Codan Radio P25 Training Guide - Manual (Page 41)

P25 RADIO SYSTEMS | TRAINING GUIDE
Chapter 3: P25 Technical Information Page 33
There are 3 methods to send a voice message, with several options and variations of each case. Each
of these 3 methods of sending a voice message can operate in clear or secure mode.
The three main types of voice message calls are:
Routine Group Call This is the most common type of call and is intended for a group of users within the
radio system. This type of call is typically initiated by asserting the PTT switch.
Emergency Group Call This type of call is similar to a Routine Group Call, but is used during an emergency
condition. An emergency condition is defi ned by the radio system users This type of
call is typically initiated by asserting the Emergency switch.
Individual Call This type of call is addressed to a specifi c individual. The caller enters the subscribers
Unit ID, that they wish to call, and this is used as the Destination ID by the radio making
the call. This type of call is made after the Destination ID is entered into the radio.
The P25 transmitter has suffi cient controls to support the three main types of voice messages. These
controls are as follows:
PTT Switch - The Push-To-Talk switch is pressed when the user wishes to transmit and released when
the transmission is over.
Channel Selector - The Channel Selector allows the user of the radio to select a radio’s mode of
operation. The Channel Selector controls the following parameters of the radio:
1. Frequency
2. NAC
3. TGID
4. Other (eg. selecting the encryption key)
Emergency Switch - The Emergency switch will allow the user to assert the emergency condition.
Once asserted, the emergency condition remains active until cleared by some other means (eg. turning
the radio off).
Numeric Keypad / Display - The Numeric Keypad / Display will allow the user to set numeric parameters
(eg. the Destination ID in an individual call).