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Motorola Reception
Motorola Tracking
There are really two types of Motorola trunking systems.
These are usually referred to as Type I and Type II systems.
Type I only occurs on some 800 MHz systems. All VHF, UHF
and 900 MHz trunking systems use Type II.
One important distinction between these two systems is the
amount of data transmitted by each radio when its push-to-
talk button (PTT) is pressed. Every radio in a trunked system
is assigned a unique ID so the central site computer can
identify it when it’s used. Both Type I and Type II systems
place radios (or radio users) into groups, called talkgroups,
and these talkgroups are also assigned unique IDs. Some
radios have access to only one talkgroup, while others have
access to many talkgroups. The talkgroup(s) each radio can
access is called the radio’s affiliation(s).
In a Type II system, when someone uses their radio, only the
radio ID is transmitted when PTT is pressed, whereas in a
Type I system the radio ID and its current affiliation are both
transmitted when PTT is pressed.
Why the difference? Type II systems are slightly more
advanced because the central computer maintains a database
which is used to determine each radio’s affiliation(s).
Changes to a Type II system are easier than Type I because
the system manager only needs to update the database
instead of reprogramming individual radios.
Another difference between the systems is that Type I
systems are arranged in a Fleet-Subfleet hierarchy.
For example, its possible for a city using a Type I system to
designate 4 Fleets, each with 8 Subfleets. Their fleets might
be the Police Department, the Fire Department, Utilities, and
Administration. The Police may decide to further divide their
fleet into subfleets such as Dispatch, Tactical Operations,
Detectives, North, South, East and West Side Patrols, and
Supervisors. All the available police radios would then be
assigned to one of the police subfleets. Determining the exact
Fleet-Subfleet hierarchy for a particular area is referred to as
Fleet Map Programming, which is discussed further in this
manual.
The disadvantage of a Type I system is that when PTT is
pressed, the brief burst of data must contain the radio’s ID
and its Fleet and Subfleet. This is three times the amount of
data a Type II system radio sends, and as a result Type I
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