Motorola PM1200 User Manual page 26

Radio Firmware Features
8.2 Scan List
The list of channels that the radio scans and other parameters
associated with scan members are specified in the scan list. Each
scan list can be configured in the CPS. Scan List has a collection of
groups and each group consists of User Scan List, Dealer Scan List,
Priority Scan Channel and Multiple Group Selection.
9.0 Standard Conventional Operation
Conventional operations of the radio are Carrier Squelch operation,
TPL, DPL and Invert DPL
Different groups of radio users share the same frequency or channel
(community repeater). Without the use of Private Line (PL) tones/
codes, each individual group would constantly listen to the
transmissions of all groups; this is known as Carrier Squelch
operation. Private Line operation is done by outfitting members of
each group with radios with a unique PL tone/code. Their radios will
then only unmute to transmissions made by other members of their
group. If radios are set to only unmute when a transmission includes
their own PL tone/code, then they are not disturbed by conversations
of other groups. The sub-audible code that is added to the voice
unmutes only those radios with an identical PL tone/code. There are
two forms of PL available: Tone Private Line (TPL) and Digital Private
Line (DPL).
TPL signal consists of a sub-audible tone that is continuously
modulated onto the carrier. The receiving radio continuously monitor
the carrier, and if the correct sub-audible tone is present, the speaker
will unmute to the recovered audio. TPL tones are summed together
with the voice information during encoding. There are 39 standard
sub-audible Telecommunications Industry Associate (TIA)/Electronic
Industry Association (EIA) tones between 67.0 Hz and 250.3 Hz. The
radio will follow the standard for sub-audible Continuous Tone
Controlled Squelch System (CTCSS) that is covered in TIA/EIA-603.
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