Signal-to-noise ratio and equalization of magnetic-tape recording

Abstract

Future tape recorders running at a speed of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1\frac{7}{8}</tex> ips must achieve an upper frequency limit of 15 kc on a quarter track recording, with better SNR than presently obtained with commercial recorders. This means that the subjective quality of present full track machines at 15 ips must be maintained in spite of a fifty-fold increase of information density. It is obvious that such an improvement cannot be obtained only by changes to the electronic circuitry and the like. In fact, the future requirement would be impossible to meet if improvements in tape and heads were not made. Such improvements must include new knowledge of head construction, tape-to-head contact problems, and optimum balancing of recording parameters. But once these improvements are effected, it is then necessary to check carefully if the most thorough use is being made of all available technical possibilities. It will be shown that recording techniques have advanced to a stage where a change in the standardization characteristics is advantageous and even necessary, though they may be more complicated than the existing standards.