There is often confusion between different types of trunked systems. One of the most confusing things is the names of some systems. We get calls and letters all the time asking about Phase 2 and Type 2 systems and whether a particular scanner will work on them. They are different and the difference will determine if your scanner will work with it.
TYPE 2 (more accurately but less often written as TYPE II) systems are older Motorola trunking systems that use 3600 baud control data channels. These are commonly referred to as just “Motorola” systems when programming scanners. These were an evolution from the original Type 1 and Type 2i systems. The difference between Type 1, 2i and 2 systems is the way talkgroups are developed. Type 1 systems use a Fleet/Subfleet system that resulted in limited flexibility to assign talkgroups. Most of these systems have been shut down or updated and very few remain in use. Type 2 systems had a different method of assigning talkgroups and allowed greater flexibility. Some systems were called Type 2i, and were a hybrid between Type 1 and Type 2 systems.
Newer Type 2 systems, referred to as APCO P16 systems, allowed either digital, analog or both forms of modulation. There are still many of these systems in use all over the country.
PHASE 1 and PHASE 2 (more accurately referred to as Phase I and Phase II) systems are totally different than Type 1 or Type 2 systems. Phase 1 and 2 systems are forms of APCO P-25 digital systems that use 9600 baud control data channels and all digital modulation. Phase I systems have a single voice path per frequency while Phase II allows 2 voice paths per frequency, effectively doubling the amount of traffic a set number of channels can handle.
It gets even more confusing when programming some radios. Some scanner program the Type 2 and Phase 1 or 2 systems with the same system type, others have different selections. On the user end, most Motorola P25 (Phase 1 or 2) radios are also capable of being used on the older Type 2 systems.
Next week we will look at some of the other trunking systems like EDACS, LTR and TRBO.
