- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
[IEEE 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Odessa (2018.9.4-2018.9.7)] 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - High Resolution Measurements and Characterization of Urban, Suburban and Country Clutter at X-Band and Related Radar Calibration
摘要： At Tor Vergata University we are working on measurements and phenomenological characterization of urban, suburban and country radar clutter at X-band (3 cm wavelength, range resolution 8 to 10 m, azimuth resolution @ 1 km about 23.5 m) and on the related radar calibration problems. Measurements are 'high resolution' when compared to most surveillance radars, and the related applications are in the frame of clutter maps for cognitive radar, drones detection, radar ornithology, and more. After calibration, done using opportunity targets with known radar cross section and a clutter fence, we carry on an analysis and a comparison of land clutter, considering different weather conditions: dry and wet soil, as well as the rare event of snow. Using fixed opportunity targets, such as lamppost and/or a large cylindrical steel tanker, we describe the attenuation effects due to the natural clutter fence (in this case due to cane thicket near to the target position) and its mitigation when the natural fence is gradually removed. Finally, but importantly, we analyze the multipath phenomenon due to reflection/scattering on ground, and propose a procedure to estimate the multipath factor and to correct for it.
关键词： urban clutter,radar calibration,high resolution radar,multipath,X-band
更新于2025-09-23 15:23:52
-
[IEEE 2018 International Carnahan Conference on Security Technology (ICCST) - Montreal, QC, Canada (2018.10.22-2018.10.25)] 2018 International Carnahan Conference on Security Technology (ICCST) - Microwave Quantum Radar: An Experimental Validation
摘要： We describe an experiment which comes very close to implementing a quantum radar based on entangled microwaves. A pair of entangled microwave beams are generated using a Josephson parametric amplifier (JPA) and measured by a pair of digitizers after amplification. We present a receiver operating characteristic (ROC) curve for the case where the signal power at the digitizers is ?83.84 dBm (corresponding to a JPA power output, before amplification, of ?148.26 dBm), as well as for a classically correlated source which attempts to approximate the covariance structure of the entangled JPA signals. The entangled signals are seen to be clearly superior to the classically correlated signals. Although the latter is still interesting from a noise radar perspective, this demonstrates that attempting to simulate entanglement with classical signals causes a measurable decrease in correlation. Our experiment validates the feasibility and desirability of a microwave quantum radar.
关键词： entanglement,Quantum radar,microwave,noise radar,correlation
更新于2025-09-23 15:23:52
-
Based on Spectrum Modeling and Optimization
摘要： Bistatic synthetic aperture radar (SAR) is able to break through the limitation of monostatic SAR on forward-looking area imaging with appropriate geometry configurations. Thanks to such an ability, bistatic forward-looking SAR (BFSAR) has extensive potential practical applications. For the focusing problem of conventional side-looking SAR, ω–k algorithm is accepted as the ideal solution. In this paper, the ω–k algorithm will be discussed in BFSAR geometry. As for the bistatic configuration, spatial domain linearization procedure should be carried out to extract a range variable from the point target reference spectrum (PTRS) in the existing ω–k algorithms. With respect to the BFSAR geometry, nevertheless, the linearization procedure reduces the accuracy of PTRS seriously. To cope with such a problem, a novel ω–k algorithm for BFSAR is proposed. In the proposed method, the range variable is modeled as a parameterized polynomial, and the corresponding PTRS with respect to two-dimensional frequencies is established. Then, the parameters are estimated by differential evolution to minimize the PTRS errors for each range coordinate and frequency point. Based on the estimated PTRS, the BFSAR data can be focused well by the proposed ω–k algorithm. Simulation results verify the effectiveness of the proposed method.
关键词： Bistatic forward-looking synthetic aperture radar (BFSAR),differential evolution (DE),ω–k,point target reference spectrum (PTRS)
更新于2025-09-23 15:23:52
-
[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Ship Discrimination with Deep Convolutional Neural Networks in Sar Images
摘要： With the advantages of all-time, all-weather, and wide coverage, synthetic aperture radar (SAR) systems are widely used for ship detection to ensure marine surveillance. However, the azimuth ambiguity and buildings exhibit similar scattering mechanisms of ships, which cause false alarms in the detection of ships. To address this problem, self-designed deep convolutional neural networks with the capability to automatically learn discriminative features is applied in this paper. Two datasets, including one dataset reconstructed from IEEEDataPort SARSHIPDATA and the other constructed from 10 scenes of Sentinel-1 SAR images, are used to evaluate our approach. Experimental results reveal that our model achieves more than 95% classification accuracy on both datasets, demonstrating the effectiveness of our approach.
关键词： ship discrimination,Sentinel-1 images,synthetic aperture radar,deep convolutional neural networks
更新于2025-09-23 15:23:52
-
[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Coastal Application of Sea Surface Height Measurement Using Direct Broadcast Satellite Signals
摘要： This paper presents results from a proof-of-concept experiment conducted at Platform Harvest to measure Sea Surface Height (SSH) using Ku- and K-band 'Signals of Opportunity' (SoOp) from DirecTV Direct Broadcast Satellite (DBS) system. The retrieved SSH was compared with the SSH measurement from a tide gauge located at the platform; the error in retrieval of Ku-band and K-band was found to be 2.78 cm and 2.58 cm, respectively. This matched the model for error with some differences that can be attributed to the difference in spatial and temporal characteristics of the SoOp and tide gauge measurements. Finally, this paper gives an overview of temporal and spatial sampling possible from a constellation of receivers observing Ku-band SoOp to resolve mesoscale eddies in coastal regions.
关键词： bistatic radar,Wideband Signals of Opportunity,coastal altimetry
更新于2025-09-23 15:23:52
-
Automatic bathymetry retrieval from SAR images
摘要： Bathymetry, the topography of the sea floor, is in high demand due to the increase in offshore constructions like wind parks. It is also an important dataset for climate change modelling, when sea level rises and changes in circulation currents are to be simulated. The retrieval of accurate bathymetry data is a cost-intensive task usually requiring a survey vessel charting the respective area. However, bathymetry can also be retrieved remotely using data from Earth observation satellites. The main point of this study is the development of a processor that allows the automatic derivation of gridded bathymetry information from spaceborne Synthetic Aperture Radar (SAR) data. Observations of sea state modifications in SAR images are used to derive the bathymetry in shelf areas using the shoaling effect, which causes wavelengths to become shorter when reaching shallower waters. The water depth is derived using the dispersion relation for surface water waves, which requires wavelength and wave period as input parameters. While the wavelength can be directly retrieved from the SAR image, for the peak period additional information and procedures are required, e.g. local measurements or complex SAR data. A method for automatically deriving the wave period for swell waves in SAR images was developed and tested in this paper. It uses depth data from public databases as initial values which are compared to derived depths iterating through possible peak periods along the calculation grid; the peak period resulting in a minimal root-mean-square deviation is then used for bathymetry calculation. The bathymetry derived from a TerraSAR-X acquisition of the Channel Islands is presented; the resulting peak wave period of 11.3 s fits well to nearby in situ measurement data.
关键词： Bathymetry,Remote sensing,Near-real time processing,Synthetic aperture radar
更新于2025-09-23 15:23:52
-
Co-polarization channel imbalance phase estimation by corner-reflector-like targets
摘要： Polarimetric calibration is a critical step to suppress the potential system distortion before implementing any applications for polarimetric synthetic aperture radar (PolSAR). Among all the distortion elements, the crosstalk and cross-pol channel imbalance are generally estimated by the use of natural media, and the co-pol channel imbalance is traditionally solved by the use of corner reflectors (CRs). However, the deployment of ground CRs is costly and may even be impossible in some areas. Many bright point targets, such as poles, lamps, and corner points of structures, are commonly found in manmade regions. In particular, if the object orientation is parallel or perpendicular to the radar flight direction, some points will present similar polarimetric responses to trihedral or dihedral CRs. These points, which are referred to here as "CR-like targets", can be treated as a supplement to approximately solve the system distortion elements when CRs are unavailable. In this paper, we propose a novel step-by-step algorithm to determine the CR-like targets and estimate the co-pol channel imbalance phase in uncalibrated PolSAR imagery. Chinese X-band airborne and C-band satellite PolSAR data were used to test the proposed method. Compared with the CR-derived co-pol channel imbalance phase, the solution errors of the CR-like targets were 1.305° and 0.03° for the X- and C-band experiments, respectively. The results of the experiments confirm that the solutions of the CR-like targets are very close to those of ground-deployed CRs, and the proposed method can be considered as an effective way to calibrate PolSAR images when sufficient CR-like point targets are detected in manmade regions.
关键词： Corner reflector,Polarimetric synthetic aperture radar,Calibration,Target detection
更新于2025-09-23 15:23:52
-
Full waveform inversion based on inequality constraint for cross-hole radar
摘要： Cross-hole radar is an effective method for geophysical exploration of underground geological conditions. Besides cross-hole radar, some geological information can be obtained by other methods, such as preliminary geological survey, geologic drilling and long-distance geophysical prospecting. This information can work as priori information to help interpret cross-hole radar detection data. Full waveform inversion (FWI) is an advanced inversion method for cross-hole radar, having higher resolution than the ray tomography method. However, traditional FWI for cross-hole radar takes less advantage of the prior information. Therefore, the introduction of the priori information into FWI is worthy of in-depth study to improve information and improve the accuracy and stability of FWI. The reasonable value inversion quality. Here we use a special penalty function to impose inequality constraint on the objective function, and then calculate a new update step length value different from the traditional FWI. We use this method to introduce the priori range of weight coefficients is discussed, which can control the strength of inequality constraint. Several inversion examples are designed to validate the effect of this improved FWI method. The inversion examples for synthetic and field data show that FWI based on inequality constraint for cross-hole radar has better inversion effect than the traditional FWI. To a certain extent, the introduction of inequality constraint can constrain inversion process, improve the inversion stability and provide higher precision inversion results.
关键词： Inequality constraint,Inverse theory,Cross-hole radar,Full waveform inversion,Priori information
更新于2025-09-23 15:23:52
-
[IEEE 2018 17th International Conference on Ground Penetrating Radar (GPR) - Rapperswil, Switzerland (2018.6.18-2018.6.21)] 2018 17th International Conference on Ground Penetrating Radar (GPR) - Noise suppression of GPR data using Variational Mode Decomposition
摘要： Ground penetrating radar (GPR) has been used in the many aspects, such as civil engineering and the earth sciences. And the analysis and noise suppression of GPR data have always been the research focus. In this study, a new self-adaptive time-frequency decomposition tool called the variational mode decomposition (VMD) is introduced. We use the VMD method to derive a set of stationary sub-components, and based on the decomposition, we separate the valid signals and the components which are corresponded to the noise. One trace of GPR data are given to test the effect of the VMD decomposition, and the empirical mode decomposition (EMD) is also employed as a comparison. And a primary noise-suppression method based on the VMD scheme is also proposed. The application of the field GPR data further demonstrates the better performance of the proposed method in both noise suppression and the retention of geophysical events.
关键词： ground penetrating radar (GPR),mode decomposition,variational mode decomposition (VMD),noise reduction or suppression
更新于2025-09-23 15:23:52
-
[IEEE 2018 IEEE 3rd International Conference on Image, Vision and Computing (ICIVC) - Chongqing (2018.6.27-2018.6.29)] 2018 IEEE 3rd International Conference on Image, Vision and Computing (ICIVC) - Change Detection in Semantic Level for SAR Images
摘要： Considering that the traditional change detection algorithms only focus on extracting the change area but ignore the change content identification, a novel change detection framework for synthetic aperture radar (SAR) images is proposed. The framework integrates the merits of unsupervised and supervised learning to detect changes in semantic level. First, the residual convolutional auto-encoder (RCAE) is designed to convert SAR image slices to the histogram representation. Then, we calculate the difference vectors and extract the change area by their norms. Finally, we classify the difference vectors of change region and identify the content of change. Experimental results indicate that the proposed method significantly achieves performance improvement over existing algorithms.
关键词： semantic,bag of visual words,synthetic aperture radar,auto-encoder,change detection
更新于2025-09-23 15:23:52