Triple-Play Service Deployment

Chapter 4: Troubleshooting the Copper Plant for IP Services
Tip and Ring
The lower the resistance of the path between the pair under
test and the working pair, the greater the measured voltage
will be. A cross can be the result of physical damage to the
cable, water ingress in the cable, or faulty splices. If excessive
VDC exists, use the insulation (leakage) resistance and opens
measurements to further refine the source of the problem,
which could be a resistive fault, wet section, etc. When the
cause of the problem has been determined, the technician
should use the time domain reflectometer (TDR) or resistive
fault locator (RFL) functions, to locate the fault for removal.
Foreign AC voltage
The presence of electrical energy from nearby power lines can
induce energy into an open pair resulting in AC voltage on the
line. This AC voltage can act as a noise source, degrading the
quality of xDSL transmission. To measure foreign AC voltage,
the technician must use a digital voltmeter.Typically the tip-toring
voltage should be less than 3V AC and the tip-to-ground
and ring-to-ground voltage should be less than 10V AC.
In telephony, the terms that represent the conductors that comprise a
circuit are known as tip and ring or A and B. The tip and ring term stems
from the early days of telephony when operators made telephone
connections using .25 inch phono plugs similar to those used today for
stereo headphones. Early systems also carried a third wire which was a
ground. The “tip” (A) was the tip of the plug and was the positive (+) side of
the circuit. The “ring” (B) was a conductive ring right behind the tip of the
plug and was the negative (-) side of the circuit. Right behind the ring was
the “sleeve” which was the ground connection.
Tip Ring Sleeve
Siemens 3-pin
The ground (sleeve) is no longer used today for individual pairs.
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