EXFO CableSHARK P3 VF/DSL Cable Qualifier - Manual (Page 222)

VF / DSL Cable Qualifier
210
If the line card is not connected or is not detectable by the CableSHARK, the Ground Resistance test
displays the following screen.
MAIN
MENU
E F CHG
SAVE /
UPLOAD
Line card = not detected
TEST
SETUP
F IGURE 13.2.4B – L INE C ARD N OT D ETECTED
The Ground Resistance measurement is executed in the following fashion.
1. Measure the open loop (on hook) tip-ring voltage (Station voltage). The voltage must be negative. If
not an error message reporting “Tip & Ring polarity reversed” will be displayed.
2. The CableSHARK will detect the balanced-unbalanced source (on hook) by measuring the ring-
ground voltage. For a grounded system it must be ≤5 V. If the ring-ground voltage is ≥5 V, the line
is balanced.
3. The CableSHARK measures the loop current (off hook) by seizing the line with a 435 ohm internal
load
4. For the constant voltage sources, the CableSHARK measures the tip-ring voltage (off hook) with
the 435 ohm load.