Inferring ambient atmospheric temperature

• US 10,239,750 B2
• Filed: 07/14/2017
• Issued: 03/26/2019
• Est. Priority Date: 03/27/2017
• Status: Active Grant

• Current Assignee: Invensense Incorporated (TDK Corporation)
• Original Assignee: Invensense Incorporated (TDK Corporation)
• Inventors: Keal, William Kerry
• Primary Examiner(s): Jerez Lora, William A
• Application Number:
  US15/650,812
• Publication Number:
  US 20180273374A1
• Time in Patent Office: 620 Days
• Field of Search: 381304
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81C 1/0023 Packaging together an electronic processing unit die and a micromechanical structure die MEMS packages B81B7/0032; MEMS packaging processes B81C1/00261
• CPC Class Codes: B81C 2201/019 Bonding or gluing multiple substrate layers
• CPC Class Codes: B81C 2203/0118 Bonding a wafer on the substrate, i.e. where the cap consists of another wafer
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: G01K 11/24 of the velocity of propagation of sound
• CPC Class Codes: G01K 15/005 Calibration
• CPC Class Codes: G01P 1/023 for acceleration measuring devices
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G01P 2015/0831 the mass being of the paddle type having the pivot axis between the longitudinal ends of the mass, e.g. see-saw configuration
• CPC Class Codes: H01H 59/0009 making use of micromechanics
• CPC Class Codes: H03H 9/1057 for microelectro-mechanical devices
• CPC Class Codes: H04R 1/08 Mouthpieces; Microphones; Attachments therefor

Abstract

In a method of inferring ambient atmospheric temperature, an acoustic signal is emitted from a speaker. A first sample of the acoustic signal is captured with a first microphone spaced a first distance from the speaker. A second sample of the acoustic signal is captured with a second microphone spaced a second distance from the speaker. The second distance is greater than the first distance, and a difference between the first distance and the second distance is a known third distance. A time delay in the acoustic signal is determined between the first sample and the second sample. An ambient temperature of the atmosphere through which the acoustic signal traveled is inferred based on a relationship between the time delay and temperature for the acoustic signal over the third distance.

Claims

1. A method of inferring ambient atmospheric temperature, said method comprising:

emitting an acoustic signal from a speaker;

capturing a first sample of said acoustic signal with a first microphone spaced a first distance from said speaker;

capturing a second sample of said acoustic signal with a second microphone spaced a second distance from said speaker, wherein said second distance is greater than said first distance, and wherein a difference between said first distance and said second distance is a known third distance;

determining a time delay in said acoustic signal between said first sample and said second sample; and

inferring an ambient temperature of the atmosphere through which said acoustic signal traveled based on a relationship between said time delay and temperature for said acoustic signal over said third distance.

2. The method as recited in claim 1, wherein said emitting an acoustic signal from a speaker comprises:

emitting said acoustic signal from said speaker in response to a request for the ambient atmospheric temperature.

3. The method as recited in claim 2, further comprising:

emitting a human audible signal from said speaker contemporaneously with said acoustic signal.

4. The method as recited in claim 1, wherein said emitting an acoustic signal from a speaker comprises:

emitting said acoustic signal contemporaneously with emission of a human audible signal from said speaker.

5. The method as recited in claim 1, wherein said emitting an acoustic signal from a speaker comprises:

emitting said acoustic signal from said speaker wherein said acoustic signal is selected from the group of acoustic signals consisting of;

a single frequency;

a plurality of frequencies;

a range of frequencies;

a known pattern of frequencies; and

a pseudorandom noise code.

6. The method as recited in claim 1, wherein said inferring an ambient temperature of the atmosphere through which said acoustic signal traveled based on a relationship between said time delay and temperature for said acoustic signal over said third distance comprises:

inferring said ambient temperature based on accessing a stored predetermined representation of said relationship between said time delay and said temperature for said acoustic signal over said third distance.

7. The method as recited in claim 1, wherein said inferring an ambient temperature of the atmosphere through which said acoustic signal traveled based on a relationship between said time delay and temperature for said acoustic signal over said third distance comprises:

inferring said ambient temperature of the atmosphere through which said acoustic signal traveled based on a humidity adjusted relationship between said time delay and temperature for said acoustic signal over said third distance.

8. The method as recited in claim 1, wherein said inferring an ambient temperature of the atmosphere through which said acoustic signal traveled based on a relationship between said time delay and temperature for said acoustic signal over said third distance comprises:

wherein said inferring an ambient temperature of the atmosphere through which said acoustic signal traveled based on a relationship between said time delay and temperature for said acoustic signal over said third distance, wherein said time delay comprises one of a time-of-flight delay and a phase shift.

9. The method as recited in claim 1, wherein said inferring an ambient temperature of the atmosphere through which said acoustic signal traveled based on a relationship between said time delay and temperature for said acoustic signal over said third distance further comprises:

determining, from data provided by a sensor physically coupled with said speaker, a characteristic of said speaker; and

responsive to said characteristic being within a predetermined envelope, accomplishing said inferring said ambient temperature of the atmosphere through which said acoustic signal traveled based on said relationship between said time delay and temperature for said acoustic signal over said third distance.

10. A sensor processing unit comprising:

at least one speaker;

a first microphone spaced a first distance from said speaker;

a second microphone spaced a second distance from said speaker, wherein said second distance is greater than said first distance, and wherein a difference between said first distance and said second distance is a known third distance;

a sensor processor coupled with said speaker, said first microphone, and said second microphone, said sensor processor configured to;

operate said speaker to emit an acoustic signal;

operate said first microphone to capture a first sample of said acoustic signal;

operate said second microphone to capture a second sample of said acoustic signal;

determine a time delay in said acoustic signal between said first sample and said second sample; and

infer an ambient temperature of the atmosphere through which said acoustic signal traveled based on a relationship between said time delay and temperature for said acoustic signal over said third distance.

11. The sensor processing unit of claim 10, further comprising:

a memory coupled to said sensor processor, said memory configured with a stored predetermined representation of said relationship between said time delay and said temperature for said acoustic signal over said third distance.

12. The sensor processing unit of claim 10, further comprising:

a sensor coupled with said sensor processor and configured to provide data to said sensor processor, wherein said sensor processor is configured to determine a characteristic of said sensor processing unit from said data, and wherein said sensor processor only accomplishes said inferring said ambient temperature of the atmosphere through which said acoustic signal traveled based on said relationship between said time delay and temperature for said acoustic signal over said third distance in response to said characteristic being within a predetermined envelope.

13. The sensor processing unit of claim 12, wherein the sensor comprises a motion sensor, and said characteristic comprises a velocity.

14. The sensor processing unit of claim 12, wherein the sensor comprises a motion sensor, and said characteristic comprises an activity.

15. The sensor processing unit of claim 12, wherein the sensor comprises an orientation sensor and said characteristic comprises an orientation.

16. The sensor processing unit of claim 10, wherein said time delay comprises one of a time-of-flight delay and a phase shift.

17. A mobile electronic device comprising:

a processor;

at least one speaker;

a first microphone spaced a first distance from said speaker;

a second microphone spaced a second distance from said speaker, wherein said second distance is greater than said first distance, and wherein a difference between said first distance and said second distance is a known third distance; and

wherein said processor is configured to;

operate said speaker to emit an acoustic signal;

operate said first microphone to capture a first sample of said acoustic signal;

operate said second microphone to capture a second sample of said acoustic signal;

determine a time delay in said acoustic signal between said first sample and said second sample; and

infer an ambient temperature of the atmosphere through which said acoustic signal traveled based on a relationship between said time delay and temperature for said acoustic signal over said third distance.

18. The mobile electronic device of claim 17, further comprising:

a memory coupled to said processor, said memory configured with a stored predetermined representation of said relationship between said time delay and said temperature for said acoustic signal over said third distance.

19. The mobile electronic device of claim 17, further comprising:

a sensor coupled with said processor and configured to provide data to said processor, wherein said processor is configured to determine a characteristic of said mobile electronic device from said data, and wherein said processor only accomplishes said inferring said ambient temperature of the atmosphere through which said acoustic signal traveled based on said relationship between said time delay and temperature for said acoustic signal over said third distance in response to said characteristic being within a predetermined envelope.

20. The mobile electronic device of claim 17, further comprising:

a temperature sensor, wherein a temperature reading from said temperature sensor is used to calibrate the inferred ambient temperature.

21. The mobile electronic device of claim 17, further comprising:

a temperature sensor, wherein said inferred ambient temperature is only inferred if a reading from the temperature sensor is within a predefined range.

22. The mobile electronic device of claim 17, wherein said processor is further configured to perform at least one of:

selecting said speaker from a plurality of speakers; and

selecting said first microphone and said second microphone from a plurality of at least three microphones.

23. The mobile electronic device of claim 17, wherein said processor is one of a sensor processor of a sensor processing unit disposed in said mobile electronic device and a host processor of said mobile electronic device.

24. The mobile electronic device of claim 17, wherein said third distance falls in a range of distances between 0.10 cm and 25 cm.

25. The mobile electronic device of claim 17, wherein said acoustic signal is selected from the group of acoustic signals consisting of:

a single frequency;

a plurality of frequencies;

a range of frequencies;

a known pattern of frequencies; and

a pseudorandom noise code.

26. The mobile electronic device of claim 17, wherein said acoustic signal is a repeating waveform with a frequency between 19 kHz and 50 kHz.

27. The mobile electronic device of claim 17, wherein said acoustic signal is a repeating waveform with a frequency between 20 Hz and 21 kHz.

28. The mobile electronic device of claim 17, wherein said time delay comprises one of a time-of-flight delay and a phase shift.