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Constant Velocity Pattern Test

IP.com Disclosure Number: IPCOM000038198D
Original Publication Date: 1989-Dec-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Grimm, CR: AUTHOR

Abstract

A hardfile pattern test is performed using a scanning method to locate errors rather than using a track seek method. This reduces lengthy test times, and it avoids the problem of not detecting errors because of being not exactly on a track.

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Constant Velocity Pattern Test

A hardfile pattern test is performed using a scanning method to locate errors rather than using a track seek method. This reduces lengthy test times, and it avoids the problem of not detecting errors because of being not exactly on a track.

A high-speed digital signal processor is used to test the servo patterns by putting the product actuator or servowriter dedicated head in a constant velocity move profile. A digital signal processor calculates the current velocity profile and projects the expected reading at the next servo sample time. When the next servo sample is actually taken it is compared to the nominal (estimated) value. If the actual reading is found to be off by greater than the allowable limit, then the site is flagged as "bad", and normal error recovery procedures take place.

In general, the constant velocity pattern test works as follows:

1. Begin the constant velocity move on the actuator.

2. While reading the servo samples, establish the velocity profile.

3. Calculate what the next servo sample value should be.

4. Read the next servo value and find the delta to the calculated value.

5. Compare the value to the allowable limit.

6. If finished, go to #9 -- error recovery.

7. If the value is within the limits, go to #3.

8. Record this sector as "bad" (head cylinder and sector) then go to #3. 9. Error recovery/sector obliteration -- evaluate the

pass/fail criteria.

Disclosed anonymously.

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