User's Manual

DMR_Manager Operating Manual 2011/07/04 Version 1v2
Reserved Document – Don’t forward without authorization
Page 6 of 51
The board is realized with surface mounting components (SMD) to maximally reduce dimensions.
On the frontal panel 2 LEDs are placed for monitoring internal PLLs lock status.
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. 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 vector, 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.
The amplifier is realized by three cascaded stages and RF output power regulation (between 1 and 25W) is
implemented by controlling the stages. Power amplifier works in C class and ensures a very high efficiency,
lowering the needed power from supply system and lowering the thermal dissipation inside the cabinet. Direct
and reflected output power are measured by a directional coupler. Power control circuit acts in a closed loop
and keeps constant the total power at MOSFET drain. Inside the module a thermal sensor is hosted and it is
directly connected to the internal microcontroller which enables the command for air forced cooling fan of the
cabinet if the temperature rises over 85°C. Anyway, if reflected power or mosfet temperature exceeds
protection threshold, regulation circuit will lower output power up to safe levels for transmitter.
The current flowing into final amplifier transistor is continuously monitored by microcontroller to verify the
correct functioning and to reveal any efficiency degradation.
The module is equipped with an harmonic filter to lower spurious emissions under required levels by existing
regulations.
2
2
.
.
2
2
R
R
A
A
D
D
I
I
O
O
A
A
C
C
T
T
I
I
V
V
I
I
T
T
Y
Y
D
D
M
M
R
R
R
R
E
E
P
P
E
E
A
A
T
T
E
E
R
R
A
A
N
N
D
D
U
U
P
P
G
G
R
R
A
A
D
D
E
E
A
A
B
B
I
I
L
L
I
I
T
T
Y
Y
T
T
O
O
S
S
I
I
M
M
U
U
L
L
C
C
A
A
S
S
T
T
N
N
E
E
T
T
W
W
O
O
R
R
K
K
Radio Activity DMR repeater is designed to be modular from both HW and SW point of view, to maximize its
flexibility and minimize costs, physical dimensions, consumptions.
Basic model already has all the characteristics to work as a double standard repeater with all the features of
analogical and digital service. It can be equipped with double receiver to counteract fading effects through
diversity space reception. It is set to host communication and synchronization embedded devices to make the
network expandable to a multi-frequency or single-frequency multi-site system, with different types of links,
operating with different transportation system topology, like microwave, UHF, optical fibers, IP connections.
Privileged communication interface is Ethernet standard type, compatible with more diffused technology. This
interface supports not only voice and data digital traffic, but also remote control management, which for
Radio Activity equipment is very powerful: it is possible to have a complete monitor system of equipment
status, it is possible to modify each parameter, to down-load each SW and configuration, launch self-test and
calibration functions, to perform specific tests through internal embedded function generators and software
analyzers of the station. For analogical voice traffic instead, a 2/4 wire and criteria line interface is available.