ADTRAN HDSL4 Installation And Maintenance Manual

Contents

ADTRAN HDSL4 Installation And Maintenance Manual Manual pdf 85 page image

HDSL4 for General Distribution Installation and Maintenance Practice HDSL NEW ENHANCED FEATURE OVERVIEW61223HDSL4L2-5C B-3Bad Splice DetectionRuntime TScan 2.0TM splice detection feature is an ADTRAN proprietary non-intrusivealgorithm for detection of anomalies (bad splices) in the copper pair.Data transmission transceivers (especially echo-cancelled technologies) are subject to perfor-mance degradations and errors in the presence of bad splice connections. A splice may bebenign 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. Thisinconsistency in behavior makes the problem difficult to locate. Additionally, an impedancechange that is large enough to cause the transceiver trouble may still be small enough to beundetected by test equipment utilized on the copper pairs. Therefore a non-intrusive methodof identifying these bad splices has been developed to aid the customer in troubleshootingtheir distribution plant.NOTEThe Splice Detection Feature is included with this product as anaid to troubleshooting. Due to inconsistency in environmental con-ditions and their effect on telecommunications plant, ADTRAN can-not guarantee the accuracy of the measurements. Comparison toexisting engineering drawings should provide exact locations ofsuspect splices indicated by ADTRAN algorithms.The support mechanisms for this feature can logically be divided into the following sixsegments:• “Splice Detection Algorithm” on page B-3• “Screen Support” on page B-4• “EOC Support” on page B-4• “FDL Support” on page B-4• “EEPROM Support” on page B-4• “Event Support” on page B-4These support mechanisms are described in the following subsections.Splice Detection AlgorithmThe splice detection algorithm is designed to detect bad splices in training mode and datamode. The training mode detection is important if the splice is bad enough to prevent synchro-nization. In data mode, the detector will run periodically after synchronization is achieved.The HDSL4 transceiver monitors the loop for impedance changes that are of a magnitude tocause the received signal of the transceiver to be degraded. When a significant impedancechange is detected by the transceiver, the approximate distance from that transceiver to theanomaly is recorded on the Splice Histogram screen by incrementing the appropriate counter.When enough counts are accumulated at a particular distance, this distance will be reportedon the Splice Results screen.