Luna 4600 - Adjusting Group Index; Data Decimation

Optical Backscatter Reflectometer 4600 75
User Guide
Adjusting Group Index
When the upper graph X-axis displays length, the Group Index field shown below
appears in the lower right corner. The user may enter the index appropriate for the
device under test.
Figure 5-8. The Group Index field, which appears
to the lower right of the upper graph.
Impo rta n t
Changing the group index in the box shown above
changes the group index for all the data loaded into
memory,
Traces A through E. In order to change the
group index of only one trace, click the
Details button of
that trace and change the group index in the details dialog
box. (see “Trace Details” on page 61)
5
The group index scales the X-axis length values according to
z =
----
c
----
t ,
2n
g
where z is the spatial dimension (X-axis) of the device under test, c is the speed of
light in a vacuum, t is time, and
n
g
is the group index of refraction of the device
under test.
Data Decimation
Selecting Options > Data Decimation (Upper Graph) > Specify Level calls up
the dialog box shown below (Figure 5-9). Here the user can select the number of
data points displayed in the upper graph, up to 524,288 points.