User's Manual
DMR repeater 18/02/2011 Versione 1.3
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The core of system’s “physical layer” is this unit which via software performs every function of signal
processing inside radio station. What other equipments implement by adding boards (like synchronizers,
phase and amplitude equalizers, signal decoders, modem, etc.), here are implemented by routines which can
be freely matched, down-loaded and with superior performance.
DSP and Processor cores
VCTCXO
reference
D/A and A/D converters
and audio filters
Ethernet LAN
RTC
I/O
AUDIO LAN
This board can process up to 8 analogical duplex signals ensuring 70 dB of SNR; it can manage 16 logical signals
which can be configured both as input and output.
Communication and control functions of module are entrusted to a microprocessor which manages
communications with external world and with other equipment modules. The microprocessor is based on
LINUX operative system; it can manage a LAN ethernet 10/100 interface both for copper line and for fiber
optic links, it is equipped with 4 serial ports to manage radio modules, GPS, auxiliary devices, external hosts; it
is equipped with a Real Time Clock with tampon battery; it controls an embedded PLL to synchronize the
entire station upon an internal (VCTCXO 0.5 ppm) or external temporal reference. DSP module is equipped
with a synchronous serial port according RS485 standard levels, which can be programmed up to 16Mbit/s and
can be used to interconnect together more transceiver or additional equipments.
Main performed functions are the following: