Military sets less ambitious goals for new tactical radio.

The Pentagon's $20 billion program to develop a family of digital combat radios is expected to see substantial changes in scope and technical requirements.

The adjustments would affect substantial portions of the Defense Department's Joint Tactical Radio System, industry sources said. The focus of the program would shift from replacing current radios to developing advanced networking technology that could be applied to existing devices.

JTRS, conceived in the late 1990s, was intended to eventually supplant more than 750,000 radios in the current military inventory. Unlike conventional radios, JTRS devices work like PCs and can be programmed to operate a variety of software communications applications, which, in the radio world, are called "waveforms."

The program fell into disarray during the past year for several reasons. Among them, experts contend, is that even though JTRS is a "joint" procurement, its organization is very much service-centric. JTRS was divided into "clusters," each managed by a different service. The Army is responsible for duster 1, which covers the service's ground-vehide and helicopter radios, and cluster 5, which are handheld radios. The Navy and the Air Force are in charge of the "airborne and maritime" cluster of JTRS radios to be installed on ships and aircraft.

Another unplanned hurdle for JTRS was the war in Iraq, which prompted rushed purchases of thousands of new combat radios. Under a 1999 Defense Department rule, each time a military service purchased radios, it had to seek a "JTRS waiver" from the Pentagon's Networks and Information Integration office. The policy gave the Defense Department an oversight tool to curb unneeded buys of legacy radios.

After much lobbying by Army and Marine Corps officials, the Defense Department suspended the waiver policy on May 23. Plagued by delays and bureaucratic wrangling, the JTRS program is being restructured under a new management team.

Government and industry sources familiar with the program predict that JTRS will continue, but that the services will "dumb down" the performance specifications. They also expect the revamped management team to set JTRS on a different course, where the emphasis will be on developing mobile network technology rather than on replacing radios.

Dennis M. Bauman, JTRS program executive officer, was unavailable to comment on the future direction of the project, his spokesman said.

Bauman's technical advisor, Howard Pace, told Pentagon officials in June that "not every part of JTRS is in dire straits," according to one of the participants in the briefing. Pace showed a chart that ranked each cluster of JTRS by its level of complexity. Clusters 1 and 5 were categorized as the highest risks.

Another reason for the change in program requirements is the dose ties between JTRS and the Army's largest ever procurement effort, the Future Combat Systems. Until recently, the Army often had stressed that JTRS was an essential element of the FCS, and that both programs needed to march in lockstep. With JTRS now years behind schedule, the Army does not want to see FCS jeopardized in any way, industry insiders noted.

The FCS program, in fact, complicated JTRS efforts by demanding more advanced networking features and increased bandwidth, explained Dan Zanini, vice president of SAIC and deputy program manager for FCS. Boeing and SMC are the lead contractors for FCS.

"JTRS got caught in a time warp," Zanini told reporters. "When FCS came along, the requirements for wideband increased in importance."

The Army does not necessarily need new radios to make FCS work, Zanini noted. But the project is highly dependent on the "wideband networking waveform" software that also is being developed under JTRS.

"JTRS was focused on replacing radios rather than on what we needed, which is the wideband waveform," Zanini said.

Boeing, which also is the prime contractor for JTRS cluster 1, is expected to deliver 40 JTRS prototypes and the wideband waveform software in January 2006, said Dennis Muilenburg, FCS vice president at Boeing.

Tactical communications experts, meanwhile, concede that, despite much hype, the JTRS technology has a long way to go before it can be used in military operations. Another concern is whether the Pentagon's goal of making future JTRS radios compatible with current devices is technologically feasible.

"The hardest part of JTRS is the backward compatibility with legacy radios," said Richard E. Hitt, general manager of Hypres Inc. The company supplies superconducting microelectronics.

JTRS originally was intended to sync up incompatible legacy radios by converting the signal in a process known as "cross-banding." That requirement had to be watered down because it was technologically too complex, Hitt said. The favored approach now is to rely on the wideband networking waveform to link the legacy frequencies.

Another hurdle in trying to make JTRS compatible with legacy radios is the encryption. Security is implemented differently in each legacy radio, Hitt said. "Merging these is one of the most complex tasks in JTRS."

In Hitt's opinion, JTRS is hampered by a more fundamental technology shortfall. "Current JTRS systems suffer from a dependence on semiconductor-based radio devices, which limit the conversion of analog radio frequency energy to digital data," he explained.

Hypres is banking on the prospect that superconducting electronics could help build complex radio networks such as JTRS. The company developed a digital receiver that converts RF signals directly to digital and eliminates the analog processing, Hitt said. Although it seems counterintuitive, JTRS are software radios that are dominated by analog processing, he added.

Three Hypres receivers will be tested at military laboratories. The company has received about $10 million worth of government contracts under the Small Business Innovation Research program.

The technology, however, is embryonic and could face an uphill climb to reach acceptance in the JTRS world. Even the commercial telecommunications industry has been hesitant to invest in this technology.

Digital receivers would be too disruptive to the status quo, said Hitt, and would require "major changes to the current RF architecture."

Superconducting devices also require cryogenic cooling, which adds size and weight. That turns off many people in the military radio market, Hitt noted. "There is 'cryophobig" in the industry ... Communications people have no experience working with cryogenic coolers in their systems."

Where this technology would pay dividends, he said, is in complex multi-channel applications that run wideband and broadband waveforms. The Air Force and Navy JTRS radios, for example, must operate many channels and execute simultaneous operations in multiple functions, such as electronic warfare and signals intelligence.

The future of JTRS is "anyone's guess right now," said Brian Curran, aerospace industry analyst at Frost & Sullivan, a market intelligence firm. The uncertainty will drive contractors to develop software radios as alternatives to JTRS, he said. "Companies such as ITT Industries, Harris RF Communications and Thales Communications will upgrade their legacy radios with new software."

Curran estimated that spending on military tactical communications should remain steady at nearly $5 billion per year. The largest share of the market, he said, is for vehicle radios and intercom devices.