The Advanced Mezzanine Card (AMC) is a small form-factor, hot-swappable module supporting high-speed serial fabric interconnect. Originally developed for PICMG AdvancedTCA platforms, AMCs were intended for communications applications, as a means to provide finer-grain I/O or processing scalability.

The recently ratified Micro Telecommunications Computing Architecture (MicroTCA) specification leverages this proven AMC form-factor and management infrastructure. MicroTCA defines a family of small, low-cost, flexible, high-bandwidth and highly scalable platforms comprised entirely of AMC modules.

With the ink barely dry on the MicroTCA specification, ideas are already in progress to broaden the adoption of the technology into applications beyond 19-inch rack packaging and telecom central office environments. Analogous to the penetration of VMEbus technology into multiple markets, ruggedized adaptations of the AMC and MicroTCA specifications for the defense and aerospace markets will spread adoption of these technologies into other harsh environments.

Example applications of rugged MicroTCA platforms include industrial automation equipment, outside plant (OSP) for telecommunications base stations and access devices, and high shock and vibration uses such as commercial vehicles, in addition to defense and aerospace applications.

Rugged, Open COTS

Certain trends are evident in today’s defense and aerospace markets, which will initially drive the need for ruggedized versions of these next-generation components and platforms. Firstly, there is the migration to open standards-based commercial off-the-shelf (COTS) technologies, and secondly, there is an emerging transition to a network-centric paradigm.

The impetus for the migration to open standards-based COTS technologies is simple—economics and time-to-market. Adoption of COTS can reduce program development costs and schedules, and improve interoperability. A network-centric architecture based on open standards will exert significant pressure for replacement of closed, proprietary elements, many of which exist at the edges of military networks where conditions are the harshest.

The adoption of COTS requires the integration of open standards-based COTS subsystems on many different mobile

platforms into a high-performance network. It will also require ruggedizing these platforms for the defense/aerospace environment.

For solution providers in these markets, developing proprietary subsystems and seamlessly integrating them into multiple mobile platforms is a daunting task, requiring significant investment of time and money. However, open standards-based COTS technologies are often not designed to operate in many military environments.

AMC and MicroTCA Enter the Mix

Many defense solution providers and prime contractors are interested in deploying platforms based on open PICMG specifications, specifically AMC and MicroTCA. This interest is fueled by the bandwidth, management and flexibility potential provided by these platforms.

As an open standards-based off-the-shelf technology, MicroTCA has a number of limitations for use in defense/aerospace environments. These include:

• Shock and vibration tolerance

• EMI/EMC emissions and immunity

• Operating temperature ranges

• Power input and conditioning

To allow AMCs and MicroTCA to become viable COTS technologies for all functional elements of the defense and aerospace architectures, ruggedization efforts must begin now. To that end, Hybricon and Motorola have teamed to develop a ruggedized version of Motorola’s first commercial MicroTCA platform, for use as a development and design-in vehicle for rugged applications.

In addition, Motorola and Hybricon have formed a Rugged MicroTCA Special Interest Group (SIG), comprised of several industry participants. The Rugged MicroTCA SIG is in the process of developing proposed draft specifications for rugged MicroTCA. These rugged-centric specifications build on, and as much as possible remain compliant with, the telecom-centric base specifications, AMC.0 and MicroTCA.0.

The ultimate goals of this effort are that COTS AMCs and MicroTCA-specific modules (MCH, PM) can be installed unmodified into ruggedized, air-cooled enclosures for more benign rugged environments. Alternatively, they may be mechanically converted for conduction cooling, with no change to the printed wiring board (PWB), components or edge connectors, and integrated in a conduction-cooled rack/enclosure for harsher environments.

How Rugged Is Rugged?

To establish a baseline for precisely how much vibration, shock, temperature, etc. a mobile platform should be expected to survive, adoption of the environmental requirements from the ANSI/VITA 47 standard is being proposed. This standard applies specifically to “plug-in units,” but may be applied somewhat more generally to the combination of a plug-in unit and the connector, subrack and enclosure into which it is installed. ANSI/VITA 47 draws from MIL-STD-810-F, considered the authority for military environmental testing, and specifies many of the test procedures therein as a means to verify compliance. It is, however, intended to address the potential environmental requirements of virtually any commercial, defense or aerospace application.