Table of Contents
Advertisement
Measurement Definition
Measurement Parameter Definition
Stability Measurement by Absolute Time
The objective of this test is to evaluate head instability by measuring the TAA, TAA
Asymmetry etc. in terms of absolute time. This test allows the user to set up the write and
read operation in each segment (sector) as a function of absolute time so that test results
can be closely correlated similar to popcorn noise test. See Figure 5-10 on page 250.
One of the causes of head instability is popcorn noise which occurs shortly after write
operation. This noise spikes causes head instability because write current pulse produces
thermal transients in the head that affects the read-back signal. In order to evaluate head
instability more accurately in addition to popcorn noise measurement, Agilent
E5022/E5023 allows the user to measure TAA Stability with a programmable gate time
setting for write operation, read operation and time delay in terms of absolute time.
In previous measurement applications the length of write and read operation is set in terms
of ratio relative to the segment (sector) length. This method does not provide sufficient test
results to evaluate the head instability. Measurement sequence of this test is similar to
"Stability Measurement" on page 248 except for gate time setting.
Figure 5-10
Segment Setting by Absolute Time
With this newly incorporated function in measuring stability, the user should decide the
number of measurement counts (i.e, counts) by setting the write time, delay and read time.
The number of segments per revolution and the number of total revolution is automatically
computed by the system. Refer to the equations provided on the next page.
The user may use the equations provided on page 209 as reference equations in
determining the total number of measurement counts. "Segment", refers to the number of
times a track is to be divided, calculated as shown in Equation 5-8. "Revolution", refers to
the number of track rotations, calculated as shown in Equation 5-9. And "Counts", refers to
the total number of stability measurements, calculated as shown in Equation 5-10. Refer to
the programming manual for details about the measurement sequence.
250
Chapter 5
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
Advertisement
Table of Contents
