{"title":"TransRAD: Retentive Vision Transformer for Enhanced Radar Object Detection","authors":"Lei Cheng;Siyang Cao","doi":"10.1109/TRS.2025.3537604","DOIUrl":"https://doi.org/10.1109/TRS.2025.3537604","url":null,"abstract":"Despite significant advancements in environment perception capabilities for autonomous driving and intelligent robotics, cameras and LiDARs remain notoriously unreliable in low-light conditions and adverse weather, which limits their effectiveness. Radar serves as a reliable and low-cost sensor that can effectively complement these limitations. However, radar-based object detection has been underexplored due to the inherent weaknesses of radar data, such as low resolution, high noise, and lack of visual information. In this article, we present TransRAD, a novel 3-D radar object detection model designed to address these challenges by leveraging the retentive vision transformer (RMT) to more effectively learn features from information-dense radar range-Azimuth–Doppler (RAD) data. Our approach leverages the retentive Manhattan self-attention (MaSA) mechanism provided by RMT to incorporate explicit spatial priors, thereby enabling more accurate alignment with the spatial saliency characteristics of radar targets in RAD data and achieving precise 3-D radar detection across RAD dimensions. Furthermore, we propose location-aware nonmaximum suppression (LA-NMS) to effectively mitigate the common issue of duplicate bounding boxes in deep radar object detection. The experimental results demonstrate that TransRAD outperforms state-of-the-art (SOTA) methods in both 2-D and 3-D radar detection tasks, achieving higher accuracy, faster inference speed, and reduced computational complexity. Code is available at <uri>https://github.com/radar-lab/TransRAD</uri>.","PeriodicalId":100645,"journal":{"name":"IEEE Transactions on Radar Systems","volume":"3 ","pages":"303-317"},"PeriodicalIF":0.0,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143422870","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}
Mengyang Shi;Yesheng Gao;Jiahui Ma;Wenxuan Shi;Bin Yuan;Xingzhao Liu
{"title":"A Novel High-Resolution Imaging Method Based on Nonlinear Wavefront Modulation","authors":"Mengyang Shi;Yesheng Gao;Jiahui Ma;Wenxuan Shi;Bin Yuan;Xingzhao Liu","doi":"10.1109/TRS.2025.3535913","DOIUrl":"https://doi.org/10.1109/TRS.2025.3535913","url":null,"abstract":"Radar can effectively conduct remote sensing detection, but antenna aperture limits the radar system’s azimuth resolution. Generally, the azimuth resolution of radar is the 3-dB beamwidth. To improve the azimuth resolution without changing the antenna aperture, we propose a high-resolution imaging method based on nonlinear wavefront modulation. The differences between the echo signals of different azimuth targets can be increased by applying multiple nonlinear modulations to the electromagnetic (EM) waves in different spatial directions. Then, we present an implementation of the nonlinear wavefront modulator. By changing the plasma state, valuable reference information can be provided for target imaging. Finally, experiments demonstrate the effectiveness of the proposed method. This is the first time a high-resolution imaging method based on plasma wavefront modulation has been reported. The measurement results demonstrate that the proposed method images three targets within a 3-dB beamwidth at the same antenna aperture.","PeriodicalId":100645,"journal":{"name":"IEEE Transactions on Radar Systems","volume":"3 ","pages":"453-466"},"PeriodicalIF":0.0,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143601921","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":"Instantaneous Single-Station Location and Velocity Estimation of Airborne Noncooperative Emitter Using Clutter Angle-Doppler Frequencies","authors":"Yuxuan Zhang;Jianxin Wu;Lei Zhang;Mengya Li","doi":"10.1109/TRS.2025.3534805","DOIUrl":"https://doi.org/10.1109/TRS.2025.3534805","url":null,"abstract":"Due to the unknown location of the noncooperative airborne emitter, their application as external radiation for passive radar is limited. Therefore, its location and velocity estimation is a significant problem. This article first proposes an airborne emitter location and velocity estimation method in airborne passive radar using angle-Doppler frequencies on the clutter spectrum peaks (SPs). First, the frequencies on clutter SPs in each range bin are estimated by the minimum variance distortionless response (MVDR) of clutter with sub-aperture smoothing (SASM) techniques. Second, a parametric approach is proposed to formulate the relationship between the frequencies and parameters of interest. Finally, an intermediate unknown is introduced to simplify the 6-D parameter optimization problem into a 1-D search. The advantages: The proposed method utilizes clutter information to enhance observability of single-station in a short period, and robustly estimate the location and velocity with a closed-form solution. Cramer-Rao lower bound (CRLB) is derived for theoretical analysis. Simulation experiments validate the effectiveness and advantages of the proposed method.","PeriodicalId":100645,"journal":{"name":"IEEE Transactions on Radar Systems","volume":"3 ","pages":"392-405"},"PeriodicalIF":0.0,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143521494","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":"Space-Domain Awareness Using Over-the-Horizon Radar","authors":"Simon Henault;Kyra Czarnowske;Yahia M. M. Antar","doi":"10.1109/TRS.2025.3534521","DOIUrl":"https://doi.org/10.1109/TRS.2025.3534521","url":null,"abstract":"The use of existing over-the-horizon radar (OTHR) systems as space-domain awareness (SDA) sensors is experimentally evaluated by tracking several International Space Station (ISS) passes under different solar activity conditions. Using range and Doppler measurements, a single-frequency ionospheric correction technique is introduced and is shown to be critical to the implementation of accurate SDA using OTHR. This single-frequency technique is also useful for monitoring the ionosphere total electron content (TEC) using a space target without very accurate prior knowledge of its orbital parameters. All measurements and orbit determination results are validated with truth data provided by the National Aeronautics and Space Administration (NASA). Although it is determined that angle-of-arrival (AOA) measurements are not accurate enough for accurate SDA, orbit determination using single-pass observations from a single site are shown to yield position and velocity errors that can be better than 500 m and 0.7 m/s with a radar bandwidth of only 10 kHz. Accurate SDA using OTHR is determined to be possible especially at night or in periods of solar minimum.","PeriodicalId":100645,"journal":{"name":"IEEE Transactions on Radar Systems","volume":"3 ","pages":"349-359"},"PeriodicalIF":0.0,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403945","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}
Liang Zhang;Qinglei Du;Weijian Liu;Hui Chen;Yongliang Wang
{"title":"Range–Doppler Resolution Enhancement of Ground-Based Radar by Data Extrapolation Technique","authors":"Liang Zhang;Qinglei Du;Weijian Liu;Hui Chen;Yongliang Wang","doi":"10.1109/TRS.2025.3533496","DOIUrl":"https://doi.org/10.1109/TRS.2025.3533496","url":null,"abstract":"A method based on data extrapolation is proposed to enhance the range-Doppler (RD) resolution of ground-based radar. The method employs both the bandwidth extrapolation (BWE), a well-known range super-resolution technique, and the time width extrapolation (TWE), an interesting extension of BWE from the fast-time frequency to slow time, to construct the radar returns with larger bandwidth and more pulses. This method consists of two key parts: first performing TWE on the echoes after pulse compression and then performing BWE on the integrated echoes, which can bring better performance because the gain in radar signal processing is fully utilized. Not only this, an improved data extrapolation technique is designed and applied to the proposed method. The improvement is the generalization of the existing linear prediction-based extrapolation method and can ensure that radar resolution is further enhanced if a parameter of the suppression factor is set reasonably. The experiments based on the simulated data and the observations of vehicles on highway by an S-band ground-based radar illustrate that radar resolution can be improved by a factor of at least 3 with almost undistorted RD images and clutter narrowed in Doppler using a conservative suppression factor setting of <inline-formula> <tex-math>$0.5sim 1$ </tex-math></inline-formula>.","PeriodicalId":100645,"journal":{"name":"IEEE Transactions on Radar Systems","volume":"3 ","pages":"290-302"},"PeriodicalIF":0.0,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143360948","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":"OFDM-Based Remote Sensing Using the 4-D Modified Matrix Pencil Method","authors":"Samuel P. Lavery;Tharmalingam Ratnarajah","doi":"10.1109/TRS.2025.3532831","DOIUrl":"https://doi.org/10.1109/TRS.2025.3532831","url":null,"abstract":"Increased demands from communications and remote sensing systems on a limited radio frequency (RF) spectrum motivate design of dual-function radar communications (DFRC) systems. Simultaneously performing dual functions from one system circumvents cross-system interference. Orthogonal frequency-division multiplexing (OFDM) waveforms are common in telecommunications, and echoes from targets can be compared with a transmitted signal to isolate phase shifts related to targets’ ranges, velocities, azimuth angles, and elevation angles. By extending the modified matrix enhancement matrix pencil (MMEMP) technique to four dimensions, and compensating for intercarrier interference (ICI), this article presents a method of estimating the phase shifts and thereby the target parameters. The Cramér-Rao lower bound (CRLB) is derived, and differently parameterized fifth-generation new radio (5G NR)-inspired systems are simulated, demonstrating superior precision to Fourier- and multiple signal classification (MUSIC)-based parameter estimation with a much smaller time-frequency resource block.","PeriodicalId":100645,"journal":{"name":"IEEE Transactions on Radar Systems","volume":"3 ","pages":"318-331"},"PeriodicalIF":0.0,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143422869","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":"Polarization-Agile Jamming Suppression for Dual-Polarized Digital Array Radars","authors":"Zhigang Wang;Jin He;Ting Shu;Ning Zhang;Xiang Lu;Junfeng Wang;Trieu-Kien Truong","doi":"10.1109/TRS.2025.3530404","DOIUrl":"https://doi.org/10.1109/TRS.2025.3530404","url":null,"abstract":"In the realm of modern radar electronic warfare, hostile jamming signals with time-variant polarization states pose a significant challenge to the performance of host radars. This article presents a signal-processing scheme specifically designed to suppress polarization-agile jamming signals in dual-polarized digital array radars (DARs). By innovatively modeling the polarization-agile jamming signal as two orthogonal linearly polarized signals sharing the same elevation-azimuth angle, a direction-cosine estimation and association algorithm tailored for such signals is derived. Furthermore, a spatial covariance matrix reconstruction (CMR) method that uniquely extracts the time-varying polarization parameters of each jamming signal is developed. Building upon this, a spatial-polarization CMR method is devised to effectively suppress all polarization-agile jamming signals. The key innovation lies in achieving adaptive polarization matching during the cancellation process, which sets this scheme apart from conventional radar signal-processing approaches. Simulation results underscore the superiority of the proposed scheme, demonstrating significant performance enhancements over commonly used methodologies.","PeriodicalId":100645,"journal":{"name":"IEEE Transactions on Radar Systems","volume":"3 ","pages":"247-259"},"PeriodicalIF":0.0,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143105941","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":"Identification and High-Accuracy Range Estimation With Doppler Tags in Radar Applications","authors":"Theresa Antes;Paul Schubert;Thomas Zwick;Benjamin Nuss","doi":"10.1109/TRS.2025.3530560","DOIUrl":"https://doi.org/10.1109/TRS.2025.3530560","url":null,"abstract":"Radar sensors are widely used to support further system automation as they reliably provide range, velocity, and angle information for multiple objects. Nevertheless, unique identification of an object is not within the typical function range of radar; often, supportive systems are required. To overcome this limitation, a multipurpose tag concept for fast chirp frequency-modulated continuous wave (FC-FMCW) radar is introduced. The Doppler tag applies an artificial frequency shift following the Doppler phenomenon for unique identification of tagged objects with conventional radar hardware. It enables simultaneous detection and feature estimation of tagged and untagged objects. The idea of the Doppler tag is presented together with a realization and the required signal processing to allow for identification and high-accuracy range estimation. Simulations and measurements are provided to support the overall understanding and prove the functionality of the radar-tag system.","PeriodicalId":100645,"journal":{"name":"IEEE Transactions on Radar Systems","volume":"3 ","pages":"260-271"},"PeriodicalIF":0.0,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143105942","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":"Flexible Compression for Efficient Information Sharing in a Network of Radio Frequency Sensors","authors":"Fraser K. Coutts;John Thompson;Bernard Mulgrew","doi":"10.1109/TRS.2025.3529760","DOIUrl":"https://doi.org/10.1109/TRS.2025.3529760","url":null,"abstract":"The efficient extraction of useful information from radio frequency (RF) sensors is one important application for artificial intelligence (AI) and machine learning (ML) approaches. In particular, there is a desire to maximize efficiency when sharing positioning, navigation, and timing (PNT) information captured by distributed networks of low size, weight, power, and cost (SWAP-C) RF sensors when operating in congested or contested electromagnetic environments (EMEs). By implementing effective PNT information-sharing strategies, these networks can more easily position the sensors or characterize targets of interest. In this work, we propose a novel ML-inspired compression design framework that improves efficiency when sharing PNT information in a network of sensors receiving radar waveforms. In addition, through novel learning procedures, the network can adapt to unforeseen EMEs such that network efficiency can be maintained in the presence of unforeseen RF waveforms and sensor surroundings. We show that our intelligent, model-driven, ML-inspired data reduction strategies can outperform alternative strategies that do not best-utilize the information content of waveforms in the EME. In addition, we demonstrate the ability of our strategies to adapt to changing mission goals by balancing different types of PNT information and learning from developing EMEs.","PeriodicalId":100645,"journal":{"name":"IEEE Transactions on Radar Systems","volume":"3 ","pages":"332-348"},"PeriodicalIF":0.0,"publicationDate":"2025-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143422868","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}
Moritz Kahlert;Tai Fei;Claas Tebruegge;Markus Gardill
{"title":"Stepped-Frequency PMCW Waveforms for Automotive Radar Applications","authors":"Moritz Kahlert;Tai Fei;Claas Tebruegge;Markus Gardill","doi":"10.1109/TRS.2025.3528773","DOIUrl":"https://doi.org/10.1109/TRS.2025.3528773","url":null,"abstract":"Digitally modulated radar systems, such as phase-modulated continuous-wave (PMCW), often struggle with high bandwidth demands for fine-range resolutions, posing challenges for cost-effective automotive applications. To address this issue, we propose an stepped-frequency PMCW (SF-PMCW) radar waveform in which the instantaneous bandwidth of a single pulse is extensively reduced while the range resolution is beyond the theoretical limit imposed by the instantaneous bandwidth. The proposed waveform spans a synthetic bandwidth across multiple pulses, achieving range estimates comparable to those typically achieved with higher instantaneous bandwidths. Simultaneously, the requirements for analog-to-digital converters (ADCs) are relaxed. Simulations have been performed to demonstrate the performance. The results indicate that the proposed SF-PMCW waveform with an instantaneous bandwidth of 100 MHz can achieve range estimates as good as a PMCW waveform with an instantaneous bandwidth of 1 GHz.","PeriodicalId":100645,"journal":{"name":"IEEE Transactions on Radar Systems","volume":"3 ","pages":"233-245"},"PeriodicalIF":0.0,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143105939","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}