A system for detecting a failure along a transmission line of a cable plant is provided. The system includes a mobile vehicle configured to travel along a pathway substantially proximate to the cable plant along a span of the transmission line, and a transmitter disposed with the mobile vehicle. The transmitter is configured to emit (i) a test signal capable of ingressing the transmission line at a location of the failure, and (ii) an information signal containing location and velocity data of the mobile vehicle. The test signal is configured to provide phase shift and Doppler frequency information to a receiver operably connected to the transmission line at a location upstream from the location of the failure.