Chapter 5
253
Measurement Definition
Measurement Parameter Definition
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PW positive is measured as the average pulse width at 50% of the positive TAA signal.
While PW negative is measured as the average pulse width at 50% of the negative TAA
signal. PW Asymmetry is defined by Equation 5-12.
Another important parameter in the analysis of waveform is the measurement of baseline.
Baseline positive (B) is the amplitude measured half way between the positive and
negative peaks (i.e., p to n order). And baseline negative (Baseline-) is the amplitude
measured half way between the negative and positive peaks (i.e., n to p order). Baseline is
the average amplitude level measured between the B and Baseline-. While
Separation is defined as the amount of baseline shift between Ba and Baseline -.
Separation occurs due to track edge effect during write operation. Head geometry such as
untrimmed write heads, unequal write pole widths and fringing fields create a transverse
component that changes sign alternately as the write head gap is switched. As a result,
dipoles with alternating directions are written at the track edges. A dipole is a pair of
magnetic poles that is separated by a fixed distance having opposite polarity or signs.
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