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Skew Measuring Circuit

IP.com Disclosure Number: IPCOM000073951D
Original Publication Date: 1971-Feb-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Crowther, EA: AUTHOR

Abstract

The measuring circuit shown by block diagram is used for measuring the dynamic skew of magnetic tape. The measuring is accomplished by comparing signals read from two tracks on the Cape, preferably the outside tracks. Skew is thus defined as the relative time difference between two signals read from a tape where the two signals were originally recorded simultaneously.

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Skew Measuring Circuit

The measuring circuit shown by block diagram is used for measuring the dynamic skew of magnetic tape. The measuring is accomplished by comparing signals read from two tracks on the Cape, preferably the outside tracks. Skew is thus defined as the relative time difference between two signals read from a tape where the two signals were originally recorded simultaneously.

In operation, the signals read from track A and track B are applied to hysteresis amplifiers 10 and 12. The function of a hysteresis amplifier is to generate a square-wave output signal where the trailing edge of each pulse has a fixed time relationship to the input signal to the amplifier 10 or 12 and the leading edge of the pulse will vary in accordance with the amplitude of the input waveform. Thus, the output of the hysteresis amplifiers 10 and 12 is a square- wave whose trailing edge is indicative of when a signal on a track was read from the magnetic tape. The waveforms produced by each of the hysteresis amplifiers 10 and 12 are shown as waveforms A and B and correspondingly labeled at points A and B in the block diagram.

The shaped waveforms out of tracks A and B are then passed to gating logic 14 and to Exclusive OR 16. Exclusive OR 16 performs the skew measurement function. The Exclusive OR 16 will have an output when the A or B waveform is up, but no output when both the A and the B waveforms are up or down together.

Referring to waveforms A and B, a pulse would norm...