User Manual

Demand Assignment
System Overview GSI 003
605-0000-450
Draft Issue 1.3dr Date 8/02/00
Page 7 of 8
In the receive direction, incoming signals from the antenna are extracted, filtered,
amplified by the LNA and split among the (up to) four RF Cards and their associated
Modem Shelves.
The RF Combiner Shelf (see Figure 13) is equipped with:
• RF Cards, (up to four) that convert the baseband signal from each modem shelf into
a single RF channel in the 2GHz range (and vice versa). This interfaces to the
Antenna/Feeder Sub-system.
• Power Amplifier (PA) modules (up to two), each of which caters for 2 RF channels
and amplifies the RF channels received from their associated Modem Shelf
equipment.
• Branching Unit (BU) module, which is essentially a passive unit that performs
signal Combiner, splitting and filtering.
• Low Noise Amplifier (LNA) module, which amplifies the low-level receive signal,
after filtering but before splitting.
• Shelf Monitor Card, which collects information from the PAs, LNA and PSUs, and
passes it to the Shelf Controller Cards.
Lamp
Test
Test Trunks
Green
White
Red
Red
Receiving
Attention
Power OK
Prompt/
Deferred
Instation/
Clear
DC SUPPLY
OFF
RF1 RF2 RF3 RF4 Mon1 Mon2
Diplexer and
Low Noise
Amplifier
DIP/LNA 1
TX Filter
DIP/LNA2
Alm55B
PSU1 PSU2 PSU3
PA1
PA2
1+ 1- 2+ 2-
Figure 13. RF Combiner Shelf