JDS Uniphase OneExpert DSL, User Manual

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Chapter 10 Test Results
Copper results
OneExpert DSL User’s Guide
90
22052280, Revision 001 April 2014
Longitudinal balance
You measure longitudinal balance to:
• measure the quality of the pair: a measurement of the degree to which the Tip (A) lead is
electrically the same as the Ring (B) lead.
The more each lead is electrically identical (capacitance, inductance, impedance), the better the
pair will resist induced noise.
The balance result should be >60 dB. Anything less indicates electrical differences between Tip (A)
and Ring (B) that can lead to noise and other signal problems.
Table 27 describes the DC current result.
Load coil
You check for load coils to ensure there are no load coils present on a digital line (such as ADSL or
ISDN). Load coil detection and elimination is essential in the installation of an xDSL circuit
Table 26 describes the load coil result.
TDR
A TDR (Time Domain Reflectometer) is used to identify and locate buried splices, shorts and low
resistance faults, opens, bridge taps, load coils, and wet cables.
Velocity of Propagation (VoP) is the speed of the TDR signal travelling down the wire pair relative
to the speed of light. The OneExpert DSL uses this value to convert reflections to distance. To
ensure an accurate distance calculation at the cursor, the VoP should match the cable gage and fill.
The default value is appropriate for 24–26 AWG (4–5 mm) telco aerial cable and provides sufficient
accuracy in most situations.
Table 26 describes the TDR result.
Table 27 Balance result specifications
Range Resolution Accuracy
28 to 70 dB 1 dB ± 2 dB
70 to 120 dB 1 dB indication only
Table 28 Load coil result specifications
Range Resolution Accuracy
Up to 27,000 ft (8229.6 m) up to 5 ± 1
Table 29 TDR specifications
Range Accuracy
0 to 40,000 ft (12000 m) ± 0.5% of distance