Side reading and side writing effects of track follower loop gain

A theoretical explanation is given for an experimentally observed dependency of track follower loop gain on the side reading and side writing properties of conventional monolithic ferrite recording heads using thin-film media in high track density disk drives. Following the problem definition and a summary of experimentally observed gain variation effects, it is shown that these effects are due to variation in the amount of side interference present in the readback servo code waveform. By applying A. van Herk´s (1977) theory of side reading and Y. Ichiyama´s (1977) equation for side writing, it is possible to make accurate quantitative predictions of the amount of variation present