi.org/10.1109/LGRS.2025.3548989","url":null,"abstract":"The high-resolution wide-swath synthetic aperture radar (HRWS SAR) system enables achieving comprehensive and extensive ground information more accurately and rapidly, enhancing the precision of target detection, identification, confirmation, and description. A common implementation approach of it is azimuth multichannel synthetic aperture radar (SAR), which has become a research hot spot in the field of SAR in recent years. In practice, there is a situation where a channel failure leads to the loss of corresponding data, and in such cases, it is impossible to obtain a high-resolution wide-swath image of quality. Currently, there is no good method to address the data recovery issue for one channel data completely missing. To solve this problem, in this letter, a scheme based on iteration adaptive approach (IAA) and weighted least squares method is proposed for azimuth multichannel SAR missing channel data recovery. Point target simulations and data generated from airborne SAR system demonstrate that the proposed scheme is effective.","PeriodicalId":91017,"journal":{"name":"IEEE geoscience and remote sensing letters : a publication of the IEEE Geoscience and Remote Sensing Society","volume":"22 ","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143667472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Dual-Branch Cross Weighting Network for Multimodal Hyperspectral Unmixing","authors":"Ziang Jiao;Yongsheng Dong;Chongchong Mao;Lintao Zheng","doi":"10.1109/LGRS.2025.3549218","DOIUrl":"https://doi.org/10.1109/LGRS.2025.3549218","url":null,"abstract":"Hyperspectral unmixing has recently attracted much attention in the field of spectral image analysis. Unsupervised methods based on autoencoder can achieve excellent unmixing performance. However, these methods have unsatisfactory unmixing results for different substances with similar materials in complex scenarios. In this letter, we propose a new dual-branch cross weighting network (DCWNet) for multimodal hyperspectral unmixing. It can not only use the spectral feature information of spectral images but also acquire the spatial feature information of light detection and ranging (LiDAR) data simultaneously. Specifically, we build a spatial channel augmentation (SCA) block to help the network acquire spatial information more accurately from the horizontal, vertical, and channel aspects, respectively. We further construct an adaptive feature selection module for effectively using the spectral feature information and spatial feature information to better focus on the discrimination of materials in the scene through weighting fusion. Experimental results on two real multimodal datasets demonstrate the competitiveness and effectiveness of our proposed DCWNet in comparison to five representative methods.","PeriodicalId":91017,"journal":{"name":"IEEE geoscience and remote sensing letters : a publication of the IEEE Geoscience and Remote Sensing Society","volume":"22 ","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143716498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Robust Sparse Unmixing via Continuous Mixed Norm to Address Mixed Noise","authors":"Jincheng Gao;Jiayu Shi;Fei Zhu","doi":"10.1109/LGRS.2025.3548697","DOIUrl":"https://doi.org/10.1109/LGRS.2025.3548697","url":null,"abstract":"Sparse unmixing, a critical task in hyperspectral image interpretation, aims to identify an optimal subset of endmembers from a predefined library and estimate the fractional abundances for each pixel. However, in real-world scenarios, various types of noise significantly degrade the performance of conventional sparse unmixing methods that usually rely on <inline-formula> <tex-math>$ell _{2}$ </tex-math></inline-formula>-norm loss function. To address this issue, this letter proposes a robust sparse unmixing method based on the continuous mixed norm (CMN), which exhibits resilience to mixed noise, particularly non-Gaussian impulsive noise. By adopting CMN as the reconstruction loss function, we formulate both the standard sparse unmixing problem and its augmented version with total variation (TV) regularizer for spatially piecewise smoothness. The corresponding algorithms are derived using the alternating direction method of multipliers (ADMM). Experiments on both synthetic and real hyperspectral datasets validate the effectiveness and robustness of the proposed method in handling diverse and mixed noise conditions over comparing methods. The code is available at: <uri>https://github.com/JinchengGao/CMNSU</uri>.","PeriodicalId":91017,"journal":{"name":"IEEE geoscience and remote sensing letters : a publication of the IEEE Geoscience and Remote Sensing Society","volume":"22 ","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143688123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Knowledge Graph-Guided Deep Network for Hyperspectral Remote Sensing Image Classification","authors":"Ruijie Tang;Li Ma;Yansheng Li;Qian Du","doi":"10.1109/LGRS.2025.3548757","DOIUrl":"https://doi.org/10.1109/LGRS.2025.3548757","url":null,"abstract":"For the classification of hyperspectral images (HSIs), most deep learning networks are data-driven and lack the usage of prior knowledge. In this letter, we propose a knowledge graph-guided classification network (KGNet), attempting to utilize the prior knowledge of land cover categories to enhance the classification performance. We first construct a knowledge graph on several hyperspectral scenes, which can characterize not only the attributes of land cover categories but also the rich connections between categories. Semantic features are then derived to represent the knowledge in the graph. Knowledge-guided learning is achieved by performing feature alignment between semantic and visual features. Finally, classification is performed on visual features that have contained the knowledge from semantic features. Experiments on three datasets demonstrate the effectiveness of applying the knowledge graph for the classification of hyperspectral remote sensing images.","PeriodicalId":91017,"journal":{"name":"IEEE geoscience and remote sensing letters : a publication of the IEEE Geoscience and Remote Sensing Society","volume":"22 ","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143688073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Assessing the Potential Impact of Microwave Sounders on Typhoon Prediction Using OSSEs: A Comparative Study Between LEO Constellation and GEO Satellites","authors":"Ke Chen;Zihao Suo;Wei Han;Bowen Cai;Yingying Chen","doi":"10.1109/LGRS.2025.3548908","DOIUrl":"https://doi.org/10.1109/LGRS.2025.3548908","url":null,"abstract":"Microwave sounders aboard small satellite constellations in low Earth orbit (LEO) and geostationary orbit (GEO) satellites represent two promising approaches to improve the temporal resolution of microwave atmospheric observations. A observing system simulation experiment (OSSE) is an effective means to assess the potential contribution of future observations to numerical weather prediction (NWP). Using the established GEO microwave OSSE framework and nature run (NR) data from the CMA-MESO model, this study aims to compare the OSSE results of microwave sounders on a LEO constellation (LEO-C) and a GEO satellite against those derived from the current LEO microwave observations. The cross-comparative analysis reveals that the assimilation of microwave observations from the LEO-C and the GEO satellite into the CMA-GFS model significantly improves typhoon track prediction compared with current LEO microwave observations.","PeriodicalId":91017,"journal":{"name":"IEEE geoscience and remote sensing letters : a publication of the IEEE Geoscience and Remote Sensing Society","volume":"22 ","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143716481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}