December 2000

©SIGNAL Magazine 2000

One Box Covers Many Systems

Digital modular tool enhances flexibility and reduces logistics, training requirements.

By Henry S. Kenyon

The U.S. Navy will equip its ships and bases with a software programmable radio that replaces several radios and computers with a single unit. The device interfaces with the service's and allied nations' existing communication and data standards and features additional bandwidth for new waveforms.

As the armed forces move toward the U.S. Defense Department's vision of a single, seamless data environment, interoperability becomes paramount. Legacy radios are less capable when voice, data and video converge into a single stream. This lack of flexibility drives the need for more versatile, multipurpose tools that can be easily reconfigured to meet commanders' immediate tactical needs.

A device capable of fulfilling these requirements is the digital modular radio (DMR), which the Navy plans to deploy in 2002. It evolved from a commercial vision by Motorola Incorporated, Scottsdale, Arizona, to develop a software programmable radio. The DMR is part of a larger company program called the wireless information transfer system (WITS), a family of communication systems that can be reconfigured via software without modifying the hardware.

According to David Kohler, director of marketing, WITS, the defense applications for the DMR grew out of SpeakEasy, which was a software-defined radio program conducted in 1996. The project created interest within the Defense Department for a digital radio operating with open-standards software.

The Navy was drawn to the radio because it wanted to lower life-cycle costs for its communications systems. According to Dan Murray, assistant program manager for the DMR at the Navy's Space and Naval Warfare (SPAWAR) Systems Command in San Diego, many ships' radios have been in service for up to 35 years and are now at the end of their operational lives. The service is seeking to take advantage of the latest commercial technology in its procurements to avoid lengthy development times. Another issue is how to avoid the logistics and maintenance costs associated with aging legacy equipment, he says.

The Navy DMR is a variant of Motorola's 6004 software redefinable communications system. While the hardware is identical, the DMR has fewer software options than the 6004. However, because the system is part of the WITS product family, the Navy can easily change or upgrade the software in the future, Kohler says.

Scope and flexibility are factors that set the DMR apart from other software-programmable radios. It can operate as a system of systems, enabling communication and information transfer, Kohler explains. The radio's open architecture allows it to operate on the Navy's standard simple network management protocol (SNMP) software. The device also interfaces with the service's Ethernet network and features standard serial port interfaces.

Because the DMR has the capabilities of four radios in one box, several radios can be removed from a ship, which saves space, weight, heat and training time. Supporting only one radio also drastically reduces the logistical tail generated by multiple systems. Murray notes that two DMRs installed on board a ship have the same functionality as 10 legacy radios. Because the device is software programmable, upgrades do not require the costly and time-consuming replacement of hardware components.

The base 6004 system features a four-channel gateway that permits independent configuration of security levels for each channel. A radio frequency interconnection also facilitates interoperability between diverse legacy and emerging network standards. The channel settings exist virtually in the software, allowing for quick changes to meet battlefield needs.

Dede Connors, WITS brand manager, emphasizes the flexibility of the off-the-shelf system. "Today, if you buy the DMR box, it has four different channels. Each channel can be separately reconfigured as to encryption type, waveform and bandwidth. You can have four different radios programmed in, one on each channel. Tomorrow, you could reprogram those same channels to be totally different radios," she says.

According to Capt. Craig Madsen, USN, program manager for advanced automated tactical communications, SPAWAR, this ability to change waveforms on the fly is another reason the Navy is interested in the system. Such flexibility will allow commanders to tailor their communications needs to the tactical environment.

For example, during an operation, the captains of widely dispersed vessels would receive their orders via the radio's satellite communications (SATCOM) function. As the battle group forms, the waveforms are changed to those of line-of-sight radios. If the operation becomes an amphibious assault, the DMR can be switched to very high frequency to communicate with U.S. Marines on the beach. As the Marines move inland, high frequency transmissions are then selected. At the end of the mission, as the battle group disperses, the radio systems are returned to SATCOM. "It gives you flexibility across the tactical battlefield," the captain says.

The DMR differs from other radios because it, like the entire WITS family of devices, features an advanced information security (infosec) machine (AIM) embedded in the system. Security is a concern because the radios can be remotely reprogrammed over the air. AIM is a programmable cryptographic engine designed to secure communications applications across a spectrum of encryption levels, from military and government through commercial grades of security.

AIM's heart is a high-speed, very-large-scale integration microprocessor device with multichannel and multialgorithm capability, enabling it to potentially replace several standard encryption functions in a single unit. Kohler notes that the device has been endorsed by the National Security Agency up to top-secret and sensitive-information levels. Because AIM is programmable, WITS devices can be sold commercially overseas without Defense Department-unique encryption, satisfying multiple markets, he says.

The DMR was selected after successfully competing in field trials held at the SPAWAR Systems Center in Charleston, South Carolina, Kohler explains. As part of the testing, the radio had to operate legacy waveforms and have capabilities such as the demand assigned multiple access 181 and 183 satellite communications systems, HAVEQUICK electronic countermeasures system, and the single channel ground and airborne radio system (SINCGARS).

These three systems were demonstrated end-to-end through the DMR, covering voice communications, security algorithms and radio frequency functions. The radio also operated in amplitude modulation and frequency modulation wavelengths across the band, from 2 megahertz to 2 gigahertz, and provided a receive-only function at 100 kilohertz. Kohler adds that all of these functions will be in the units being deployed to the Navy.

For channeling data on board Navy ships, the DMR demonstrated SNMP, Ethernet and serial connectivity requirements. Additionally, because of growing wireless data networking needs, there will be room for future data and waveform algorithms, which Motorola treats as application software because they fit directly into the system's open architecture, Kohler explains. For example, during the testing period, the Navy introduced a new digital waveform, placed it on a compact disc, and loaded it onto a DMR with no difficulty, he says.

Bandwidth capability varies according to the type of signal being used. The DMR can operate up to T-1 speeds, or 1.544 megabits per second. Legacy communications bands such as SINCGARS and HAVEQUICK operate at 16 kilobits per second and below. Currently, no wireless waveforms exist that require more than 64 kilobits per second, Kohler says. However, the radio's bandwidth capability is higher than existing requirements so that future signal types can be added without hardware modifications.

The DMR also can be controlled via a personal computer or laptop in the field. Kohler notes that, under the SpeakEasy program, a version of the radio was field tested during the task force 21 exercise. Operators had two options for setting the devices. One featured a screen that was specific to each radio type. The second choice was a Windows-based screen that treated all of the radio's preloaded waveform types as a generic format. All users at the event preferred the latter method, he says.

Besides featuring a single Windows-based format, the interface offers control of elements such as volume, squelch and frequency. The DMR's computing functions can also be regulated through the interface software. Connors notes that users must only be familiar with one screen type, instead of multiple screens. "It's the same. They just learn it once. It doesn't matter which radio they've configured their WITS box to look like, it's all the same," she says.

The DMR is designed for installation in rack-mounted maritime and fixed environments. The radios also fit into the Defense Department's joint tactical radio system vision, complying with the system's requirements for maritime and fixed domains.

Initial field testing of the DMR is scheduled to take place aboard selected ships between January and August 2001, Capt. Madsen says. Once the system passes this phase, it will go out to the fleet. The plan is to begin equipping entire battle groups in 2002.

The first application for the radio is to provide satellite communications for Navy vessels, either by replacing legacy equipment or becoming the primary system. Some smaller ships, such as minesweepers, currently do not have SATCOM capability, Murray notes.

Navy officials also are interested in foreign military sales to enhance communications with allied nations. "From the Navy's standpoint, it is the fact that it is programmable and that it permits much more connectivity and interoperability with other countries' systems than they had in the past," Kohler says.

Beyond the Navy, Kohler sees a number of potential military and government roles for the technology, noting that the U.S. Customs Department will begin fielding WITS devices in a slightly different configuration than the Navy's. Other applications can be at the state and local levels, where DMR-type equipment can replace the multiple radios and bands used for police and fire department communications.

Additional information on Motorola is available on the World Wide Web at http://www.motorola.com.

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