7
English
INTRODUCTION
INTRODUCTION
Your PM400™ radio can operate on both LTR
®
trunked and conventional radio systems. This
radio combines the very latest in two-way
technology while delivering outstanding
functionality at the touch of a button.
CONVENTIONAL RADIO SYSTEMS
Conventional typically refers to radio-to-radio
communications through a single channel.
Conventional systems also allow radio users to
extend communication coverage by relaying
their messages through a repeater. To ensure
coordinated use by multiple users, each radio
user must monitor the channel or repeater
before transmitting to verify that the system is
not currently busy.
TRUNKED RADIO SYSTEMS
A trunked radio system allows a large number
of users to share a relatively small number of
frequencies or repeaters without interfering
with each other. The airtime of all the repeaters
in a trunked system is pooled, which
maximizes the amount of airtime available to
any one radio and minimizes channel/
talkgroup congestion.
Some of the benefits of trunked two-way radio
systems are:
• No channel/talkgroup monitoring required prior
to transmission
• Improved system access
• Automatic channel/talkgroup selection
• Increased privacy among members of the same
group
LTR Trunked Systems
LTR (Logic Trunked Radio) is a transmission-
based trunking protocol developed by the E. F.
Johnson Company for primarily single-site
trunking applications. In transmission trunking,
a repeater is used for only the duration of a
single transmission. Once a transmission is
completed, that repeater becomes available to
other users. This means that a conversation
comprised of many transmissions may occur
over several different channels/talkgroups
within the LTR system. This method of trunking
provides system efficiency by making
repeaters available to all users after every
transmission.
When an LTR trunked radio user wants to
communicate with another radio, the user’s
00_Introduction.fm Page 7 Monday, August 2, 2004 10:34 AM
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