PAL-AT® uses a pulsed cable-radar technology to detect leaks. PAL-AT sends out low voltage pulses on a cable and monitors reflections received back at the panel. PAL-AT electronically divides the cable into short increments and measures the reflections from each increment. It stores the measured values in memory during the reference procedure in a permanent record called the “master” map. When in monitor mode, PAL-AT compares the current condition with the master map. Significant changes from the master, for instance when the cable gets wet, cause PAL-AT to enter the alarm mode.