Browse Prior Art Database

Calibrating Digital Signal Recorders

IP.com Disclosure Number: IPCOM000083826D
Original Publication Date: 1975-Aug-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Current, HG: AUTHOR [+2]

Abstract

Digital signal recorders employing a rotating head and having a tachometer head position indicator identify points along the record track D0-D5, by normalizing a tachometer fiducial mark position to the head gap position as it relates to the record track.

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Calibrating Digital Signal Recorders

Digital signal recorders employing a rotating head and having a tachometer head position indicator identify points along the record track D0-D5, by normalizing a tachometer fiducial mark position to the head gap position as it relates to the record track.

In fabricating the digital signal recorder, there may be an angular alignment error between the fiducial mark and the head gap. To ensure ease or normalizing, the timing position of the fiducial mark always precedes the nominal position of the head gap. The actual position of the head gap, as it scans the record medium, can vary as indicated by signals labeled "ACTUAL".

The location along the record tracks is normalized by a correction factor, which calibrates the initial position of the head gap with respect to a reference position on the record track. The correction factor is digitized by counting tachometer marks on the tachometer.

All positions D0-D5 on the record track are referenced with respect to the nominal position. Hence, the correction factor can be either negative or positive with respect to the nominal position. Such normalized position is stored in the read-only memory (ROM) or other form of memory. Correction factors are added to or subtracted from the stored normalized record track displacement, to yield the actual physical location in the time domain for a given digital signal recorder.

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