Wide-Area Airborne Surveillance (WAAS) Application Ideal for VPXBy Cheryl Coupé, Contributing Editor
Richard Lourette, chief scientist and principal investigator for ITT, worked closely with Dynatem to develop a VPX board for a payload sensor processing application that he describes as similar to the US Air Force’s “Gorgon Stare” program deployed last year. That program is a wide-area airborne surveillance (WAAS) system that supports multiple cameras and gives ground operators access to imagery from up to 12 different angles at the same time, at rates of 16 MegaPixels per second for each camera. For the new system, demands were high and the project was underway at the same time that the draft standard for VPX was being developed. Together, Dynatem and ITT started the design, tracked changes as the standard developed, and spun the final board to meet the ratified standard.
The resulting VPX single board computer (SBC) is based on a quad-core Intel® Xeon® processor for high performance. The board (which Dynatem dubbed “VPQ”) includes a 24- port, 10 Gigabit Ethernet switch that allows full-mesh backplane data-layer interconnectivity and up to eight VPQ SBCs to be integrated into a single chassis without the use of an additional switch board. A PCI Express switch provides connectivity to two fully capable PMC/XMC sites with extensive user I/O.
Despite the challenges of designing the board in parallel with the standard, Lourette explains why VPX was the way to go for this demanding sensor application:
- Intel® processor-friendly. With support for PCI Express and 10 Gigabit Ethernet, VPX is inherently Intel® CPUfriendly and Lourette needed the processing power of the high-performance quad-core Intel Xeon processor. When Apple bought P.A. Semi (in 2008), Lourette abandoned all efforts around Power Architecture. “I looked at that and said I’m not going to wait around for someone else to come up with something more powerful,” he stated. “At that point, all my designs were based on the Intel® platform and I’ve never looked back.”
- Signaling in backplane. At the time, VPX was the only mil/aero backplane that could accommodate up to 6 Gigahertz of digital signaling in the backplane. ITT used XAUI, following the Open VPX standard for the VPX P1 connector for 10 Gigabit Ethernet. The additional slot width in the design also allows room for more cooling fins and higher signal integrity for the XMC sites.
- GPGPU friendly. The VPX platform lends itself well to utilizing general-purpose computing on graphics processing units (GPGPU) technology. ITT and Dynatem repurposed NVIDIA and ATI graphics controllers for very high-performance number-crunching.
- Cluster-capable. The 10 Gigabit Ethernet switch built into the board supported flexible data flow topologies. Lourette was able to gang multiple CPUs in a system to create a supercomputing cluster that can process massive amounts of sensor data. The predecessor system to this design used a CompactPCI board that was limited to Gen 1 SATA IO signaling and had reached capacity at 65 watts per slot. The new VPX board can go up to 150 watts per slot for plenty of payload processing.
- Cooling. Thermal design is somewhat less of a challenge now that the standard is ratified, but ITT and Dynatem worked closely with backplane and chassis vendors to develop a reference design that software developers could use that was electrically and software equivalent to the final system. Plenty of advanced thermal analysis ensured that ITT could power a system with seven boards and provide both air- and conductioncooled designs depending on the final application’s mission.
- Mechanical. One of biggest – and unexpected – challenges was seating the cards in the backplane. Lourette explains, “It takes 250 pounds of force to insert a VPX card into the backplane. As thick as a 20-layer backplane is, it would bow like a credit card.” Reinforcements had to be applied to the backplane to make sure all the contacts were made. ITT and Dynatem also had to find metal front panel ejectors that were robust enough to handle the cards and adapted conduction-cooled levers to air-cooled cards so they could get them in and out without special tooling.
The Dynatem VPQ is a high-performance single board computer (SBC) based on the 6U VPX (VITA 46) form factor.
Developing the VPX board was not without its challenges:
Looking forward, Lourette is watching new VME technologies, including small form factor and optical developments. ITT has worked with Dynatem on 3U VPX and will be interested to watch developments in smaller form factors. About new small form factor developments he says, “It needs to be a little bit more mature before I can stand up a project on it, but I would certainly entertain that.” As for optical developments, he says, “Everything I work on is always pushing the envelope on data processing.” He continues, “I’m already saturating the VPX bus with data. VPX is only good to 20 gigabits per channel and then it runs out of steam. Right now I’m at 10 gigabits per channel. There’s technology available for us to go faster but the limit is 20 gigabits and then you have to go to optical.”
Cheryl Berglund Coupé is Editor of EECatalog. com. Her articles have appeared in EE Times, Electronic Business, Microsoft Embedded Review and Windows Developer’s Journal and she has developed presentations for the Embedded Systems Conference and ICSPAT. She has held a variety of production, technical marketing and writing positions within technology companies and agencies in the Northwest.