A method and system for estimating the location of an injection point of foreign
signals in a network comprises the steps of measuring signal samples at two points
along the cable network distribution system, correlating the two signal samples
to estimate propagation delay differences between the measurement locations and
the source, and calculating the location and magnitude of the ingress. The propagation
delay, or time correlation, is proportional to the offset of the injection point
from the midpoint between the measurement sites, where the two parameters are related
by the velocity of propagation in the cable. The amplitude of the correlation peaks
represent the magnitude of the ingress at that location. Sensitivity may be increased
by time-averaging the output of the correlation step. Multiple sources and/or ingress
and egress sites may be measured simultaneously.
