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Browse Prior Art Database

Automatic Amplitude Adjustment

IP.com Disclosure Number: IPCOM000078328D
Original Publication Date: 1972-Dec-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Birdsall, IP: AUTHOR [+2]

Abstract

The amplitude of a read amplifier in a magnetic tape drive is automatically adjusted by a power driven tool.

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Automatic Amplitude Adjustment

The amplitude of a read amplifier in a magnetic tape drive is automatically adjusted by a power driven tool.

Data is written on tape by a write head and then read by a read head located in the direction of tape movement. A test circuit is connected during adjustment procedures to the test output TP1 of read digital circuits, and the test input TP2 of write circuits. A correct adjustment is defined as one where 30% of the digital data to the read circuits is not correctly detected after recording.

As data is recorded, counter n2 counts the number of bits passed from the write circuit to the write drivers. The number of recorded bits detected by the amplifiers at the given adjustment level is counted by counter n1. After 16 bits have been recorded, counter n2 output, n2=16, gates the current counter n1 contents into a decoder which indicates if the number of bits read equals, is more or less than, 70% (i.e., n1=12 or n1=13) of the bits recorded. Flip-flops FF1 and FF2 are set to drive a motor clockwise (lowering the amplitude) if the number of bits detected is high, and counterclockwise (raising the amplitude) if the number of bits detected is low.

The motor, connected to the adjustment potentiometer by a mating shaft, may be hand-held and moved from one tape drive track to another. The same principles may be applied to adjustment of disc drive circuits.

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