User's Manual

DMR_Manager Operating Manual 2011/07/04 Version 1v2
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Page 5 of 51
2 CONCEPTS OVERVIEW
The Radio Activity DMR Base Station can include several TRX (master and slaves), where TRX refers to a
transmitter, one or many receivers, DSP, IO board and a power supply.
Radio Activity DMR Base Stations allow many different applications: they can work like a single repeater or in a
radio network made of different repeaters linked together in different way such as Ethernet link, RF link.
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The core of “physical layer” of the system is a unit which via software performs every function of signal
processing into radio station.
So, it is not necessary to add boards (like synchronizers, phase and amplitude equalizers, signal decoders,
modem, etc.) because the functions can be implemented by routines which can be freely matched, down-
loaded and with superior performance.
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 optical
fiber 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:
∞ Frequency self-tuning device
∞ Deviation self-calibration device
∞ Analogical and digital demodulation
∞ RF circuits testing
∞ Phase modulator calibration
∞ RF output power control
∞ Low frequency lines management
∞ DMR protocols management
∞ Digital signals processing
∞ Management, conditioning and routing of traffic and remote control signals from and towards
external world
Receiver can be supplied as single or double for space diversity reception. Main and diversity channels are
completely independent and coherent (sharing the same local oscillators) and they are designed according to
an heterodyne structure, with vectorial conversion to base-band.
Channel standard bandwidth is 12.5 KHz, but the receiver is prepared to accept also a settable channel
bandwidth of 25 KHz, 20 KHz, 10 KHz (with double funnel option) for special applications.
Receiver module is managed by a microcontroller unit whose program is hosted inside internal e2prom flash
memory to lower parasitic emissions. This FW can be loaded through serial connection. The microcontroller, in
addition to managing internal function of the unit, transfers measured parameters to the control unit through
115.2 Kb/s serial line.