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 currentaffiliation are
both transmitted when PTT is pressed.
Why the difference? Type II systems are slightly more
advanced because the central computer maintainsa
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 need updatethe
database instead of reprogramming individualradios.
Another difference between the systems is that Type I
systems are arranged in a Fleet-Subfleet hierarchy. For
example, it’s possible for a city usinga Type I system to
designate 4 Fleets, each with 8 Subfleets. Theirfleets
might be the Police Department, the Fire Department,
Utilities, and Administration.The Police may decide to
further divide their fleet intosubfleets 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 referredto as Fleet Map
Programming.
The disadvantage of a Type I system is that when PTT is
pressed, the brief bust of data must contain the radio’sID
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 Hybridsystems
which are a combination of bothType 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.
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