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Testing Servo Positioning Circuits

IP.com Disclosure Number: IPCOM000088380D
Original Publication Date: 1977-Jun-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 20K

Publishing Venue

IBM

Related People

Barr, ER: AUTHOR [+5]

Abstract

Some servo positioning circuits respond to varying amplitude servo signals. Such servo circuits include a threshold T for passing servo signals to be processed. Such signals may be used, for example, in connection with positioning a magnetic tape within a magnetic recorder. Typically, such servo signals bracket a data signal area to be transduced. Many such servo circuits have a large number of digital components for digitally processing the sensed servo signals. Such digital circuits cannot always be reliably and easily tested because of the analog perturbations in the threshold T.

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Testing Servo Positioning Circuits

Some servo positioning circuits respond to varying amplitude servo signals. Such servo circuits include a threshold T for passing servo signals to be processed. Such signals may be used, for example, in connection with positioning a magnetic tape within a magnetic recorder. Typically, such servo signals bracket a data signal area to be transduced. Many such servo circuits have a large number of digital components for digitally processing the sensed servo signals. Such digital circuits cannot always be reliably and easily tested because of the analog perturbations in the threshold T.

A solution to the threshold problem for testing is to eliminate the threshold T by supplying a set of constant amplitude test signals from a test control computer via a switch for manipulating the servo circuits to be tested. In this situation a magnetic recorder having a tachometer sync pulse, identifying the time relationship of the servo signals to movement of the tape with respect to the transducer, activates the test control computer programs for supplying test signals through a switch to the servo circuits. The servo circuits are synchronized by the same tachometer sync pulse. In an automatic setup a switch control from the test control computer activates the switch to receive signals from the magnetic recorder for operating the servo circuits which are physically in the recorder or to pass the test signals through the switch to the servo circu...