scholarly journals Small UAV-based SAR system using low-cost radar, position, and attitude sensors with onboard imaging capability

2021 ◽  
pp. 1-12
Author(s):  
Jan Svedin ◽  
Anders Bernland ◽  
Andreas Gustafsson ◽  
Eric Claar ◽  
John Luong
Keyword(s):  
Low Cost ◽  
Projection Algorithm ◽  
Synthetic Aperture ◽  
Back Projection ◽  
Data Link ◽  
Sar Images ◽  
Imaging Capability ◽  
Small Uav ◽  
Aerial Vehicle ◽  
High Resolution Images

Abstract This paper describes a small unmanned aerial vehicle (UAV)-based synthetic aperture radar (SAR) system using low-cost radar (5–6 GHz), position (GNSS/RTK) and attitude (IMU) sensors for the generation of high-resolution images. Measurements using straight as well as highly curved flight trajectories and varying flight speeds are presented, showing range and cross-range lobe-widths close to the theoretical limits. An analysis of the improvements obtained by the use of attitude angles (roll, pitch, and yaw), to correct for the relative offsets in antenna positions as the UAV moves, is included. A capability to generate SAR images onboard with the back-projection algorithm has been implemented using a GPU accelerated single-board computer. Generated images are transmitted to ground using a Wi-Fi data link.

scholarly journals An Improved Back-Projection Algorithm for GNSS-R BSAR Imaging Based on CPU and GPU Platform

2021 ◽  
Vol 13 (11) ◽  
pp. 2107
Author(s):  
Shiyu Wu ◽  
Zhichao Xu ◽  
Feng Wang ◽  
Dongkai Yang ◽  
Gongjian Guo
Keyword(s):  
Graphics Processing Units ◽  
Low Cost ◽  
Computational Cost ◽  
Satellite System ◽  
Projection Algorithm ◽  
Synthetic Aperture ◽  
Processing Unit ◽  
Back Projection ◽  
Imaging Quality ◽  
Central Processing

Global Navigation Satellite System Reflectometry Bistatic Synthetic Aperture Radar (GNSS-R BSAR) is becoming more and more important in remote sensing because of its low power, low mass, low cost, and real-time global coverage capability. The Back Projection Algorithm (BPA) was usually selected as the GNSS-R BSAR imaging algorithm because it can process echo signals of complex geometric configurations. However, the huge computational cost is a challenge for its application in GNSS-R BSAR. Graphics Processing Units (GPU) provides an efficient computing platform for GNSS-R BSAR processing. In this paper, a solution accelerating the BPA of GNSS-R BSAR using GPU is proposed to improve imaging efficiency, and a matching pre-processing program was proposed to synchronize direct and echo signals to improve imaging quality. To process hundreds of gigabytes of data collected by a long-time synthetic aperture in fixed station mode, a stream processing structure was used to process such a large amount of data to solve the problem of limited GPU memory. In the improvement of the imaging efficiency, the imaging task is divided into pre-processing and BPA, which are performed in the Central Processing Unit (CPU) and GPU, respectively, and a pixel-oriented parallel processing method in back projection is adopted to avoid memory access conflicts caused by excessive data volume. The improved BPA with the long synthetic aperture time is verified through the simulation of and experimenting on the GPS-L5 signal. The results show that the proposed accelerating solution is capable of taking approximately 128.04 s, which is 156 times lower than pure CPU framework for producing a size of 600 m × 600 m image with 1800 s synthetic aperture time; in addition, the same imaging quality with the existing processing solution can be retained.

scholarly journals UNMANNED AERIAL VEHICLE APPLICATIONS OF 3D MODELLING, VISUALIZATION AND PARAMETER CALCULATIONS

2018 ◽  
Vol XLII-5 ◽  
pp. 649-652 ◽  
Author(s):  
V. Lambey ◽  
A. D. Prasad
Keyword(s):  
Point Cloud ◽  
Low Cost ◽  
3D Modelling ◽  
Aerial Photogrammetry ◽  
Average Accuracy ◽  
Aerial Vehicle ◽  
High Resolution Images ◽  
Institute Of Technology ◽  
Uav Images ◽  
Economical Alternative

<p><strong>Abstract.</strong> Photogrammetric surveying with the use of Unmanned Aerial Vehicles (UAV) have gained vast popularity in short span. UAV have the potential to provide imagery at an extraordinary spatial and temporal resolution when coupled with remote sensing. Currently, UAV platforms are fastest and easiest source of data for mapping and 3D modelling. It is to be considered as a low-cost substitute to the traditional airborne photogrammetry. In the present study, UAV applications are explored in terms of 3D modelling, visualization and parameter calculations. National Institute of Technology Raipur, Raipur is chosen as study area and high resolution images are acquired from the UAV with 85% overlap. 3D model is processed through the point cloud generated for the UAV images. The results are compared with traditional methods for validation. The average accuracy obtained for elevation points and area is 97.99% and 97.75%. The study proves that UAV based surveying is an economical alternative in terms of money, time and resources, when compared to the classical aerial photogrammetry methods.</p>

scholarly journals ESTIMATION OF DATA MEMORY CAPACITY FOR CIRCULARLY POLARIZED SYNTHETIC APERTURE RADAR ONBOARD UNMANNED AERIAL VEHICLE PLATFORM (CP-SAR UAV)

2011 ◽  
Vol 7 (1) ◽  
Author(s):  
P. Rizki Akbar ◽  
J.T. Sri Sumantyo ◽  
V.C.Koo ◽  
H.Kuzel
Keyword(s):  
Synthetic Aperture Radar ◽  
Unmanned Aerial Vehicle ◽  
Early Stage ◽  
Low Cost ◽  
Image Data ◽  
Memory Capacity ◽  
Synthetic Aperture ◽  
Circularly Polarized ◽  
Aerial Vehicle ◽  
Aperture Radar

Previously only linear polarization is widely used in the Synthetic Aperture Radar(SAR) system onboard spaceborne and airborne platforms. In such linearly polarized SAR(LP-SAR) systems, Faraday rotation in the ionosphere and platform posture will contribute tothe system noise. Therefore to improve this situation, currently a novel Circularly PolarizedSynthetic Aperture Radar (CP-SAR) sensor is developed in Microwave Remote SensingLaboratory, Chiba University. Moreover, from this research, a new backscattering data basedon circularly polarized wave in the remote sensing field can be obtained. As an early stage ofthe development of this CP-SAR sensor, we built an Unmanned Aerial Vehicle (UAV)platform for testing CP-SAR sensor capabilities. In this paper, we describe the novel CP-SARsensor and the method to design CP-SAR UAV especially in estimating the requirement ofdata memory capacity. Also a smaller antenna is possible to be implemented since the 3-dBaxial ratio on antenna characteristic becomes the main parameter in this new CP-SARtechnique. Hence, a compact CP-SAR sensor onboard a small and low cost spaceborneplatform yielding a high accuracy SAR image data can be realized in the near future.

scholarly journals A New Fast Factorized Back-Projection Algorithm with Reduced Topography Sensibility for Missile-Borne SAR Focusing with Diving Movement

2020 ◽  
Vol 12 (16) ◽  
pp. 2616
Author(s):  
Xinrui Li ◽  
Song Zhou ◽  
Lei Yang
Keyword(s):  
Adverse Effects ◽  
Cross Section ◽  
Time Domain ◽  
Projection Algorithm ◽  
Synthetic Aperture ◽  
Back Projection ◽  
Practical Application ◽  
Echo Signal ◽  
Cylindrical Coordinate ◽  
Significant Performance

Time-domain algorithms have significant performance advantages for missile-borne synthetic aperture radar (SAR) focusing with diving movement. However, due to the diving curve trajectory of the missile platform, the range and angular histories of the target become very sensitive to unknown tomography, which provides difficulties for SAR algorithm development. To address this problem, we have proposed a new fast factorized back-projection (FFBP) algorithm with reduced topography sensibility for missile-borne SAR focusing. The new algorithm was designed based on an orthogonal cylindrical coordinate (OCC) system, in which the cross section of a cylinder in the coordinate system is approximately orthogonal to the diving curve trajectory. Owing to the acquisition symmetry of the OCC system, the range and the angular histories of the grid in the OCC geometry become less dependent of the topography in every recursion of FFBP implementation, which can dramatically reduce the adverse effects of unknown topography and achieve high focusing performance. In the simulation, echo signal based on a set of typical parameters from a missile-borne SAR system is generated with unknown tomography. Promising results with 1 m resolution are finally achieved, which demonstrates the performance of the proposed algorithm. The limitation of the algorithm is also discussed in the final part, which will facilitate the development of raw data processes in practical application.

IN-HOUSE DEVELOPMENT OF UNMANNED AERIAL VEHICLE AUTOMATIC ANTENNA TRACKING SYSTEM

2015 ◽  
Vol 76 (4) ◽  
Author(s):  
Md Fahmi Abd Samad ◽  
Mohd Izhar Harun
Keyword(s):  
Unmanned Aerial Vehicle ◽  
System Integration ◽  
Tracking System ◽  
Low Cost ◽  
Radio Communication ◽  
Data Link ◽  
Testing Stage ◽  
Software Development System ◽  
Cost Development ◽  
Aerial Vehicle

The control of an unmanned aerial vehicle (UAV) requires a two-way radio communication between the UAV and ground control station (GCS). This radio communication is achieved through the use of antennas as medium of recital and transmission in the data-link system. This paper presents the project of an in-house low-cost development of a UAV automatic antenna tracking system. The presentation includes the control system design, hardware and software development, system integration and testing stage. The development ended with a successfully operational automatic antenna tracking system in a benchtop testing and validation.

scholarly journals N-YOLO: A SAR Ship Detection Using Noise-Classifying and Complete-Target Extraction

2021 ◽  
Vol 13 (5) ◽  
pp. 871
Author(s):  
Gang Tang ◽  
Yichao Zhuge ◽  
Christophe Claramunt ◽  
Shaoyang Men
Keyword(s):  
Noise Level ◽  
Detection Method ◽  
Synthetic Aperture ◽  
Target Area ◽  
Original Image ◽  
Sar Images ◽  
Ship Detection ◽  
Target Extraction ◽  
High Resolution Images ◽  
Potential Area

High-resolution images provided by synthetic aperture radar (SAR) play an increasingly important role in the field of ship detection. Numerous algorithms have been so far proposed and relative competitive results have been achieved in detecting different targets. However, ship detection using SAR images is still challenging because these images are still affected by different degrees of noise while inshore ships are affected by shore image contrasts. To solve these problems, this paper introduces a ship detection method called N-YOLO, which based on You Only Look Once (YOLO). The N-YOLO includes a noise level classifier (NLC), a SAR target potential area extraction module (STPAE) and a YOLOv5-based detection module. First, NLC derives and classifies the noise level of SAR images. Secondly, the STPAE module is composed by a CA-CFAR and expansion operation, which is used to extract the complete region of potential targets. Thirdly, the YOLOv5-based detection module combines the potential target area with the original image to get a new image. To evaluate the effectiveness of the N-YOLO, experiments are conducted using a reference GaoFen-3 dataset. The detection results show that competitive performance has been achieved by N-YOLO in comparison with several CNN-based algorithms.

scholarly journals A Low-Cost Active Reflector for Interferometric Monitoring Based on Sentinel-1 SAR Images

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 2008
Author(s):  
Guido Luzi ◽  
Pedro F. Espín-López ◽  
Fermín Mira Pérez ◽  
Oriol Monserrat ◽  
Michele Crosetto
Keyword(s):  
Urban Areas ◽  
Low Cost ◽  
Cost Benefit ◽  
Weather Conditions ◽  
Severe Weather ◽  
Synthetic Aperture ◽  
Stable Phase ◽  
Dense Network ◽  
Sar Images ◽  
Active Reflector

The effectiveness of radar interferometric techniques in non-urban areas can often be compromised due to the lack of stable natural targets. This drawback can be partially compensated through the installation of reference targets, characterized by a bright and stable radar response. The installation of passive corner reflectors (PCR) often represents a valid aid, but these objects are usually cumbersome, and suffer from severe weather conditions; furthermore, the installation of a PCR can be difficult and costly, especially in places with hard accessibility. Active reflectors (AR) represent a less cumbersome alternative to PCRs, while still providing a stable phase response. This paper describes the design, implementation, and test of an AR prototype, designed to operate with the Sentinel-1 synthetic aperture radar (SAR), aimed at providing a fair performance/cost benefit. These characteristics, obtained through a tradeoff between the use of off-the-shelf components and a simple architecture, can make the setup of a dense network (i.e., tens of devices) in the monitored areas feasible. The paper reports the design, implementation, and the analysis of different tests carried out in a laboratory, and in a real condition in the field, to illustrate AR reliability and estimate its phase stability.

A Novel Fast Factorized Back-projection Algorithm for Synthetic Aperture Radar Imaging

2014 ◽  
Vol 35 (6) ◽  
pp. 1435-1441 ◽  
Author(s):  
Hao-lin Li ◽  
Lei Zhang ◽  
Lei Yang ◽  
Ya-chao Li ◽  
Meng-dao Xing ◽  
...  
Keyword(s):  
Synthetic Aperture Radar ◽  
Radar Imaging ◽  
Projection Algorithm ◽  
Synthetic Aperture ◽  
Back Projection ◽  
Aperture Radar
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