CONTACT OSCILLATION-SPECTRUM ANALYSIS FOR MAGNETIC RECORDING MEDIA.

Parasitic amplitude modulation (PAM) occurs in playing back signals from magnetic recording media MRM, and leads to change in channel transfer coefficients, and in some cases to signal dropout. The characteristics of PAM enable one to formulate specifications for the recording and playback equipment, as well as for the equipment for producing MRM. A major factor influencing PAM characteristics is the surface finish or microgeometry of the MRM working layer. Ridges and hollows in the working layer alter the contact between layer and the heads, and the random character of the fluctuations determines the PAM characteristics. It is shown that contact fluctuations producing PAM in the main are determined by the surface undulation, and the mean step in the unevenness exceeds 1. 5 mm.