Narrowband digital signals as good as P25

Dec 1, 2006 12:00 PM, By Glenn Bischoff

ICOM America soon will release the results of an internal test that indicate narrowband digital signals compare favorably to Project 25 digital signals, according to Chris Lougee, vice president of the company.

Specifically, audio quality is comparable and the bit-error rate is lower for digital signals produced using the company's FDMA technology — developed in partnership with Kenwood USA — when compared with P25, “which already has been accepted as the standard in the marketplace. So it's a good, reliable digital signal,” said Lougee, who was speaking at the inaugural IWCE/MRT Wireless Summit in Charlotte, N.C.

In addition, the narrowband digital signal keeps its integrity over a significantly longer distance compared with analog, “which is inherent to digital technology,” Lougee said.

The ICOM/Kenwood alliance chose FDMA over TDMA — selected by Motorola for its narrowband digital portfolio — in part because it lets users leverage existing FM radio hardware to lower equipment costs. FDMA also requires no infrastructure to operate, which comes in handy during a disaster.

“We saw during Hurricane Katrina, when all of the infrastructure was blown down, the FDMA radios could talk to each other,” Lougee said. “Of course, the range was greatly diminished because you don't have a repeater up there. But you can still communicate in an emergency situation.”

The system is backward-compatible with legacy 25 kHz and 12.5 kHz systems, Lougee said. “That's the real excitement about this product,” he said. “If you have radios that are operating in analog right now, you can take these new radios and merge them into that legacy fleet and slowly combine — over time — the digital and analog channels. So the user doesn't recognize that on one channel they're on analog and on another they're on digital. They won't recognize the difference.”

ICOM only has narrowband digital portable radios available right now but the company is developing gateways, mobile radios and repeaters, with plans to demonstrate a repeater at IWCE 2007 in March. It also expects to introduce simulcast capability in about a year, Lougee said.