Boards In Each Unit - Nera Inmarsat-c Service Manual

2.1.2 Boards in each unit

Table 2.1.1 lists the function of boards in each unit.
Unit Board
ANT RF
(16P0207)
Antenna
(IC-115)
Daisy loop
type antenna
Terminal RF
unit CON/CPU
(IC-215) (16P0208A)
Function
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
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: Outputs +42dBm by
inputting +3 +3 dBm
- Continuous-time
minutes
Directional characteristics
Horizontal: Non-directivity
Vertical: EL=90°: 0 dBi and more
EL= 5°: +1.3 dBi and more
Polarization
Right circular polarization wave
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.
2-2
Table 2.1.1 Boards in each unit
transmission is
of transmitting: 8
2.1 Configuration
Remarks
The difference from
Nera C12.
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.
When replacing RF
CON/CPU board,
remove the EEPROM(U15)
from old board and put it on
the new board.