Getting on the Same Wavelength

Incompatible radio technologies force the Pentagon to refocus its high-tech vision.

Tomorrow's military should be faster, lighter and even more lethal, owing to myriad battlefield sensors feeding information to troops. Thanks to their information edge and speed, soldiers in the future should be able to find and shoot enemies before they attack. Speed comes at a price, however; the military says combat vehicles will carry less heavy armor than today's, substituting the virtual armor of situational awareness for hard steel encasing.

That's the idea behind network-centric warfare, the new paradigm of warfighting the Defense Department is spending billions of dollars to develop. Communication networks lie at the heart of this high-tech vision, and they must penetrate down to the troop level or else their virtual armor will fail to materialize.

Key to making that possible is a tactical radio capable of high-bandwidth transmissions for voice, data and video; one that can send and receive on multiple frequencies. The Joint Tactical Radio System program was ambitious when it launched in 1997. In the years since, its objectives escalated to the point where the Pentagon formally scaled it back in March.

JTRS "was not on a path to execute and deliver a capability to the warfighter," said Dennis M. Bauman, JTRS joint program executive officer, speaking with reporters from his San Diego office earlier this year. The program will now concentrate on moderate- and low-risk technologies. "We're not going to do science projects," Bauman added.

The basic idea behind JTRS is to integrate dozens of incompatible radio designs, none of which will be removed from the field anytime soon, and in the process expand the data capacity available to warfighters.

The problem with military radio incompatibility begins with something called a waveform, a catchall term for the method of converting into a radio signal the sounds that go into one radio and come out the same from another. Traditionally, much of that process, which involves modulating (and demodulating) a carrier wave, message formatting, transmission protocol-and especially for the military, cryptography-has been tightly coupled with application-specific circuitry or proprietary hardware. A soldier using a Single-Channel Ground-Air Radio can't receive an Enhanced Position Location Reporting System signal because the hardware for waveform processing simply isn't there.

Joint Tactical Radio System seeks to bridge that gap by decoupling signal processing from hardware and making it a function of software where possible. With JTRS, waveforms become analogous to the applications running on a desktop computer, says Ralph Moslener, the proj-ect's manager of ground mobile radio at Boeing Co., the prime contractor for JTRS vehicle-mounted and hand-held radios. In addition, the program will implement a new waveform with a throughput of 2 Mbps, designed for high-bandwidth transmissions such as video.

But there are limits to how far that interoperability can scale without running into barriers imposed by weight restrictions, heat generation, energy consumption or immature technology.

Before its springtime reorganization, JTRS sought to create one device that could process 33 different waveforms. Program managers have scaled that down to a more manageable dozen waveforms, with the ability to handle four of them at one time. Users might have to switch antennas to receive signals from the entire range.

"The universal radio, a single box that can talk to every other radio, is a myth," says John Chapin, chief technology officer of Vanu Inc., a Cambridge, Mass., software radio developer. But it is a compelling myth, and the JTRS program had fallen for it, he adds.

Program officials acknowledge their eyes were bigger than their stomachs. Among other things, encryption requirements grew tremendously once JTRS became a data networking device for use in the field. Initially, the technology was meant to solve only the interoperability problem created by hundreds of thousands of legacy radios, which the military can't afford to replace in one fell swoop. But as network-centric warfare gained currency in the Pentagon, JTRS grew into a program that delivered data and ad hoc networking at the tactical level. "That change represented a huge requirements increase," Bauman said.

All of the planned capabilities would have required $6 billion of research and development money over five years, according to Bauman. The program now will spend $4 billion for R&D, ditch interoperability with some legacy waveforms, but preserve the high-bandwidth transmission capability. "We have done a significant revamping of both the requirements and the budgeting, and we've adopted an incremental, moderate-risk program," he said.

But even in their decision to be carefully pragmatic, JTRS officials should keep an eye peeled for future technological developments lest the project sets itself up for a collision with Moore's Law, the observation that computing power doubles every 24 months, says Chapin. Boeing's Moslener says JTRS software will be portable among different radio manufacturers, and Bauman noted that the program even has developed a software repository for use when contractors develop future radio devices-presumably built with faster processors. "We do not want to be in a sole-source position for hardware with anyone," Bauman told reporters.

But, according to Chapin, true software portability for anything other than relatively narrow and slow waveforms has been an unattainable goal. "The $20 billion question for JTRS is whether, with proper technological and management and acquisition choices, the bulk of the JTRS software can come down on the side of, 'Yes, we can reuse most of this stuff,' " he says.