Triple-Play Service Deployment

Chapter 5: Troubleshooting the Premises Wiring
Traditional certification testers, based on TIA-568, certify the ability
of the wiring plant to carry a specific frequency, which in theory
corresponds to a data rate. Newer certifiers, based on IEEE 802.3
specifications, test the wiring and perform live data tests to certify
the quality of the data connection and the connection rate.
Ethernet specifications up to and including 100 MHz Fast Ethernet
are based on physical parameters and measurements that are
linked to frequency signals that infer performance against a set
standard of bandwidths. When the standards were developed,
there was no clear roadmap depicting the network speeds or data
requirements that would be necessary to support triple-play
service deployment. Now, gigabit Ethernet uses all four pairs
simultaneously, and requiring measurement of the other pairs’
influence on the pair under test. This has resulted in the creation
of a measurement for power sum near- and far-end crosstalk
(PSNEXT and FENEXT).
Traditional certifiers use frequency sweep signals to measure
likely conditions for failure on a cable, and to measure the results
of these signals against a set of pre-determined limits on each
measurement with respect to TIA-568 specifications. The
frequency sweep based certifiers are useful for testing the
construction of the data cable. New certification tools use digital
signal generation to measure the signal-to-noise ratio (SNR) and
add the bit error rate test (BERT) as a demonstration of error free
transmissions of actual digital data over that line. The BER test
measures actual data flow rates from both ends of the cable run
while FENEXT and PSNEXT try to infer data carrying capability by
simulation with transient frequency signals.
This new class of certifiers is very applicable and useful for premises
testing since they test the systems actual data performance. Speed
standard testing, is performed by the newer certifiers, accurately
determines how a cable will work in real network conditions. In
addition, these new certifiers incorporate TIA-568 test specifications
because the SNR contains all of the noise measurements of
TIA-568 and the SKEW measurement is the same.
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