Subj : Todays New Gear Tip
To   : All
From : Daryl Stout
Date : Tue Nov 14 2017 12:05 am

Scanning

Radios on the market today can rapidly switch from frequency to frequency
to look for signals. This is called scanning. It allows the operator to
monitor many different frequencies without having to manually tune to
each one.

There are three types of scanning. Basic scanning consists of the receiver
starting from the scan start frequency and tuning continuously to the
scan stop frequency. If a signal is detected, scanning is stopped or
paused for the operator to listen in. This is most useful in the
weak-signal or satellite segments of the VHF and UHF bands and when
listening for simplex FM signals. 

Channel scanning is jumping from channel to channel in sequence. Again,
scanning stops or pauses when a signal is detected. Channel scanning
requires a start channel and a stop channel. Channels may be designated
to be skipped, as well. This type of scanning is the most useful for
watching many repeater or simplex channels. 

Programmed scan is the most flexible of all and allows the user to set
up lists of channels to be scanned. This is most conveniently done with
a PC instead of the radio keypad. Channels can generally be scanned in
any order. The PC software often allows the operator to set up
"profiles" of programmed scans (for example, parade communication or
ARES drills in which different sets of channels are in use) so that the
radio can be configured quickly and efficiently.

Scanning is much more convenient to use if you have control over scan
delay and scan resume. Scan delay is the time the radio spends listening
to each channel before moving to the next one. A longer delay catches
more activity and lets you listen longer to each channel, but slows down
the overall scanning process. Scan resume tells the radio to how long
to pause or to stop if a signal is detected. Some radios offer voice
detection to distinguish between a voice signal and a steady tone or
noise that may result from interference.


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