Almost a decade ago, the United States Department of Defense (DoD) came to the conclusion that investing in electronic technologies for military applications alone was an expensive proposition. At the same time, healthy investments by electronics manufacturers to complete in the commercial sector were having little impact on the performance of military electronic systems. The solution was to use more commercial hardware and software in military system designs, in the form of commercialoff- the-shelf (COTS) designated products. Basically, these are products that are available to commercial customers but may also be suitable for use in military electronic systems, such as power supplies, RF/microwave components, memory chips and drives, microprocessors, and even field-programmable gate arrays (FPGAs) and digital-signal-processing (DSP) components.

Among various electronic systems components, aircraft and vehicle power supplies have fared well as COTS products, with a long list of COTS power-supply manufacturers offering a wide range of products suitable for both commercial and military applications. For example, Vicor Corp. (www.vicorpower.com) recently added to its lines of MIL-COTS products with the introduction of the +28-VDC MIL-COTS VIPAC family of low-profile, configurable power systems (Fig. 1). Available in a variety of size and performance configurations, including sizes of 4.96 x 6.80 in., 3.15 x 6.80 in., and 3.15 x 9.15 in., the modular power supplies include pretested front ends, rugged DC-to-DC converters, and a choice of output connections. The +28-VDC supplies can be specified with 1, 2, or 3 outputs with output voltages as low as +3.3 VDC or as high as +48 VDC with power levels from 40 to 400 W per output. Package profiles are as low as 0.75 in. The power supplies feature a host of protection features, including in-rush current limiting, input transient protection per MILSTD- 704E/F, reverse polarity protection, and electromagnetic-interference (EMI) filtering per MIL-STD-461E. Controlled by local or remote operation, the COTS supplies are compliant to MIL-STD-810F for vibration and shock.

The LCE series of 1-kVA inverters from Transistor Devices, Inc. (TDI, www.tdipower.com) are COTS assemblies that have been well received in military applications, demonstrating MTTF of more than 900,000 hours per module for more than 9000 units in the field. Designed for indoor and outdoor applications, the LCE series inverters accept inputs from +19 to +29 VDC and provide outputs of 120 or 208 VAC as well as 220 or 230 VAC as specified at 50 or 60 Hz. The units can be combined and scaled for single-phase applications to 36 kVA and three-phase applications to 20 kVA per phase. They are designed to deliver full power over an ambient temperature range of -20 to +55C and exhibit total harmonic distortion (THD) of less than 1 percent while providing regulated output voltages to all loads. They operate with typical efficiency of 73 percent.

Abbott Technologies (www.abbotttech.com) offers several "military-off-theshelf" (MOTS) AC-DC switching power supplies including the CS500 family of supplies. These 500-to-2000-W switchers work with input voltages from 90 to 264 VAC at 47 to 880 Hz and provide output voltages from +3.3 to +48 VDC with 90-percent typical efficiency. The low-profile units feature a height of only 0.65 in. and weigh only 4.4 to 5.0 lbs., and maintain output voltage within 1 percent for changes in input voltage and even in load. They are rated for a MTBF of 40,000 hours as calculated per MIL-HDBK-217F in a naval sheltered environment. The supplies, which are engineered for operating temperatures of -50 to +85C, meets MILSTD- 1399 requirements for spike voltage testing, MIL-STD-810F for vibration, MIL-S-901 for high-impact shock, and MIL-STD-461D for EMI. Single units provide 100 A at +5 VDC, 42 A at +12 VDC, 21 A at +24 VDC, and 10 A at +48 VDC, and two or more units can be run in parallel for higher output current. Two units in parallel provide twice the output current at each respective output voltage.

Advanced Conversion Technology (www.actpower.com) recently announced its model SR-23031 single-output COTS power supply with programmable output voltages. It is built to work with two input voltages of +375 and +18 VDC and provide 150 W output power at a choice of output voltages: +12, +15, +24, +28, +36, and +48 VDC. Designed to provide power to a DC fan, the COTS power supply incorporates a DC/DC brick converter with integrated metal cage for shielding. Measuring just 3.25 x 2.40 x 1.00 in. for a power density of 20 W per cubic inch, the power supply is equipped with 25-pin D-subminiature connectors.

Rantec Power Systems, Inc. (www.rantec.com) recently introduced a line of +28-VDC COTS VME/ATR power supplies for avionics applications. The power supplies are available in conduction-cooled 6U x 160 mm single-slot units as well as convection-cooled 6U x 160 mm two-slot units. The supplies are rated for outputs to 250 W with output voltages of +3.3, +5.0, and 12 VDC. Two versions are available: a basic configuration for cost-sensitive applications and a wide-input ANSI VME64 compliant version for performance-driven applications. The power supplies meet MIL-STD-461 EMI requirements, MILSTD_ 901C for shock, and MIL-STD-810F environmental requirements.

In the area of embedding computing solutions, manufacturers have actually supported COTS solutions since 1984 through the industry group VITA and the VITA Standards Organization (VSO). VITA (www.vita.com), which is an incorporated, nonprofit organization, consists of COTS suppliers and prime contractors, working in support of open system architectures rather than proprietary system architectures. The VITA group supports real-time embedded solutions based on the use of VME technology.

Much of the thinking behind continuing and evolving COTS efforts in embedded computing can be found in an excellent white paper from Mercury Computer Systems, Inc. (www.mc.com), "A VITABased Framework for Ruggedized COTS Electronics with Emphasis on Liquid Cooling--VITA 48 (REDI)." Written by Mercury Computer's Randy Banton and Donald W. Blanchet, the white paper reviews the efforts of the VITA 48 "Ruggedized Enhanced Design Implementation" (REDI) working group and the creation of a practical standard in support of COTS embedded computing systems, notable for 3U and 6U COTS modules using air conduction or liquid cooling.

Shaping Software
A recent article on the Defense Science & Technology Agency (DSTA) web site (http://www.dsta.gov.sg/) explored an interesting twist in a COTS product: the use of commercial computer games for military simulation applications. It details an initiative by the DSTA and the Singapore Armed Forces (SAF) to leverage commercial computer games for military applications, and how several SAF schools have adopted modified commercial computer games in support of classroom instruction. The article, "Adapting Commercial Off-The- Shelf Games for Military Simulation," written by DSTA Development Engineer Gwenda Fong Su-Yi from the SAF Center for Military Experimentation,

As in many COTS applications, both types of software have a common set of enabling technologies, and it can be beneficial for both the computer game industry and the military simulation community to tap into each other's solutions. The convergence of the two types of applications has been accelerated by the increasing processing power of the common commercial personal computer (PC). As standard PCs have closed the gap in processing power compared to the "supercomputers" formerly used by the military to run their simulations, computer games have taken on more of the traits of military simulators, with realistic three-dimensional (3D) graphics and built-in artificial intelligence (AI) in their programs.

In recent years, the lines have blurred between commercial computer games and military simulators, largely because of military technologists taking advantage of available commercial developments. For example, in 1995 the US Marine Corps leveraged the shareware game Doom to develop Marine Doom, designed to finetune four-soldier fire teams. The US Army has invested heavily in software with developers to create a number of games, including America's Army. What began as a recruitment tool has grown into software that has been used for officer training at West Point Academy. The US Army has also used Full Spectrum Warrior software to train squad leaders for the use of combat tactics in urban warfare. Developed by the Army, these gaming tools have made their way to commercial gamers. But it is not a one-way street. Such games as Delta Force 2, Steel Beasts, and Falcon 4.0 have been adapted for military training.

Commercial computer games can be adapted to military use by means of readily available game-development toolkits, allowing developers to create new content, such as customized characters, weapons, vehicles, maps, and even missions. Known as "mods" in the gaming community, commercial games are typically customized and shared over the Internet using such toolkits; the same approach can be used to create tools for the military community.