Method and apparatus for canceling fan noise in a computer system

• US 7,693,292 B1
• Filed: 08/16/2005
• Issued: 04/06/2010
• Est. Priority Date: 08/16/2005
• Status: Active Grant

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Urmanov, Aleksey, Bougaev, Anton, Gross, Kenny C.
• Primary Examiner(s): Chin; Vivian
• Assistant Examiner(s): BLAIR, KILE O
• Application Number:
  US11/205,473
• Time in Patent Office: 1,694 Days
• Field of Search: 381/71.13, 381/71.3, 381/71.9, 381/94.7, 381/71.11, 381/94.1, 381/71.12, 381/94.2, 381/94.3, 381/71.14, 381/71.5, 381/71.8, 181/206, 700/280
• US Class Current: 381/71.14
• CPC Class Codes: G10K 11/17823 Reference signals, e.g. ambient acoustic environment
• CPC Class Codes: G10K 11/17835 using detection of abnormal input signals
• CPC Class Codes: G10K 11/17855 for improving speed or power requirements
• CPC Class Codes: G10K 11/17873 using a reference signal without an error signal, e.g. pure feedforward

Abstract

One embodiment of the present invention provides a system that cancels fan noise in a computer system. During operation, the system obtains a fan noise signal using a microphone. Next, the system generates a spectral pattern based on the obtained fan noise signal. The system then uses the spectral pattern to identify a corresponding cancellation spectrum in an anti-spectra library. Next, the system generates a noise-canceling signal using the cancellation spectrum. Note that the amount of computation required to cancel fan noise is reduced because generating the noise-canceling signal using the anti-spectra library requires less computation than generating the noise-canceling signal using dynamic noise-cancellation techniques.

Claims

1. A method for canceling fan noise in a computer system, the method comprising:

obtaining a fan noise signal using a microphone;

generating a spectral pattern based on the obtained fan noise signal;

identifying a cancellation spectrum in an anti-spectra library using the spectral pattern, wherein the anti-spectra library includes at least one cancellation spectrum computed based on a fan noise signal that includes a combination of multiple fan speeds; and

generating a noise-canceling signal using the cancellation spectrum;

wherein the amount of computation required to cancel fan noise is reduced because generating the noise-canceling signal using the anti-spectra library requires less computation than dynamically generating the noise-canceling signal.

2. The method of claim 1, further comprising:

computing cancellation spectra based on fan noise signals measured at various fan speeds; and

storing the cancellation spectra in the anti-spectra library.

3. The method of claim 1, wherein identifying the cancellation spectrum involves:

determining a fan speed based on the spectral pattern; and

identifying the cancellation spectrum based on the fan speed.

4. The method of claim 1, wherein generating the noise canceling signal involves playing back the noise canceling signal on a speaker.

5. The method of claim 1, further comprising:

detecting one or more fan failures; and

stopping noise-cancellation if one or more fan failures are detected, wherein stopping noise-cancellation can prevent suboptimal noise-cancellation because, if one or more fans fail, the spectral pattern can be substantially different from the cancellation spectrum which is associated with a system configuration in which all fans are operational.

6. The method of claim 5, wherein detecting one or more fan failures involves:

determining a thermal distribution using thermal sensors, wherein an anomalous thermal distribution can indicate a fan failure; and

determining whether a fan speed is below a normal operating speed using a Hall-effect RPM (revolution per minute) sensor.

7. The method of claim 6, wherein the thermal distribution can be used to validate the output of the Hall-effect RPM sensor, thereby improving fan operability assurance.

8. A computer-readable storage medium storing instructions that when executed by a computer cause the computer to perform a method for canceling fan noise in a computer system, the method comprising:

obtaining a fan noise signal using a microphone;

generating a spectral pattern based on the obtained fan noise signal;

identifying a cancellation spectrum in an anti-spectra library using the spectral pattern, wherein the anti-spectra library includes at least one cancellation spectrum computed based on a fan noise signal that includes a combination of multiple fan speeds; and

generating a noise-canceling signal using the cancellation spectrum;

wherein the amount of computation required to cancel fan noise is reduced because generating the noise-canceling signal using the anti-spectra library requires less computation than dynamically generating the noise-canceling signal.

9. The computer-readable storage medium of claim 8, wherein the method further comprises:

computing cancellation spectra based on fan noise signals measured at various fan speeds; and

storing the cancellation spectra in the anti-spectra library.

10. The computer-readable storage medium of claim 8, wherein identifying the cancellation spectrum involves:

determining a fan speed based on the spectral pattern; and

identifying the cancellation spectrum based on the fan speed.

11. The computer-readable storage medium of claim 8, wherein generating the noise canceling signal involves playing back the noise canceling signal on a speaker.

12. The computer-readable storage medium of claim 8, wherein the method further comprises:

detecting one or more fan failures; and

stopping noise-cancellation if one or more fan failures are detected, wherein stopping noise-cancellation can prevent suboptimal noise-cancellation because, if one or more fans fail, the spectral pattern can be substantially different from the cancellation spectrum which is associated with a system configuration in which all fans are operational.

13. The computer-readable storage medium of claim 12, wherein detecting one or more fan failures involves:

determining a thermal distribution using thermal sensors, wherein an anomalous thermal distribution can indicate a fan failure; and

determining whether a fan speed is below a normal operating speed using a Hall-effect RPM (revolution per minute) sensor.

14. The computer-readable storage medium of claim 13, wherein the thermal distribution can be used to validate the output of the Hall-effect RPM sensor, thereby improving fan operability assurance.

15. An apparatus for canceling fan noise in a computer system, comprising:

a microphone, which is configured to obtain a fan noise signal;

a spectral-pattern-generating mechanism configured to generate a spectral pattern based on the obtained fan noise signal;

an identifying mechanism configured to identify a cancellation spectrum in an anti-spectra library using the spectral pattern, wherein the anti-spectra library includes at least one cancellation spectrum computed based on a fan noise signal that includes a combination of multiple fan speeds; and

a signal-generating mechanism configured to generate a noise-canceling signal using the cancellation spectrum;

wherein the amount of computation required to cancel fan noise is reduced because generating the noise-canceling signal using the anti-spectra library requires less computation than dynamically generating the noise-canceling signal.

16. The apparatus of claim 15, further comprising:

a computing mechanism configured to compute cancellation spectra based on fan noise signals measured at various fan speeds; and

a storing mechanism configured to store the cancellation spectra in the anti-spectra library.

17. The apparatus of claim 15, wherein the identifying mechanism is configured to:

determine a fan speed based on the spectral pattern; and

to

identify the cancellation spectrum based on the fan speed.

18. The apparatus of claim 15, wherein the signal-generating mechanism is configured to play back the noise canceling signal on a speaker.

19. The apparatus of claim 15, wherein the apparatus is configured to:

detect one or more fan failures; and

to

stop noise-cancellation if one or more fan failures are detected, wherein stopping noise-cancellation can prevent suboptimal noise-cancellation because, if one or more fans fail, the spectral pattern can be substantially different from the cancellation spectrum which is associated with a system configuration in which all fans are operational.

20. The apparatus of claim 19, wherein detecting one or more fan failures involves:

determining a thermal distribution using thermal sensors, wherein an anomalous thermal distribution can indicate a fan failure; and

determining whether a fan speed is below a normal operating speed using a Hall-effect RPM (revolution per minute) sensor.

21. The apparatus of claim 20, wherein the thermal distribution can be used to validate the output of the Hall-effect RPM sensor, thereby improving fan operability assurance.