SHIELDING FLAW DETECTION AND MEASUREMENT IN QUADRATURE AMPLITUDE MODULATED CABLE TELECOMMUNICATIONS ENVIRONMENT

摘要

Signal egress from a shielding flaw in a cable telecommunication system is detected, even where signals carried by the cable telecommunication system are quadrature amplitude modulated signals that statistically resemble broadband noise by generating a marker signal comprising a double side band, suppressed carrier signal in the fringes of contiguous frequency bands and at a power level which cannot cause perceptible interference with signals in those contiguous frequency bands. The separation of the sidebands comprising the marker signal can unambiguously identify the marker signal and can distinguish between different cable telecommunication systems installed in the same geographic area. The marker signal can be additionally coded by varying the frequency and/or amplitude of the modulating signal used to create the marker signal.