User's Manual
DMR repeater 18/02/2011 Versione 1.3
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Pag. 9 / 32
The switching between normal and test input is implemented through PIN diodes.
Receiver modules 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.
The board is realized with surface mounting components (SMD) to maximally reduce dimensions.
Modular unit is housed in a shielded, 4TE high box for 220mm Eurocards. On the frontal panel 2 LEDs are
placed for monitoring internal PLLs lock status.
3
3
.
.
4
4
T
T
R
R
A
A
N
N
S
S
M
M
I
I
T
T
T
T
E
E
R
R
Transmitter module is realized with surface mounting components (SMD) and it is housed in a shielded, 8TE
box for 220mm Eurocards, with an heatsink mounted on side, with a thermal resistance of about 1.2°K/W. The
unit can be extracted from the front side of the rack.
MOS power amplifiers
power detecting strip lines
microcontroller
synthesizer
On the frontal panel two LEDs are placed to monitor the transmitter status.
Base-band functions, equalizing, limiting, low-pass filtering end eventual emphasis functions are performed by
the DSP unit, which provides also for nominal and maximum deviation calibration by looping modulator with
receiver.
Modulator is digital vectorial, then the synthesized signal by local oscillator implements the frequency shifting
of the signal which has been directly modulated in base-band by DSP unit and transferred to transmitter
through its I and Q components.