Until recently, the slower I/O system speeds have not created a major problem for the military and aerospace, but as commercial technologies advance and create greater possibilities for what military and aerospace systems can achieve, speed requirements rise. The ability to achieve greater throughputs provides military users with more data that can help them perform more safely and effectively on networked battlefields.
Many military vehicles today are now fully equipped with electronics, including on-board networks. The data volume is thus going through the roof; meanwhile, the demand to connect with other systems and exchange data with other systems continues to rise. These factors combine with system complexity to push the need for reliable, high-speed interconnects that will hold up in harsh environments. Computer systems and supporting sub-systems must operate at higher speeds. High-speed I/O will also be required to support high-definition video recognition systems. As video and vehicle computing technologies evolve, 10GB and eventually 25GB throughput will soon be requirements—particularly for single-board system manufacturers.
The limitations of RJ-45 and Mil-C-38999
Currently, ruggedized system manufacturers face pressure to use COTS electronics for interconnects in their system enclosures. Boards of this type from leading manufacturers exist in sufficient quantities, and manufacturers have relied on them for a long time. Because there’s a comfort level with these connectors, which include RJ-45 and 38999 types, military and aerospace manufacturers have been reluctant to consider other interconnect technologies. At the same time, system manufacturers are finding it difficult to modify RJ-45 connectors so that they perform properly and over long periods of time in extreme temperatures. These connectors also have difficulty handling shock and vibration while connecting to harder systems such as sensors and traditional military electronics. Ruggedizing the I/O interconnects is thus becoming the focus of making the overall systems perform properly according to military and aerospace requirements.
Circular 38999 connectors were not designed for high-speed digital signaling. As a result, they are not capable of running at Gigabit Ethernet speeds with standard contacts. Some manufacturers have tried to address this challenge by embedding RJ-45 connectors in circular housing, but with the large amount of permutations among these connectors, they do not handle the required I/O consistently. The amount of permutations is so great that there’s a lack of standardization, which creates issues for manufacturers that prefer, and often must partner with, more than one supplier.
Another approach manufacturers have considered is embedding commercial Ethernet and USB connectors inside ruggedized military circular shells for I/O connectors. This tactic makes the connectors more rugged and able to stand up to external shock but thus far has not enabled them to properly handle vibration—a constant factor on all moving vehicles on the ground, in the air, and under water.
Other manufacturers have tried embedding RJ-45 style connectors inside 38999 housing, but this approach does not change the characteristics of RJ-45, which remain vulnerable to vibration. The connectors will work—but at degraded speed and efficiency, while remaining susceptible to corrosion, which would lead to the eventual need for cabling replacement. This is a major job to undertake, and thus relying on such a design is very expensive.
"experts in the interconnect industry are now recommending...standardized M12 connectors, which are much more durable in harsh environments compared to...38999 connectors."
Commercial inserts aside, I am wondering what experts are saying this, and whether they tested any "non-commercial insert" 38999 solutions for high-speed, hi-rel applications.
January 2016 Cartoon Caption ContestBob's punishment for missing his deadline was to be tied to his chair tantalizingly close to a disconnected cable, with one hand superglued to his desk and another to his chin, while the pages from his wall calendar were slowly torn away.122 comments