SECTION 3: TRACE ANALYSIS
13
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 somewhere
after the event.
Make sure that only one reflective event is included between the
cursors.
The trace information (located below the trace) will show the reflectance (in dB)
of the highest reflective event between the cursors.
In this example, the reflective event being measured has a reflectance of
.
red
green
-34.26
dB
REFLECTANCE MEASUREMENT
Automatic event location can be performed from the trace screen by accessing the
function option. See page 5 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
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.
The type of event is denoted by color:
black
for loss events and
for reflective events.
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.
light blue
EVENTS
VIEW
PAGE
DONE
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
TRACE EVENTS MENU
4786m
6126m
24718m
RFL dB
-34.26
1340
dB
0.52
7.43
L m
Fiber #
CURSOR
LOCK
ZOOM
TEST
ENTER
AUTO
1550nm
1550nm
