TITLE: Early Fault Detection in Cable Television Networks (the Case of the 
       Reverse Pilot)

AUTHORS: N. P. Kourounakis, S. W. Neville and N. J. Dimopoulos

IN: 1997 IEEE Pacific Rim Conference on Communica tions, Computers, and Signal
    Processing, Victoria, Canada, August 20-22, 1997


Abstract:
In this work, we present a model based method for reliably detecting Reverse 
Pilot faults within cable amplifier networks. This method has the advantage 
over traditional fixed bound fault detection techniques in that it is able to 
compensate for changes in the environmental conditions and, hence, reduce the 
occurrence of false alarms.
Cable television distribution networks are used to distribute cable signals 
from a centrally located injection site (head-end), to subscribers' homes. 
Typically cable amplifier plants are two way asymmetrical communication 
networks. The downstream path, from the head-end to the subscribers' homes, 
is used mainly for delivering cable television services. Traditionally, the 
upstream path has been used to transmit the status data from the trunk 
amplifiers to the head-end. More recently it is used to provide a data path 
from the subscribers to the head-end for use in interactive services. Hence, 
the ability to detect the occurrence of faults inthe reverse path is quite 
important.
We have implemented a general approach based on using a back propagation 
neural network to model the behaviour of the Reverse Pilot signal of cable 
television amplifiers. This technique was able to provide good temporal 
localization of the start of fault conditions and a clear indication of the 
presence of the fault through its occurrence.