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Measurement Definition
Measurement Parameter Definition
Equation 5-15
Absolute Polarity
Absolute polarity is computed from the given equation above. Analyzing Equation 5-15, in
simple terms if "Absolute Polarity" > 0, then the pinned layer is normal and the head is
considered good. If "Absolute Polarity" < 0, then the pinned layer is reversed and head is
assumed to be damaged.
NOTE
If the initial pulse of Figure 5-13 is isoTAA- (i.e, a negative pulse) then the pinned layer for
"Absolute Polarity" < 0 is normal. And when "Absolute Polarity" > 0 then the pinned layer
is reversed. Read second paragraph of "Absolute Polarity Test" on page 254.
The measurement sequence of Absolute Polarity Test is as follows.
1. Write the isolated pulse pattern.
2. Measure TAA of isolated pulse by denoting TAA+ and TAA- of the isolated pulse as
3. Write the 1-3 bit pattern or user defined absolute polarity pattern
4. Measure (Tribit -TAA) by denoting TAA+ and TAA- of the 1-3 bit pattern as triTAA+
5. Iterate steps 1to 4 for averaging.
258
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triTAA +
----------------------------
isoTAA +
---------------------------------------------------------------------------- -
AbsPol
=
triTAA +
----------------------------
isoTAA +
isoTAA+ and isoTAA- respectively.
and triTAA- respectively.
triTAA Ð
-----------------------------
Ð
isoTAA Ð
triTAA Ð
-----------------------------
+
isoTAA Ð
Chapter 5
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