As the market for asset management and locating systems expands, however, new passive RFID systems are in the works, according to Jerry McNerney, a senior director with Motorola Inc. ( www.motorola.com), which recently acquired Symbol Technologies ( www.symbol.com)."

"In the past, passive technology hadn't matured enough to provide the read ranges, accuracy and read rates that active tags could provide in an industrial setting," says McNerney. "But today, passive tags are coming to market that can operate in those environments at a much lower price."

The solutions do operate differently.

In a yard management system using active tags, for instance, active tags on trailers are constantly transmitting a signal to fixed readers located throughout the yard.

In a passive yard management system, the yard jockeys that shuttle trailers from a parking space to the dock are equipped with mobile readers. The readers interrogate passive tags on the trailers as the yard jockey travels up and down storage lanes.

"You do make some sacrifices, like read ranges," says McNerney. "But when you take the price point into consideration, passive technology is becoming a compelling solution."