Software Enables Radio Family Ties

Different waveforms pose no compatibility problem.

The software programmable radio era has spawned a new generation of units designed to interoperate while simultaneously serving specific service and platform needs. The result of these digital genetics is instant interoperability among land, sea and air forces as well as software-driven upgrades and compatibility with other systems.

Each radio in this family is designed for the unique requirements of a specific military service. This provides easy interoperability among the three varieties. But, because they are software-driven, the radios also can interoperate with other radios using NATO-standard waveforms such as HaveQuick and Saturn.

Rohde & Schwarz, Munich, Germany, has developed three software-defined radio systems to serve the needs of the individual services. Ulf Reissberg, head of the communication division at Rohde & Schwarz, explains that each of these radios has been developed around the operational needs of the army, the navy and the air force. The differences among the three varieties reflect the different priorities that each service faces in its deployment.

The family of radios is called the M3xR, for multiband, multimode, multirole radio. The x is a place holder for one of the three variant designators. All three are now operational, either as fieldable versions or prototypes, and they can hold as many as four complex waveforms depending on the version of the radio and the particular waveforms.

“This radio is, to some extent, obsolete-proof,” Reissberg declares. “Even if new waveforms appear, these waveforms can be developed as a software package and downloaded.

“These radios are more or less little computers with a small part that is a radio,” he concludes.

The army radio is known as the M3TR, for tactical radio. It is designed as a manpack unit, but it also can be deployed with an installation kit for integration into ground vehicles. The vehicle-mounted version includes a power amplifier with a management unit.

The M3TR covers high frequency (HF) and very high frequency (VHF) tactical communications. Its operations range from 1.5 megahertz to 108 megahertz. A second version of the M3TR features VHF-ultrahigh frequency (UHF) communications from 25 megahertz to 512 megahertz.

Dr. Ruediger Leschhorn, strategic marketing and product pre-definition, Rohde & Schwarz, explains that the M3TR’s receiver and low-power transmitter are identical for both versions. Accordingly, the radio can work with one platform and two different power amplifiers to cover the full range of HF to UHF frequencies from 1.5 megahertz to 512 megahertz. It can accept waveforms such as HaveQuick, Saturn or the company’s proprietary SECOM and SECOS frequency-hopping waveforms. SECOS is a medium- to high-speed hopping system.

Reissberg notes that HaveQuick and Saturn are UHF waveforms that more customarily are used in air force and naval applications. The basic frequencies for the M3TR tactical radio are VHF frequency modulation (FM), and the radio employs different electronic protection measures (EPM) modes when it communicates on HaveQuick or Saturn. The tactical radio’s UHF capability is included for special missions, he adds.

Among the different applications that can be performed by the M3TR are tactical communications between two soldiers, forward air control and tactical Internet use with transfer control protocol (TCP)/Internet protocol (IP). It can transmit data at 64 kilobits per second with overhead on 25 kilohertz using TCP/IP. Forward error correction reduces that data rate slightly. Similarly, poor propagation conditions also can reduce the data rate.

As with its other two counterparts, the M3TR was designed with advantages geared for its specific service customer. Leschhorn relates that this army radio was optimized for weight and power consumption.

The navy radio is known as the M3SR, for surface radio. It is a 19-inch rack-mounted unit designed for land stationary or shipboard use, although it can be installed on a land vehicle equipped with 19-inch rack mounts. This radio also differs from the other members of its family in that it includes different power amplifiers and other equipment.

Leschhorn describes the M3SR as a highly modular radio, both in terms of software and hardware. It consists of a platform with several slots that permit adding receivers, synthesizers and filters, for example. In principle, he adds, a user could remove the UHF receiver module and plug in a higher frequency module that ranges up to 2 gigahertz. Custom-designed interface units could be added to provide interoperability with legacy systems.

Its primary applications are naval uses and air defense. The air defense waveforms are HaveQuick and Saturn. For naval applications, it includes Link-11, and Leschhorn states that a future addition will allow Link-22. The M3SR can work with UHF demand assigned multiple access according to Military Standard 188-181 up to 184. This is standard for both the United States and NATO.

Standard platform interfaces include RS-232 and Ethernet local area network (LAN). Users also can insert customized interface modules into the back of the unit. In addition, it is optimized for collocation with optional internal filters, and external filters can be added if needed for shipboard applications.

Rainer Bott, senior research engineer for data communications at Rohde & Schwarz, explains that this radio’s main interface is a LAN interface. Even a customer with a two-wire or four-wire system can adapt the radio using commercial off-the-shelf interfaces.

Leschhorn notes that this radio was optimized for upgradability, modularity and multiple applications. A high-power amplifier also allows 100-watt FM transmission. He adds that its mean time between failures is 33,000 hours.

The air force radio is known as the M3AR, for airborne radio. It also is suited for army and navy applications, Reissberg relates. Its distinguishing characteristic is that it is a compact unit—a black box—designed to be installed aboard an aircraft. It weighs only 4 kilograms (8.8 pounds), and it can replace the ARC-164 radio. It also can come with a larger ARINC 600 housing, which permits adding options such as embedded cryptography, specialized modems and a higher output rate of 25 watts.

This unit’s frequency bands cover 108 to 174 megahertz VHF, 30 to 88 megahertz and 225 to 400 megahertz. Its capabilities include HaveQuick, Saturn and SECOS. Preplanned product improvement capabilities cover the tactical range and the 30- to 88-megahertz band.

Leschhorn explains that this radio was optimized for performance under a range of temperatures and limited space requirements. As it is designed for aircraft, the M3AR meets operational requirements for temperatures ranging from minus 40 to 55 degrees Celsius (minus 40 to 130 degrees Fahrenheit). Leschhorn states that it actually can operate from minus 54 to 71 degrees Celsius (minus 65 to 160 degrees Fahrenheit).

New waveforms can be developed and downloaded into all three radios from a server or a laptop. Leschhorn describes how a user would connect a laptop physically with a radio to download a new waveform. In principle, a radio could download a new waveform from over its radio network. However, this would be unwieldy with a complex waveform that eats up many megabytes and clogs bandwidth during transmission. A small file such as a standard modulation scheme would work well with this approach, he notes.

Leschhorn observes that these radios can interoperate with many of the other software-programmable radios currently under development. Clearly defined interfaces also permit hardware upgrades when new technology becomes available. The radios’ memory will be upgraded in the future so that they can store more waveforms. This upgrade might take the form of additional chips or replacement of the existing memory.

Robert Vielhuber, marketing manager for radio communications systems and former product manager for M3SR, Rohde & Schwarz, notes that the 19-inch unit is designed to fit a standard rack mount. It has a considerable amount of unused interior space, and this permits various hardware upgrades. It features eight free slots for hardware-based improvements such as increased processor power and new modems.

The M3TR and M3AR each have one free slot for waveform processors. If either radio needs additional processing power in the future, a small module can be added to this slot.

Vielhuber offers that one of the biggest challenges faced by company engineers was to design hardware that could accommodate many different standards. This includes processors, memory chips and the hardware for the radio frequency (RF) front and components. Designing a single RF front end for different standards was difficult.

Reissberg states that one advantage these radios offer is their different EPM modes. In addition to HaveQuick I and II and Saturn, the SECOS and SECOM company modes also are available. Being able to ship the radios with these two proprietary modes opens up export markets that do not have access to the NATO waveforms. He adds that these non-NATO markets comprise friendly nations that do not belong to the alliance, such as in the Asia-Pacific region, the Near East and Latin America.

These radios are targeted for the world market except the United States, Vielhuber offers. Many new and prospective NATO members could benefit from the system’s NATO waveforms as well as company EPM modes for national use. License agreements may lie in the future, depending on the specific country and circumstances.

The U.S. market largely is closed, Reissberg says. A large U.S. program probably would not make use of a company the size of his firm, he suggests. Some smaller niche applications in the United States, such as land and maritime border patrol and search and rescue, might be a good market for the M3xR systems.

Additional information on Rohde & Schwarz is available on the World Wide Web at http://www.rohde-schwarz.com.