SOSA and open standards for military embedded computing

The Open Group’s Sensor Open Systems Architecture (SOSA) has become arguably the most influential embedded computing standard in the embedded computing industry as companies think about the boards and other components they are making for American warfighters.

Last fall, The Open Group — an industry consortium in San Francisco dedicated to ensuring vendor-agnostic technology requirements set by the Department of Defense (DOD) are established — rolled out the SOSA 1.0 standard. Now, the military embedded technology sector is hard at work making SOSA goals a reality.

In 2019, the U.S. Department of Defense (DOD) issued a directive to the U.S. Army, Navy, and Air Force dubbed the “Tri Services Memo.” The use of modular open standards is a “warfighting imperative” according to the DOD.

The high-level goals of SOSA include openness and being platform- and vendor-agnostic while being aligned with Modular Open Systems Approach (MOSA) using standardized software and hardware. The consortium aims to leverage existing and emerging open standards and align with DOD service objectives. Finally, SOSA aims to keep technology affordable and adaptable.

Open architectures support aerospace and defense applications for manned and unmanned surface vessels, submarines, aircraft, land vehicles, and spacecraft. The goal is to reduce development and integration costs and reduce time to field new sensor capabilities.

Thankfully, the embedded computing industry had years of lead time and a fundamental philosophy to work around before aligning products to the SOSA standard. With that standard set, there is still plenty of work to do as The Open Group sets up a third-party system to certify products as SOSA compliant.

“There wasn’t a future shock of what it was,” says Rodger Hosking, director of sales at Mercury Systems Inc. in Upper Saddle River, N.J. “1.0 was really a clean-up of a lot of details and loose ends that were being debated and discussed and refined so we could drive a stake in the ground and say, ‘there it is.’”

This July, The Open Group released the first edition of its SOSA Business Guide, which experts say is a new comprehensive guide in the acquisition, deployment, modernization, and sustainment of sensor systems that support command, control, communications, computers, cyber, intelligence, surveillance, and reconnaissance (C5ISR).

“As threats to sensing and communications advance and accelerate, the US Government needs to acquire sensor capabilities in a more agile and affordable way than traditional acquisition methods,” Dr. Ilya Lipkin, SOSA Steering Committee Chair and US Air Force Open Architecture Technical Expert said when the business guide was launched this summer. “Moreover, the industry needs a viable business model with real opportunities to compete for business. The Open Group SOSA Consortium provides these differing interests with a balanced open approach where all stakeholders’ needs are fairly represented in a collaborative forum.”

Beyond standards

While the SOSA standard aims to make systems and their components less expensive and easier to work on, industry experts note that end users may receive a more powerful product than non-aligned offerings.

Justin Moll, the vice president of sales and marketing at Pixus Technologies Inc. in Waterloo, Ontario, notes that the SOSA efforts have driven backplane designs with new routing configurations and even increased performance.

“Typically, these designs incorporate VITA 67 and/or VITA 66 interfaces for RF/optical through the backplane,” Moll says. “Some of the larger backplanes incorporate a timing slot. The speeds are typically higher in the SOSA designs, where 100 Gigabit Ethernet requirements are not uncommon. The enclosures are affected by the typically hotter boards in SOSA applications and more I/O and cabling complexity.”

Mercury’s Hosking echoed similar sentiments about what can be done over Ethernet with SOSA products.

“SOSA really allows the connectivity to the outside world to also be done over the same high-speed Gigabit Ethernet links. So, for example, you can have a sensor and antenna that’s acquiring data. The sensor will digitize the data closer to the antenna so that all the data that antenna delivers to the to the SOSA chassis will be Gigabit Ethernet and that will be immediately compatible with the links that are internal to the chassis for SOSA and then allow the same kind of interface to be used for both internal and external connectivity. It’s really nice — it makes sense. It’s kind of neat and it’s clean and very scalable.”

Openness onboard

Jacob Sealander, the chief architect for C5ISR systems at Curtiss-Wright Defense Solutions, explains that while SOSA is a “big catch all,” the approach still allows options to refine systems to what is required both technologically and to each branch’s needs.

“What I think we’re seeing is people aligning with sort of the philosophy of SOSA, but as they make their decisions about which of the different options in SOSA to use, they’re creating what I would call subset documents,” Sealander explains. As an example, Sealander cites the U.S. Army’s GCS Common Infrastructure Architecture (GCIA), which is based on the Modular Open Systems Approach (MOSA) model.

“They’re creating architecture standards that really reflect all the same philosophies and leverage SOSA,” Sealander says and also notes similar endeavors like the Future Airborne Capability Environment (FACE) and VITA 65 being leveraged as well. “It’s interesting because I feel like SOSA is the influencing standard behind all these things, but you’re still seeing these sorts of focused subsets coming to existence. So, all of these things really driven by the DOD’s push for MOSA. All of these things are kind of playing together, and I see SOSA as sort of the backbone for all of them.”

Sealander’s colleague, Dominic Perez, who is the chief technology officer at Curtiss-Wright, notes that the limitations in the SOSA standard allows companies to focus on the variances rather than base it is built upon.

“So, we can very clearly go, hey, this is going to be the most popular profile or couple of profiles for this style of card. Certainly, if we have other legacy systems that are using different profiles, we can support those, but typically what we’re moving to is a SOSA-aligned-profile-first design inside of Curtis Wright.”

Pixus’ Moll agrees, saying “There is the potential for our chassis managers, SOSA aligned backplanes, and base-chassis platforms to be utilized in a lot of different applications/programs. The overall size, dimensions, slot count, etc. would be the same as they would incorporate the same main enclosure, utilized in varying customer projects.

That could mean more re-use of existing designs, less customization. But, for backplanes and I/O, it seems likely that there is going to be enough differentiation in configuration requirements that it will drive ‘modified standards’ for SOSA aligned systems. So, less customization, but still some modification.”

Pros and cons

Curtiss-Wright’s Perez notes that there are benefits aplenty for the SOSA revolution including easily swapping and upgrading systems, however, he sees potential growing pains as companies begin their drive to get their embedded systems approved as being fully certified in the program.

“But I think there’s a little hair on the vision that may prevent it from coming true, at least in the next couple of years,” says the Curtiss-Wright CTO. “One is that the conformance profile or the conformance programs are not fully established yet, so there are no conformant products on the market. There are a lot of companies putting their best effort towards being aligned in hopes of doing future performance, but we’re not quite there yet. The other is if we’re going to insert a different vendor or a technology upgrade, even though the profiles are the same, there are a lot of other pieces of system design that may or may not be the same. One thing that springs to mind is I can have a compute intense profile that could be an intel processor versus, say, an Arm processor.”

Perez continues, “And certainly the system and software that lays on top of those is not interchangeable, so there’s more to it than [hardware]. The other issue is testing qualification — things like vibration and shock testing. Those are going to be unique to each vendor’s instantiation. Yes, they may both conform to the same spec, but often government programs are required to do system tests, so things like EMI can change.”

Mercury’s Hosking, who along with other experts at Mercury — and previously at Pentek — says that the roll-out of the certification process could take another four to six months.

“Last fall, I was predicting by this time [in 2022] we’d have the first boards certified. I’ve talked to people at shows and in general, people are behind it, but it’s inertia. It’s new, and there’s a lot of processes that need to be put into place,” Hosking says.

Ready for takeoff

While the industry patiently waits for the certification process to work itself out, companies are definitely developing products with the SOSA standard in mind.

“Pixus has also developed a SOSA aligned 19-inch rugged rackmount enclosure for mil-aero applications. It features conduction-cooled card mats with fins to dissipate 1600 Watts in the system,” Moll says. “Rear fans pull airflow over the fins for enhanced thermal management.

The chassis can support up to 16 slots and 100 Gigabit Ethernet signals in the backplane. The SOSA aligned SlotSaver mezzanine-based chassis manager is optional.

Likewise, Mercury engineers had SOSA alignment in mind when they designed the company’s Quartz Model 5553 3U OpenVPX board. The 5553 is based on Xilinx Zynq UltraScale+ RFSoC. The RFSoC integrates eight RF class A/D and D/A converters into the Zynq’s multiprocessor architecture, creating a multichannel data conversion and processing solution on one chip.

The 5553 boasts a sophisticated clocking section for single board and multiboard synchronization, a low-noise front end for RF input and output, 16 gigabytes of DDR4, a 10 Gigabit Ethernet interface, a 40 Gigabit Ethernet interface, a gigabit serial optical interface capable of supporting dual 100 Gigabit Ethernet connections and general-purpose serial and parallel signal paths to the field-programmable gate array (FPGA).

The factory-installed dual 100 Gigabit Ethernet UDP IP cores provides greater than 24 GB/sec data transfers, and other protocols are supported with user installation IP.

Curtiss-Wright Defense Solutions offers a SOSA-aligned radial clock LRM for assured position, navigation, and timing (A-PNT) with its VPX3-673. The A-PNT is also CMOSS aligned and is designed with size, weight, and power (SwAP) concerns in mind. The SWaP-efficient VPX3-673 delivers technology services including a GPS/GNSS receiver, chip scale atomic clock (CSAC), and an on-board inertial measurement unit (IMU), all of which are contained within one slot.

Curtiss-Wright says the VPX3-673 is also ideal for radial clock distribution applications and can provide a server for various low-power timing services. Serving as a low-skew clock master powered by a GPS-disciplined CSAC, the module offers a variety of configurable clock reference sources and support for up to 16 synchronized clock outputs.

The VPX3-673’s onboard 10 degree of freedom IMU makes it capable of precise motion tracking in a denied or untrusted GPS environment. Support for an onboard GB-GRAM type II GPS with SAASM or MCODE support is provided, including dedicated zeroize and keyfill functionality. An RS-232 port and RF 1 PPS input are provided for interfacing with an external RS-232 GPS sources.