A method and system for providing simultaneous localization of defects in both the time and frequency domain. A high frequency repeating pattern is written on media, and the pattern is read to generate a readback signal, which is converted into ADC samples. The ADC samples are analyzed, in-line, to determine the type of wavelet, level of decomposition, and threshold level for a wavelet transform of the particular readback signal. The wavelet transform provides details and/or approximations (wavelet coefficients) that are analyzed to determine the type, location, and duration of any identified defects. Any noise in the details and/or approximations (wavelet coefficients) is removed by a wavelet based denoising operation. Flags indicating the type, location, and duration of any defects are generated so that the defects may be mapped.