Head-to-tape spacing and recording process evaluated from modulation noise spectra

Four modulation noise sources are distinguished: surface roughness, inhomogeneities, and spacing variations during recording and playback. It is shown that the modulation noise shoulders in the flux spectrum are slightly asymmetric. The asymmetry depends on the recording wavelength, the head-to-tape spacing, the recording depth and the modulation noise source. The experimental results show the relationship between recording depth and coercivity and indicate that the modulation noise at a wavelength of 2 μm does not originate from the surface solely. For the head-to-tape spacing, an upper limit is estimated that is significantly smaller than the spacing plus the transition parameter, the sum of which is obtained from the frequency response