For the public-safety community, software-defined radio, or SDR, isn't science fiction, but already is reality. The real question is whether it will take a form that public safety finds valuable enough to make the investment.

“Most everything we buy today is a software-defined radio,” said Harlin McEwen, chairman of the International Association of Chiefs of Police's communications and technology committee and a technology adviser to three other major law-enforcement associations. “Most equipment is now more or less computer-driven, no longer driven by crystals and tubes. The point is, as software-defined radio develops, it becomes more able to provide more capability.”

SDR technology ultimately offers the promise of delivering a communications device that can be programmed to operate across multiple bands with multiple waveforms, providing a “universal radio” for first responders. However, to make good on that promise, equipment vendors must listen more carefully to first responders to avoid delivering features that aren't useful. Furthermore, waveform intellectual property issues likely will become one of the larger headaches in the development of multi-band public-safety SDR devices.

“When we start discussing bleeding-edge technology for public-safety people, it involves real blood,” said John Powell, a senior consulting engineer to the Department of Justice and the Department of Homeland Security. “We're going to have to take some very definitive steps to make sure [SDR] meets our requirements rather than what someone in the industry thinks we need.”

Powell said the land mobile radio industry historically has devised solutions they thought were appropriate, rather than adhering to the requirements of the public-safety community. “We've got to make sure it doesn't happen with SDR,” Powell said.

Representatives of the public-safety community and SDR advocates agree on the need for companies to listen better. “The manufacturers claim they're building things their customers are asking for, but the public-safety community says they are building things with features that they don't need,” McEwen said.

Fred Frantz, chairman of the SDR Forum's Public Safety Special Interest Group (SIG) agreed. “[First responders] are more interested in requirements,” he said. “They know what they need.”

M-A/COM Vice President John Vaughan said the disconnect between vendors and public safety is the inability to agree on a working definition for SDR. “The one thing about software-defined radio is that they're not well defined,” he said. “You're seeing a technology in development, and people are experiencing it as it is being developed and defined.”

However, the national public-safety community has published a comprehensive description of interoperability requirements — including guidance on features that would be desirable in future SDR products — through the Department of Homeland Security's SAFECOM project, according to Frantz. It is an effort that has helped Motorola gain a better understanding of what public safety is seeking, said Geoff Hobar, federal systems planning manager.

“SAFECOM was the first time the federal government tried to pull [public-safety requirements] together,” Hobar said. “Before that, we had to take the initiative to survey our customer base. The SAFECOM document is a nice change. It is a public-safety agency soliciting public-safety people.”

Everyone interviewed for this article agreed that SDR technology continues to evolve, with manufacturers currently enhancing radios where they see benefit. The next step would be in harnessing the technology to add functionality that's not available in current radios and, ultimately, demonstrating an SDR capable of operating on a wide range of frequencies and supporting multiple waveforms. For example, the National Institute of Justice's communications technology working group has identified the development of a multi-band radio using SDR as a No. 1 priority.

“If you can buy radio products that have the ability to work in multiple frequency bands, that would be more practical than buying radios for multiple bands,” McEwen said.

Powell indicated an initial demonstration of a multi-band radio in a public-safety environment might take place in the near future. The DOJ is working with the San Jose Police Department to place Department of Defense SDR equipment into public-safety use, specifically the AN/PRC-148 Thales Multiband Inter/Intra Team Radio (MBITR) currently used by U.S. Army Special Forces. Weighing less than 2 pounds, the MBITR portable handset can operate in a range from 30 MHz to 512 MHz and would replace five different radios that city departments operate from 150 MHz to 512 MHz.

The demonstration won't be cheap, with Powell citing cost estimates of $5000 per handset, but it isn't as bad as it sounds, he said.

“You've got small quantities, number one. The DOD product is typically more expensive, number two. But that price is not atypical for what agencies are paying today for a full-featured … P25 radio.”

Ironically, one waveform that won't be supported during the initial trials is the APCO Project 25 standard. “DOD has had some problems with the company initially developing the P25 waveform,” Powell said, adding that they're looking for another company. “For any of their stateside operations, they're going to need P25 to talk to local, state and federal agencies. Base security is required to use P25 now and has been for several years.”

A successful demonstration in San Jose would only be the first step in the wider use of SDR in the public-safety community, with many issues still to be resolved, such as power sources and antennas, according to Powell. “There's a tremendous amount of computing power involved,” he said. “You need a power source to provide the extra power with the same amount of service length as we have with the existing battery.” He added that solutions likely would emerge from the cellular world.

Proprietary interests likely will present an additional and much more significant challenge to the development of SDR technology. “The largest hurdle we have to overcome in integrating legacy waveforms into a single box is going to be intellectual property rights issues,” Powell said. “How do we cross-license waveforms from Motorola, M/A-COM and EFJohnson so we can put them in the same box? That will not be a trivial issue in my opinion. … Potentially, it will require negotiation at higher levels of government, potentially some legislation.”

McEwen agreed that government, particularly the federal government, must be more involved in SDR's development if the technology is to reach its potential, particularly from a funding perspective. But he acknowledged that there's only so much money to spread around.

“The amount of funding that is required to replace or upgrade old technology is pretty significant,” he said. “The financial resources of the state and local communities are not in good shape to fund [SDR] … which means there is greater reliance on federal funding. But there's also greater competition for federal funding.”