EXFO FVA-600 - Manual (Page 34)

Typical Test Configurations 28
OSNR Loading
The Optical Signal to Noise Ratio (OSNR) is an indication of the amount of noise
present in a given transmission signal.
The FVA-600 is used to adjust the relative power of the data carrying signal (from Tx)
and the ASE noise (from FLS) while monitoring that ratio on the OSA until a given
target error rate is obtained at the receiver.
ROADM
You can use the FVA-600 to help you with ROADM testing; by adjusting and
controlling the power level of the incoming power signal from a tunable laser
source sent into the ROADM or system under test.
TX
FVA-600
RX
FVA-600
FTB-500
OSA
FLS-2300B
ASE Source
FLS-2600B
Tunable laser
FVA-600
Drop filter
OSA: Insertion
loss and Isolation
Low-loss
through path
Blocker
OSA: Isolation and
cross-talk measurement
ADD
filter
OSA: Power
uniformity and
long-term
monitoring