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10.19.1 Wide Area System Scanning
The P5400 series radio can be programmed for Wide Area System Scan operation for roaming across
mobile systems. Upon the loss of the currently selected system's control channel, radios can be
programmed to automatically scan the control channels of other systems. If a new control channel is
found, the radio will switch to the new system and sound an alert tone.
10.19.2 Priority System Scan
The radio can also be programmed for Priority System Scan. The priority system is the desired or
preferred system. While receiving the control channel of the selected system, the radio will periodically
leave the selected system and search for the control channel of the priority system. This is done at a
programmable rate defined by the value in the Priority Scan Time control (unless the ProScan
™
algorithm
is enabled, as explained in the following sections). This priority scan timer is reset each time the PTT
button is pressed or when the call is received. If the priority system control channel is found, (or meets the
predefined criteria <ProScan>), the radio will automatically switch to the priority system.
10.19.2.1 Enabling the Wide Area System Scan Function
If the radio cannot find the control channel of the selected system and begins to wide area system scan,
the radio will only scan for the priority system control channel if the priority system is in the wide area
scan list.
10.19.2.2 When ProScan is Enabled
The radio monitors the priority system and will switch to the priority system if the criteria defined by the
controls in the ProScan Options dialog box are met. If ProScan is enabled, the rate at which the radio will
scan for the priority system is defined by the System Sample Time control, located in the ProScan
Options dialog box. See Section 8.20.3 for more information on ProScan.
10.19.3 ProScan
The radio may be programmed for ProScan system scan operation for multi-site applications depending
on the version of radio flash code. ProScan is an improved multi-site system scanning algorithm designed
to replace ProSound
™
scanning. ProScan provides the radio with the ability to select a new system for the
radio to communicate on, when the selected system drops below a predefined level. This is accomplished
by enabling each radio to analyze the signal quality of its current control channel and compares it with the
signal quality of the control channel for each site in its adjacent scan list. (The signal quality metric used
for the ProScan algorithm is based on a combination of both Received Signal Strength Indicator (RSSI)
and Control Channel Verification (CCV) measurements.) When the selected system degrades to a pre-
programmed level, the radio will begin to look for a better control channel. Once a control channel that
exceeds the pre-programmed parameters is found, the radio will change to the new system and emit a tone
(if enabled through programming). If the control channel is completely lost, the radio will enter Wide
Area System scanning and search the programmed adjacent systems until a suitable control channel is
found.
10.20 EMERGENCY OPERATION
The radio's ability to declare an emergency, clear an emergency, remain locked on an emergency system
and group, and the emergency audio and display freeze can each be enabled or disabled through
programming. When an emergency is declared scanning will stop and restarts only after the emergency
has been cleared.
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