Lapeer County Switches to Digital

logoAfter several years of work, Lapeer County Central Dispatch switched from an analog radio system to a digital radio system at 12:05pm on December 18, 2012.

We have doubled the amount of radio towers we use from three to six. We now have sites in Almont Village, Metamora Village, Imlay City, Lapeer City, Burnside Township and Deerfield Township. We absorbed the State of Michigan’s Deerfield site into our simulcast as part of the project.

The analog system had ten frequencies and two of them were dedicated for data usage while the remaining eight were left for voice channels in the trunking system. The new digital system now has fourteen frequencies allotted for voice. Data is no longer used since we changed to a cellular configuration earlier in the year for police in-car computers.

Also, the analog system had a total of 72 talkgroups and through some changes in setups, the digital system has a total of 74 talkgroups available to the various Lapeer County users plus a plethora of neighboring county and state talkgroups.

Lapeer County users are among the first in the state to be ready and capable of utilizing 700MHz frequencies should they become available in the area. Our radios are already programmed for it which means if that time comes, we shouldn’t have to make a fleet-wide change to accommodate it.

We contracted with Motorola Solutions for 95% county-wide coverage on a 3-watt portable radio. Due to FAA regulations at the Metamora site, we had to reduce the tower height by 80 feet which put our coverage projections to 94.96% coverage. Once we completed actual coverage tests earlier this month, we ended up with an amazing 99.89% coverage throughout the county. That includes attenuating the test radios at -15db to simulate in-building coverage in the city/village areas of the county. The rest of the county had the test radio set to be attenuated at -6db to simulate vegetation on the trees.

On the day of the system cut-over, at about 9:00am we began processes of shutting down half of the analog system, moving feed lines and other things at the MPSCS Deerfield site and then turning on half of the channels in the new system. Then the MPSCS began enabling all of our new talkgroups on our towers and surrounding towers. By about 10:30am we began moving users over to the digital system. Once roll call radio checks and pager tests were complete, we finished the cut-over process by turning off the remaining channels of the analog system and turned on the remaining channels in the new system. By 12:05pm the analog system was completely shutdown and all users were operating on the new system.

We are still operating on our old paging system due to licensing issues with the FCC and Canadian Coordination for our VHF frequency. The FCC has granted us a time waiver for the narrowbanding requirement that we must meet. The old paging system is incapable of being narrowbanded. Once we get a license for the new paging system and turn it on, we will be in compliance as that system is already narrowbanded to 12.5KHz.