Nera Inmarsat-c, Service Manual

Page: 22 / 228

2.1 Configuration
2-2
2.1.2 Boards in each unit
Table 2.1.1 lists the function of boards in each unit.
Table 2.1.1 Boards in each unit
Unit Board Function Remarks
ANT RF
(16P0207)
1) Consisting of RF amplifier circuit and
the dielectric filter which dividing
TX/RX signal.
2) Changing TX and RX circuit by
antenna supplied voltage, TX 29 V/RX
7 V.
3) Automatically the transmission is
stopped when the temperature of the
board is over +95 °C.
- Receiving gain: 36 dB+3 dB NF=2.0 dB
max. (Output: -108 to -90 dBm)
- Transmitting gain: O42dBm by
inp3 +3 dBm
- Continuous-time of transmitting: 8
minutes
The difference from
1) The diplexer is changed
to the dielectric filter.
2) The circulator is not
installed.
3) TX/RX voltage is changed
from +29/18 V to +29/7 V.
4) The continuous-time of
transmitting is limited.
Antenna
(IC-115)
Daisy loop
type antenna
Directional characteristics
Horizontal: Non-directivity
Vertical: EL=90°: 0 dBi and more
EL= 5°: +1.3 dBi and more
Polarization
Right circular polarization wave
Terminal
unit
(IC-215) RF
CON/CPU
(16P0208A)
RX: Changing RF signal, -120 dB to –100
dBm from antenna unit to I signal and
Q signal of the base band.
After decoding, the signal is sent
Term CPU board.
TX: After encoding the data from Term
CPU board, the data is modulated at
DDS and changed to TX RF signal,
+14 dBm.
Oscillation circuit: The following
frequencies are oscillated at DDS and
PLL synthesizer circuit.
TX=1626.5 MHz to 1646.5 MHz
RX=1530 MHz to 1545 MHz
EEPROM(U15): Memorizing FW/RT ID,
DNID and ENID. See page 2-27.
When replacing RF
CON/CPU board,
remove the EEPROM(U15)
from old board and put it on
the new board.
Nera C12.