EXFO CableSHARK P3 VF/DSL Cable Qualifier - Manual (Page 66)

VF / DSL Cable Qualifier
54
4. Press the RUN / STOP button located on the front of the unit to initiate the TDR test.
5. Once the AUTO TDR finds any valid reflection, up to four reflections could be plotted on screen. The
TDR test will automatically place the cursor at the initial rising slope (leading edge) of a major reflection.
6. When the test is completed, the user can move the cursor or marker, zoom in and out, change reading
units, or press the function button corresponding to MORE to save the resultant trace. Pressing the
function buttons associated with ZOOM IN / OUT VERT and ZOOM IN / OUT HORIZ will enable the
user to see all reflections in detail (not as much detail as with a Manual TDR Test, however).
The Automatic TDR test is a ‘quick test’ to locate faults while the Manual TDR test is a much more detailed
rendering of the physical aspect of the twisted copper pairs under test. The Auto TDR also returns the found
(determined ideal) pulse width to the TDR Test Setup menu so that the user can use the width for the
Manual TDR Test.
To repeat the test, press the RUN/STOP key or press the function button associated with Test Setup, should
you wish to change some settings.
7.2.2 Manual TDR Test
Note: this is a Single-Ended Test
1. From the Main Menu, select CABLE TESTS (function button F1)
2. Choose TDR from the pop-up menu, and MANUAL from the sub-menu. Press the RUN/STOP key.
3. Select the appropriate Graph Scale option to a scale that is greater than the actual distance of the line
under test
4. Be sure to set the most critical parameter: Pulse Width and any other parameters as required for the
particular situation (cable type, Smoothing).
5. Press the RUN/STOP located on the front of the unit to initiate the TDR test.
6. When the test is completed, the results screen will appear and the cursor will reside on the rising slope
of the first major reflection found. The user can move the cursor or marker, zoom in and out, change
reading units or press the function button corresponding to MORE to save the resultant trace. Pressing
the function buttons associated with ZOOM IN / OUT VERT and ZOOM IN / OUT HORIZ will enable the
user to see all reflections in detail. If no reflection was found, the message, "TDR test complete. …" is
displayed on the status bar.
To repeat the test, press the RUN / STOP key. You can also change option settings if you wish by pressing
the function button associated with Test Setup.
Note: When using a Manual TDR, be sure to use the CableSHARK’s zoom function to amplify results. Often,
the reflected pulse is difficult to see, so by using the zoom function, the faults can more easily be seen.
Ensuring that the correct VOP and appropriate pulse width and other parameters are selected will allow for a
successful TDR test (refer to Section 8.2.1 and 8.2.4.6 for more details).