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Challenges

It's important to note that other defense electronics manufacturers have, out of necessity, developed their own ways to integrate RF and microwave technology onto board-level products. The difference is that, unlike Mercury, none has gone so far as to put a standards proposal on the table.

The first major challenge is getting the member companies within VITA to give approval for incorporating OpenRFM in OpenVPX after the usual standards development process. Interestingly enough, OpenVPX was also proposed by Mercury in 2009 as a way to broaden the acceptance of the VPX standard, and a working group of 28 companies participated in its development. The challenge will be to get many of these same companies — almost none of which have interest or technical capability in RF and microwave technology — to buy into the concept. If they do, they would effectively be signing up to adhere to the standard if and when they do choose to add this technology to their product portfolio.

If OpenRFM takes root after adoption by VITA, the next and unquestionably most formidable challenge will be enticing the microwave industry to participate. This will be orders of magnitude more difficult than with OpenVPX for two reasons. First, VPX was already a VITA standard and required introduction of no new or drastically different technology. The challenge was getting Mercury's competitors on board. Second, the microwave industry, at least those parts of it serving aerospace and defense, has no standards body like VITA and is unaccustomed to dealing with any standards other than those dictated by DoD or other government agencies. It also has no relationship with VITA or the embedded systems business. Consequently, OpenRFM is likely to be a tough sell to these companies, although it may not initially matter whether this industry participates or not as it takes its orders from DoD and prime contractors; however, if DoD mandated its use, IMA manufacturers would have to conform to it.

Limitations and Opportunities

Figure 3. Silicon Labs Si468x Digital Radio Receivers are an all-in-one solution.

OpenRFM is inherently best suited for applications in which RF power output is low, as higher power requires larger components, resulting in subsystems too large to be integrated within OpenVPX. This means it will be used in receive rather than transmit sections of systems and in the low-power driver stages of RF power amplifiers, low-noise amplifiers, and other small-signal subsystems.

It would, however, be appealing for use in subsystems operating at very high frequencies (the millimeter-wave region), where components are much smaller than at lower frequencies, and power levels are lower as well. While it may not be possible to incorporate higher-power RF and microwave subsystems within Open-RFM, it may still be possible to make them compatible with it, which would still allow systems from various microwave manufacturers to build to the standard.

What's Next

OpenRFM was first exposed to the embedded community at a VITA meeting called Embedded Tech Trends. For the microwave industry, however, the next step is for Mercury to present its case for Open-RFM at IEEE's International Microwave Symposium. Sponsored by IEEE, the industry's primary international symposium and exhibition brings together almost the entire industry throughout the world. At this year's event, the company introduced its first 500-to-18 GHz digital microwave tuner targeted at electronic warfare applications. The Ensemble RFM-1RS18 consists of three OpenRFM modules in a single-width 6U VXS-format package. Within this space is a converter with four IF outputs and a frequency synthesizer.

It's important to note that Mercury wins regardless of whether or not Open-RFM is accepted within the embedded systems and microwave communities or is made part of OpenVPX, as it can still use this formula for its own products. Nevertheless, the impetus for integrating RF and microwave IMAs within boardlevel products that, with few exceptions, are totally digital, was to meet the looming challenges facing both industries as DoD is serious about changing the design paradigm. It makes this case at every available opportunity, in programs conducted by the Defense Advanced Research Projects Agency (DARPA) and at R&D laboratories in the Army, Air Force, and especially the Navy. It may take some time before the defense industry broadly accepts this challenge, but in the long term, it has little choice.

Another factor behind the development of OpenRFM was the most basic: to integrate digital and microwave technologies that have existed in their impenetrable stovepipes since World War II. After all, design engineers are only human and typically resistant to the disruptive challenges of change. Without some force driving these two technologies together in the embedded space, who knows when — or if — it would ever occur, and OpenRFM may just be such a catalyst.

This article was written by Barry Manz for Mouser Electronics, Mansfield, TX. Reprinted with permission from Mouser Electronics. For more information, visit here.

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