One of our defense clients had extremely tough requirements on all specifications. The unit had to stand up to shocks and vibrations and resist EMC interference, both from radiation and from power lines. It had to be compatible with special circular military connectors that the clients installed themselves.
It took a 28 volt power supply, but had to be able to deal with a voltage range from 12–36 V. Cooling the unit was also a major challenge – and these are just a few items on a lengthy list of requirements. We delivered a complete solution – a rugged modular computer, including both the CPU and the box, and we have kept it running smoothly ever since.
Removable disks
“The biggest challenge in this development project was making the two solid-state disks removable.”
The computer is permanently mounted in the vehicle. However, when leaving confidential data unattended is out of the question, or if you want to be able to analyze the data elsewhere, removable disks are the solution. They are also convenient to use if you have large amounts of data that is not easily transmitted. More and more customers are asking for this feature.
The biggest challenge in this development project was making the two solid-state disks removable.They were going to come out twice a day over the course of five years, meaning the connectors had to stand up to at least 5,000 cycles. We developed a special aluminum cassette in house to hold the card and a unique custom connector that is specified to handle 100,000 cycles. Overkill? Maybe – but it’s not going to fail.
Rugged chassis
To deal with shocks and vibration, the box is built in a self-supporting aluminum frame that is screwed directly into the vehicle. The entire box is also made of aluminum to keep weight down. The cover plate is grooved to double-seal it against the box.
The application has fans, so it doesn’t have to be completely moisture-proof. It can be made water resistant enough to stand up to spray cleaning by adding IP65 rated rubber gaskets, but then it can’t be cooled with fans. As for radiation from the power supply, there are heavy-duty filters right inside the power connection to shield the electronics.