Magnetic Peripherals Inc.

Modern Controls, Inc.

Guss L Krake

William N Mayer

Stephen D Tuomela

A process for measuring the vapor transmission rate characteristics of a test material by first measuring the vapor transmission through a test chamber and sample material and subsequently repeating the measurement with the test material adjacent the sample material. By subtracting the first measured transmission rate reciprocal from the second measured transmission rate reciprocal, a value is determined which is the reciprocal of the vapor transmission rate characteristic of the test material.

Process for measuring vapor transmission through materials

A track centering servo pulse noise filter is provided. Prerecorded pulses on a disk track's even and odd half tracks are sensed by the disk's read head, preamplified, DC biased, peak detected, and stored on a FIFO basis into a noise filter comprising two sets of N analog sample and hold cells, one set for the even pulses and one set for the odd pulses. The output of each even-pulse sample and hold cell is input to a summing junction to form an average of the last N pulses. The same is done with the outputs of the odd-pulse sample and hold cells. The two summing junctions are then input to a differential amplifier to form a position error signal to the disk head track centering servo system for keeping the head centered on the track.

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Richfield, MN, United States of America

Guss L Krake