Radio Communications

Emergency Radio Communication Issues

Greenville County continues to improve radio redundancy.

As with all aspects of emergency services, the radio system is a critical component because this is how emergency crews on the street receive calls for assistance, so there has to be built in levels of redundancy.

1st Level – “Site Trunking” – this indicates the ethernet circuits going to Columbia (Master site) have been disconnected in some way.  Operations continue as normal but radios will display “site trunking”. This is also happens during system maintenance. When this happens most of the towers on the Greenville Simulcast will communicate with each other, just not outside of the county.  If it cannot find the simulcast, it will lock on to a single site. Users can talk to others on the same site or on the simulcast.  No site to site or wide area communications exist when in site trunking mode. Procedures at each 911 center for Greenville County are in place to handle radio traffic during these times.  Users of the system will sometimes have to site lock their radio, so it stays affiliated with the Greenville Simulcast, instructions for this process are on the website.

2nd Level – “Failsoft” – this indicates that the simulcast system has lost the ability to “trunk” and reverts to a programmed frequency per our simulcast failsoft plan.  The failsoft plan groups “alike” agencies together on frequencies so they can continue working.  This is preprogrammed in radios, so users won’t have to change any settings. The only thing to consider is having more users on the consolidated channels.  Radios will display “failsoft” and will beep periodically to indicate the failsoft scenario. This is a more severe situation with radios working in a traditional repeater setup and could be caused by a multitude of things. Procedures for this scenario combine several channels into one, so 911 centers have to adjust the amount of radio traffic occurring.

Radio tower sites in Greenville County have multiple sources of power – primary and backup systems are also accompanied by generator backups in the event of power failures. Motorola has contracts with fuel companies to replace fuel when needed.

The statewide system partnership is monitored 24/7/365 by Motorola and have local radio shops on stand-by anytime they are needed for system problems and repairs.