User's Manual Part 1

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Scanning Channels
Scanning allows a HF transceiver to monitor several channels for incoming calls. It
is particularly useful as the nature of HF signal propagation means that not all
channels are available for communications at one time. For instance, a station
calling a station that is in scanning can send a “Beacon Call” on any channel
knowing the station it is calling is monitoring all its available channels. A response
from the scanning station will only occur on channels that are “open” for
communication.
Stations in scan can also monitor channels for voice activity or signals received that
has a signal strength over a preset level.
Selcall Scan
When a Selcall signal is detected, and the channel has Selcall enabled, no matter
which mute type is selected the transceiver will stop scanning and decode the
Selcall. The transceiver will only stop scanning when a Selcall is detected.
Signal Strength Scan (SSL Scan)
If the signal strength mute (squelch) is active and a signal with a level greater than
the pre-set threshold is received the scan will halt. Scan will remain halted while the
signal level stays above the preset threshold. Once the signal decreases below the
pre-set threshold level, for a period greater than the scan dwell period, scanning will
resume.
Voice (Syllabic) Scan
If the audio mute (squelch) is active and is opened scanning will halt. Scanning will
remain halted while the audio mute is open. Once the mute closes, for a period
greater than the scan dwell period, scanning will resume.
The Barrett PRC-2090 transceiver has up to eight scan tables available each table
being able to be programmed with up to thirty channels. (See Menus and
Programming for details on channel entry)