agencies to efficiently allocate a small number of frequencies (as few as three) to many groups of users (as many as several thousand). To do this, each group of users in the system is assigned to a specific talkgroup. For example, a city’s east side patrol officers might all be assigned to talkgroup 2160. One channel in the system is continuously transmitting data that identifies which talkgroups are active on which channel. In addition, this talkgroup information is also transmitted as subaudible data on each active channel.

When the scanner receives a transmission on a channel set to the Motorola mode, it first decodes the talkgroup ID data included with the transmission. In the Open Mode, the scanner stops on the transmission and displays the talkgroup ID on the bottom line of the display. In the Closed Mode, the scanner only stops on the transmission if the talkgroup ID matches a talkgroup ID that you have stored in the bank's talkgroup ID list and have not locked out.

Trunking systems covered by the Motorola mode come in four categories: Type I, Type II, Type I/

IIHybrid and APCO-25. Each category displays and uses talkgroup IDs in slightly different ways.

Motorola Type I IDs are in the form FFF-SS, where;

FFF=Fleet ID

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