Microtest TSB-67 - 568A Annex E - Manual (Page 22)

signal and the difference is reported as the NEXT value (in dB). When measuring Injector end
NEXT, the roles of the devices are reversed. The Scanner provides the 100 ohm termination for
the Injector measurements and the Injector transmits a signal which is varied (or swept) through a
frequency range. The signal is monitored by the Injector on the receive pair through a narrow band
receiver and the difference in the transmitted and received signal levels is reported as the Injector
end NEXT (in dB).
Customizing NEXT Limits
To display the NEXT LIMITS screen, press the Extended Functions key, then select Setup
Autotest , then highlight the Autotest to edit, then press Edit (F2), then select Limits , then select
NEXT .
The NEXT LIMITS screen lets you specify the PASS/FAIL limits, frequency range and step size
used in testing NEXT. Press the
Ñ
or
Ò
arrow key to select the NEXT limit to be changed.
The selected limit will be enclosed in a box.
If your Scanner has an alphanumeric overlay on the keypad, use the keypad to enter the limit. If
your Scanner does not have an alphanumeric overlay, press
Edit (F2) to display the edit screen.
Note: Limit only applies when Criteria is set to Fixed . When Criteria is set to Fixed , the decibel
value entered in the Limit field will be used as the PASS/FAIL criteria across all frequencies.
The PentaScanner+ allows you to set a limit based on an Offset value. When Criteria is set at
something other than Fixed , the Offset field replaces the Limit field. The value entered in the
Offset field will be added to the NEXT criteria calculations, allowing you to set tighter NEXT
limits in your Autotests. For example, if you enter a dB offset of 5.0 dB, the criteria calculations for
Cat 5 Link, Cat 5 Channel, etc. will be increased by 5.0 dB. You can enter offset values from 0.0
— 60.0 dB.
When Step or Criteria is selected, Change (F2) lets you toggle through the available settings.
After editing, press Save (F1) to store the new NEXT limit settings and exit or press the ESCAPE
key to exit without saving.
NEXT Test Results
To display the NEXT screen, press View (F1) from the AUTOTEST RESULTS screen, then press
the
Ò
key until the NEXT screen is displayed. This screen displays Near End Crosstalk (NEXT)
test results.
When using the 2-Way Injector+ (or the 2-Way Injector ), the top line of the screen indicates if
NEXT is being reported for the Scanner ( Penta ) or Injector ( Inj ) end of the link.
At the upper left of the screen, the pair combination is shown. The PASS/FAIL bar across the
screen compares the measured NEXT value to the NEXT limit value. The Autotest name is
displayed after
Spec: at the lower left of the screen.
Press Detail (F1) to display the Frequency Sweep range and test results for all pairs.
Press Pair (F3) to toggle through the NEXT results for each pair combination.
When using the 2-Way Injector+ (or the 2-Way Injector ), press F4 to toggle between NEXT
results for the Scanner ( Penta ) or Injector ( Inj ) end of the link.