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Symmetrical Digital Window Control for Separating Phase Encoded Data

IP.com Disclosure Number: IPCOM000077340D
Original Publication Date: 1972-Jul-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Dumstorff, EF: AUTHOR [+2]

Abstract

A digital system to separate phase-encoded data uses a six-stage counter (PE counter) to control the opening and closing of a "window", that prevents phase transitions from being interpreted as data transitions. Additionally, a five-stage up/down counter (U/D counter) is used to control the width of the "window" dependent upon variations in the speed of the tape. The U/D counter is not incremented or decremented unless the "window" has to be adjusted.

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Symmetrical Digital Window Control for Separating Phase Encoded Data

A digital system to separate phase-encoded data uses a six-stage counter (PE counter) to control the opening and closing of a "window", that prevents phase transitions from being interpreted as data transitions. Additionally, a five- stage up/down counter (U/D counter) is used to control the width of the "window" dependent upon variations in the speed of the tape. The U/D counter is not incremented or decremented unless the "window" has to be adjusted.

Initially, for example, using a 1600 bpi tape normally moving at 6 ips, the PE counter is reset to 30 and the U/D counter is reset to 16. The first transition on the tape will be a phase transition and upon its occurrence, the PE counter will begin counting at 750 kc rate. Referring to Fig. 1, when the count reaches 46, the "window" is opened and the PE counter is reset to 0. At this time, the U/D counter (equals 16) is gated into the PE counter which continues counting. At the center of the "window", (PE count equal 40) the data transition should take place. At the PE count equal 64 the "window" is closed, the PE counter is reset, and the U/D counter (still at 16) is gated into the PE counter which continues counting. When the PE counter reaches 46 again, the "window" is opened and the above process repeated.

If a tape should move faster than normal, the data transition would take place earlier, for example, at PE count equal 32 (see Fig. 2). Immediately, the U/D counter would count up at the...