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Measurement Definition
Parametric Sweep Measurement Definitions
Parametric Sweep Measurement Definitions
Track Profile Measurement
Track Profile is a graphical plot of the read head voltage as a function of the read head
position on a written track. It is also used to observe the TAA, PW and Narrow Band TAA.
The Agilent E5022/E5023 allows you to select forward, backward or both directions for
head displacement. Measurements of track profile and micro-track profile are often carried
out to observe the influence of fringing fields for components integration in a drive.
The Track Profile measurement serves as a preliminary step prior to error rate test, i.e.,
before bit error rate test. It is also used to observe the effect of fringing fields and to study
the asymmetry in the output signal across the track. 'Fringe' are magnetic fields that occur
at the edges of the head it is a part of the head construction. It serves as a guard band
between two separate adjacent tracks. Guard bands serves as a buffer to avoid track
misregistrations. It has a different magnetic orientation and can re-magnetize the medium.
Factors that influence fringing fields is as follows.
1. Coercivity, high coercivity for hard magnetic material such as media and low
coercivity for soft magnetic material such as magnetic head.
2. Head geometry.
3. Degree of asymmetry in the head read/write response.
Building the Track Profile
Measurement procedure in building the track profile is as follows:
1. DC erase the track and its vicinity in order to provide a noise-free medium background.
2. Write the test track.
3. Read the test track when the head center is at the position sufficiently far from the left
side of test track. Then progressively step-up the head displacement as defined by
'head offset' to the right side of the test track and measure the output voltage.
4. Continue to step-up the head offset until full trace of the curve is obtained.
Using Track Profile Test to measure the Width of the Read/Write Head
The track profile can also be used to measure the width of the write and read head. The
write head width is observed by calculating the width at half amplitude level of the Track
Profile. The same way, the read head width is observed by calculating the width at half
amplitude level of the Micro Track Profile. The read head width is also observed by
calculating from the Track Profile measurement. The
"hpe5022_calculateRWOffsetAndWidth_Q" returns the write/read head widths from the
track profile curve. This function is not available in the VEE measurement program.
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Chapter 5
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