Bandwidth of apparatus with magnetic recording

Conclusions

• 1. The largest recorded frequency spectrum and maximum distortion are obtained in direct recording, both are reduced in pulse-frequency modulation, and still further reduced in pulse-width modulation; moreover, the value of distortions in a first approximation is proportional to the maximum recorded frequency. Therefore, in designing and selecting magnetic recording apparatus, it is necessary to compromise.

• 2. In practice, for a given tape propulsion speed, the maximum recorded frequencies in PWM and PFM depend on the adopted pulse-repetition factors and the depth of modulation. The latter effect the precision characteristics of the apparatus, which in turn depend on a number of factors not dealt with in this article.