User`s guide

A Background to Return Loss Measurement Getting Started with Return Loss
Agilent 81610A/11A/12A/13A/14A Return Loss Module, Fifth Edition 41
If we substitute equation 3 into equations 2 and 4, this gives us the
following two equations:
If we subtract P
para
from equations 5 and 6, this gives us the following
equations:
If we divide equation 8 by equation 7, this gives us the following
equations:
Thus we can use the equation below to calculate return loss:
The return loss of the reference reflection is given by:
Calculating the Front Panel Delta
The Front Panel Delta is the change in loss variation that is caused by
replacing the reference cable, as used in “Reflectance Calibration” on
page 26, with the measurement patchcord, as used in “How to
Measure Return Loss” on page 31. This is caused by differences in
reflections from the front panel connector and also differences in the
backscatter level of the fibers.
3 F
1
0 5
0
0
---------------
3
+=
(5)
3 F
1
0 5
0
0
---------------
3+=
(6)
3
0
0
---------------
3
– F
1
0 5=
(7)
3
0
0
---------------
3
– F
1
0 5=
(8)
5
0
0
---------------
P
0
0
---------------
3
–
P
0
0
---------------
3
–
--------------------------------------------------------
5
=
(9)
5/ 10 5log–=
10
0
0
---------------
P
0
0
---------------
3–
P
0
0
---------------
3
–
--------------------------------------------------------
10 5
log–log–=
(10)
5/ 10 5log–=
(11)