Claims
- 1. A method of determining head-media spacing (HMS) due to waviness of a disc media surface, comprising:
generating an interpolated air bearing transfer function for a spectral density comprising:
providing a simulated disc topography having a wavelength; selecting a head to model; providing air bearing code for the head selected; providing operation parameters; determining an air bearing transfer function from the air bearing code; simulating the head passing over the disc topography with the air bearing code; determining simulated head-media spacing modulation for each of a plurality of disc wavelengths; interpolating the air bearing transfer function with gradations of the wavelengths to provide the interpolated air bearing transfer function for the spectral density; generating a power spectral density function comprising:
sampling actual disc topography of the disc media surface; discrete Fourier transforming the actual disc topography sampled to a frequency domain to provide a sample topography spectrum; root-mean-squaring the sampled topography spectrum to provide the power spectral density function; convolving the power spectral density function with the air bearing transfer function to provide an HMS modulation spectrum for the sample topography spectrum; and summing the HMS modulation spectrum to provide a value for the HMS of the disc media surface sampled.
- 2. The method of claim 1 wherein the providing of the simulated disc topography comprises providing a sinusoidal waveform having amplitude set at unity.
- 3. The method of claim 3 wherein the wavelength is in a down track direction.
- 4. The method of claim 3 wherein the operation parameters comprise at least one of linear velocity, temperature and ambient pressure.
- 5. A method of determining a portion of a head-media spacing modulation spectrum of a portion of an actual disc media surface, comprising:
simulating a head passing in near proximity to a simulated disc media surface to generate an air bearing transfer function for a spectral density; generating a topography function for the actual disc media surface; and multiplying the topography function and the air bearing transfer function to provide the head-media spacing modulation spectrum.
- 6. The method of claim 5 further comprising summing the head-media spacing modulation spectrum to provide a head-media spacing waviness value for the disc media surface.
- 7. The method of claim 5 wherein the generating of the power spectral density function comprises:
sampling topography of the portion of the actual disc media surface; translating the actual disc topography sampled to wavelengths to provide an sampled topography spectrum; and averaging the sampled topography spectrum to provide the topography function.
- 8. The method of claim 5 wherein the simulating comprises:
providing a simulated disc topography having a wavelength; selecting a head to model; providing air bearing code for the head selected; providing operation parameters; determining an air bearing transfer function from the air bearing code; determining simulated head-media spacing modulation for each of a plurality of disc wavelengths; and interpolating the air bearing transfer function with gradations of the wavelengths to provide the air bearing transfer function for the spectral density.
- 9. The method of claim 5 further comprising:
providing a group of substrates; determining head-media spacing for waviness for each substrate in the group of substrates; and determining head-media spacing for roughness for each substrate in the group of substrates.
- 10. The method of claim 9 further comprising:
square-root summing the head-media spacing for roughness and the head-media spacing for waviness for each substrate in the group of substrates; and correlating results from the square-root-summing.
- 11. The method of claim 5 further comprising providing a model for glide avalanche (GA), the model comprising:
an equation where the GA equalsa[Λ2(λ)Y(λ)dλ]½+b, where a and b are constants, Λ is an air bearing transfer function, Y is a topography function, and λ is wavelength.
- 12. The method of claim 11 wherein the model comprises integral boundaries from zero to one revolution of the disc media.
- 13. The method of claim 5 further comprising providing a model for glide avalanche (GA), the model comprising:
an equation where the GA equalsa[Y(λ)dλ+Λ2(λ)Y(λ)dλ]½+b, where a and b are constants, Λ is an air bearing transfer function, Y is a topography function, and λ is wavelength.
- 14. The method of claim 13 wherein the model comprises a constant c for breaking the equation into two integrals.
- 15. The method of claim 14 wherein the constant c is between high frequency region and resonant frequency region.
- 16. A method of determining head-media spacing (HMS) modulation model, comprising:
providing a simulated disc topography having a wavelength; selecting a head to model; providing air bearing code for the head selected; providing disc drive operation parameters; determining an air bearing transfer function from the air bearing code; simulating the head passing over the disc topography with the air bearing code; and determining simulated head-media spacing modulation for each of a plurality of disc wavelengths.
- 17. The method of claim 16 further comprising interpolating the air bearing transfer function with gradations of the wavelengths to provide the air bearing transfer function with enhanced spectral lines.
- 18. An apparatus for determining head-media spacing (HMS) due to waviness of a disc media surface, comprising:
means for generating an interpolated air bearing transfer function for a spectral density and a power spectral density function for a sample topography spectrum; and means for providing an HMS modulation spectrum for the sample topography spectrum using the power spectral density function and the air bearing transfer function.
- 19. The apparatus of claim 18 further comprising means for summing the HMS modulation spectrum to provide a value for the HMS of the disc media surface sampled.
- 20. The apparatus of claim 19 wherein the means for generating comprises means for simulating disc topography.
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit of U.S. provisional Patent Application, application No. 60/276,764, filed Mar. 16, 2001, which is incorporated by reference herein in its entirety.
Provisional Applications (1)
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Number |
Date |
Country |
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60276764 |
Mar 2001 |
US |