Navy Warship Radios Shrinking in Size, Weight.

• Author: Lundquist, Edward

Ships rely on communications, and communications rely on radios. But while the demand and complexity for shipboard tactical comms is growing, the radios are shrinking.

The Navy uses the AN/USC-61 (C) Digital Modular Radio (DMR), which is well established in the U.S. fleet, as well as the newer, more compact Badger software-defined radio to save space, weight and power aboard ships.

General Dynamics Mission Systems' Digital Modular Radio and Badger both have eight circuits per channel, with DMR having four channels for a total of 32 circuits and Badger being a smaller unit and having two channels for a total of 16 circuits, said Bill Rau, vice president for surface ship warfare systems at General Dynamics. The Digital Modular Radio can handle 18 different waveforms, from ultra-high frequency tactical voice circuits to satellite communications.

Software-defined radios digitize several functions needed to establish a waveform and securely transmit and receive information, he said.

With the Digital Modular Radio, the software defines how and what the frequency is, what the power will be, the modulation, the crypto, and then selects the appropriate antenna. It can do this for each of those different circuits across all the 18 different waveforms.

The result is the traditional radio room with racks of transmitters, receivers, power amplifiers, crypto gear and antenna couplers can be pared down dramatically, saving space, weight and power, as well as reducing the amount of heat generated, Rau said.

It's the software that defines the path for each waveform being used. The Digital Modular Radio is built around a semiconductor integrated circuit chip called a field programmable gate array, or FPGA, according to Michael Anderson, head of the joint technical communications and the software defined radio group Naval Information Warfare Center-Pacific in San Diego.

"The world of electronics has really changed significantly from the days of needing massive circuit boards with hundreds of integrated circuits and complex connections to today when it all fits on one chip," he said.

Different waveforms can use very different antennas, said Cesar Garcia, head of the SATCOM control systems branch and lead for the DMR engineering and test integrated product team at the warfare center. "We can't communicate with a satellite 23,000 miles out in space with an antenna that's a half a centimeter long."

Anderson said the "next-generation radios, such as the DMR, can...