- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
[IEEE 2018 China International SAR Symposium (CISS) - Shanghai (2018.10.10-2018.10.12)] 2018 China International SAR Symposium (CISS) - An Automatically Steering Optical Beam-Forming Network for Phased Array Antenna Based on Dense Wavelength Division Multiplexing
摘要： It is proposed an automatically steering optical beam-forming network (OBFN), which is consisted of an optical fiber loop structure. The loop structure is composed by an optical switch, an optical fiber splitter, and an optical true time delay lines based on dense wavelength division multiplexing (DWDM). The channel number of the DWDM is matched with the number of the phased array antennas (PAA). The true time delay difference between two adjacent channels is set as a basic step. And the optical wave modulated by radio frequency (RF) signal can run into the loop and suffer increased delay with increased circles. Thus the PAA is steered automatically without additional controlling and programming. The performance of this design is analyzed with its maximal circle numbers and the splitting ratio of the optical splitter in theory. The concept-proof experiments with 8 optical channels for DWDM are carried out and the simulation of the PAA radiation pattern is given.
关键词： optical switch,optical beam-forming network,optical fiber loop,optical controlled phased array radar,wavelength division multiplexing
更新于2025-09-23 15:22:29
-
[IEEE 2018 Wave Electronics and its Application in Information and Telecommunication Systems (WECONF) - Saint-Petersburg, Russia (2018.11.26-2018.11.30)] 2018 Wave Electronics and its Application in Information and Telecommunication Systems (WECONF) - The Problem of Determination of Coordinates of Unmanned Aerial Vehicles Using a Two-Position System Ground Radar
摘要： the features of modern methods for detecting and determining the coordinates of small unmanned aerial vehicles using a two-position ground radar system are considered. It is proposed to use the methods developed for multi-sensor radar systems. The limitations and advantages of the two-position radar system are shown. The main potential characteristics of the system and the corresponding restrictions on the conditions of its effective application are determined. Potential characteristics are obtained by simulation methods using mathematical models built on the basis of experimental data.
关键词： two-position system,radar system,detection of objects,trajectory coordinates,unmanned aerial vehicle,determination of coordinates,air object,joint information processing
更新于2025-09-23 15:22:29
-
Method to improve degraded range resolution due to non-ideal factors in FMCW radar
摘要： This paper reports a method to improve a degraded range resolution for FMCW radar. The proposed post-processing method can achieve an improved range resolution without increasing a signal bandwidth by eliminating factors that can degrade the range resolution based on the non-negative least-squares method. For an FMCW radar adopting the post-processing method with the center frequency of 76.5 GHz and the signal bandwidth of 200 MHz, simulation results show that the degraded range resolution of 160 cm is improved to 70 cm, and measurements show that two corner reflectors with the radar cross section of 10 dBsm located at 70 cm range intervals can be distinguished.
关键词： FMCW,non-negative least-squares method,radar,range resolution,signal bandwidth
更新于2025-09-23 15:22:29
-
[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 - Relationship Between Bistatic Radar Scattering Cross Sections and GPS Reflectometry Delay-Doppler Maps Over Vegetated Land in Support of Soil Moisture Retrieval
摘要： This paper presents the application of a coherent bistatic radar scattering model from vegetated terrains and the extension of the model to circularly polarized incident wave cases for GNSS signals. It will then present an analysis relating the bistatic scattering Radar Cross Sections (RCS) of vegetated land cover to the customary Delay Doppler Maps (DDMs) resulting, e.g., from GNSS reflectometry (GNSS-R) observations. This step is key in being able to use GNSS-R data in soil moisture retrieval algorithms. While some analyses exist for this purpose for scattering from sea surface, such analysis has not been carried out specifically for vegetated land surface. The proposed model and methods are envisioned to be applied to the airborne GNSS Reflectometer Instrument for Bistatic SAR (GRIBSAR) project currently under development, as well as to the CYGNSS mission.
关键词： GRIBSAR,Coherent bistatic radar scattering model,GNSS-R,RCS,Delay Doppler Map
更新于2025-09-23 15:22:29
-
[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 - The Recovery Algorithm of Saturated Sar Raw Data Based on Compressed Sensing
摘要： Because of the unprediction of the scene scattering characteristic and the finite quantization bits, saturated data always exists. Saturation phenomenon leads to a non-linear distortion and interferes to the recognition of the target so that it affects the image quality. Especially when the scene scattering characteristic largely varies, it can generate false targets and degrade signal-to-noise ratio (SNR). Compressed sensing (CS), a non-linear reconstructed algorithm, is that samples in sub-Nyquist rate is used to recover the sparse signal with few non-zero elements. This paper proposes the recovery method based on the non-linear characteristic of CS to recover the saturated part of the raw data to the unsaturation state and ensure the unsaturated parts maintain the original state. Simulation results validate the proposed method.
关键词： non-linear,compressed sensing,SAR raw data,saturation,Synthetic aperture radar
更新于2025-09-23 15:22:29
-
[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 - Analysis of NsRCM in BiForSAR Imagery
摘要： As for the bistatic forward-looking synthetic aperture radar (BiForSAR) imaging, frequency-domain imaging algorithms integrated with autofocus is advisable to get a well focused BiForSAR image in the presence of uncompensated motion errors. Nevertheless, a severe drawback of the autofocus algorithms is that they are only capable of removing one-dimensional azimuth phase errors. In range direction, there exists nonsystematic range cell migration (NsRCM) originated from motion errors and RCM correction procedure in frequency domain imaging algorithms as well. In this paper, the causes of different NsRCM in BiForSAR imaging are analyzed, and the corresponding relationship between different NsRCM is deduced. Based on the analyses, we propose an autofocus NsRCM correction scheme for BiForSAR imagery using frequency domain imaging algorithms, being capable of eliminating the range-dependent NsRCM.
关键词： Bistatic Forward-looking Synthetic Aperture Radar (BiForSAR),autofocus,nonsystematic range cell migration (NsRCM),minimum-entropy,spatially-variant
更新于2025-09-23 15:22:29
-
[IEEE 2018 China International SAR Symposium (CISS) - Shanghai (2018.10.10-2018.10.12)] 2018 China International SAR Symposium (CISS) - Extended Map-Drift Algorithm for Spaceborne Sliding Spotlight SAR Data
摘要： For flexibly steering antenna in along-track direction, space-borne synthetic aperture radar (SAR) can achieve high resolution with wide swath conveniently, especially in sliding spotlight mode. In order to overcome azimuth folding effects in this mode, the three-step focusing algorithm was been proposed. However it is difficult to perform fine focus of image due to Doppler rate errors. In this paper, a kind of auto-focusing approach based on Map-Drift (MD) is proposed, which is compatible with the three-step imaging algorithm and efficient. Firstly, the Doppler-rate error transfer mechanism in de-ramp operation (the third step of the three-step focusing algorithm) is illustrated. Secondly, the accurate images draft due to Doppler-rate error is conduced based on this mechanism. Thirdly, a new efficient strategy of iteration is present. Finally, the validness and efficiency of the proposed approach is tested by simulation data and real SAR data.
关键词： synthetic aperture radar (SAR),Map-Drift,auto-focusing,sliding spotlight,focusing algorithm,three-step approach
更新于2025-09-23 15:22:29
-
[IEEE 2018 China International SAR Symposium (CISS) - Shanghai (2018.10.10-2018.10.12)] 2018 China International SAR Symposium (CISS) - Velocity Estimation for Moving Target Refocusing in the Long-Time Coherent Integration SAR Imaging
摘要： A novel procedure is proposed to estimate the two-dimensional (2-D) velocity parameters of moving targets from single-channel synthetic aperture radar (SAR) data in a long-time coherent integration for motion compensation. First, the SAR data is divided into several sub-band data by sub-aperture decomposition, since target motion may be changing in the whole long-time aperture, so that the velocity estimation for each sub-band can be performed respectively. Then, the range walk correction is carried out via Doppler centroid analysis based motion estimation and compensation, by which the energy of the moving target is concentrated into a single range cell. This processing is especially advantageous to the following exact Doppler parameter estimation. Finally, the fine 2-D motion parameters are estimated based on mismatched compression simultaneously. Compared to conventional algorithms with a time-consuming searching process, the 2-D velocity estimation of moving targets can be carried out using this algorithm more efficiently, and the SAR image can be well focused and right located after further motion compensation. Experimental results for numerically simulated SAR images demonstrate the effectiveness of the proposed technique.
关键词： doppler centroid analysis,synthetic aperture radar (SAR),refocusing,mismatched compression,velocity estimation
更新于2025-09-23 15:22:29
-
[IEEE 2018 China International SAR Symposium (CISS) - Shanghai (2018.10.10-2018.10.12)] 2018 China International SAR Symposium (CISS) - A Novel Algorithm for Spacebome SAR DBF Based on Sparse Spatial Spectrum Estimation
摘要： A novel method of digital beam forming (DBF) based on sparse spatial spectrum estimation for spaceborne synthetic aperture radar (SAR) is proposed in this paper. This method converts the estimation of target scene elevation into the estimation of sparse spatial spectrum, which reduces the impact of the number of signal samples. Finally, the simulated results confirm the validity of the method.
关键词： Sparse Spatial Spectrum Estimation,Synthetic Aperture Radar (SAR),Digital Beamforming (DBF)
更新于2025-09-23 15:22:29
-
[IEEE 2018 China International SAR Symposium (CISS) - Shanghai (2018.10.10-2018.10.12)] 2018 China International SAR Symposium (CISS) - Two Dimensional Image Formation of Interrupted FMCW SAR Through Spectral Analysis
摘要： Most of spaceborne Synthetic Aperture Radar (SAR) systems are based on pulsed mode of operation. Such systems are quite expensive and large sized. Frequency Modulated Continuous Wave (FMCW) based SAR is a light weight and less expensive solution, but the disadvantage is that it requires two antennas – one for transmit and other for receive. Interrupted-FMCW is a recently proposed idea for spaceborne SAR that uses a single antenna for transmission and reception. The main problem of this approach is discontinuity of data in azimuth. This paper proposes a two-dimensional image formation algorithm that uses spectral analysis methods for processing of interrupted-FMCW SAR data. The algorithm has been tested on simulated point target data as well as on a real FMCW data, and the results have been discussed.
关键词： spectral analysis,synthetic aperture radar,interrupted-FMCW,all-pole model,image formation
更新于2025-09-23 15:22:29