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2 61223441L1-5C
Description T200 H4R Installation and Maintenance Practice
2. DESCRIPTION
HDSL4 provides extended range T1 (DS1) transport on the telecommunications network. HDSL4 features spectral
compatibility with ADSL and other transport technologies.
The T200 H4R performs signal regeneration to extend the range of the HDSL4 circuit.
The H4TU-C (Central Office Transceiver) unit receives DSX-1 input signals from the network through the chassis,
transports them across the HDSL4 circuit, and terminates them through an H4TU-R remote unit which provides a
traditional DS1 signal to customer equipment. The H4TU-C provides testing, provisioning, and performance
monitoring capabilities that address circuit status.
An ADTRAN HDSL4 loop may consist of an H4TU-C, an H4TU-R, and up to three H4Rs.
Features
The basic features of the T200 H4R, include the following:
• TC PAM line coding
• Lightning protection
• In-band loopback control
• Standard Type 200 or Type 400 form factor repeater apparatus case design
• Remote provisioning and pass-through performance monitoring
• Bad Splice Detection
• Fast Retrain
Bad Splice Detection Feature
The T200 H4R supports the Runtime TScan 2.0
TM
bad splice detection feature, an ADTRAN proprietary non-intru-
sive algorithm for detection of anomalies (bad splices) in the copper pair.
Data transmission transceivers (especially echo-cancelled technologies) are subject to performance degradations
and errors in the presence of bad splices. A splice may be benign for a period of time, allowing a circuit to behave
appropriately for portions of the day. However, over time the splice will oxidize and incur small, rapid changes in
impedance. This inconsistency in behavior makes the problem difficult to locate. Additionally, an impedance
change that is large enough to cause the transceiver trouble may still be small enough to be undetected by test
equipment utilized on the copper pairs. Therefore a non-intrusive method of identifying these bad splices has been
developed to aid the customer in troubleshooting their distribution plant.
NOTE
The Splice Detection Feature is included with this product as an aid to trouble-
shooting. Due to inconsistency in environmental conditions and their effect on
telecommunications plant, ADTRAN cannot guarantee the accuracy of the
measurements. Comparison to existing engineering drawings should provide exact
locations of suspect splices indicated by ADTRAN algorithms.
Splices that are varying in impedance will cause the HDSL data pump to see a reduced and/or fluctuating signal
quality (margin). The HDSL data pump will attempt to track these changes. When the changes become too severe,
errors or loss of synchronization result.