DISTANCE MEASUREMENT

• US 20160025836A1
• Filed: 06/23/2015
• Published: 01/28/2016
• Est. Priority Date: 07/25/2014
• Status: Active Grant

• Current Assignee: Goodix Technology Co., Ltd. (Shenzhen Goodix Technology Co., Ltd.)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Derom, Koen
• Granted Patent: US 10,061,010 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01S 15/08 Systems for measuring distance only indirect measurement G01S15/46
• CPC Class Codes: G01S 15/104 wherein the transmitted pulses use a frequency- or phase-modulated carrier wave
• CPC Class Codes: G01S 3/808 using transducers spaced apart and measuring phase or time difference between signals therefrom, i.e. path-difference systems
• CPC Class Codes: H04B 11/00 Transmission systems employing sonic, ultrasonic or infrasonic waves

Abstract

A method for determining a distance between a device and an object, the method comprising: emitting an acoustic reference signal from a speaker of the device; receiving an acoustic input signal at a microphone of the device, the acoustic input signal including a measurement portion including a reflection of the acoustic reference signal off the object; cross correlating at least the measurement portion with the emitted acoustic reference signal to provide a cross correlated signal; receiving information relating to the object; extracting a section of the cross correlated signal corresponding to reflection of the acoustic reference signal by the object, based on the received information; analysing the extracted section of the cross correlated signal to determine a time of flight between emitting the acoustic reference signal and receiving the reflection; and determining the distance between the device and the object based on the determined time of flight and known characteristics of the acoustic reference signal. A chipset for performing the method is also disclosed.

Claims

1. A method of determining a distance between a device and an object, the method comprising:

emitting an acoustic reference signal from a speaker of the device;

receiving an acoustic input signal at a microphone of the device, the acoustic input signal including a measurement portion including a reflection of the acoustic reference signal off the object;

cross correlating at least the measurement portion with the emitted acoustic reference signal to provide a cross correlated signal;

receiving information relating to the object;

extracting a section of the signal corresponding to reflection of the acoustic reference signal by the object, based on the received information;

analysing the extracted section of the cross correlated signal to determine a time of flight between emitting the acoustic reference signal and receiving the reflection; and

determining the distance between the device and the object based on the determined time of flight and known characteristics of the acoustic reference signal.

2. The method of claim 1, wherein emitting the acoustic reference signal comprises:

mixing the acoustic reference signal with a primary acoustic signal to be emitted by the speaker to form a mixed signal; and

emitting the mixed signal.

3. The method of claim 1, wherein the acoustic reference signal is pulsed or continuous and the known characteristics of the acoustic reference signal comprise one or more of:

a constant frequency or frequency sweep details;

a signal loudness;

a pulse duration; and

an exact form of the signal.

4. The method of claim 3, further comprising:

processing the acoustic input signal to extract the measurement portion.

5. The method of claim 4, wherein processing the acoustic input signal to extract the measurement portion comprises:

filtering the acoustic input signal to identify regions of the acoustic input signal having similar characteristics to the acoustic reference signal; and

extracting these regions as the measurement portion.

6. The method of claim 3 comprising:

controlling one or more of the characteristics of the acoustic reference signal based on the received information relating to the object.

7. The method of claim 1, wherein the information relating to the object comprises information enabling determination of an approximate arrival time of the reflection of the acoustic reference signal off the object, after emission of the acoustic reference signal at a first time.

8. The method of claim 7, wherein extracting a section of the cross correlated signal corresponding to reflection of the acoustic reference signal by the object comprises:

extracting a section of the cross correlated signal corresponding to a section of the acoustic input signal received during a time window centred at the approximate arrival time.

9. The method according to claim 1, wherein analysing the extracted section of the cross correlated signal to determine the time of flight comprises:

rectifying the extracted section of the cross correlated signal to provide a rectified signal;

detecting a centre of gravity of the rectified signal;

determining the time of the centre of gravity; and

determining the time difference between the time of the centre of gravity and a first time at which the acoustic reference signal was emitted.

10. The method according to claim 1, wherein the measurement portion comprises a component corresponding to direct coupling from the speaker to the microphone, and wherein the method further comprises:

removing the section corresponding to direct coupling from the measurement portion.

11. The method of claim 1, wherein the information relating to the object is received from a user input at a user interface of the device.

12. The method of claim 11, wherein the user input confirms the object on a display of the device or indicates an approximate distance to the object.

13. The method of claim 1, wherein the device is a mobile communication device and the speaker and microphone are primarily for voice communication via the device, the method further comprising:

controlling at least one behaviour of the device based on the determined distance.

14. A chipset configured to enable a mobile communications device to perform the method of claim 1.

15. A mobile device configured to perform the method of claim 1.