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Detection Method for Signals With Unequal Alternate Peak Time Displacement

IP.com Disclosure Number: IPCOM000034620D
Original Publication Date: 1989-Feb-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 4 page(s) / 133K

Publishing Venue

IBM

Related People

Seger, PJ: AUTHOR

Abstract

This article describes a method to detect signals or events which have unequal alternate time displacement. Such signals may occur in systems which sense event transitions and whose transition spacing may vary due to changes in the transmitted or recorded event size. Similarly, such signals may occur in systems having unequal timing offsets between positive to negative and negative to positive events. (Image Omitted) Information may be encoded in numerous ways. The technique described herein is independent of specific encoding or detection schemes. Therefore, in the following discussion of an event, the exact manner in which this event is detected is inconsequential, that is, it may be detected as an edge zero crossing, or be transformed into the peak of a inconsequential to the method to be described.

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Detection Method for Signals With Unequal Alternate Peak Time Displacement

This article describes a method to detect signals or events which have unequal alternate time displacement. Such signals may occur in systems which sense event transitions and whose transition spacing may vary due to changes in the transmitted or recorded event size. Similarly, such signals may occur in systems having unequal timing offsets between positive to negative and negative to positive events.

(Image Omitted)

Information may be encoded in numerous ways. The technique described herein is independent of specific encoding or detection schemes. Therefore, in the following discussion of an event, the exact manner in which this event is detected is inconsequential, that is, it may be detected as an edge zero crossing, or be transformed into the peak of a inconsequential to the method to be described. Systems which sense the time location of events require that the events, or some processed equivalent thereof, be located within a timing window for proper detection. Any action which causes the event to fall beyond the window results in an error. See Fig. 1. A data 1 (0) is output for every clock window in which a recorded event is detected. An error occurs if an edge is detected in a window in which no edge was written, or if no edge is detected in a window in which an edge was written.

(Image Omitted)

Some systems are subject to event distortion in which the event size changes. It may grow or shrink during or after the initial generation. The resulting signal features correspondingly grow and shrink. This results in timing distortion and error as shown in Fig. 2. The events, and the resulting signal features, move alternately toward and away from their neighbors. The actual event edges are detected in the wrong clock window resulting in data errors. An example of a system which experiences this distortion is any data recording technique which changes magnetization or polarization form an initial state to a second state, but not back. Optical recording systems which write by switching a laser on and off in the presence of a fixed bias is an example of such a system. Magnetic recording systems which write by energizing the write head while passing over pre-biased media is another example. In these cases, the event may be the magnetic structure recorded on the media or it may be the reproduce signal disto...