Optical time domain reflectometer (OTDR) systems, methods and integrated circuits are presented for locating defects in an optical cable or other optical cable, in which a first optical signal is transmitted to the cable and reflections are sampled over a first time range at a first sample rate to identify one or more suspected defect locations, and a second optical signal is transmitted and corresponding reflections are sampled over a second smaller time range at a higher second sample rate to identify at least one defect location of the optical cable for relaxed memory requirements in the OTDR system.