GE LOGIQ 5 PRO, Руководство по обслуживанию

Страница: 142 / 462

GE M
EDICAL
S
YSTEMS
D
IRECTION
2380207, R
EVISION
7 LOGIQ™5 PRO S
ERVICE
M
ANUAL
5-8 Section 5-4 - Front End
5-4-3 PMP
5-4-3-1 Overview
The PMP (Pre-Amplifier) board receives and amplifies each 64 echo signals. Then, all 64 echo signals
(from 0 to 63ch) are outputted to the RDS sub-system (two RDS ASSYs) and following 32 echo signals
(from 32 to 63ch) are simultaneously outputted to the CWDOP ASSY via the SIG ASSY.
The PMP ASSY can amplify 64 echo signals. So, the echo signals are received by a PMP ASSY under
appropriate control. The PMP ASSY are inserted into Nest box, which is composed of BACKPLANE
board and other several daughter boards.
The PMP ASSY have main three blocks: Pre-amp and Gain Control and Mode control block.
the PMP ASSY amplifies the echo signals. The mode control block selects a maximum gain code via
dedicated control signals from FEC.
The analog signal provided by Gain Control block gives total amplified gain.
The block diagram above of the PMP ASSY for a received signal is given. Actually, there are 64
channels equivalent to figure above for a PMP ASSY.
The Pre-amp block consists of Low Noise Amplifier (LNA) and Variable Gain Amplifier (VGA). A
received signal is amplified by LNA (fixed gain), then amplified by VGA (variable gain).
Figure 5-7 PMP Block Diagram For a Channel
Rx Ch#0
Rx Ch#2
Rx Ch#1
Rx Ch#3
Rx Ch#32
Rx Ch#34
Rx Ch#33
Rx Ch#35
Rx Ch#28
Rx Ch#30
Rx Ch#29
Rx Ch#31
PGC
Signal
Buffer
Test
Signal
Buffer
PGC Analog Sig
From FEC
Test Sig. From FEC
For Assy Diagnositic
Rx Ch#60
32
64
STCW Sig[31:0]
To CWDOP Assy
Rx Sig[61:0]
To RDS Assy
Rx Ch#62
Rx Ch#61
Rx Ch#63