EXFO CableSHARK P3, Руководство пользователя, Страница: 95 / 321

CableSHARK
P3
User Guide
83
Once the test is set up, press the RUN / STOP key located on the front panel of the CableSHARK to start
the test. Another screen will appear indicating to the user that the TDR test has been started. When a TDR
test is complete, the test result is displayed on the screen.
8.2.2 Manual TDR Testing
With the appropriate pulse width selected, the CableSHARK should be able to automatically locate any
reflection, up to four reflections, from 30 feet (9 meters) up to 20,000 feet (6000 meters) of AWG 24 cable
(lab conditions). Results will be displayed in feet, meters, or nanoseconds. Figure 8.2.2A shows a sample
TDR test screen (with TEST TYPE set to MANUAL).
Cursor position =
Marker position =
Cursor / Marker Delta =
0.0 1250.0 2500.0 5000.0 3750.0
ZOOM IN
VERT MAIN
MENU
E F
CHG
-1.000
-0.750
-0.500
-0.250
0.000
0.250
0.500
0.750
1.000
1998.7
0
1998.7
Pulse Width: ft
ft
300 ns
ZOOM IN
HORIZ SELECT
MARKER MORE AUTO
REPEAT
End of cable detected at 1998 ft. DBRL = 33.8+
Cursor position =
Press or to move cursor
(TIP - RING)
F
IGURE
8.2.2A - R
UNNING A
M
ANUAL
TDR T
EST
The information about reflections that are found is shown on the status line in several formats, including “End
of cable detected at x ft. dBRL = y” or "Reflections at distance (dBRL +/-): ...", where the distance will be in
feet, meters or nanoseconds as selected. dBRL stands for the reflection loss of the sent pulse at the
reflection point in dB and the +/- sign indicates the polarity of the reflection with reference to the sent pulse.