Tektronix TekRanger 2 TFS3031, Service Manual

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Performance Check – TekRanger (serial nos. below B052000)
3–22
TFS3031 TekRanger/TekRanger 2 Service Manual
Singlemode Dead-Zone Check
NOTE . If the instrument has two laser output ports, this check must be done on
both ports. If the instrument has two wavelengths, this check must be done on
both wavelengths.
1. Connect the singlemode dead-zone test fixture to the TFS3031 laser output
port under test.
2. Push the
ON/OFF
button to power on the TFS3031.
3. Push the
Setup
softkey to access the setup menus.
4. Select the following setups in the Test Setup menu:
H
Fiber scan: Manual
H
Test range: 8 km
H
Pulsewidth: 10 m
H
Averages: 4,096
5. Push the
START/STOP
button to begin a test.
6. When the test is complete, use the
SELECT
button Cursor and Zoom
options to select a single event on the fiber for zooming, then push the
Zoom On
softkey to magnify the event.
7. Use the
SELECT
button Cursor option to position the active cursor on the
backscatter area that follows the event.
8. Hold down the
Cursor A/Cursor B
softkey to join both active and inactive
cursors at the location of the active cursor.
9. Push the
Cursor A/Cursor B
softkey to select the other cursor as the active
cursor.
10. Move the active cursor to the event in question until the Cursor A–B reading
at top screen reads 0.5 dB.
If the cursors are separated by more than 100 m, a correction is needed for
the fiber loss between the cursors. The Cursor A–B reading of 0.5 dB would
be adjusted as follows:
0.5 dB + (fiber loss in db/km distance between cursors in km)
Example: If the cursors are separated by 1 km and the fiber loss is 0.35
db/km, the adjusted Cursor A–B reading would be:
0.5 dB + (0.35 dB/km 1 km) = 0.85 dB.