Abstract: In a method and apparatus for scanning a fiber optic network, a light source emits optical pulses into an optical fiber under test. A detector detects reflected light for each of the optical pulses and converts the reflected light into an electrical signal for each of the optical pulses. A sampling circuit samples the electrical signal for each of the optical pulses to generate sets of sample data points associated with the respective optical pulses. A signal processor is programmed to ensemble average the sets of sample points with each other to generate a merged set of avenge sample points. The signal processor then compresses the merged set of average sample data points to obtain a current set of trace data points. The data compression is preferably accomplished using "boxcar" time-avenging of the sample points. The current set of trace data points is compared with a reference set of trace data points stored in memory to determine whether or not a fault exists in the fiber under test.