EXFO CableSHARK P3 VF/DSL Cable Qualifier - Manual (Page 131)

CableSHARK P3 User Guide
119
8.5..Longitudinal Balance Test
The longitudinal balance test ensures that the twisted pair is balanced. Longitudinal balance ratio is defined
in ITU-T Rec. O.9, which is important when it comes to reducing the effects of common-mode voltage to
ground. The CableSHARK can perform a longitudinal balance measurement to determine if the longitudinal
balance ratios are compliant with this standard. The CableSHARK displays results for ADSL applications
respective of the ANSI T1.413 standard. The better the balance of the cable pair under test, the higher the
dB reading resulting from the measurement.
8.5.1 Setting up a Longitudinal Balance Test
From the Main Menu, pressing function button F1 (CABLE TESTS) will bring the user to the CABLE TESTS
pop-up menu. Choosing LONGITUDINAL BALANCE will invoke the LONGITUDINAL BALANCE TEST
SETUP menu. The sections that follow will explain the operation as each of the control keys is pressed and
their respective screens appear. Figure 8.5.1A below shows the Longitudinal Balance Test Setup Menu.
EDIT /
SELECT MAIN
MENU
Test Type :
Term Impedance:
100 OHMS
E F CHG
LONG BAL NEAR END
WARNING
Note: telephone cables may have dangerous A.C. or D.C.
voltages on them, therefore caution should be taken when
connecting this test set.
!
F IGURE 8.5.1A – L ONGITUDINAL B ALANCE T EST S ETUP