STONewsArchive: Multidimensional Radar Imaging

Title: Multidimensional Radar Imaging
Start_Publishing: 22/11/2021
Panel_Page: SET
Page_ID: 3856
Main_Body_Multi:

NATO SET-250 RTG Trials in Spadeadam (UK) on “Multidimensional Radar Imaging”






Multi-aspect angle SAR imagery over three days




Synthetic Aperture Radar (SAR) and Inverse Synthetic Aperture Radar (ISAR) images have been largely used for monitoring small to large areas and more specifically for target recognition/identification. Nevertheless, limited resolution, self-occlusion effects, geometrical limitations and some difficulties in the image interpretation strongly affect the imaging system effectiveness and, therefore, the performance Automatic Target Recognition (ATR) systems. Some of these limitations are due to the use of classical monostatic, single-channel, single-frequency and single-polarization systems, as they are simpler to build and handle than complex systems. In such systems, only image resolution can be increased to enhance ATR performance, which has both physical and processing limitations. The use of additional information on targets, such as response to variation in frequency, polarization and aspect angle of imaging may provide more robust methods of finding and identifying targets.


In the recent NATO SET-196 RTG, solutions have been proposed that show the benefit of using multi-channel/multi-static radar imaging systems when dealing with non-cooperative targets, which can be realized without enormous costs. 


The goal of SET-250 RTG is to further develop systems and algorithms by improving what has been previously done and by extending the system dimensionality to include also multi-frequency, multi-polarization and multi-pass radar. Specific focus is on the increase of radar imaging system’s performances in order to improve the effectiveness of ATR systems. With the aim of demonstrating the superiority of multi-dimensional radar imaging as a combination of multi-dimensional radar data and the use of multi-dimensional radar imaging algorithms, a large measurement campaign was planned and executed in August 2019 in Spadeadam (UK), namely the Spadeadam Trials. 


The Spadeadam Trials 


The Spadeadam trials have been an important milestone for SET-250, which aims at proving the effectiveness of multi-dimensional radar systems in support of Automatic Target Recognition. During the Spadeadam trials, real data were acquired in relevant scenarios in order to test and validate algorithms in close to operational scenarios and to allow for the employed systems to collectively (as a whole multi-dimensional system) reach a high Technological Readiness Level (TRL), at least equal to 5.  


Description of Trials


The trials were carried out in July/August 2019 at the RAF Spadeadam (GBR) and were completed over one week. Experiments were run by simultaneously flying up to three systems in parallel in order to gather multi-dimensional radar data. Details of the systems, targets and scenarios that were put in place are shortly presented here below before showing some preliminary results that have been obtained by single systems. SET-250 members are currently analyzing the collected data from a multi-dimensional point of view. 


Systems: Four radar systems were used during the Spadeadam trials, namely AEXAR (X-Band), MIRANDA-94 (W-Band), PAMIR-Ka (Ka-Band) and the MetaSAR-L (L-Band). 


Targets: Several disused military targets were present in the scene including real and mock-up versions. Targets were arranged in various configurations and in different positions: in the open, close to and underneath canopies and close to buildings. Moving targets were also present that were imaged as well as GPS-tracked.


Scenarios: Various scenarios were considered, such as 

multi-aspect, multi-frequency and multi-polarization imaging of static targets for complete characterization
multi-channel radar for ground moving target imaging
multi-frequency imaging of both real and mock-up versions of targets for discrimination capability analysis
multi-frequency imaging of targets close to and underneath canopy (FOPEN capability)

Preliminary results: Preliminary results have been obtained in terms of production of several SAR images with all the systems that were deployed. An example of multi-aspect SAR imagery of one of the targets is shown in Figure 1, which was obtained by processing PAMIR-Ka data with a resolution of 10x10 cm. Similar images have been obtained with all the other systems at different frequencies and with different polarizations. Additional results are expected soon from a multi-dimensional analysis of all the collected data. Such results will be made available in the final SET-250 Technical Report.


Outcome of the Spadeadam trials


A very large dataset has been collected over the same set of targets by four different SAR systems, which operate from L-Band to W-Band. Such a dataset is unique within the NATO and represents an ideal dataset with which to perform target characterization analysis, multi-dimensional/data fusion algorithm test and validation, target classification algorithm test and also inspire new algorithms that make use of multi-dimensional radar data that will improve the current state of the art in terms of target characterization and classification. 


Outcome of SET-250 and look ahead


SET-250 has reached his main goal of demonstrating the importance and effectiveness of multi-dimensional radar imaging. There is no doubt that increasing the dimensionality of radar data brings a number of benefits which primarily produce more effective radar imaging for both target detection and imaging with direct consequence in ATR effectiveness. 


Nevertheless, these results should be considered as the beginning of a roadmap that sees additional work to do in terms of technology optimization, both in terms of algorithms and in the cost-effectiveness of this technology. A follow on activity (SET-316 RTG) has already been planned and proposed within the SET Panel that will see this roadmap implemented and that will make full use of the Spadeadam dataset and additional data that may come both from the participating countries and/or from additional trials.

Page_Intro:
 

Synthetic Aperture Radar (SAR) and Inverse Synthetic Aperture Radar (ISAR) images have been largely used for monitoring small to large areas and more specifically for target recognition/identification. Nevertheless, limited resolution, self-occlusion effects, geometrical limitations and some difficulties in the image interpretation strongly affect the imaging system effectiveness and, therefore, the performance Automatic Target Recognition (ATR) systems.

HomePageImage: 2021-SET-250.png
HomePageBodyText:

NATO SET-250 RTG Trials in Spadeadam (UK) on “Multidimensional Radar Imaging”






Multi-aspect angle SAR imagery over three days




Synthetic Aperture Radar (SAR) and Inverse Synthetic Aperture Radar (ISAR) images have been largely used for monitoring small to large areas and more specifically for target recognition/identification. Nevertheless, limited resolution, self-occlusion effects, geometrical limitations and some difficulties in the image interpretation strongly affect the imaging system effectiveness and, therefore, the performance Automatic Target Recognition (ATR) systems. Some of these limitations are due to the use of classical monostatic, single-channel, single-frequency and single-polarization systems, as they are simpler to build and handle than complex systems. In such systems, only image resolution can be increased to enhance ATR performance, which has both physical and processing limitations. The use of additional information on targets, such as response to variation in frequency, polarization and aspect angle of imaging may provide more robust methods of finding and identifying targets.


In the recent NATO SET-196 RTG, solutions have been proposed that show the benefit of using multi-channel/multi-static radar imaging systems when dealing with non-cooperative targets, which can be realized without enormous costs. 


The goal of SET-250 RTG is to further develop systems and algorithms by improving what has been previously done and by extending the system dimensionality to include also multi-frequency, multi-polarization and multi-pass radar. Specific focus is on the increase of radar imaging system’s performances in order to improve the effectiveness of ATR systems. With the aim of demonstrating the superiority of multi-dimensional radar imaging as a combination of multi-dimensional radar data and the use of multi-dimensional radar imaging algorithms, a large measurement campaign was planned and executed in August 2019 in Spadeadam (UK), namely the Spadeadam Trials. 


The Spadeadam Trials 


The Spadeadam trials have been an important milestone for SET-250, which aims at proving the effectiveness of multi-dimensional radar systems in support of Automatic Target Recognition. During the Spadeadam trials, real data were acquired in relevant scenarios in order to test and validate algorithms in close to operational scenarios and to allow for the employed systems to collectively (as a whole multi-dimensional system) reach a high Technological Readiness Level (TRL), at least equal to 5.  


Description of Trials


The trials were carried out in July/August 2019 at the RAF Spadeadam (GBR) and were completed over one week. Experiments were run by simultaneously flying up to three systems in parallel in order to gather multi-dimensional radar data. Details of the systems, targets and scenarios that were put in place are shortly presented here below before showing some preliminary results that have been obtained by single systems. SET-250 members are currently analyzing the collected data from a multi-dimensional point of view. 


Systems: Four radar systems were used during the Spadeadam trials, namely AEXAR (X-Band), MIRANDA-94 (W-Band), PAMIR-Ka (Ka-Band) and the MetaSAR-L (L-Band). 


Targets: Several disused military targets were present in the scene including real and mock-up versions. Targets were arranged in various configurations and in different positions: in the open, close to and underneath canopies and close to buildings. Moving targets were also present that were imaged as well as GPS-tracked.


Scenarios: Various scenarios were considered, such as 

multi-aspect, multi-frequency and multi-polarization imaging of static targets for complete characterization
multi-channel radar for ground moving target imaging
multi-frequency imaging of both real and mock-up versions of targets for discrimination capability analysis
multi-frequency imaging of targets close to and underneath canopy (FOPEN capability)

Preliminary results: Preliminary results have been obtained in terms of production of several SAR images with all the systems that were deployed. An example of multi-aspect SAR imagery of one of the targets is shown in Figure 1, which was obtained by processing PAMIR-Ka data with a resolution of 10x10 cm. Similar images have been obtained with all the other systems at different frequencies and with different polarizations. Additional results are expected soon from a multi-dimensional analysis of all the collected data. Such results will be made available in the final SET-250 Technical Report.


Outcome of the Spadeadam trials


A very large dataset has been collected over the same set of targets by four different SAR systems, which operate from L-Band to W-Band. Such a dataset is unique within the NATO and represents an ideal dataset with which to perform target characterization analysis, multi-dimensional/data fusion algorithm test and validation, target classification algorithm test and also inspire new algorithms that make use of multi-dimensional radar data that will improve the current state of the art in terms of target characterization and classification. 


Outcome of SET-250 and look ahead


SET-250 has reached his main goal of demonstrating the importance and effectiveness of multi-dimensional radar imaging. There is no doubt that increasing the dimensionality of radar data brings a number of benefits which primarily produce more effective radar imaging for both target detection and imaging with direct consequence in ATR effectiveness. 


Nevertheless, these results should be considered as the beginning of a roadmap that sees additional work to do in terms of technology optimization, both in terms of algorithms and in the cost-effectiveness of this technology. A follow on activity (SET-316 RTG) has already been planned and proposed within the SET Panel that will see this roadmap implemented and that will make full use of the Spadeadam dataset and additional data that may come both from the participating countries and/or from additional trials.


Created at 22/11/2021 09:17 by ad.rodes
Last modified at 22/11/2021 09:17 by ad.rodes
 
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