ViSAR: A 235 GHz radar for airborne applications
ViSAR: A 235 GHz radar for airborne applications - IEEE Conference Publication
This radar, developed under the DARPA (Defense Advanced Research Projects Agency) ViSAR (Video Synthetic Aperture Radar) program operates at 235 GHz over multiple GHz of bandwidth and provides high resolution, video SAR imagery at a very low frame latency to support real time operations. The imagery is generated at a high refresh rate which provides the operator, whether on a manned platform or remotely piloted unmanned air vehicle (UAV) tactical situational awareness of moving targets or changes to stationary scene content. The system was flight tested onboard a DC-3 aircraft and flown in a variety of environmental conditions. The test results produced exceptional SAR imagery and ground moving target indicator (GMTI) detections to validate many model based assumptions about the operation and RF performance in this frequency band.
The DARPA ViSAR program objective is to integrate state of the art technologies and demonstrate an airborne sensor that can engage ground areas of interest in all weather conditions. A sub-Terahertz (THz) radar like the ViSAR system provides the cloud penetrating capability to allow sensor operation under all weather conditions, particularly through the cover of clouds. Fig. 1 is a notional scenario from an AC-130 looking through clouds.
The system is designed with flexible waveforms and a low latency signal processing architecture to support real-time operations. The Raytheon team along with a team of world class subsystem providers developed, integrated, and tested the world's first 235 GHz Airborne Video Synthetic Aperture Radar (SAR) system. A successfully executed flight campaign demonstrated key system capabilities and performance metrics.
Key Performance Parameters
The ViSAR System is designed to meet latency, frame rate, image quality, and target detection objectives while operating under all weather conditions.
High Frame Rate, Low Image Latency
This metric drives the algorithm suite, signal processing architecture, and the throughput capability of the processor hardware. The imaging geometry and short SAR aperture times at 235 GHz requires minimal data formatting with low order autofocus to produce high quality images. Given the processing throughput capabilities of the FPGA processors, the algorithms are sized to perform all required signal processing in real time
Fine SAR Resolution
The transmit pulse bandwidth is sized to achieve a fine range resolution in the ground plane. Given the short frame rate requirement, square image pixels in the ground plane at a slant range of 4 km are generated using an airborne demonstration platform which can exceed ground speeds of 80 m/s.
Will ViSAR Revolutionize Close Air Support?
Soldiers slogging it out on the ground will get a much-needed boost when Video Synthetic Aperture Radar (ViSAR) technology takes the field. The miniaturized extremely high-frequency band (EHF) sensor, developed by the Defense Advanced Research Projects Agency (DARPA), promises uninterrupted imaging of moving and stationary ground targets when sensors are blinded by the dust and smoke of battle or when clouds obscure their view.
Now a flight-tested prototype, ViSAR aims to close these gaps and provide tactical situational awareness — targeting information and battle damage assessment — throughout an engagement. The problem with close air support today is that, once an engagement starts, the aircraft can’t see. AC-130 gunships, for example, typically use infrared (IR) sensors to target and engage maneuvering forces on the ground.
But once an action begins, “infrared sensors are unable to image through the dust caused by explosions and incoming rounds,” according to the ViSAR broad area announcement (BAA) dated Dec. 19, 2012.
The program’s biggest achievement was the physical implementation of a working prototype that fits into a compact tactical gimbal, known as the Multi-Spectral Targeting System-B (MTS-B), said George Nowak, ViSAR program manager in DARPA’s strategic technology office. DARPA also had to develop hardware and image-processing software that works at the high end of the EHF band, which extends from 30 to 300 GHz. Northrop Grumman developed the exciter subsystem, L3 the high power amplifier, and Technical Service Corp. the processing algorithms, while Raytheon was the systems integrator.
DARPA has not publicly identified which military aircraft will be first to try ViSAR technology as it cycles through further development and testing and into the field. But the agency said that eligible platforms will host a complete battle management system capable of real-time target engagement as well as the 20-inch-diameter, moveable electro-optical/IR MTS-B gimbal or a gimbal of similar size. The BAA cited the AC-130 gunship as the “primary transition path for this effort.”
But the DC-3 flight test — to proof SAR electronics, pointing, data collection and processing systems — used geometries that are relevant to a range of potential transition platforms, Nowak said. The BAA language, he clarified, was “intended to provide guidance to potential bidders as to the desired form factor and size of the system.” Although the ViSAR development program concluded at the end of 2017, DARPA continues to tweak the design to improve the data presentation so visualization gets closer to the “natural” visualization provided by electro-optical and IR sensors, Nowak said.
Future automatic target recognition and datalink applications may also be possible.
More at the link below:
https://www.aviationtoday.com/2018/0...e-air-support/
Here's an image of the MTS-B sensor for size:
ViSAR: A 235 GHz radar for airborne applications - IEEE Conference Publication
This radar, developed under the DARPA (Defense Advanced Research Projects Agency) ViSAR (Video Synthetic Aperture Radar) program operates at 235 GHz over multiple GHz of bandwidth and provides high resolution, video SAR imagery at a very low frame latency to support real time operations. The imagery is generated at a high refresh rate which provides the operator, whether on a manned platform or remotely piloted unmanned air vehicle (UAV) tactical situational awareness of moving targets or changes to stationary scene content. The system was flight tested onboard a DC-3 aircraft and flown in a variety of environmental conditions. The test results produced exceptional SAR imagery and ground moving target indicator (GMTI) detections to validate many model based assumptions about the operation and RF performance in this frequency band.
The DARPA ViSAR program objective is to integrate state of the art technologies and demonstrate an airborne sensor that can engage ground areas of interest in all weather conditions. A sub-Terahertz (THz) radar like the ViSAR system provides the cloud penetrating capability to allow sensor operation under all weather conditions, particularly through the cover of clouds. Fig. 1 is a notional scenario from an AC-130 looking through clouds.
The system is designed with flexible waveforms and a low latency signal processing architecture to support real-time operations. The Raytheon team along with a team of world class subsystem providers developed, integrated, and tested the world's first 235 GHz Airborne Video Synthetic Aperture Radar (SAR) system. A successfully executed flight campaign demonstrated key system capabilities and performance metrics.
Key Performance Parameters
The ViSAR System is designed to meet latency, frame rate, image quality, and target detection objectives while operating under all weather conditions.
High Frame Rate, Low Image Latency
This metric drives the algorithm suite, signal processing architecture, and the throughput capability of the processor hardware. The imaging geometry and short SAR aperture times at 235 GHz requires minimal data formatting with low order autofocus to produce high quality images. Given the processing throughput capabilities of the FPGA processors, the algorithms are sized to perform all required signal processing in real time
Fine SAR Resolution
The transmit pulse bandwidth is sized to achieve a fine range resolution in the ground plane. Given the short frame rate requirement, square image pixels in the ground plane at a slant range of 4 km are generated using an airborne demonstration platform which can exceed ground speeds of 80 m/s.
Will ViSAR Revolutionize Close Air Support?
Soldiers slogging it out on the ground will get a much-needed boost when Video Synthetic Aperture Radar (ViSAR) technology takes the field. The miniaturized extremely high-frequency band (EHF) sensor, developed by the Defense Advanced Research Projects Agency (DARPA), promises uninterrupted imaging of moving and stationary ground targets when sensors are blinded by the dust and smoke of battle or when clouds obscure their view.
Now a flight-tested prototype, ViSAR aims to close these gaps and provide tactical situational awareness — targeting information and battle damage assessment — throughout an engagement. The problem with close air support today is that, once an engagement starts, the aircraft can’t see. AC-130 gunships, for example, typically use infrared (IR) sensors to target and engage maneuvering forces on the ground.
But once an action begins, “infrared sensors are unable to image through the dust caused by explosions and incoming rounds,” according to the ViSAR broad area announcement (BAA) dated Dec. 19, 2012.
The program’s biggest achievement was the physical implementation of a working prototype that fits into a compact tactical gimbal, known as the Multi-Spectral Targeting System-B (MTS-B), said George Nowak, ViSAR program manager in DARPA’s strategic technology office. DARPA also had to develop hardware and image-processing software that works at the high end of the EHF band, which extends from 30 to 300 GHz. Northrop Grumman developed the exciter subsystem, L3 the high power amplifier, and Technical Service Corp. the processing algorithms, while Raytheon was the systems integrator.
DARPA has not publicly identified which military aircraft will be first to try ViSAR technology as it cycles through further development and testing and into the field. But the agency said that eligible platforms will host a complete battle management system capable of real-time target engagement as well as the 20-inch-diameter, moveable electro-optical/IR MTS-B gimbal or a gimbal of similar size. The BAA cited the AC-130 gunship as the “primary transition path for this effort.”
But the DC-3 flight test — to proof SAR electronics, pointing, data collection and processing systems — used geometries that are relevant to a range of potential transition platforms, Nowak said. The BAA language, he clarified, was “intended to provide guidance to potential bidders as to the desired form factor and size of the system.” Although the ViSAR development program concluded at the end of 2017, DARPA continues to tweak the design to improve the data presentation so visualization gets closer to the “natural” visualization provided by electro-optical and IR sensors, Nowak said.
Future automatic target recognition and datalink applications may also be possible.
More at the link below:
https://www.aviationtoday.com/2018/0...e-air-support/
Here's an image of the MTS-B sensor for size: