Abstract: An improved data recording system incorporates a detection circuit directly into the data read channel circuitry of the recording system to provide the capability of automatic self-testing and mapping of media flaws. The flaw detection circuit outputs an error signal in response to distortions in the readback signal caused by a defect on the medium. Firmware code is utilized for controlling the scanning of the medium by the flaw detection circuit and for recording the locations of the defects on the medium in response to the error signal. The detection circuit itself comprises a phase-splitter for splitting the readback signal into in-phase and quadrature-phase components. These components are then squared and summed to generate a phase independent flaw signal having an amplitude modulated in relation to the locations of the defects.