SWAP - the surveillance challenge
Whichever UAVs the ADF and Coastwatch select for their separate surveillance requirements, processing their imagery and disseminating it in a useful timeframe will be a critical challenge.
Unmanned Aerial Vehicles (UAVs) have taken on a number of roles that once required manned platforms, freeing human pilots from the risks involved in these missions. The wide range of air, land and sea implementations for UAVs require rugged and flexible processing systems that are able to manage multiple types of sensors on a single platform. UAVs such as Global Hawk and Predator employ commercial off-the-shelf (COTS) processing systems that provide flexibility and processing power in challenging environmental conditions, and are readily available on the market.
The development of systems using COTS products developed to industry standards allow common operational procedures such as those governed by Standing NATO Agreement 4586 (STANAG 4586) which governs UAV flight and payload control systems, and also provide benefits through rapid time to market and future upgrade paths. Performance in these COTS products is increasing from GFLOPS to TFLOPS of processing power, and developments in switch fabrics allow exceptional bandwidth for increasingly demanding multi-sensor processing applications.
The Current state of embedded computing for surveillance
Two widely deployed UAVs today are the Global Hawk and the smaller Predator.
The well known Global Hawk developed by Northrop Grumman has been used extensively in Bosnia, Afghanistan and Iraq. As part of a joint Australian-US exercise in 2001 it has also flown between the USA and Australia, with Global Hawk vehicle no. 5 taking 23 hours and 23 minutes to fly from Edwards Air Force Base California to the RAAF Base Edinburgh in South Australia. Features of the Global Hawk's Integrated Sensor Suite (ISS), developed by Raytheon, include real-time, onboard processing, integrated synthetic aperture radar (SAR) and electro-optic and infrared sensors (EO/IR) with a common signal processor and common SEU. The signal processing subsystem for the high performance SAR system is based on Mercury's ANSI/VITA standard RACEway switch fabric multicomputer architecture to process the high volume stream of SAR data. It has a track record of hundreds of operational hours and high MTBF.
The General Atomics Predator, a medium-altitude, long-endurance, remotely piloted craft has a basic crew of one pilot and two sensor operators. Its primary mission is armed reconnaissance, airborne surveillance and target acquisition. Since 1995 it has flown surveillance missions over Iraq, Bosnia, Kosovo and Afghanistan. The Predator is about one tenth the weight of Global Hawke. The Predator A has a payload of 204 kilograms, while Predator B has an internal payload of 363kg and an external payload of 1,361kg.
This means that SWAP constraints (size, weight and power) are driving requirements. Just like the processors for SIGINT and COMINT applications, SAR processing systems are under pressure to become smaller, lighter and consume less power, and be able to perform in unpressurised bays under a range of environmental conditions. For a SAR system, the information processor can consume half the power and comprise one third of the weight of the entire SAR payload. To process the high volume of data from the SAR that forms part of its payload, the Predator uses a Mercury COTS-based signal processor, comprising several multiprocessors interconnected by RACEway switch fabric. The onboard RACE computer system performs extensive processing on the radar signals before the resulting data is down linked to the ground station.
One of the goals in the United States OSD (Office of the Secretary of Defense) Unmanned Aircraft Systems Roadmap 2005-2030 is to "reduce the complexity and time lag" in information chains. (see http://www.acq.osd.mil/uas/). Integral to achieving this is to do more processing on board the UAV or the UAS (Unmanned Aircraft System). The ability to process more data in-flight increases the range of mission capabilities available to the UAS, including increased targeting or other functions. Faster on-board data processing also allows more options in high risk missions such as suppression of enemy defences, where the UAS would need the data processing capability to participate in broader targeting networks and sensor cueing.
Australia's UAV program, through the Automation of the Battlespace Initiative (ABSI), is focused on many of the same challenges, including the effective use of COTS technologies, reducing the cost of operations to the ADF, and enhancing the effectiveness of UAV applications. The size and weight constraints of projects such as JP129 and Air 7000 mean that technical advances in on-board processing can add significantly to the UAV's multiple mission capabilities. The future benefits of protocols such as STANAG 4586 (Standing NATO Agreement 4586), which governs UAV flight and payload control systems and allows a ground control system to control more than one type of UAV, also enhance the value of flexible, high-capacity processing systems. Northrop Grumman's teaming with Australian companies to develop an Australian ground system to integrate with the Global Hawk UAV (announced earlier this year) shows the value placed on interoperability between allied forces.
SWAP constraints - size, weight and power - are also the technology trends driving deployed systems decisions.
For many UAVs currently being developed, the size of collection platform sizes is going down. The trend in larger unmanned platforms is to incorporate more sensors, which require more processing power per cubic centimetre. Leading edge systems offer extreme processing density based on open hardware and software standards like the Mercury Computer Systems' PowerStream 7000, which is a third generation Multiport system, offering 1 to 4 TFLOPS of processing power in an air-cooled, deployable chassis. For smaller collection platforms, 3U Compact PCI (cPCI) modules with a user defined multi-tuner compatible high bandwidth bus are a widely accepted standard. The 3U cPCI connector offers high pin density and compatibility with system software components.
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The trend is towards smaller collection platforms, which require lower power systems, some with only battery power. Using industry open standards can contribute to cost savings through easier interoperability, reduced training requirements through common operational procedures, and lower cost of ownership through increased reliability, addressing budget constraints.
Rapid technological change - hardware, software, communications, control
The increasing range of available platforms and form factors gives designers and system integrators more choices from which to make effective design decisions.
New processors - both RISC and FPGA - with much faster clocks increase the capabilities of processing systems. These newer processors can also be hotter, leading to 100W+ boards, and a requirement for effective cooling solutions. Mercury's innovations in conduction cooling for processor boards eliminate the need for pressurised equipment bays (such as those on the Global Hawk) with their associated costs and complexity. Mercury's ManagedAir(tm) technologies increase the possibilities for deployment of these systems by meeting more stringent cooling requirements.
New switch fabrics increase the bandwidth available to processing systems and enable the use of next generation of adaptive signal processing algorithms on large images and data sets. The leading edge of UAV applications involves combining multiple types of sensors in a single platform, with the associated processing burden of being able to manage and switch from one imaging systems to another in battlefield conditions to provide comprehensive data for more effective and informed combat decisions.
Multicomputers using the RACE++ switch fabric interconnect allow multiple paths between each processor in the system. This results in exceptional bandwidth for data-intensive applications, and increases the flexibility of the system, for example by building a reconfigurable system that uses a pool of multiprocessors to service multiple UAV applications. This effectively reduces the size and weight of each payload by using a system that can effectively reconfigure to handle transitions in processing capabilities. Mercury's Serial RapidIO and RocketIO-like FPGA meshing offers remarkably rich fabric interconnection, copious back-panel I/O or 1GB/s full duplex and faster, and helps overcome increased signal integrity challenges created by increased demands on processing systems.
New standards are also increasing the options available to systems designers. VME is reaching limits for some areas such as power and fabric signal handling, and increases the importance of understanding potential upgrade paths. Mercury's PowerStream(tm) 7000 is an example of the increasing performance available. It is a 3rd generation of MultiPort(tm) Systems, part of a progression in processor capabilities from 300GFLOPS in the late 90's to 1 to 4 TFLOPS of processing power available now.
For small UAVs where space and weight allowances are at a premium, 6U systems may simply be too large to physically fit in many new platforms. 3U form factor solutions are becoming more common, and to provide the greatest ease of use for designers and flexibility for the physical requirements of new applications, they should make available multiple I/O options, all with high bandwidth connections to processing components. The use of open standards makes it easy for developers to integrate improved technology to their applications (among other advantages). For example, 3U Compact PCI (cPCI) is a widely used standard for smaller collection platforms, with good pin density as it uses PCI as the system bus, and compatibility with the system software components of Mercury's larger systems.
Given budget, platform and technological constraints, obtaining the greatest benefit from system components is a constant development challenge. Industry standards increase the availability of products that can work together, giving more possibilities to combine different products in new applications and keep pace with rapid technological change.
Appendix F from the OSD Unmanned Aircraft Systems Roadmap 2005 - 2030, shows a detailed and extensive list of standards, including data, control, interface and flight operations standards. Using COTS products manufactured to industry standards can reduce acquisition costs, allow shared sensor data among disparate users, ease issues of operational and tactical control, allow common operational procedures and reduce training requirements.
By allowing interoperability between equipment from different manufacturers, open standards also help build ongoing competition into the marketplace. Suppliers work to achieve rapid time to market, while commercial production volumes increase implantation reliability via reuse, and lower the cost of delivering warranty and support, reducing risk. Increased reliability and ongoing design improvements reduce the system cost of ownership.
Government agencies, integrators, suppliers and other bodies all have a crucial role to play in developing and influencing these standards so that they best meet their future requirements. The future of embedded computing for persistent surveillance is enhanced by the effective use of open standards that keep pace with rapid technological change in hardware, software, communications and control.
Christine Tursky is Marketing Manager, SouthTech Systems; Joey Sevin is Director of Business Development, Radar Business Segment, Mercury Computer Systems.
By Christine Tursky, Joey Sevin, Melbourne