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CALHOUN COUNTY

The P25 radio system keeps emergency responders connected — but it needs an upgrade

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911 radio system

911 director Kevin Jenkins and Shelby Smith dispatch calls inside the 911 / EMA building in Jacksonville.

JACKSONVILLE — It wasn’t so long ago that Calhoun County 911 dispatchers took it on faith that police were nearing a caller’s location. 

But modern radio technology has given dispatchers digital maps with live updates of first responder locations, so they can say with authority that help is nearby.

Police and fire and EMS units hooked up with the county P25 radio system — a complex set of equipment, software and signals fired over high-powered microwave frequencies — share their GPS locations, which helps not only reassure 911 callers, but adds a layer of safety for responders. 

“Not only can you see where an officer is, but you can see where their portable is,” said Kevin Jenkins, 911 director, during a tour of the P25 system’s inner workings at the agency’s headquarters this week. “Imagine if they have to chase a suspect out into the woods. We can still send backup to their location.”

The P25 radio system allows first response agencies throughout the county and state to instantly connect to one another during joint operations. For instance, the system was critical after the March 2018 tornado that hit Jacksonville, allowing quick coordination among police, fire and medical services, including agencies responding from outside Calhoun.

The radio system has been a regular topic for local government since July, when the Calhoun County 911 Board began negotiating a necessary upgrade to the system with city and county leaders.

The upgrade will cost about $5.9 million with service provider Motorola, and 911, which manages the system, has most local governments on board to help pay. 

Understanding the value of the system, which unifies contact for most police, fire and EMS agencies in the county, has been simple enough. 

But visualizing what the system actually is, or how it works, hasn’t been so easy.

Faster than a speeding chase

The radio system’s brain lives in a server room at 911 headquarters, a former National Guard post shared with the county Emergency Management Agency, located on Francis Street. 

There are 18 black, boxy controller units mounted to server racks, each corresponding to a channel on the network. 

According to Brad Campbell, systems manager at 911, the equipment is about 16 years old, but it’s still a powerhouse of communications: Each time someone hits “talk” on their portable radio, a complex set of computations begins to fire between the controllers, the nine local communications towers and the central broadcast tower at 911. 

Each tower in the system receives the broadcast, and each piece of equipment in the “talk group” with the portable radio receives it, too. The process takes milliseconds, but it happens thousands of times each day. 

These analog units aren’t supported by Motorola any longer. If one buckles under the processing strain, there’s no hope for repairs, and a channel simply disappears.

“I can’t go down to Best Buy and buy the parts I need,” Campbell joked. “Motorola certifies the parts to be used on the system. They’re not consumer-grade.” 

The portable radios are just as complex, Jenkins said. The nature of the system, which sends any one signal to each tower, making that message available countywide, allows the handsets to poll local towers and choose the strongest one, like a mobile phone does. 

That’s a big deal during a pursuit on the highway, Jenkins said, when police vehicles are moving fast, multiple officers are talking and every message is critical. 

If any part of the process is off by even a fraction of a second, the system is thrown into chaos, Jenkins said, and messages turn into digital noise. A pair of time-keeping devices on the server rack sync and regulate to keep the controller units on cue. 

After the upgrade, Campbell said, the 18 controller units and other equipment supporting them will become a single, digital unit, leaving analog circuitry behind and buying back a lot of server space.

Flowing over microwave frequencies

Downstairs, next to the dispatch call center, equipment that regulates 911’s high-power microwave broadcasting tower is mounted to another server rack in its own room. 

“For us, that’s beyond the foundation of the house,” Jenkins said. “That’s like the earth the foundation sits on.” 

Two processing units managing the microwave produce 150 megahertz of bandwidth for the system. Right now, that includes the audio transmissions, GPS service and data. 

The upgrade will boost that bandwidth to more than 500 megahertz, Campbell said, which will enable future growth, and create space for more complex data, such as video transmissions.