Obsolescence Mitigation: When Simple Redesigns Become So Much More
Obsolescence mitigation is a complex process.
Especially when you are mitigating issues found within products of your own design, where just the right components were selected previously and now, through no fault of yours – you must replace those once ideal components. Radio Design Group, Inc. found ourselves in this position when the US Navy was interested in a potential singular replacement for all of the previous RFDU variants, core products in the RDG lineup since 2003.
The Challenge: resolve all obsolete components while maintaining or improving performance along the way
The RFDU variants (the RFDU-100, 100A and 101A, RFDU-200 and RFDU-300) have been a RDG core offering since the first product was accepted for installation into the US Navy’s fleet of submarines in 2003. Since then, we have improved each variant while incorporating key performance advantages at the Navy’s request. The RFDU-300 had already enjoyed a stellar 11 year run as a workhorse distribution unit for the Navy, but 11 years is a lifetime with electronic components. Several key connectors handling interconnectivity between RFDU modules), critical RF amplifiers and dozens of other components all required replacement with newer, more readily available models.
This alone would be a large undertaking, but we realized we had an incredible opportunity in front of us at the same time: what if instead of a simple redesign, we solve those issues while adding massive performance and logistical improvements by creating a RFDU that could mimic the operational nature of EACH of the previous variants?
RFDU-400 idea is conceived
Instead of just taking the easy path in front of us to replace components with more readily available models and offer the Navy an improved RFDU-300, we focused on a more complex but far more rewarding effort of bringing the RFDU into a modern state while also looking back to what successes the previous variants offered. With a single box that could replicate what came before, we could simplify the Navy’s logistics and training issues by having a single stocked item that would easily replace ANY of the previous RFDU variants. This creates simplification for stocking the items at government warehouses, reduces the complexity of multiple stock numbers that must be installed into the correct, larger comms system and removes any need to re-train operators as to how the new unit works. We understood the software controls and comm paths each of the variants previously used – so why not give the Navy a single source replacement solution for each of the RFDU variants?
We had to work through multiple components that had since gone End of Life (EOL) in order to even begin thinking about multiple modes of operations. Radio Design has years of experience in finding components that solve problems, and in this case multiple RF amplifiers were replaces with newer, better performing models. Connectors and switches were also sourced that would allow for a longer lifespan than the previous components. We redesigned circuits to accommodate the newer components, built test boards to prove the concepts and garner early performance abilities. With a general blueprint ready and newer components selected; it was time to see if emulation of previous variants would be possible.
Better Understanding the Customers’ Needs
We worked closely with the US Navy team at NUWC (Naval Undersea Warfare Center) to determine what performance levels they wished to see from each of the emulations, on a path by path basis. Multiple back and forth communications began to illustrate the key performance parameters we would target.
Understandably, the team at NUWC wanted improvements wherever we could provide them. The nature of the good working relationship we both had nurtured overs years of working together netted a compromise where we targeted the specific areas the Navy wanted improvements, and we leveraged those opportunities against other paths where the effort wasn’t worth the reward.
We are forever grateful to the NUWC team and their ability to work so closely with us as the designer to better understand their needs and put the best possible product together. At RDG, we’re committed to extending your legacy equipment’s lifespan. Read more about our obsolescence mitigation capabilities here.
RFDU-400 takes shape
Our engineers and technicians reviewed and studied hundreds of paths to ensure that the back panel I/O would be sufficient, regardless of which RFDU variant the new RFDU-400 was to emulate. This required very careful connector placement to ensure each RF cable would reach the I/O on the RFDU, regardless of configuration of comm system. Careful switching and software control allowed us to have a command set that any user, regardless of training, could operate in any comm system. If a sailor was trained to operate a RFDU-101A in a BLQ/10 system designed for a 101A – they simply would install the new RFDU-400 and the software behaves exactly as the operator expects. Ditto for any other variant – RFDU-200 or RFDU-300. We designed a new chassis and front panel that would display the variant configuration to the operator, so all of the guesswork was eliminated. Just as we were ready to build the prototype chassis and front, the Navy communicated that the RFDU-100 and 101 series were no longer needed for emulation. While not ideal given the work completed to date, this aided our design team in the form of simplification. No front panel readout would be needed as the configuration between the RFDU-200 and -300 models were similar enough that we could handle everything though command sets in the software.
We began building the prototype circuit board assemblies to prove the concept out three-tiered solution: obsolescence mitigation through installation of newer and better performing components, installation into any RFDU-200 or -300 comm system and full command set operation regardless of emulation and improved performance regardless of which variant was being emulated. It became clear when the first PCBAs were placed into the prototype chassis, we were on the right track.
Our testing revealed the I/O of the RFDU-400 was ideally suited to emulate either variant of the previous RFDUs with no additional complication to the installation for shipboard personnel. The initial performance was on par with the previous versions, however not yet to the levels of performance we were pushing for.
Pushing Farther
We continued development on the software and hardware side. We were able to improve performance through circuit design improvements to make better use of the newer sourced components, particularly with the newer RF amplifiers. We were able to see improved noise figures in well over half of the paths we were testing. Further improvements were made to the software to solve issues discovered when switching between RFDU-200 and -300 paths.
Additionally, we wanted to develop better testing software to assist with not just development of this new RFDU-400, but to aid in diagnosis for all variants that returned to Radio Design for upgrades, repairs and overhauls. We were able to develop new automated testing processes, including the ability to perform automated tuning to filters, replacing the older more labor-intensive manual processes. We tested and re-tested, and sought out improvements wherever we could – even marginal – in an attempt to deliver the best possible product. We were ready to show the efforts to the Navy.
Not to Be
In the end, the US Navy was not able to approve funding to push the RFDU-400 into production. The platform the RFDU variants were designed to distribute signals for was slated for replacement with a comms platform that would not utilize the RFDU in its current rack mounted configuration. The move to a newer VPX based platform effectively killed the concept of the RFDU-400, but the valuable lessons learned in our mitigation of obsolescence and gains in performance will continue serving the fleet for a decade plus while the RFDU variants continue to serve the fleet.