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15.4.1 Changing Selected Radio A radio unit can be selected by pressing the radio selection button (pre-programmed) on the
control unit. In addition, a button can be pre-programmed to rotate selection through the radio
units. For example, if radio #1 is selected, pressing the radio selection button will select radio #2.
Similarly, radio #1 will be selected if the radio selection button is pressed when radio #2 was
selected.
15.4.1.1 Shared Control Unit Display Modes
Radios in the multiple radio operation share the control unit display. Pre-programming the radios
determines what the control unit displays. There are two modes of display: alternating radio
display or first-come first-serve display. See also the following paragraph on Audio Modes.
15.4.1.1.1 Alternating Radio Display
In this mode, the control unit display will alternate between showing the call information for the
radios when more than one call is being received. This mode is available only if audio is summed
(see following paragraph on Audio Modes).
15.4.1.1.2 First-Come First-Serve Display
In this mode, the control unit display will show the call information of the radio that is providing
the audio. A call in process prevents audio from other radios from being heard for the duration of
the call. This mode corresponds with the first-come first-serve audio mode (see following
paragraph on Audio Modes).
15.4.1.2 Audio Modes
In multiple radio operation, the audio from the mobile radio units can be pre-programmed to be
summed or available on a first-come first-serve process.
15.4.1.2.1 Audio Summed
When audio is summed, the audio from all radios will be available whenever the radios receive a
call. If two radios receive a call simultaneously, both calls will be heard in the speaker.
15.4.1.2.2 Audio First-Come First-Serve
When audio is pre-programmed for first-come first-serve, the audio from the radio that receives a
call first will be heard from the speaker for the duration of the call. During this time, audio from
the other mobile radios will be muted.
15.4.1.3 Muting a Specified Radio
Pressing the control unit mute button associated with a particular radio will mute its audio for a
pre-programmed time period. The time period can be cleared by pressing the control unit mute
button or the radio selection button.
15.4.1.4 Multiple Radio and Siren & Light Operation
For siren and lights to function correctly, both the master and slave radios must be programmed
with the same siren and light information.