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Military Radio Versatility Now Includes Civilian Functions

November 1999
By Robert K. Ackerman
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Hardware interchangeability teams with replaceable software to enable multifunctional radio platforms.

German engineers have combined modular hardware components with the flexibility of software-driven operation to produce a new line of radios for military and civil applications. These units can operate across a range of different frequencies while maintaining interoperability with similar equipment on varied platforms.

The open architecture radio system can engage in both line-of-sight and beyond-line-of-sight communications. These digital radios are designed to work with state-of-the-art counterparts and legacy units in both the military and civilian arenas. Their software-based design permits flexible network solutions as well as compatibility with a range of national and military service standards.

Individual units can be employed as high frequency (HF), ultrahigh frequency (UHF), very high frequency (VHF) or satellite communications radios as well as in Link-11 applications. Available military waveforms enable a variety of communications modes, including amplitude modulation (AM), frequency modulation (FM), MIL-STD-188-141A, North Atlantic Treaty Organization standard and UHF demand assigned multiple access (DAMA) satellite communications.

This new multiband, multimode, multirole tactical radio system is known as the M3TR. Designed and built by Rohde & Schwarz GmbH & Co., Munich, Germany, the system operates from 1.5 megahertz to more than 500 megahertz. It serves military applications such as tactical communications in 30 to 88 megahertz and 225 to 400 megahertz, but it also can perform in civil applications such as air traffic control. Engineers also can implement a terrestrial trunked radio, or TETRA, waveform for law enforcement applications. Its multirole capabilities allow it to be used as a terminal, a relay station, a range extension node, a radio access point or even a base station for trunked radio systems.

Peter K.H. Iselt, director of strategic marketing and studies for Rohde & Schwarz, explains that the shift from analog to digital has changed the nature of the military radio. Instead of a communications station, the radio has become a highly programmable device that is part of an information system. “The modern radio just looks like a radio, but in principle is a camouflaged computer,” he declares.

Iselt relates that engineers must design new developments in radio equipment within five, or even three, years. This encompasses rapidly emerging groundbreaking technologies as well as performance improvements. Advances in technology bring a broader range of performance capabilities, which in turn lower the overall cost of fielding communications equipment.

The company’s newest radio is only one element of a whole family of new products. Derived from multifunctional technology, the unit is designed as a technology platform, Iselt says. This includes its own specific architecture, bus system, processor hardware design and signal processing for modulation schemes and waveforms. The complete unit can be packaged in any of several different designs, depending on its application. For, example, a compact design serves tactical communications uses, a mounted version is useful for static operation, and a civil application configuration serves air traffic control.

Unlike many other new systems that define their variations solely by software, major distinctions among M3TR versions are hardware-oriented. This approach of avoiding exclusive reliance on software, with its inherent differences, ensures “100 percent interoperability” among M3TR units, Iselt states.

For example, a user can equip shelters, aircraft, ships and land vehicles with slightly different, yet fully interoperable, units from the M3TR stable. Operators would employ similar control units and control philosophies, and maintenance personnel would be able to tap related spare part inventories.

This commonality also provides a degree of redundancy. For example, different applications may require five different types of service in as many frequency ranges, but not all would necessarily be in use at the same time. Instead of installing five separate units to handle the differing tasks, a user could opt for only three radios that could be tuned to the appropriate waveforms as needed. Similarly, any of the radios could be rapidly reconfigured to replace another unit that fails.

The system does not forego software reconfiguration and upgrading, however. Users can load new waveforms from external sources such as personal computers. The system’s hardware commonality permits easy hardware upgrades that could enable further software improvements. The next generation of processors, for example, could be incorporated to allow engineers to download more complex waveforms. Functional block modules within the radio enable changing the technology without changing the radio’s design.

“The idea is to upgrade it just like a PC,” Iselt says.

The keys to this system can be found in three areas. Iselt cites the unit’s digital signal processing power, which enables conversion of analog to digital at higher frequencies with higher bandwidth and data rates, along with more complex waveforms and regulation schemes. Other key enablers are the unit’s bus systems, which are obtained from the commercial marketplace. The processor power of the unit’s controller also is a vital element. In addition to the controller’s power, a related asset is its low power consumption, Iselt notes.

Users have the capability to perform data routing and switching. Units also can interface with tactical analog and digital networks, with local- and wide-area networks, and with personal computers and other data terminals. The local area network interface allows e-mail, Internet browsing and tactical internet access. The system uses standard international protocols such as transmission control protocol and user datagram protocol, and it can interface with integrated services digital network or asynchronous transfer mode networks.

In addition to its ability to serve as a terminal in a combat network radio or packet radio network subnetwork, the M3TR also can serve as an interface between individual subnetworks. It also can be used in intelligent gateway and relay functions such as call autorouting for subscribers external to the unit’s network.

High-data-rate waveforms allow beyond-line-of-sight HF links up to 5.4 kilobits per second. Line-of-sight VHF or UHF data rates can run as fast as 64 kilobits per second, with future enhancements possible. Digital voice and data can be transmitted simultaneously over one channel. Civil waveforms that can be handled in the unit include TETRA; air traffic control HF datalink; VHF air traffic control of 25/8.3 kilohertz; AM; and VHF-FM public services of 12.5/5 kilohertz.

The system features embedded communications security and is compatible with several external security devices. Its embedded communications and transmission security for voice and data is built around a smart adaptive hopping waveform for both beyond- and line-of-sight communications. It offers fast frequency hopping, digital fixed frequency, free channel search mode, intelligent hopping mode, mix mode and advanced user-tailored key and frequency management. Over-the-air management permits wireless rekeying, zeroing and reprogramming through ciphered transmission and access protection.

The toughest part of developing the radio, Iselt relates, was to provide a service-specific solution. This involved using the same technology platform to fulfill the particular requirements of different applications. Having a unit that could serve as a battery-operated tactical radio, for example, requires good performance with low power consumption for as much as 24 hours or more of operation. Fixed units would require high collocation aspects. Finding a common solution for these and many other requirements was the toughest task to achieve, Iselt says.

Ultimately, meeting 100 percent of all possible requirements in the same design simply was not possible. Some cases, such as those requiring low power consumption, necessitated application-specific solutions. The aim—which was realized—was to incorporate a high degree of common modules, Iselt maintains.

The result, Iselt declares, is a system that can cover the frequency range from 1.5 megahertz to 512 megahertz with only one hardware change. All other adjustments are performed by software. The hardware change is manifested in two different radio units for frequency ranges. Serving HF and VHF-FM operation ranging from 1.5 megahertz to 108 megahertz is the MR3000H radio. This unit addresses traditional terrestrial military applications such as vehicle and manpack uses. VHF, VHF-FM and UHF communications from 25 megahertz to 512 megahertz are the domain of the MR3000U radio. This device encompasses air traffic control and military aviation applications.

A single MR3000H unit measures 199 x 234 x 74 millimeters (7.8 x 9.2 x 2.9 inches) and weighs less than 3.3 kilograms (7.3 pounds) without its battery. Its vehicular mount can include VHF/UHF power amplifiers up to 50 watts.

The first M3TR prototype has undergone field tests, and the company already is in contact with several “highly interested” prospective military customers in Europe, Iselt allows. For the global marketplace, the company offers international standardized waveforms such as a proprietary frequency hopping waveform. For applications where a customer already is using other equipment from the company, the unit can be easily configured to provide ready interoperability, he notes.