Description
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2.4
DESCRIPTION OF THE FUNCTIONS
2.4.1
General information
The function of the IDR IDO 3G is to set up communications between TETRAPOL radio
terminals placed under its radio coverage, referred to as a radio cell. The cell depends on
the antenna, the transmission power and the frequency used.
To communicate, the IDR IDO 3G and the terminals must first be configured (manufacturer
procedure):
• the following parameters are defined for the IDR IDO 3G:
- software licence,
- IP configuration,
- list of channels in IDR mode,
- private dialing range (depending on the project).
Note:
The radio parameters of the IDR IDO 3G (channel number, RX1 receiver and TX
transmitter frequency) semi-channel offset, inter-channel gap duplex spacing) are
related to the project and predefined by the manufacturer.
• the following parameters are defined for the terminals:
- authorisation to communicate in IDR mode,
- list of channels in IDR mode,
- private dialing range (depending on the project).
Communications are carried out as follows:
• on a permanent open channel, which means that the IDR IDO 3G is in permanent
transmission/ reception mode,
• in full-duplex mode for the IDR IDO 3G, and in half-duplex mode (PTT) for the terminals.
The channel number is selected first using the control and configuration web interface by
the operator when the IDR IDO 3G is commissioned. An interference detection function
informs the operator of the reception level on the channel selected.
The IDR IDO 3G is master of all the clocks it requires to operate: The terminals slave in
frequency and in phase on the transmission signal of the IDR IDO 3G, which acts as
control channel.
The IDR IDO 3G also manages push to talk. If a terminal detects that the PTT function is
not enabled, it continues to transmit the same padding frame. If a terminal receives
padding frames, it can then switch to transmission mode. The IDR IDO 3G then transmits
the voice frames of the transmission terminal to all the reception terminals. When the
IDR IDO 3G stops receiving voice frames, it again transmits padding frames.
The IDR IDO 3G is composed of three main functional chains:
• repeater,
• power supply,
• cooling.
