EXFO FOT-930 Multifunction Loss Tester - Manual (Page 57)

Performing Automated IL/ORL/Length Measurements (F
AS T ES T )
Multifunction Loss Tester 49
Referencing Units for F AS T ES T
Referencing Units for F
AS
T
ES
T
Referencing subtracts the loss caused by the test setup components from
the overall loss measured during F
AS T ES T. The final result represents the
loss inserted by the system under test alone.
Two referencing methods are available:
Side-by-Side Method (Best) Loopback Method
Description Reference taken with both units
together using their F
AS
T
ES
T ports.
Slightly more accurate value than
loopback method.
Reference taken separately on
each unit (F
AS
T
ES
T port connected
to power meter port).
Location of units Must be at same location. Can be at different locations.
Loss included in
F
AS
T
ES
T result
Loss due to system under test and
one connector mating.
Loss due to system under test and
the two connector matings.
Elements to
consider
Includes neither an ORL
reference nor an ORL zero
measurement . To obtain them,
use the ORL Meter pane (see
Performing ORL Reference and
Setting ORL Zero Value on
page 42).
With multiple referencing, you
may coordinate an FTB-3930 with
up to 10 FOT-930 units.
When measuring ORL (F
AS T ES T or
ORL meter), accounts for
connector loss and adjusts ORL
calibration accordingly.
Not recommended for short links.
System
under test
Connector
mating Connector
mating
System
under test
Connector
mating