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M-UM041-04 OTDR 800 6/2020
Set Range
To set the Range, tap the textbox on the display to open the available range list and choose the desired range for the test. Only one
range can be selected for testing.
NOTE
When setting the Range and Pulse Width, it is necessary to keep in mind that using certain pulse widths with some ranges
is not beneficial. Pulse widths are not all available for use with all of the ranges. The chart below indicates the pulse
widths that are available with each range.
Pulse Width
5 ns
10 ns
30 ns
100 ns
300 ns
1 µ
3 µ
10 µ
20 µ
Ra
nge
250 m
500 m
1 km
2 km
4 km
8 km
16 km
32 km
64 km
128 km
Fig. 8.3
Set Pulse Width
To set the Pulse Width, tap the Pulse Width indicator on the display to open the available pulse widths for the selected range and
choose the desired setting for the test.
Pass/Fail Threshold Settings
There are five configurable pass/fail threshold settings for the event table and schematic views: ORL, Loss, Reflectance (Refl.), Link
and End OF Fiber (EOF). Refer to chart below. The EOF is not a true Pass/Fail threshold, but it is used to set a loss value to determine
the end of fiber. If the EOF threshold is set at 3 dB, then the first event that has a loss of 3 dB or greater will be designated as the EOF.
To set the thresholds, tap the textboxes for the range of the values and set them using the same steps as for the test parameters.
NOTE
There is an ORL and a Reflection Threshold setting. The ORL is the return loss for the entire link/system and the Reflection
Threshold is the return loss value of an event. Thresholds are "pass thresholds" where a value entered as a threshold is a
passing value.
Setting Examples:
LOSS
If a 1.00dB splice/event loss is acceptable, set the threshold to 1.00. If an events loss of 1.00 is the fail point, set the threshold to 0.99.
ORL
If a system ORL of -35 dB reflectance is acceptable, set the threshold to 35. If -35 dB is the fail point, set the threshold to 35.1.
REFL
If a -45 dB, event reflection is acceptable, set the threshold to 45. If -45 dB link loss is the fail point, set the threshold to 45.1.
LINK
If a 20 dB, link loss is acceptable, set the threshold to 20. If 20 dB link loss is the fail point, set the threshold to 19.5.
EOF
If an event loss of 3 dB should trigger the end of fiber, set it to 3.0. If the end of
fiber should be anything greater than 3 dB loss, set it to 3.1.
Set IOR
It is necessary to have the Index of Refraction set as close as possible to the actual IOR of the fiber. If this is unknown, it is best to
use the default setting in the OTDR. The default IOR for the wavelength chosen is shown in the text field. If an adjustment needs
to be made to the IOR, tap the textbox and enter an appropriate value for the IOR for the fiber and wavelength used. Tap the "OK"
button to set the IOR.
