User's Manual
Why the difference? Type II systems are slightly more advanced
because the central computer maintains a database used to
determine each radio’s affiliation(s). Changes to a Type II system
are easier than Type I because the system manager only need
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, it is 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 might 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.
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 systems usually accommodate
fewer users than Type II systems.
Even though there are many Type II systems, Type I systems are
still in use. There are also Hybrid systems, which are a combination
of both Type I and Type II. Your scanner defaults to monitor Type II
systems, but it’s possible to select a Preprogrammed Fleet map or
create a Custom Fleet map for your area.
Motorola Trunking
While there are 4 different types of Motorola trunking systems, they
all use the same basic trunking method. The system consists of one
control channel plus one or more voice channels (typically 10, 20,
or 30 total channels). When a user presses Push To Talk (PTT) to
transmit, their radio first sends their talk group information to the
control channel. The computer then assigns that talk group to a
specific voice channel and transmits that data over the control
channel. All radios in that talk group switch over to the assigned
voice channel and the user can begin speaking. This all typically
takes place in about a second...the person transmitting hears a
beep from their radio when the channel is assigned and it is OK to
start talking.
The systems in use are:
z Motorola Type I – the radios send the radio ID, the fleet and
subfleet talk group ID to the control channel each time they
transmit. To program a Type I system, you need to know the
system’s fleet map. The most common fleet maps are
included at the back of this manual. You can also find fleet
map resources on the web.
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