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Measurement Definition
Measurement Parameter Definition
In measuring SHNR, the noise reference and signal (i.e, Narrow Band TAA) is measured
by the spectrum analyzer at the frequency specified by "hpe5022_shnrConfig" function. At
various frequencies the amplitude of the signal will vary over time. In general, SHNR is
measured at low frequency where signal to noise ratio is poor. When baseline popping
occurs the measured noise (noise reference) will distort the output signal which degrades
the performance of the MR head.
Measurement Sequence of SHNR is as follows:
1. Perform three track erase.
2. Move the head to the read offset.
3. For sense current = ib[0] to ib[ib_points-1].
4. Measure the signal and denote the result as Noise_Ref[i]. This noise reference is
measured at the frequency specified by "hpe5022_shnrConfig" function.
5. Next sense current go to step 3.
6. Write data at the track center specified by "hpe5022_write" function.
7. For read offset = 'offtrk_pos[0]' + 'readOffset' to offtrk_pos[offtrk_pos_points-1] +
readOffset.
8. For sense current = ib[0] to [ib_points-1].
9. Let Sum TAA = 0
10. For average = 1 to n
11. Perform write excitation during wrTime. ('wrTime' is specified by the
"hpe5022_shnrConfig" function.)
12. Wait for delay time to elapse. ('delay' is specified by the "hpe5022_shnrConfig"
function.)
13. Measure the Narrow Band TAA (i.e, TAA) during rdTime. ('rdTime' is specified by the
"hpe5022_shnrConfig" function). Narrow Band TAA is measured at the frequency
specified by "hpe5022_shnrConfig" function similar to step 4.
14. Get the summation of the measured TAA (i.e, Sum_TAA= Sum TAA + TAA).
15. Next average go to step 10.
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Chapter 5
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