Magnetic recording

Abstract

A method and apparatus for encoding or decoding data in accordance with a coding format, referred to herein as Y.phi. and which is based on the 3PM coding format. Data encoded in accordance with the Y.phi. format is generated by initially encoding, at a prearranged clocking frequency, binary data in accordance with 3PM format, applying such encoded data to one input terminal of an exclusive OR gate and applying clocking pulses, at the prearranged frequency to the other input terminal. Decoding is similarly achieved by passing the encoded data through an exclusive OR gate. Data encoded according to the Y.phi. format is particularly advantageous on account of the relatively high density of flux transitions which it generates, which may be desirable in certain circumstances particularly if both high and low rate data is to be encoded on the same magnetic tape.

Dependencies are inferred from the claim text.