Unmanned Aircraft Leverage PC/104, COM Express, and Other Small Form Factors

Military Embedded Systems

Authored by John McHale, Editorial Director of Military Embedded Systems

While PC/104 has been around for decades it has never been healthier. Its main advantages - ruggedness, compact size, and modularity - have never been more in demand in the military electronics market, especially in unmanned systems. 

Unmanned aircraft systems (UASs) continue to shrink in size, as do their payloads, requiring system designers to leverage small-form-factor, embedded-computing standards like PC/104, COM Express, and others. 

Reduced size, weight, and power (SWaP) requirements in military UAS payloads, ground control stations, avionics, reconnaissance (ISR) applications, and other military electronics systems are forcing designers to leverage small-form-factor designs such as COM Express, SMARC, and the PC/104 standard. 

While PC/104 has been around for decades it has never been healthier. Its main advantages – ruggedness, compact size, and modularity – have never been more in demand in the military electronics market, especially in unmanned systems. 

“Because of their low-SWAP characteristics and affordability, systems based on embedded PC/104 and Computer-on-Module (COM) technologies routinely find a home in a multitude of military and civil applications, including MALE and HALE UAS platforms in ISR/combat roles, attack/utility/cargo helicopters, various fixed-wing cargo/fighter/ISR aircraft, and a host of tactical and combat ground vehicles, along with missile defense platforms and shipboard applications,” says Mike Southworth, Product Marketing Executive at Curtiss-Wright Defense Solutions. “As electronics payloads on board manned and unmanned platforms look to add new technical capabilities – such as high-speed network backbones, ISR sensor/video processing, and/or avionics databus interfaces – the smaller system architectures like PC/104 and COM modules have been well received by [our] customers.” 

Not just SWaP, but stringent ruggedization and extreme environmental requirements may also preclude users from choosing PC/104 products. 

“With the long history that PC/104 has in the marketplace, the list of applications is significant, the technology is an ideal fit for any rugged commercial, industrial, or military applications,” says Michele Kasza, vice president of sales for Connect Tech in Guelph, Ontario. “PC/104 is as well-suited to vehicle-based solutions, manned or unmanned, as in industrial environments where unregulated power is a concern as is dirt and dust; also outdoor applications where extreme temperatures, rain, humidity, and salt can be factors. PC/104 is often living in environments where the user may not realize that PC/104 is the architecture driving their application. Crack open a number of small-form-factor, rugged system solutions and you will find PC/104 at its finest; quite often a multivendor stack carefully architected for the ultimate in interoperability.” 

PC/104 Lives on

“I believe that in the case of PC/104 [military users] are looking to use a proven platform that they have seen years of success with,” Kasza says. “These customers may also prefer to stay with a known footprint as it may reduce their design efforts from a mechanical perspective. That said, we at Connect Tech are seeing our military customers wanting the rugged and compact features of the PC/104 of the past combined with the most current technologies.  

“Here is where PCIe/104 (The PCI Express version of PC/104) comes into play, offering single-board computers (SBCs) with the latest generation low-power Intel Atom [processors], through to high-performance Intel Core i7 options,” Kasza continues. “Stack this with high-end GPU solutions such as NVIDIA GTX950Ms and high port density Managed Carrier Ethernet Switches or a 10G Ethernet Controllers and suddenly what was old technology is now leading edge.” Connect Tech offers the Xtreme/GbE 24-Port Managed Carrier Ethernet Switch solution for military small-form-factor requirements. Ports can be accessed via a breakout board/carrier that can mate directly to the XDG024/25 or by mating to a high-density high-speed Twinax cable. The XDG025 is designed for standalone applications, with all thermal extraction on one layer and connector/cabling on the opposite layer, whereas the XDG024 is intended to stack directly into a PCIe/104 stack. 

Reliability and consistency have ensured continued support for the PC/104 standard in military applications that often have various levels of requirements. 

“The requirements of military customers for PC/104 varies from program to program,” says Dr. Paul A.T. Haris, president and CEO of RTD Embedded Technologies, Inc., in State College, Pennsylvania. “But some of the common threads have included a need for rapid prototyping, development, and uptime that the PC/104 architecture provides, given its vast array of product functionalities and numerous manufacturers found on the market.  

“Additionally, users have required the need for an inherently rugged architecture at the board level, which also provides modularity for future maintainability and upgradeability,” he continues. “Very few standards over the history of the embedded market have been able to provide these capabilities in such a small form factor. And none can boast the history of this standard and its ability to advance with time while maintaining backward compatibility. This provides military customers with the ability to reduce total lifetime program costs as well as reduce the need for product changeovers. This is why you find many military customers making the PC/104 architecture the architecture of choice for a vast number of military applications in all extremes of environments.” 

Military users “are increasingly looking for small-form-factor embedded technologies that reduce the size, weight, and power for their deployed line-replaceable units (LRUs) and reduce or eliminate NRE fees and development schedules,” Southworth says. “At the same time, [they] are seeking increased multicore processor and graphics performance, along with I/O scalability from modular open standard PCI-Express based architectures like PCIe104 [as well as] COM Express, SMARC, and Mini-PCIe.” 

Reduced SWaP

Every defense application today wants five to 10 times more performance in system upgrades, but they want it in the same – if not smaller – footprint of the previous system and with lower power characteristics. This is something PC/104 has been doing for years; it is also a feature of standards such as COM Express and SMARC. 

“The PC/104 architecture family of specifications has been serving SWaP requirements even before SWaP was an acronym,” Haris says. “The unique stackable architecture, which also can serve as a true SBC architecture, as well as a mezzanine architecture, has been providing the military with embedded, rugged board, and system-level solutions for years. With its embedded stackable bus system and onboard I/O connectivity, reductions in enclosure size and weight can be either tailored for each application or realized in standard modular enclosures. With the addition of considering the overall program life cycle cost factor, the PC/104 architecture enables users to quickly upgrade and maintain their systems with backward compatibility and interoperability of multivendor products, all based on well-defined and controlled standards and specifications.” 

Just as no military application is the same with the same embedded computing requirements, no small-form-factor architecture is the right size for every application. 

“We live in a world of many small-form-factor options which simply means that one size does not fit all,” Kasza says. “At a small footprint size of 90 mm by 96 mm, PC/104 has a solid ecosystem that allows for easy integration of current technologies with multivendor support and interoperability. In some cases, the physical footprint of a system is what a customer least wants to change as they may be working within a space that was previously defined around PC/104. From a processor perspective, PC/104 single-board computers are available with lower-power ARM processors as well as x86 options ranging from low-power solutions through to Intel Core i7s.”  

“Small-form-factor CPU card standards like PC/104, COM Express, and SMARC offer a physical size that is a fraction of traditional 3U or 6U VME/VPX architectures,” Southworth says. “This provides an obvious advantage when it comes to packaging for lowest SWaP. In addition, COM Express and SMARC have multiple physical footprint options, including boards roughly the size of a credit card, which allows for further miniaturization targeted at demanding SWaP requirements. For this space, Curtiss-Wright offers the 39-inch, 1.5-pound rugged mission processor, the Parvus DuraCOR 310, which makes use of integration of a low-power SMARC COM CPU card with Mini-PCIe I/O card expansion slots,” Southworth says.  

Other companies – such as Diamond Systems and WinSystems – continue to offer PC/104-based products to meet the demand for reduced SWaP in military systems. 

Diamond Systems has a family of Jupiter PC/104 & PC/104-Plus DC/DC high-efficiency, high-precision power supply modules. Each power supply consists of a PC/104 form factor module with complete DC-DC voltage regulator circuitry, integrated thermal solution, detachable screw terminal block I/O connections, and PC/104 bus connectors. Its input voltage range of 7 to 34 VDC is compatible with industry-standard 12 V, 24 V, and 28 V inputs.  

Engineers at WinSystems leverage the Intel E3800 Atom processor family for their PPM-C407, a fanless low-power PC/104 SBC. The solution is designed for harsh environments and has soldered RAM for added shock and vibration resistance with an operating temperature range from -40 °C to +85 °C. 

Looking Forward with PC/104

“The number of applications where one finds PC/104 is vast,” Haris says. To say that any one application dominates would be misleading and would do a disservice to the PC/104 architecture: PC/104 is based on standard stackable and modular bus architectures widely accepted across most industries and then packaged on a standard small form factor. The use of the vast array of functionalities of these products is endless.  

“The architecture provides all the building blocks for designing SWaP-based products to enable overall lifetime program cost reductions,” Haris continues. “This architecture has been proven from the depths of the oceans to outer space, and from the Antarctic ice caps to the desert sands. You will find PC/104 running mission-critical weapon systems as well as general-purpose monitoring, tracking, and processing systems. In the end, the question should not be what are the types of applications that often make use of PC/104 technology, but are there any applications that have not made use of it.”  

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