The military electronics industry is reinventing itself as DoD budget cuts are creating a need for rugged solutions that deliver long-term viability. Despite reduced resources, the DoD doesn’t want to sacrifice the performance or quality of its battlefield electronics — an understandable sentiment since the effectiveness of these electronics can ensure mission success and soldier safety. As a result, the task of developing costeffective, powerful and rugged military electronics has fallen into the hands of manufacturers that must reengineer, rethink and redesign current electronics to meet the DoD’s budgetary and performance requirements.

There are basically two strategies employed by rugged electronics manufacturers to meet these demands: the first is modular system design, as this allows for customization and long-term usability; and the second is ruggedization of commercial products, which provides the military with proven technology, but hardened and ruggedized to withstand battlefield conditions.

Longevity and Flexibility

To provide the best defense possible for the country, the military needs to keep its vehicles and other platforms current with the latest technologies. However, creating and developing new technologies from the ground up is not only costly, but time consuming. With the goal to make existing systems last longer, military programs are looking to COTS suppliers to provide newer hardware to extend the life of existing programs. By designing electronics that can be used in multiple applications; satisfy size, weight and power (SWaP) requirements; and provide more multi-function solutions, COTS suppliers are quickly gaining traction within many DoD programs.

One of the design techniques implemented by many COTS suppliers to help mitigate shrinking DoD budgets is modularity. A sought-after feature in today's military electronics, modular designs provide superior longevity and flexibility as subassemblies can be upgraded in the future without a complete system redesign, which is an especially attractive feature to organizations faced with tightening budgets. With a broad base of PC/104-compatible options, modular designs for military computing systems are enabling expandable systems solutions that can combine multiple functions in a single box and be tailored to application requirements.

Designing a Modular, Rugged, Military Computer

Recently, Parvus engineers created a modular rugged computing subsystem, called the DuraCOR 80-40, to support a stackable PCI-Express bus architecture for I/O card expansion, and a modular mechanical design that could grow based on I/O requirements. Offering a computing subsystem that allows this flexibility extends the life and usability of a system — a must for budget-conscious DoD programs.

Many PC/104-based subsystems have traditionally offered a fixed number of card slots, which require substantial mechanical and electrical modifications to integrate and route I/O signals for any new add-on expansion cards. In contrast, the new Intel Core i7-based DuraCOR 80- 40 subsystem features modular interlocking chassis segments with preinstalled DTL-38999 connectors and spare I/O pins, along with an integrated power/control bus to ease the integration of application- specific PCIe/104 or PCI/104- Express I/O cards. Simplifying subsystem integration and minimizing mechanical changes ultimately helps speed the deployment of rugged systems on the battlefield, especially for prime contractors with dense I/O requirements needing to install high pin-count analog and digital I/O cards into their system (i.e. FPGA/DSP engines, ARINC 429 / MIL-STD-1553 bus controllers, RS232/422 interfaces), not easily done with most previous rugged computers. By reducing the difficulty of making modifications to the card stack, this new system can be deployed quickly and with minimal engineering costs.

This building-block approach — along with provisions for direct thermal transfer to the chassis for I/O cards, high wattage and low wattage cards — enables I/O to be more easily integrated in the system. With many rugged computing systems, each PC104 I/O card should not typically exceed 8 watts or risk overheating. This wattage limitation created problems as many military applications require high wattage cards. By supporting a flexible card stack approach with built-in thermal management provisions, higher wattage cards can be integrated and allow for operation in hot environments or high altitude situations where there is less air to dissipate the heat. The flexibility of this card stack design allows the military to adapt the rugged computing system to meet changing requirements.

SWaP Constraints

Reducing size, weight and power (SWaP) has become a familiar mantra in the military electronics industry since the size and efficiency of a mission computer subsystem mounted inside military vehicles must be engineered to fit as much functionality as possible into a small footprint. As the number of electronic payloads within the military’s air and ground vehicles has increased significantly, designers of mission computer subsystems must provide greater embedded processing capabilities while trying to mitigate large power consumption.

Taking this into consideration, the DuraCOR 80-40 was designed with a modular chassis that can mechanically and electrically scale to support a standalone computer or an all-in-one computer- router-switch solution. Rather than install separate standalone computers, routers, and switches, this combined solution optimizes SWaP when used in military vehicle and aircraft applications. Leveraging the same chassis design as used with the DuraMAR Cisco 5915-based mobile router, this rugged Core i7 computer can support optional configurations as an integrated all-inone network/computing appliance.

By designing the router and the computing subsystem to be mateable, an Ethernet port from the CPU is linkable directly to the router or switch. As the computer, router and switch are internally linked and integrated within the same mechanical housing, this eliminates the need to cable together the different components of the communication infrastructure, and reduces the overall mounting footprint compared to multiple stand-alone devices. The combined computer-router-switch solution also provides for a single power interface, which provides additional cabling savings, plus a simpler power distribution system as it interfaces to one box instead of multiple subsystems.

“Ruggedizing” Saves Costs, Speeds Deployment

Another solution for military customers requiring systems that are economical — yet robust — is a “ruggedized” commercial product. Ruggedized products, such as computer networking appliances, can take advantage of the technological advancements made by the world’s leading networking manufacturers, and when combined with proven ruggedization techniques, offer a ro bust, cost-effective computing choice engineered to meet today’s military requirements.

For example, with the government’s wide-spread adoption of Cisco Systems products and the comprehensive feature set offered in the Cisco IOS software, military contractors are increasingly seeking Cisco-based rugged computing solutions for deployment in tactical military applications on board land and air vehicles. Ruggedized Cisco products are also in high demand due to the fact that many military personnel are trained to operate Cisco’s network management software — reducing time to deployment on the battlefield. While Cisco products may contain superior networking capabilities, their original mechanical design is not traditionally capable of enduring rugged military conditions. To allow the military to benefit from Cisco technologies, ruggedization techniques can be implemented by COTS systems engineering companies to harden and secure the systems to make them military ready.

Perhaps the most vital ruggedization technique is thermal management as heat issues cause a large number of system failures. Thermal management for defense applications has always been a challenge because of the high operating temperatures of the latest processors and dense packaging needed for environmental ruggedness. As many commercial networking products rely on convection cooling, which has severe limits, ruggedized systems can incorporate conduction- cooling techniques to maximize the heat transfer, while the unit still remains fanless and passively cooled.

Although a cableless design is optimal for rugged conditions, when ruggedizing an existing commercial product that includes cables, not all cables may be eliminated; thus, additional steps need to be taken to ensure stability. For example, rigid flex circuits and board-toboard interfaces can be implemented where possible, as well as cable braiding, tie-downs, and other strain-relief features to maximize reliability and prevent the cables from disconnecting or being severed in vibration or shock.

To further ruggedize commercial products for military applications, additional techniques such as potting and conformal coating can be implemented to stabilize the components during shock and vibration. Other ruggedization procedures include protection against input voltage inversion, voltage surges, and overvoltage spikes in accordance with MIL-STD- 704 and -1275.

Commitment to Innovation

While the DoD maintains its tight purse strings, it is critical for manufactures of rugged military electronics to implement innovative and cost-saving techniques that are not only budgetfriendly, but enhance reliability and performance. As evidenced by such methods as modular and SWaP-conscious designs, plus ruggedizing existing commercial products, today’s electronics manufacturers are demonstrating their commitment to helping the military achieve its goals.

This article was written by Mike Southwork, Director of Marketing, Parvus Corporation (Salt Lake City, UT). For more information, Click Here .