New Aerial Surveillance Techniques using IMSAR’s Synthetic Aperture Radar on a Primoco UAV One 150

In August and September this year, the Czech company Primoco UAV SE integrated a new radar with a synthetic aperture from the leading American company Imsar into its unmanned aerial vehicle Primoco UAV One 150. In this configuration, the machine is designed primarily for military customers and provides very interesting reconnaissance and detection capabilities which are currently only offered by UAVs from Israeli and American companies.

The aircraft manufacturer has been working on the standardization of the aircraft for a long time, and therefore certification according to the Stanag 4703 standard was started some time ago which will ensure easy approval of the aircraft for operation in all NATO and associated countries. Of course, the ongoing development of the aircraft also includes improving its sensor equipment, as the ability to carry a day and night camera is no longer a competitive advantage and is offered in various qualities by dozens of constructors. For this reason, supported by the interest of customers, the company began to look for opportunities to add to its sensor equipment. After lengthy negotiations, an agreement was reached with the US company Imsar to integrate its family of NSP-3, NSP-5 and NSP-7 Synthetic Aperture Radars. These vary in size and therefore performance, with the largest and heaviest – the NSP-7 shown in the attached images selected for initial integration. Smaller types can then easily be integrated into the Primoco UAV One 150 without any modifications. 

Mutually Advantageous Choice

The integration of a Synthetic Aperture Radar into a UAV is still not standard, although the benefits of combining both devices are obvious. This is mainly due to the fact that for optimal radar viewing conditions, a movable mount is required, while on the market there exist only radar modules with a mechanically deflected antenna or AESA radars with a fixed field of view. Imsar’s NSP models are the only commercially available types that are of the AESA type and utilise a rotating slot antenna. Compared to the mechanical antenna, the AESA radar offers advantages in the form of lower weight, higher performance (the size of the mechanical antenna and servomechanism is very limited in a UAV due to the weight of the installation, its dimensions and its potential to degrade flight performance) and many times greater reliability. For integration, Imsar needed to ensure optimal operating conditions, including a continuous power supply even at peak loads, minimizing take-off and landing shocks, as well as sufficient flight endurance for several hours. These properties were found only in the Primoco UAV One 150, which, with its maximum take-off weight of 150 kg, falls into the category certifiable according to the Stanag 4703 standard but not according to the higher Stanag 4671 standard. The different Stanag standards have enormous implications in practice, as the latter document requires a very time-consuming and costly certification equivalent to a manned aircraft, which can only be provided by some NATO nations, and which would place such a certified UAV in the same price category as combat aircraft.

The radar for the Primoco UAV One 150 is located outside the fuselage on its left side. The antenna can rotate in the housing to ensure proper coverage of the scanned area. The NSP-7 radar offers Ku band Strip mode, Spotlight, Ground Moving Target Indication (GMTI) and Coherent Change Detection (CCD). All modes work with libraries of captured images where thanks to the extremely sophisticated Lisa 3D software, the operator can compare the currently captured image with a previously taken image from the library in real time. The first mode is used for scanning of the area of interest and allows the detection of moving and static targets or an overview of the monitored area. The second mode allows for scanning the area of interest (point target) from different angles as the aircraft flies over or around, while different viewing angles of the images allow easy identification or detection of changes. GMTI mode allows searching for moving targets from people to vehicles or military equipment or naval targets, and the sensitivity of the device is such that movement can be detected at speeds less than human walking pace. The coherent CCD change detection mode in principle compares a reference image of the earth’s surface (taken, for example, before the start of the action) with an image taken just before or during the action. The advanced algorithm can compare the two images in real time and highlight changes to the operator, either in areas where there is no new radar energy (for example, where the vehicle was in the first image and not in the second) or, conversely, energy increased (for example, where a vehicle is newly located).

Excellent Detection Capabilities

Radar sensitivity and performance enable monitoring of environments with a surface distance of 22 to 32 km from the radar (at a resolution of 0.3 m and 1 m, respectively, for NATO customers there is even an option of NSP-7 (X) with an ultra-fine resolution of 0.1 m). The maximum distance for tracking a target of the size of a vehicle in GMTI mode is up to 17 km, the maximum detection capability when searching for large vessels is up to 128 km. Depending on the size of the target, the radar is able to search around 4,000 km² per hour when searching for a target of the size of a car to between 6,000 to 10,000 km² when searching for a tank column, up to more than 20,000 km² when searching for a tanker or military ship. For comparison, for example, an area the size of the Benešov district can be searched in less than half an hour with a target resolution of 1 m. Therefore, with several hours of endurance, the system offers full area monitoring, while the radar also works even under  poor viewing conditions (night, clouds, fog, dust). The Primoco UAV One 150 can also be equipped with an EO/MWIR observation unit or other devices that can also be operated using the Lisa 3D software. Thanks to this, it is possible, for example, to switch between the image from the radar and the camera with one click and to direct both sensors to one target at the same time.

The radar’s capabilities predispose it towards the conduct of military reconnaissance. In conjunction with the Primoco UAV One 150, equipped with a quiet four-stroke engine, any deployment over enemy territory is free of unmasking phenomena, as the aircraft is not visible or heard at its working altitude, while radar and optical sensors have optimal working conditions. Radar detection sensitivity also allows for other uses, such as remote detection of IED traps on the road, as the system is able to compare the homogeneity of the route surface with an older image from the library, or autonomous perimeter protection using density detection and direction.

Conclusion

The Primoco UAV One 150 in the M military version now available offers tremendous detection capabilities, with the entire aircraft being fully developed and manufactured in the Czech Republic, (with the exception of only three components produced in Spain and Norway). In terms of performance, the aircraft can be compared with much larger (and more costly) UAV from American or Israeli producers, which can be evidenced, for example, by remote control operation over a distance of more than 9,600 km carried out this summer in Malaysia. Several European, Asian and African customers are now interested. For the Primoco UAV SE, the manufacturer, this is just one of many applications as it continues to work on expanding the range of special options for its aircraft.

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