Military Embedded Systems

For many COTS [commercial off-the-shelf] vendors and VITA members, the Tri-Service Memo issued in January 2019 by the secretaries of the Army, Navy, and Air Force was the highest validation of several decades of their combined efforts.

For critical and intelligent deployed embedded modules, air-flow-through (AFT) cooling describes an approach that brings the coolant much closer to heat-generating electronics than standard conduction-cooled approaches. As a result, compared to conduction cooling, AFT increases the amount of power that can be cooled and decreases device temperatures.

For many COTS vendors and VITA members, the Tri-Services Memo issued in January 2019 by the secretaries of the Army, Navy and Air Force was the highest validation of several decades of their combined efforts. The memorandum clearly stated that, going forward, modular open systems approach (MOSA) supporting standards “should be included in all requirements, programming and development activities for future weapon system modifications and new start development programs to the maximum extent possible.” Examples of MOSA standards include the Sensor Open Systems Architecture (SOSA) and CMOSS, both of which rely on OpenVPX hardware as their foundation.

At the 2018 Embedded Tech Trends conference, results were presented from early simulations that conclusively established 100 Gigabit Ethernet could be successfully implemented on VPX using existing and newly announced copper connectors. At that time, many in the industry thought that optical interconnects and fiber would be required to support 100 GbE speeds.

A new, higher-performance era of VPX (VITA 46) computing was launched in January - at the Embedded Tech Trends (ETT) 2018 Conference in Austin, Texas - with the announcement that Gen 5 VPX data rates will run on today's standard VPX connector. The initial Gen 5 VPX protocols are expected to be 100 Gigabit Ethernet (100G-KR4) and Infiniband EDR [enhanced data rate]. In addition, a next-generation VPX connector, the MULTIGIG RT3, which is able to support data rates of 25.8 Gbaud, also made its debut.

The ongoing challenge for commercial off-the-shelf (COTS) system developers is to balance the competing approaches to reduce the system's size, weight, power, and cost (SWaP-C) while trying to deploy the most modern technologies. Today, system integrators are confronting a rapidly narrowing margin for achieving that balancing act. While the power and density of devices has increased, platform ambient boundary conditions haven't changed. The result is tighter and tighter margins. The only option: Become more efficient in removing heat from the system.

All vendors of commercial off-the-shelf (COTS) hardware intended for use in harsh defense and aerospace environments insist that their products are reliable as well as rugged. But without a consistent baseline for comparison, it's almost impossible for system integrators to objectively confirm whether one COTS product is more reliable than another. The VITA 47 standard gives system integrators just such a baseline as it is an American National Standards Institute (ANSI) standard.

How rugged is "rugged"? The answer to that question should have a clear and consistent answer that gives system integrators the confidence and surety that a specific module from a commercial off-the-shelf (COTS) supplier will perform and survive in the conditions their application requires. All too often though, claims made by COTS vendors that their module will meet a certain range of durability (temperature, shock, and vibration) are not based on a common, industry standard that enables the customer to make meaningful comparisons between different boards from different vendors.

The introduction of the European Union (EU) WEEE/Restriction of Hazardous Substances (RoHS) legislation in 2006, which restricted the use of lead components in many electronic products, means that it has become increasingly important for defense and aerospace embedded-system designers to understand the challenges of lead-free design.

As Lead-Free (LF) electronics continue to supplant Tin-Lead (TL) alternatives, new research shows LF devices can match or exceed the reliability of TL components with proper mitigation techniques.

High-speed fabrics driven by the commercial market are also revolutionizing the military embedded market, by way of the VITA 46, 65, and 68 open standards - which aim to keep VPX on track to deliver the ever-increasing need for speed.

Considering the environmentally intense environments faced by modern military electronics, the ability to meet the widest range of ruggedization and operating temperature requirements is an absolute must. And, when traditional Direct Forced Air (DFA) and conduction-cooling techniques are insufficient, designers are turning to more advanced approaches to save the day: Airflow Through (AFT) cooling, spray cooling, and Liquid Flow Through (LFT) cooling.