Vittoria Bruni;Rosanna Campagna;Michela Tartaglione;Domenico Vitulano
{"title":"Instantaneous Frequency Estimation via Spectrogram Projection and P-Spline Approximation","authors":"Vittoria Bruni;Rosanna Campagna;Michela Tartaglione;Domenico Vitulano","doi":"10.1109/LSP.2025.3610345","DOIUrl":"https://doi.org/10.1109/LSP.2025.3610345","url":null,"abstract":"Frequency Modulated (FM) signals are usually characterized by two or more components having different waveforms and time-dependent frequencies. The estimation of the instantaneous frequency (IF) represents a very challenging topic when there are two or more interfering components. In this case, available approaches, like the reassignment-based ones, fail in correspondence to the interference region, where IFs of each individual mode are not far enough to be considered separable. In this paper, a novel approach for IF estimation based on spectrogram analysis is proposed. Firstly, it is proved that the projection of signal spectrogram on the temporal axis is itself an amplitude and frequency modulated signal. Its IF depends on the instantaneous frequencies of the individual signal components and the functional dependence can be explicitely given. Then, under proper assumptions, a regression method for the individual IFs estimation is provided using a few selected ’good’ points lying in the interference region. The regression method benefits from a penalized-spline (P-spline) model where a second-order discrete penalty term is also used. Experimental results show that the proposed model is very effective to estimate the individual IFs of multicomponent FM signals in the interference region, making it a suitable method for correcting reassignment estimation where the separability condition is not satisfied.","PeriodicalId":13154,"journal":{"name":"IEEE Signal Processing Letters","volume":"32 ","pages":"3725-3729"},"PeriodicalIF":3.9,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145210042","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ali Javidani;Babak Nadjar Araabi;Mohammad Amin Sadeghi
{"title":"Beyond Augmentation: Leveraging Inter-Instance Relation in Self-Supervised Representation Learning","authors":"Ali Javidani;Babak Nadjar Araabi;Mohammad Amin Sadeghi","doi":"10.1109/LSP.2025.3610549","DOIUrl":"https://doi.org/10.1109/LSP.2025.3610549","url":null,"abstract":"This letter introduces a novel approach that integrates graph theory into self-supervised representation learning. Traditional methods focus on intra-instance variations generated by applying augmentations. However, they often overlook important inter-instance relationships. While our method retains the intra-instance property, it further captures inter-instance relationships by constructing <inline-formula><tex-math>$k$</tex-math></inline-formula> -nearest neighbor (KNN) graphs for both teacher and student streams during pretraining. In these graphs, nodes represent samples along with their latent representations. Edges encode the similarity between instances. Following pretraining, a representation refinement phase is performed. In this phase, Graph Neural Networks (GNNs) propagate messages not only among immediate neighbors but also across multiple hops, thereby enabling broader contextual integration. Experimental results on CIFAR-10, ImageNet-100, and ImageNet-1K demonstrate accuracy improvements of 7.3%, 3.2%, and 1.0%, respectively, over state-of-the-art methods. These results highlight the effectiveness of the proposed graph-based mechanism.","PeriodicalId":13154,"journal":{"name":"IEEE Signal Processing Letters","volume":"32 ","pages":"3730-3734"},"PeriodicalIF":3.9,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145210099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tao Wang;Hui Wang;Yunli Zhu;Xinang Fan;Guoliang Luo
{"title":"Infrared-Visible Object Detection via Distillation-Fermentation Dual Processing","authors":"Tao Wang;Hui Wang;Yunli Zhu;Xinang Fan;Guoliang Luo","doi":"10.1109/LSP.2025.3610025","DOIUrl":"https://doi.org/10.1109/LSP.2025.3610025","url":null,"abstract":"This paper proposes a novel dual-processing framework for infrared-visible object detection, inspired by the fermentation-distillation paradigm in traditional Chinese liquor brewing. To address the complementary characteristics of RGB and thermal modalities, we first design a Dual-stage Feature Complementary Fusion module (DFCF) that sequentially performs coarse and fine processing on cross-modal features. Subsequently, a Polymorphic Convolution module (PCM) is developed by extending the YOLOv11 architecture with variable kernels and channel separation strategies. Furthermore, an Adaptive Semantic Aggregation module (ASA) effectively integrates shallow boundary details with deep semantic features. Extensive experiments on multiple datasets demonstrate that our method achieves superior performance compared to widely adopted approaches, with particularly significant improvements in challenging scenarios like low-light conditions. The ablation studies validate the contributions of each proposed component.","PeriodicalId":13154,"journal":{"name":"IEEE Signal Processing Letters","volume":"32 ","pages":"3680-3684"},"PeriodicalIF":3.9,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145210041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Research on Distributed Synthetic Aperture Passive Positioning and Optimal Geometric Configuration","authors":"Junhua Yang;Hao Huan;Ziming Xu;Ran Tao","doi":"10.1109/LSP.2025.3610355","DOIUrl":"https://doi.org/10.1109/LSP.2025.3610355","url":null,"abstract":"Synthetic aperture passive positioning (SAPP) has gradually become a hot spot in radiation source location research. However, there are relatively few studies on three-dimensional synthetic aperture passive positioning methods. Moreover, synthetic aperture passive positioning is significantly affected by residual frequency offsets (RFO) resulting from noncooperative operation between transceivers. To address the challenges, a distributed synthetic aperture passive positioning method is proposed. Considering frequency synchronization among platforms, this method leverages the SAPP algorithm to obtain high-precision slant angles. Subsequently, it formulates positioning equations related to the 3D target position and RFO. The distributed geometric configuration is studied under certain constraints, and the analytical solutions for the optimal configuration are obtained. Space-borne simulations illustrate that the positioning accuracy of the proposed method is an order of magnitude higher compared to that of the FOA, FDOA, and DOA methods. Additionally, airborne experiments indicate that in the presence of RFO, the proposed method improves the positioning accuracy by two orders of magnitude and exhibits strong convergence properties.","PeriodicalId":13154,"journal":{"name":"IEEE Signal Processing Letters","volume":"32 ","pages":"3685-3689"},"PeriodicalIF":3.9,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145210044","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An Yan;Lan Lan;Xiaorui Li;Shengqi Zhu;Ximin Li;Guisheng Liao
{"title":"Recognition of LPI Radar Waveforms via RCMNet in Low SNR Scenarios","authors":"An Yan;Lan Lan;Xiaorui Li;Shengqi Zhu;Ximin Li;Guisheng Liao","doi":"10.1109/LSP.2025.3609636","DOIUrl":"https://doi.org/10.1109/LSP.2025.3609636","url":null,"abstract":"This letter designs a radar convolution-matrix long short-term memory (mLSTM)-based network (RCMNet) for low probability of intercept (LPI) radar waveform recognition. At the modelling stage, the proposed RCMNet architecture operates directly on time-domain I/Q data while incorporating handcrafted interpretable features (including the amplitude and phase) as auxiliary inputs to provide shallow priors for initial signal interpretation. To address the low-SNR challenge, an integrated denoising mechanism is designed in RCMNet, which employs a joint training strategy aiming to optimize both reconstruction loss and cross-entropy loss. Numerical results demonstrate that the devised RCMNet achieves an average recognition accuracy of 88.17% across 12 types of radar waveform at SNR = −15 dB.","PeriodicalId":13154,"journal":{"name":"IEEE Signal Processing Letters","volume":"32 ","pages":"3650-3654"},"PeriodicalIF":3.9,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145141586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Deep Preprocessing Method for Speech Restoration in Parametric Array Loudspeakers via Time-Frequency Domain Modeling","authors":"Wenyao Ma;Yunxi Zhu;Jun Yang","doi":"10.1109/LSP.2025.3609247","DOIUrl":"https://doi.org/10.1109/LSP.2025.3609247","url":null,"abstract":"The parametric array loudspeaker inherently introduces baseband distortions in directional sound applications due to the nonlinear process in air. Recently, DNNs have been used to model this forward process and to generate preprocessed signals for distortion-free speech restoration. However, when trained on real-world audio, the preprocessing network can exploit weaknesses in the forward model, producing adversarial outputs. To address it, we propose a reorganization strategy for the two-stage framework, comprising a causal TF-GridNet for preprocessed signal generation and a modified time-frequency (T-F) domain differential Volterra Filter (DiffVF) as the forward model. The causal TF-GridNet estimates real and imaginary components using a T-F band-split mechanism. The modified forward model integrates the second-order difference and kernel convolution operations of the original time-domain version into the T-F domain, preserving interpretability while stabilizing training. A refined <inline-formula><tex-math>$N$</tex-math></inline-formula>th-order equalization, based on the T-F domain DiffVF model, is implemented as a competitive baseline. Simulated and real-world experiments demonstrate state-of-the-art reconstruction performance of the proposed method across various objective metrics.","PeriodicalId":13154,"journal":{"name":"IEEE Signal Processing Letters","volume":"32 ","pages":"3720-3724"},"PeriodicalIF":3.9,"publicationDate":"2025-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145210043","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"GraphFusion: Robust 3D Detection via Cross-Modal Graph and Uncertainty-Aware Bayesian Fusion","authors":"Huishan Wang;Jie Ma;Jianlei Zhang;Fangwei Chen","doi":"10.1109/LSP.2025.3609243","DOIUrl":"https://doi.org/10.1109/LSP.2025.3609243","url":null,"abstract":"Multimodal 3D object detection significantly enhances perception by fusing LiDAR point clouds and RGB images. However, existing methods often fail to adaptively estimate modality confidence under challenging conditions such as heavy occlusion or sparse point clouds, leading to degraded fusion performance. In this letter, we propose GraphFusion, a multimodal framework that integrates cross-modal graph modeling with Bayesian uncertainty-aware fusion for robust 3D object detection. Specifically, a heterogeneous graph driven by geometric and semantic cues aligns 3D points with 2D pixels. A Bayesian attention mechanism then leverages predictive uncertainty to dynamically reweight modalities, prioritizing high-confidence information and enabling noise-resilient and spatially adaptive fusion. The proposed module is highly generalizable and can be seamlessly integrated into existing detectors as a plug-and-play component. Extensive experiments on KITTI and nuScenes demonstrate that GraphFusion achieves significant accuracy improvements with superior robustness and generalization, especially in complex environments.","PeriodicalId":13154,"journal":{"name":"IEEE Signal Processing Letters","volume":"32 ","pages":"3645-3649"},"PeriodicalIF":3.9,"publicationDate":"2025-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145141585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Efficiently Trained Real Image Dehazing Network With Dual Discrete Priors for Enhanced Naturalness","authors":"Min Woo Kim;Nam Ik Cho","doi":"10.1109/LSP.2025.3608622","DOIUrl":"https://doi.org/10.1109/LSP.2025.3608622","url":null,"abstract":"In this paper, we efficiently train a dehazing network with enhanced performance by introducing new network architectures and objective functions. Our dehazing network uses high-quality discrete priors from a vector quantization network pretrained on clean images. To mitigate the prolonged pretraining time of existing methods, we analyze the metrics related to discrete priors and propose criteria for early stopping, significantly reducing training time. Furthermore, we introduce dual branches, namely the texture and structure branches, into the dehazing network. The branches act as priors, consisting of pretrained components. To enhance naturalness, we apply our new Structure Alignment Loss with the structure branch which is active only during training, and adopt losses in the frequency domain. Moreover, our analysis of the quantization gap between real and synthetic data shows that additional domain adaptation is unnecessary. Experiments demonstrate that our method outperforms strong baselines on real-world datasets.","PeriodicalId":13154,"journal":{"name":"IEEE Signal Processing Letters","volume":"32 ","pages":"3640-3644"},"PeriodicalIF":3.9,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145141584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lu Zhang;Zhongze Liu;Junjie Li;Ziqing Lu;Yuqing Liu
{"title":"A NeRF 3D Based Fish Weighing Model Under Fluctuating Measuring Condition","authors":"Lu Zhang;Zhongze Liu;Junjie Li;Ziqing Lu;Yuqing Liu","doi":"10.1109/LSP.2025.3608626","DOIUrl":"https://doi.org/10.1109/LSP.2025.3608626","url":null,"abstract":"Robust fish weight estimation is vital for sustainable fisheries, preventing overfishing and conserving resources, yet traditional methods are prone to environmental factors causing significant errors. To address the challenge, a vision-based fish weight estimation model is proposed, which generates a half-fish three dimensional point cloud from multi-angle images using neural radiance fields (NeRF), then applies bayesian optimization to identify the optimal hyperplane for full-fish reconstruction. This process estimates the fish volume, which is subsequently used to predict its weight through a generalized linear model. During the validation of the established dataset, the proposed method demonstrates remarkable performance with a mean square error of 0.007, root mean square error of 0.084 and a mean absolute error of 0.070, highlight its considerable application potential.","PeriodicalId":13154,"journal":{"name":"IEEE Signal Processing Letters","volume":"32 ","pages":"3675-3679"},"PeriodicalIF":3.9,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145210082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"An Optimal Hybrid Fake-Acknowledgment Attack Strategy on State Estimation With Energy Constraint","authors":"Yao Li;Jiaxin Zhang;Xiaolin Wang;Xinping Guan","doi":"10.1109/LSP.2025.3606839","DOIUrl":"https://doi.org/10.1109/LSP.2025.3606839","url":null,"abstract":"Security issues of cyber-physical systems have attracted more and more attentions these years. In this letter, we investigate an energy-constrained optimal hybrid fake-acknowledge attack strategy on state estimation over infinite-time domain, where an attacker will choose certain time instants to generate or block (denoted as Phase I and Phase II, respectively) the feedback flag-acknowledgment (ACK) signals based on a given sensory transmission schedule (STS). We first provide an explicit threshold form of the optimal STS under power constraint. Based on this, the optimal attack strategy for Phase I is presented and proved to satisfy a threshold form. We continue to discuss the optimal state distribution at the threshold, which contributes as a bridge to link these two phases, and consequently derive out the optimal attack strategy for Phase II. Moreover, the condition of convergence is also analytically provided. Comparisons with other feasible schedules are accomplished to verify the correctness and effectiveness of our proposed results.","PeriodicalId":13154,"journal":{"name":"IEEE Signal Processing Letters","volume":"32 ","pages":"3804-3808"},"PeriodicalIF":3.9,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145255892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}