An Experiment on the Effect of Particle Orientation on Peak Shift in Magnetic Tapes

One of the limiting factors in high-density recording on magnetic tape is the phenomenon of peak shift. With the NRZI code (flux change on a one, no flux change on a zero) this means that the reproduced signals from two successive ones preceded and followed by zeros are separated in time by more than the natural bit period. The peaks in the signal output from the two ones are thus shifted outwards. An experiment is described in which the peak shift is measured in particle-oriented tape as a function of the angle θ between the direction of recording and the direction of orientation. The dc hysteresis properties of the tape were also measured as a function of θ. It was found that the peak shift had a minimum when θ was approximately 65° for the tape and recording head used in this experiment. At this angle the remanence-coercivity was high, while the coercivity and the ratio of remanence to saturation intensity were low. Qualitative explanations of these results are offered and their significance is briefly discussed.