Military budgets are growing at rates not experienced since the Cold War, rooted in concern over world events and potential threats to US and international security. This concern has pushed the development of defensive and offensive weapon systems to counter the elusive nature of the threats, where fast-strike response is critical. Sophisticated sensors, intelligence-gathering devices, highly accurate guided weapons, and integrated communications systems are all needed to achieve the aims of defense- and war-planners. This article provides an overview of the trends in Military systems spending that is driving the procurement of sophisticated systems. These systems create challenges for military systems designers, with system testing being paramount to maximizing mission success.
To accommodate mission objectives, designs must be small, lightweight, durable and reliable. This drive pushes packaging design issues related to denser concentration of electronics, that in turn creates challenges for thermal management, power consumption and electromagnetic interference (EMI) control. In addition to fitting more into tighter spaces, the growing use of wireless technologies for control and communication creates more activity in an already-crowded spectrum. Add the threat of electronic warfare and the re-emergence of Electromagnetic Pulse (the "E-Bomb") as a potential systems-crippling weapon and the technical challenges ratchet higher. The severe environment of the battlefield electromagnetic, thermal and mechanical are wrapped into the general arena of "Environmental Effects"; an overview of the tests mandated to assess systems against these is presented herein.
Where does the dough go?
Reflecting a major shift toward defensive federal spending since September 11, 2001, military budgets are on the rise. Figure 1 shows the rise in planned budgets for the next several years.
Figure 1 Defense Budgets FY03-FY09
The FY 2004 budget calls for nearly $400 billion in allocation for National Defense, representing 16% of the entire federal budget, is approximately 13% higher than spending during the Cold War. This equates to a burn rate of nearly $43 million per hour, not including the estimated $100B for the recent Iraq war. This budget includes many items that reflect the prominence that is given to special forces, spy planes and precision-guided bombs, such as those used in Afghanistan and Iraq
Table 1 shows the allocation of the FY2004 budget for various programs and items requiring funding.
Table 1 FY2004 Budget Allocation
Of the above items, the combined categories of Procurement and R&D, Testing, and Evaluation consume $134B of the budget -- huge sums of money in anyone's reckoning.
The largest single program in the budget is $9.1 billion for missile defense; an increase of $1.5 billion over last year. In FY2004 ten land-based missile interceptor systems are planned to be located in California and Alaska, with an additional 10 more systems to be added in FY2005. These funds are slotted under R&D and include no procurement amounts as the systems have not yet passed development testing.
Detailed allocations of significant weapons systems are shown in Table 2. These systems represent highly computerized and automated systems that require a high level of integration to operate as intended.
Table 2 Allocation for Weapons and Support Systems
What is common in these procurements is the increasing sophistication of the electronics required to execute the designed missions. Environmental issues, reliability and EMC are concerns overall. Of particular concern for airborne and soldier-carried systems are the weight and size restrictions that put design demands on the packaging of the equipment. Often, these restrictions raise potential design trade-off issues. Lighter packages may lead to less-robust mechanical designs. Thinner material or the use of composites to save weight affect the shielding performance of the equipment.
An example of the level of sophistication is manifest in the Predator Unmanned Aerial Vehicle (UAV). The Predator is a remote-control aircraft, capable of flying at 25,000 feet controlled by a pilot over a C-Band line-of-sight data link or a Ku-Band satellite data link for beyond line-of-sight flight. The aircraft is equipped with a color nose camera (generally used by the aerial vehicle operator for flight control), a daylight variable aperture TV camera, a variable aperture infrared camera (for low light/night), and a synthetic aperture radar (SAR) for looking through smoke, clouds, or haze. The cameras produce full motion video, and the SAR provides still-frame radar images. The Predator can be equipped with Hellfire anti-tank weapons with guidance systems integrating electro-optical, infrared, laser designation and laser illumination into a single sensor package.
Figure 2. Predator UAV
To accomplish its intended mission, the environmental effects issues that impact the design and packaging of the system must be considered. Thermal management, heat dissipation, cabling and wiring aspects must all be considered.
Thermal Management: Removing waste heat from dense electronics mandates the use of innovative thermal transfer systems, such as heat pipes and conduction systems. As many military systems must be environmentally sealed to prevent moisture and corrosion, the use of air-cooling is often not a ready option.
Power management, including reducing supply voltages, using hibernation techniques and selective use of precious battery power, is paramount for mission success and serves to reduce unwanted heat. The soldier in modern combat carries sophisticated communications and sensor technologies, including laser-assisted targeting, video-capture, electro-optical systems, night vision and mine avoidance.
Providing power to these electronic systems requires conventional techniques, such as portable generator/ charging systems, use of solar cells and fuel cells. Some more unconventional sources of energy include the "power boot" which contains a system of chambers, fitted into the boot, which drive air back-and-forth through tiny turbines as the soldier walks. These turbines are connected to generators, which produce electrical power.
The requirement to provide long-lasting sources of power push the state-of-the art in battery design, requiring the development of exotic metallurgy to store power, charge cells quickly and maintain necessary voltage during the entire discharge cycle.
To validate the operation of the equipment under the anticipated environmental conditions, two critical specifications have been developed and are applied to Military Systems. The current EMC standard is MIL-STD-461E. The principal environmental specification is MIL-STD-810F.
An overview of the tests specified in these documents is provided in the paragraphs below. Earlier versions of MIL-STD-461 (prior to revision D of the document) required tailoring of the specification and left much to the interpretation of the test personnel. Version D brought more specific practice, limits and procedures to limit variation in the results.
Table 3 List of Tests Called Out in MIL-STD-461
The severity and limits for the tests are often tailored to the location on the vehicle or installation. For example, equipment located below-decks on a surface ship may have to meet a level of radiated susceptibility of 10 V/m whereas equipment located above-decks, say, in the Pilot House, Chart Room, Signal Shelter, or Helicopter Control Station, must meet a higher limit of 200V/m to possibly >1000 volts-per-meter.EMC is achieved by proper circuit, package, cabling and power system design. See www.wll.com/Newsletter.html for common design guidance.
MIL-STD-810F calls out specific tests to simulate the environmental conditions during operation. The following list of tests is tailored according to the installation and operating location of the system. These tests are normally called out in a procurement specification and may not all apply to any one system. It is critical to review the applicability of these test methods to assure that the testing is appropriate, necessary and covers potential conditions the equipment may encounter during its service life.
For the foreseeable future, ignoring any "sea change" in the world situation, the development of expensive, complex and sophisticated military systems will proceed. And, the challenges for system designers will rise with the increasing sophistication; pushing packaging, EMC and environmental performance requirements.
The Cost of War|
The first Persian Gulf War cost $61B ($80B in today's dollars). The Saudis, Japanese and Germans paid $12B ($16-$17B) toward that cost. Currently, no-fly zones cost around $1-1.5B per year. The cost for the current war is estimated at $60B. About $30B was spent to get our forces there, support them, and bring them home; most of the money went for special payments, operation, support. Only 15-20% was spent for munitions. The other quarter or so was listed under consumables, and does not include peace-keeping and post-war activities. For 100,000 persons, a peace-keeping effort could cost about $50B over a 5-year period. (Notably, the second World War cost over $2.2T in constant dollars.)
CE: Conducted Emissions: Unwanted emissions flowing on wiring and cables
RE: Radiated Emissions: Unwanted emissions radiating from wiring and enclosures
CS: Conducted Susceptibility: Interference energy injected into wiring and cables
RS: Radiated Susceptibility: Interference radiated into wiring and enclosures
List of test methods called out in MIL-STD-810
500 Low Pressure (Altitude)
501 High Temperature
502 Low Temperature
503 Temperature Shock
504 Contamination by Fluids
505 Solar Radiation (Sunshine)
509 Salt Fog
510 Sand and Dust
511 Explosive Atmosphere
515 Acoustic Noise
518 Acidic Atmosphere
519 Gunfire Vibration
520 Temperature, Humidity, Vibration, and Altitude
521 Icing/Freezing Rain
522 Ballistic Shock
- The Re-emergence of the Electromagnetic Pulse Threat
- "Analysis of New FY 2004 Military Budget" Council for a Livable World
- Center for Strategic and Budgetary Assessments
- U.S. Air Force Fact Sheet: RQ-1 Predator Unmanned Aerial Vehicle "2004 military budget contains no money for Iraqi conflict" Tom Infield Knight-Ridder Newspapers February 03, 2003
This article is reprinted from the Washington Laboratories, Ltd. Newsletter, T&E Update, Issue 21. Washington Laboratories is a full service compliance testing laboratory for manufacturers of electronic and electrical equipment. For more information on global compliance contact WLL at 800/839-1649, www.wll.com or email@example.com.