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Chapter 5
Measurement Definition
Measurement Parameter Definition
Waveform Analysis Measurement
The Waveform Analysis measurement requires the use of an oscilloscope in order to
evaluate the waveform characteristics of the read signal. It measures the standard TAA,
PW50 and Baseline parameters.
This measurement is a graphical plot of the read TAA voltage vs. time as observed through
an oscilloscope. The problem in working with an oscilloscope is that it takes longer time to
measure, but this is usually used in trouble shooting the test system. The Agilent
E5022/E5023 measures the TAA, PW50, Baseline and Time Asymmetry parameters in
order to evaluate the head performance.
Figure 5-11
Measurement of TAA and PW50 Parameters
Equation 5-11
TAA Asymmetry Definition
As shown in Figure 5-11 TAAp-p is measured as the average peak-to-peak amplitude for
several waveform periods. TAA positive is defined as the average amplitude measured
between the baseline reference and the positive peak value. While TAA negative is defined
as the average amplitude measured between the baseline reference and the negative peak
value. With TAA Asymmetry defined as the ratio between the difference of positive and
negative TAA and the peak-to-peak TAA. TAA Asymmetry simply reports the amount of
non-linearity of the read back signal. At high recording densities it may not be a problem,
but it could affect other measurement parameters such as partial erasure and NLTS.
Equation 5-12
PW Asymmetry Definition
TAA
Asymmetry
TAA
positive
TAA
negative
Ð
TAA
positive
TAA
negative
+
---------------------------------------------------------------
=
PW
Asymmetry
PW
positive
PW
negative
Ð
PW
positive
PW
negative
+
----------------------------------------------------------
=
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