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Another type, scan based trunked systems, (not shown) do not have a control channel. Frequencies are for discussion purposes and do not correspond to any specific system. A trunked radio system is a two-way radio system that uses a control channel to automatically assign frequency channels to groups of user radios.
Motorola Type II refers to the second generation Motorola trunked radio systems that replaced fleets and subfleets with the concept of talkgroups and individual radio IDs. [1] [2] There are no dependencies on fleetmaps, therefore there are no limitations on how many radio IDs can participate on a talkgroup.
The general category of this kind of trunked system is called, "Scan-based trunking." In the U.S. and Australia, these systems used analog FM, operated in the 806–869 MHz band, and were primarily used for commercial, non-public-safety trunking. Some earlier systems offered half-duplex, (push-to-talk) telephone interconnect and later versions ...
In 2011, Motorola deployed ASTRO 25 systems with P25 Time Division Multiple Access (TDMA) trunking to double the voice capacity of Frequency Division Multiple Access (FDMA) technology. [21] The P25 Phase 2 products were the first in the industry. [22] By October 2013, over 30 customers had contracted for Motorola's P25 TDMA technology. [23]
In Type II systems the trunk system maintains a database that determines each radio's affiliation. 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 four fleets, each with eight subfleets.
The Tier 3 standard for these systems defines a trunking protocol very similar to MPT1327 and is intended as a potential migration path for existing and perhaps future trunking customers. Tier 3 equipment is (late 2011) now becoming available, so the impact on TETRA and MPT 1327 is yet to be seen, but may well be significant.
Logic Trunked Radio (LTR) is a radio system developed in the late 1970s by the E. F. Johnson Company. [1] LTR is distinguished from some other common trunked radio systems in that it does not have a dedicated control channel. LTR systems are limited to 20 channels (repeaters) per site and each site stands alone (not linked).
Trunking in telecommunication originated in telegraphy, and later in telephone systems where a trunk line is a communications channel between telephone exchanges. Other applications include the trunked radio systems commonly used by police agencies. [1] In the form of link aggregation and VLAN tagging, trunking has been applied in computer ...