Measurement of noise in magnetic media

A model for medium noise in thin film and particulate discs is presented. The model is based on both time jitter and spectrum analyzer measurements. Thin metallic film discs have different noise mechanisms from either particulate or sputtered γ-Fe
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discs. A signal-to-noise ratio equal to the signal /rms noise measured at the predetection filter output gives accurate prediction of peak jitter only if the noise is measured at the transitlon density giving maximum noise.