Chapter 5
297
Measurement Definition
Parametric Sweep Measurement Definitions
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SNR Triple Track Test
The SNR Tripe Track Test is used to evaluate the OTRC (unsqueezed OTRC) and
squeezed OTRC using both the signal and off-track noise at each test point.
Measurement procedure of the SNR Triple Track Test is as follows:
Note: In this description, data name with [ ] shows that the data type is an array.
1. Track Profile Measurement
a. Perform band erase to eliminate noise from the media.
b. Write data and adjacent data pattern at four different sectors of the track as follows:
NOTE
Squeeze position is described as a distance in meter from the test track. OTRC write
position is described as a ratio to the track pitch.
c. Measure the track profile of the TAA for each sector at once.
2. Sector Normalization
If sector normalization check box is selected, execute the sequence for sector
normalization and all profile data are normalized.
3. “Noise Floor” Calculation
Calculate “Noise Floor” using both “Data[ ]” and “Squashed Data[ ].” See “Noise
Floor Calculation Method” on page 302 for the calculation algorithm.
4. “OTRC Signal[ ]” and “Normalized OTRC Signal[ ]” Trace Calculation
a. Remove “Noise Floor” from “Data[ ]” using the following equation:
Data1[ ] =
b. Perform smoothing for “Data1[ ].” The derived trace is called “Data2[ ].”
c. “OTRC Signal[ ]” is derived from the following equation:
Table 5-2
Write Data Pattern for Each Sector
Sector #
Profile Name
Write Pattern
0
“Data[ ]”
Data pattern at track center
1
“Squashed Data[ ]”
Data pattern at track center
Adjacent data pattern at + squeezePos
Adjacent data pattern at
−
squeezePos
2
“Side Noise ID[ ]”
Data pattern at + otrcWrPos
Adjacent data pattern at track center
3
“Cockpit Noise[ ]”
Data pattern at + otrcWrPos
Data pattern at
−
otrcWrPos
Adjacent data pattern at track center
Adjacent data pattern at + squeezePos
Adjacent data pattern at
−
squeezePos
4
“Side Noise OD[ ]”
Data pattern at
−
otrcWrPos
Adjacent data pattern at track center
Data
[ ]
2
NoiseFloor
2
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