OTDR MODE
TEST PROCEDURES
OTDR MODE
The reflectance of a specific event can be determined by placing the cursors on either side
of an event. The OTDR will show the reflectance in dB of the highest reflective event
between the cursors.
CURSOR PLACEMENT
Proper cursor placement is important when determining the reflectance of a reflective
event.
The
cursor should be placed on the backscatter line directly before the event, on
the sloping line before the spike.
The
cursor should be placed on the backscatter line at the point where the
backscatter line returns to its normal slope.
Cursor information is located below the trace.
and
cursor information shows
the distance to the cursors, and the
information shows the length, relative power, and
reflectance between the
and
cursors.
With cursors placed as shown at right, the
reflectance number is the point of highest
reflectance (in dB) between the cursors.
In this example, the reflective event being measured has a reflectance of
.
red
green
Red
red
NOTE: if multiple reflective events are included between the cursors, the reflectance number will display the most reflective
of the events.
green
green
blue
blue
-34.26 dB
REFLECTANCE MEASUREMENT
4786m
6126m
24718m
RFL dB
-34.26
1340
dB
0.52
7.43
L m
Fiber #
CURSOR
LOCK
ZOOM
TEST
ENTER
AUTO
1550nm
1550nm
Automatic event location can be performed from the trace screen by accessing the
function option. See Section 1: INTRODUCTION – DISPLAY for more
information about function option menus.
LOCATION
the distance to the start of the event
TYPE
type of event (reflective, loss, etc.)
REFL
reflectance of the event
LOSS
loss of the event
moves the cursor up and down in the list of detected events
returns the user to the trace screen, zoomed in on the selected event
displays the next page of events, if there are more events than will fit on the screen
returns the user to the trace screen
view events for additional wavelength (if available)
Once an event has been selected from this menu, each individual event will be marked with a “tic” mark at the top of the trace area.
IMPORTANT NOTE: automatic event location is only meant to be used as a
guideline for the location of possible events. It is ultimately up to the user
to verify and determine if an event actually exists at that location.
EVENTS
VIEW
PAGE
DONE
WAVE
TRACE EVENTS MENU
1310nm TRACE EVENTS
Location
14m
24011m
50539m
Type
REFL
LOSS
REFL
Refl
-47.38
-81.00
-17.54
Loss
0.87
0.21
11.63
VIEW
PAGE
DONE
WAVE
NOTE: red text in the event table
indicates that the event fails to
meet user-set thresholds
