User's Manual
DMR repeater 24/01/2011 Versione 1.1
Documento Riservato - non divulgabile senza autorizzazione
Pag. 7 / 55
2.3.2 SATELLITE BASE STATION IN “RF LINKED” NETWORKS
The duty of the Satellite is:
∞ receiving the signals from the terminals and sending them to the Master through the RF link,
∞ transmitting to the terminals the signals received by the Master (voted) through the RF link.
The satellite performs also the group delay and absolute delay equalization on broadcasting transceivers both
down link and up link.
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2
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Simulcast type networks operate on the same radio channel on the whole coverage area.
Communications can be both open and selective channel, semiduplex mode between mobile terminals or
duplex mode between Central and terminals. The network will make the automatic selection of accessing
terminals and will broadcast the signal on the same frequency throughout the coverage area. The terminals
are served regardless of their position as if they were covered by a single repeater.
All transmitters send the same information signals
on the same carrier frequency
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fc
fc
2.4.1 SYNCHRONIZATION, VOTING AND EQUALIZATION
Simulcast radio network are able to realize the maximum radio coverage of the territory with minimum use of
radio frequency.
In a simulcast network, unlike a cellular system in which each cell is characterized by a particular frequency, all
the terminals operate at the same frequency, like a big cell.
Therefore it is necessary that the carriers of all transmitters are frequency locked and phase coherent with the
master one.
Frequency synchronism of the
R
RR
R
R
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R
a
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y station can be extracted from multiple sources, depending on
network needs and the references availability, and transmitted to all the base stations from the master one.
This signal is received from all the satellites that reset their clock on it.