Hewlett-packard Company

Leo S Miller

Freddie W Wenninger

A method and apparatus are provided for decoding digital information stored on magnetic tape. The 'zero' and 'one' bits are represented respectively on the tape by 'short' and 'long' distances between flux transitions. Decoding is accomplished by measuring the time between flux transitions and comparing that time with a reference time. Times longer than the reference time are decoded as 'ones' while time intervals shorter than the reference time are decoded as 'zeroes.' To make the decoding independent of variations in tape speed the reference time is variable and in particular is made dependent on the tape speed. This is accomplished by updating the reference time based on previous 'long' and 'short' intervals between flux transitions. Circuitry is provided in which the various times are converted to voltages which are appropriately sampled and updated in accordance with the tape speed.

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Loveland, CO, United States of America

Leo S Miller