The aim of this article is to give an overview on the basic implementation of Emergency mode for PoC devices.
When a device initiates an emergency call (DN radio or Smartphone), a new ‘dynamic’ group is created.
(a dynamic group is a temporary group)
DN radios participating in the emergency call move to the emergency dynamic group.
note: Dispatchers have an options for what action to take server and user settings to configure the action taken when receiving emergency calls in relation to moving Talkgroups manually or automatically- e.g. talkgroup scan for emergency channels.
By default, (options available)
1. Emergency calls are semi-full duplex. The initiating radio transmits ‘open’ mic continuously (no TX/RX cycles) on a new ‘dynamic’ Emergency group. (not related to the current selected group). The receiving radio or dispatcher must press their PTT to talk back to the initiating radio (or smartphone), and while PTT is pressed, the call is then in ‘full duplex’ mode. (i.e. transmitting and receiving simultaneously).
2. All devices are always listening for this ‘Emergency’ group when ‘receive emergency calls’ is enabled.
note: 'receive emergency calls' is enabled/disabled per user via T.Commander. DN radios additionally have a menu option for disabling emergency RX/TX which allows user control. (but cannot override server user settings if emergency is disabled)
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Dispatcher:
When an emergency call is initiated from a DN radio (or smartphone), the ‘Emergency’ group/channel is created, and ‘live mic' voice is continuously transmitted (no cycles). The dispatcher will see this new group (RED highlight) added to the list of existing channels. It will also hear the audio from the live mic. (there are options in how the dispatcher views/hears/responds to emergency calls in the T.Commander config)
At this point there are options in how to set up the dispatcher config to respond to emergency calls.
The 'default’ set up requires the dispatcher to manually join the Emergency group (by clicking on it) and then to press the PTT button to talk back to the initiating radio. (if PTT is pressed without doing this, the dispatcher will transmit on the currently selected channel).
The call will continue until either the initiating radio cancels the emergency, or it is cancelled from the dispatcher. (right click on channel name).
Note, when an emergency call is cancelled, the DN radio will revert back to the previously selected channel, and the emergency dynamic group is only cleared when the last user leaves the channel. (in some instances the dispatcher may be the only user left on the channel, in which case they must then manually switch channels or cancel the emergency)
One useful setting for the dispatcher is to use ‘enable talkgroup Talkgroup scan for emergency channels’ which will automatically move the dispatcher to the emergency group.
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There are also options (set in T.Commander) to acknowledge emergencies (this disables every other functionality until acknowledged) and to add a pop up on an incoming emergency - it is advisable to look over and test the other settings available here as there are other options, e.g. time out timer for live mic, that may be preferredto suit the customer requirements.
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