Digital radio communications in « TRUNKED» mode 
 

Under "SIMPLEX" and "DUPLEX" conventional mode, radio frequencies are allocated by channels, each one having its dedicated function (ex : channel 911, channel team 1, channel team 2). These channels are only used when necessary, leaving some others overused and without availability while others are unused and too many time available.

Under digital  "TRUNKED" mode, frequencies are not allocated only to a group of radios ; its can also be for each individual radio, allowing a single communication between 2 stations of a group. Each radio has a identification number ( Unit ID). The communication frequencies of these units of groups of units are allocated dynamically through a channel controller, called the Control Channel. It be used to distribute communications on different channels in addition to managing multiple types of data (GPS, text messages, radio states, etc.)

In this mode, the radios are constantly listening to the Control Channel to know if a communication is dedicated to them or if they are still in the coverage area. For a device (UID. A)  of a group establishing a communication with a available colleague (UID. B), the Control Channel will assign to both same frequencies of transmissions and receptions available.

For a device from a Group B wishing establish a communication with another device in the same time that another user in the same group, this first one will have other frequencies for the duration of the transmission. If a user wants to talk to the whole group, it will make what we call a "Group Call", which will tell to the Control Channel to assign the same frequencies of reception for everyone in this group.

Thus, under digital  "TRUNKED" mode, it's possible to attribute to several groups and radios a few different frequencies and to increase the numbers of different communications. We increase by the fact the flexibility and the efficiency and we have a better management of the communications.