HOUSTON — Upcoming changes in the “intrinsically safe” standard for LMR portable radios used by insurance company FM Global could impact the technical design, operational functionality and cost of mission-critical communications systems used by public-safety agencies, speakers at the Association of Public-Safety Communications Officials (APCO) conference said yesterday.

“If you don’t know about this, it will hit you like a freight train,” John Facella, director of public-safety markets for Harris, said during a presentation on the APCO show floor. “This is a big deal, and it’s going to impact a lot of stuff.”

New FM guidelines approved more than a month ago call for LMR portable devices to operate at power outputs of 0.5 watts or less — instead of the current 3-watt limit — to be deemed intrinsically safe as a Class 1, Division 1 device as of Jan. 1, 2012, said Dirk Young, manager of national public-safety markets for Harris. Existing radios in a system would be grandfathered, but new radios purchased after 2012 would not be certified as intrinsically safe if they exceed the 0.5-watt threshold, he said.

For public-safety entities that want to maintain the intrinsically safe standard for their systems for safety and insurance purposes, the proposed dramatic decrease in radio power levels could be problematic in several respects, Young said.

For instance, many fire agencies opt to communicate in peer-to-peer simplex mode while on the fireground, so they are not impacted by potential problems encountered within the radio network. While this can be done effectively at the scene of a large fireground using 3-watt radios, a 0.5-watt device likely may provide only about a quarter mile of signaling in an open area and would have considerable difficulty penetrating through walls of a building, Young said.

In addition, general portable coverage for LMR systems also would be impacted, because the lower power levels would drastically reduce the distance that a portable-radio signal could travel to reach a tower. To compensate, LMR systems would have to erect more towers to maintain existing coverage.

“Exponentially, you have to have more tower sites in a geographic area in order to have coverage for a half-watt portable radio,” Young said in an interview.

For vendors, the proposed FM guidelines — not just the power levels, but other aspects — would mean that LMR radios would have to “be redesigned from scratch,” Young said. Such an overhaul would require considerable engineering resources, meaning the price of radios would increase, he said.

Such guidelines have been adopted in Europe, where public-safety entities use the TETRA standard that requires more towers than P25 and other U.S. LMR technologies. As a result, the lower device power limits in Europe are not a problem, but that will not be the case in the U.S., where each tower needs to cover more geographic area to provide first responders with radio coverage in a cost-effective manner, Young said.

Young and Facella said they do not know of any safety issues regarding the current FM guidelines but noted that there was a sentiment to adopt a worldwide standard for intrinsically safe radios.

Young and Facella encouraged attendees to lobby for the FM guidelines to be changed.

“If the vendors just come back and complain, then [FM officials will say,] ‘Oh, you just don’t want to build a new radio,’” Facella said. “So, it’s better if this comes from the user community and the industry trade associations, I believe.”