June 24, 2011 By Corey McKenna
As the FCC’s deadline for narrowbanding VHF and UHF frequencies approaches, some public safety agencies in Minnesota are electing to switch bands and migrate to the statewide Allied Radio Matrix for Emergency Response (ARMER) system that uses the 800 MHz band.
Public safety agencies that have switched to 800 MHz from the VHF band reported better coverage on the latter frequency, according to Ron Whitehead, a program manager for the state Department of Public Safety’s Emergency Communications Networks division. “One of the things you have with VHF is it’s a dirty spectrum,” he said. “The background level in VHF is a lot higher.”
Another benefit of migrating to 800 MHz is that the state has plenty of licenses, he said, whereas there aren’t enough VHF licenses for a statewide network using that frequency.
Agencies in Hennepin County have been using the Project 25 network since 2002 when they transitioned from a variety of UHF and VHF analog trunked systems that lacked interoperability.
Hennepin County Sheriff Richard Stanek said three events point to the degree of interoperability of the ARMER network. The most recent was a tornado that tore through Minneapolis killing one and destroying more than 100 homes. According to Stanek, 60 to 70 law enforcement, fire and emergency medical agencies responded. “Everything was seamless and interoperable,” he said.
The other two events were the 2008 Republican National Convention and I-35W bridge collapse in 2007, which both included more than 100 agencies from all levels of government.
ARMER provides improved clarity, reliability and interoperability to the public safety agencies in the nine counties served by the Minneapolis Metropolitan Emergency Services Board, according to Jill Rohret, regional radio services coordinator for the board. “Because of a number of shared talkgroup resources available in the system, agencies who previously could not communicate via radio now can,” Rohret commented via e-mail. “In the metro region, a tower site could be down and the microwave loop would reroute traffic the other direction. Traffic is also carried via fiber-optic lines.”
While early VHF implementations of Project 25 (P25) were kind of loose, Whitehead said, that’s being improved. “There’s been a lot of discussion about how P25 was kind of a loose standard where I know in some of the VHF implementations early things were being called P25 that really weren’t, or there were some pieces that could be implemented in different ways,” he said. “But I think that’s being tightened up on pretty decently.”
Because of recent investments in upgraded radio infrastructure and lower costs, 11 counties in the state are opting to narrowband their UHF and VHF networks instead of transitioning to ARMER, according to a December 2010 status report.
Agencies in Mahnomen County have been planning the migration from a conventional P25 VHF network to a digital network for several years and have invested $200,000 to $250,000 in the upgrade, according to the county’s sheriff, Douglas Krier. He didn’t know how much it would have cost to transition to ARMER, but it would have required replacing the radios the department purchased a few months ago, which he said “would be a royal chunk of change.”
Krier said interoperability will continue to be achieved through the use of dual-band radios and channel sharing.
During disasters and large-scale incidents, communications operability and interoperability can also be achieved through the deployment of a satellite-equipped communications trailer maintained by the Hennepin County Sheriff’s Office that includes an 800 MHz trunked radio site as well as VHF and UHF repeaters.
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