January/February 2023 – Software-Defined Radios: Critical for the Military’s Future Secure Communications Needs

The U.S. Army is in the midst of a multifaceted effort to build a mobile battlefield network that is both modular, open, and immune to interference from enemy electronic warfare systems.

A significant part of this network for ground troops, combat vehicles, command posts and aviation assets are software-defined radios built with open architectures that enable rapid adaptation to adversary capabilities and efficient deployment of emerging technologies.

Standardized radio hardware that can be easily upgraded with new waveforms will allow US forces to communicate between the services within the developed Joint All-Domain Command and Control (JADC2) environment. Launching multiple waveforms at once would allow US troops, aircraft and vehicles to broadcast and receive audio, video and data without being spied on by opposition forces.


Russia’s war against Ukraine highlights the need for secure multi-waveform battlefield communications. Ukrainian forces regularly target radio transmissions from commercial-grade radios and cellphone conversations used by poorly trained and equipped Russian soldiers. Maj. Gen. Jett B. Ray, director of the network cross-functional team within Army Futures Command, said the war in Ukraine validates the Army’s pursuit of secure communications capabilities.

“What we’re seeing in Ukraine reinforces the need for secure communications and greater mobility and survivability,” Wray told the Armed Forces International Communications and Electronics Association (AFCEA) in a Q&A published in November. “There is also great innovation happening with our Soldiers supporting operations in Europe.”

Bringing secure communications technologies into large-scale military formations, installing them in thousands of vehicles and aircraft, and training soldiers to use them has been hampered by the speed of technological innovation, Ray said. Following traditional DoD development and procurement paths, through which a specific radio or waveform can take years to perfect and use, cannot keep pace with the speed at which digital technologies are emerging, said Ray.


“The network will always face challenges with the rapid development of commercial technology and how we can adapt it to military requirements and scale it appropriately across different elements of the military,” Ray told AFECA. “Based on recent observations, the main challenges to achieving network modernization in support of the 2030 Army are velocity to launch – the pace of delivery of new equipment to the force – and alignment of capabilities across echelons.”

Ray referred to JADC2 as a “critical capability” based on a data-centric tactical data fabric. In 2023, the Army is focusing on creating what it calls Network Capability Set 23, or CS23, which will bring together more than 40 separate communications systems, ranging from handheld soldier radios to communications satellites and software-defined network operating systems, into a single system that must to increase overall security and capacity. CS23 will introduce high-bandwidth satellite communications through commercial services while integrating EW, intelligence, targeting and fire control capabilities into the system while easing maintenance, Ray said.

At the heart of these technologies are software-defined radios that feature reconfigurable open-architecture hardware and software capable of digitally processing data. Software-defined radios can be tuned to any frequency band and use multiple waveforms through plug-and-play software applications built to published Army standards.

Mike Shepherd, who leads the FlexLink radio program at Collins Aerospace, now owned by Raytheon, said the Army wants to increase competition for communications software by establishing hardware architecture standards into which more and smaller companies can plug their applications and wireless shapes.

FlexLink SDR aboard a UH-60M from Project Convergence 22Collins

Besides Raytheon, more than a dozen major defense and communications companies are working to develop SDR hardware, software, or both. These include Elbit Systems, L3 Harris, BAE Systems, General Dynamics, Thales, German firm Rohde & Schwarz, Chinese telecommunications giant Huawei and Texas Instruments to name a few.

Shepard said the Army intends to level the playing field not only for major defense contractors, but also for smaller, more nimble companies that may have unique waveforms or applications that could provide an operational advantage. Flexible, rapidly reconfigurable SDRs also increase capacity without weighing down vehicles and taking up as much space as traditional communications equipment, Shepherd said. The real deal is the balance between their capabilities and the size, weight and power, or SWAP, they require of an aircraft, he said.


“If you’ve traveled in an Army vehicle lately, there’s a lot of equipment, a lot of boxes,” Shepherd told Avionics in a recent interview. “So many boxes, which we call ‘boxology,’ and it’s all new hardware. The software allows you to get multiple waveforms on a map. Army aviation needs more waveforms than ground vehicles, for example, because they perform air-to-air, air-to-space, and air-to-ground communications. Earthlings generally don’t need all that. So it allows for mobility. Levels the playing field. This allows other smaller companies to play, not necessarily the big primaries. They can provide a unique waveform or provide a map. So it’s really big picture, adding capabilities and flexibility, reducing costs and adapting to emerging threats.”

“The services, especially in the military, because they are quite active, have made it very clear,” Shepherd added. “No one company is going to build everything, whether it’s the chassis, the cables, the cards or the software. They really want to level the playing field so multiple providers can participate.”

The US Army has engaged industry to create a reference architecture to establish parameters and how industry can collectively begin to develop communications technologies that meet them. Multiple cross-functional teams at Army Future Command, in addition to Rey’s CFT network, are working on the problem.

The CFT network at Aberdeen Proving Ground, led by Gen. Ray, is one. It is joined by the Future Vertical Lift CFT based at Redstone Arsenal in Alabama, the Precision Navigation and Timing CFT also at Redstone, and the Next-Generation Combat Vehicle FCT at Detroit Arsenal.

Last year, the Army published an RFI for a reference architecture. Another final draw is expected in March, Shepherd said. Any open-architecture approach to developing communications equipment will only work if all services align so they can communicate and share technology and data across the Air Force, Army and Navy, he said.

During the Army’s Project Convergence exercise late last year, Raytheon recently demonstrated several solutions to connect defense networks and simplify the US military’s command and control systems. Among those technologies was FlexLink, an open-system radio technology developed by its Collins subsidiary designed to connect multiple air and ground platforms.

During the exercise, FlexLink was installed on the Army’s UH-60M helicopters and created a joint command and control network over 200 nautical miles, validating the Army’s contribution to the JADC2 multipurpose network.

The demonstration integrated the first open-systems radio into a legacy Black Hawk helicopter that had been saddled with Shepherd’s “coxology” for decades as new technologies were bolted onto the airframe first introduced in 1979. The size, weight and power are less of an issue with the Army’s new Future Long Range Assault Aircraft (FLRAA) and Future Attack Recon Aircraft (FARA), both of which are being developed with open-architecture systems from the ground up. Shepherd said the Army must manage 11 simultaneous communications waves hosted on multiple SDR cards for these aircraft. The only way to achieve such a wide communications spectrum is with software-defined radios like FlexLink, he said.

Other services are equally interested in the flexibility and capabilities provided by SDR. Boeing has integrated Rohde & Schwarz MR6000R multiband airborne transceivers from the SOVERON family of software-defined radios into the Air Force’s new T-7A Red Hawk flight trainer. Weighing less than 9 pounds (4 kilograms), the MR6000R meets SWAP requirements for the aircraft, of which the Air Force has ordered 351 to replace its 57-year-old fleet of T-38C Talons. It covers the frequency range from 30 MHz to 400 MHz and supports the NATO HAVE QUICK II frequency algorithms for interoperability and the SATURN fast frequency hopping digital standard, according to Rohde & Schwarz.

“Along with the updated technology and features, the T-7A will be equipped with an improved radio communications package, which will give it an added benefit, preparing pilots for fifth-generation aircraft,” Michael Hostetter, vice president of Boeing Defense & Space, Germany, said in statement.

Frank Dunn, President and CEO of Rohde & Schwarz USA (and Canada), said, “The SOVERON family of radio transceivers provide excellent RF performance suitable for applications in harsh military environments for all types of airborne platforms. Because it’s software-defined radio, we can adapt it for additional learning opportunities.”

Rohde & Schwarz also recently delivered the 1,000th AN/ARC-238 Software Defined Radio (SDR) to Lockheed Martin for integration into F-16 aircraft. The AN/ARC-238 consists of two onboard radios from the SOVERON family of radios, namely the R&S MR6000R/L radios, and meets specific communication requirements while being fully qualified for the F-16.

“Achieving this milestone is a great privilege and demonstrates our team’s ability to continuously produce and distribute high-quality software-defined airborne radios in support of the F-16,” said Stephan Pleyer, vice president of the avionics market segment at Rohde & Schwarz. “I am confident that our SOVERON radios make the F-16 even more effective. We are proud to be working with Lockheed Martin delivering the 1000th SDR.”

These are by no means the only military applications of SDR. Thales, for example, offers a wide range of open system communications devices, but focuses primarily on tactical radios for ground forces. It recently won a contract to provide combat network radios based on the AN/PRC-148 Joint Tactical Radio System Enhanced Multiband Inter/Intra Team Radio (IMBITR) that will be compatible with existing but outdated waveforms while allowing the Army to add new waveforms and improved capabilities to address changing requirements.

As the US Army begins fielding JADC2 and its component communications technology, software-defined radios will be vital to maintaining network relevance as technology and threats evolve. Expect to see the rapid integration of new software capabilities, applications and technologies once the system goes online. It should also provide the communications industry, from top to bottom, with an open door to doing business with the Department of Defense.

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