Methods for measuring media performance associated with adjacent track interference
View Patent ↗Methods for measuring media performance associated with adjacent track interference are provided. One such method includes iteratively writing data to a target track for each of a plurality of n frequencies, measuring a first signal amplitude and a first noise for each of the n sectors on the target track, writing an aggressor track pattern proximate the target track, measuring a second signal amplitude and a second noise for each of the n sectors on the target track, calculating a weighted sum for each of the signal amplitude measurements for each of the plurality of n frequencies, and calculating a weighted sum for each of the noise measurements for each of the plurality of n frequencies, and repeating the writing the aggressor track pattern, the measuring the second signal amplitude and the second noise, and calculating the weighted sums for preselected numbers of times.
1. A method for measuring performance associated with adjacent track interference on a magnetic disk media for a storage device, the method comprising:
iteratively writing data to a target track for each of a plurality of n frequencies, wherein iteratively writing data for an ith iteration comprises writing an nth sector of the target track on the disk with an nth pattern at an nth frequency, wherein the ith is an iteration count extending from 1 to n, wherein n is a positive integer;
measuring a first signal amplitude and a first noise for each of the n sectors on the target track;
writing an aggressor track pattern proximate the target track;
measuring a second signal amplitude and a second noise for each of the n sectors on the target track;
calculating a weighted sum for each of the first and second signal amplitude measurements for each of the plurality of n frequencies;
calculating a weighted sum for each of the first and second noise measurements for each of the plurality of n frequencies;
repeating the writing the aggressor track pattern proximate the target track for a preselected number of times to generate cumulative measurements;
repeating the measuring the second signal amplitude and the second noise for each of the n sectors on the target track; and
repeating the calculating the weighted sum for each of the first and second signal amplitude measurements and the calculating the weighted sum for each of the first and second noise measurements using the cumulative measurements to generate adjacent track interference performance information.
2. The method of claim 1 , wherein n is 6.
3. The method of claim 1 , wherein the preselected number of times is 299.
4. The method of claim 1 , wherein n is 6 and the weighted sum of the measured signal amplitude comprises:
a weight for the first and second signal amplitude measurements of the first frequency of 0.25;
a weight for the first and second signal amplitude measurements of the second frequency of 0.25;
a weight for the first and second signal amplitude measurements of the third frequency of 0.1875;
a weight for the first and second signal amplitude measurements of the fourth frequency of 0.125;
a weight for the first and second signal amplitude measurements of the fifth frequency of 0.071825; and
a weight for the first and second signal amplitude measurements of the sixth frequency of 0.046875.
5. The method of claim 1 , wherein n is 6 and the weighted sum of the measured noise comprises:
a weight for the first and second noise measurements of the first frequency of 0.25;
a weight for the first and second noise measurements of the second frequency of 0.25;
a weight for the first and second noise measurements of the third frequency of 0.1875;
a weight for the first and second noise measurements of the fourth frequency of 0.125;
a weight for the first and second noise measurements of the fifth frequency of 0.071825; and
a weight for the first and second noise measurements of the sixth frequency of 0.046875.
6. The method of claim 1 , further comprising modifying a media structure of the magnetic disk media based the adjacent track interference performance information.
7. The method of claim 1 , wherein the target track is a track extending around the disk at a preselected radius.
8. The method of claim 1 , wherein the target track is about circular.
9. The method of claim 1 , further comprising repeating the iteratively writing to the target track a second preselected number of times with additional sectors along the target track until the target track is about full.
10. The method of claim 9 , wherein the measuring the first and second signal amplitude and the first and second noise at the target track for each of the sectors comprises:
measuring the first and second signal amplitude and the first and second noise for each of the sectors written at the nth frequency.
11. The method of claim 9 , wherein the second preselected number of times is greater than 20.
12. The method of claim 1 , wherein repeating the calculating the weighted sum for each of the first and second signal amplitude measurements and the calculating the weighted sum for each of the first and second noise measurements using the cumulative measurements to generate adjacent track interference performance information comprises:
calculating a difference in successive signal amplitude measurements; and
calculating a difference in successive noise measurements.
13. The method of claim 1 , wherein the writing the aggressor track pattern proximate the target track comprises writing the aggressor track pattern proximate the target track on a first side and a second side of the target track.
14. The method of claim 1 , wherein each of the plurality of n frequencies are different frequencies.
15. The method of claim 1 , wherein each of the plurality of n frequencies are positive integer multiples of each other.