Browse Prior Art Database

F/2F Decoding Method

IP.com Disclosure Number: IPCOM000088316D
Original Publication Date: 1977-May-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Nassimbene, EG: AUTHOR

Abstract

This article describes an F/2F decoding technique where decision window timers are started on transitions not affected by pulse crowding.

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F/2F Decoding Method

This article describes an F/2F decoding technique where decision window timers are started on transitions not affected by pulse crowding.

In decoding a pulse train read from a double-frequency encoded medium, pulse crowding is compensated for by generating data separation pulses as follows: Timer 1. When a "zero" bit is sensed, start a first timer on the last transition of the bit that will generate an output pulse at 175% of the nominal clock-to-clock time. Timer 2. When a "one" bit is sensed, start a second timer on the center transition that will generate output pulses at 125%, 175%, and 225% of the nominal clock-to-clock time.

In the above cube logic and timing diagrams, the identification of "zero" and "one" bits based upon the output pulses of these timers is illustrated for an arbitrary double-frequency encoded data stream.

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