Systems and methods for determining distance between networked electronic devices each equipped with a loudspeaker and a microphone

Abstract

To provide a method for determining a distance between a first device and a second device.SOLUTION: A first sound signal including a first measuring wave having a first frequency and carried on a first carrier wave having a first carrier wave frequency higher than the first frequency is emitted by a first device. A second device receives the first sound signal. The second device defines a second sound signal including a second measuring wave having the first frequency and carried on a second carrier wave having a second carrier wave frequency different from the first carrier wave frequency. A phase of the second measuring wave is set such that the phase simulates reflection of the first measuring wave on the second device. The second sound signal is emitted by the second device. The second sound signal is received by the first device. A distance between the first device and the second device is calculated on the basis of a phase shift between the emitted first measuring wave and the received second measuring wave.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to determining distances between networked electronic devices, and in particular to determining such distances using characteristics of sounds emitted and received by the networked electronic devices using their loudspeakers and microphones. [Background technology]

[0002] In many applications, it is necessary to determine the distance between a first device and a second device. It is known to perform distance measurements using various methods, such as using a tape measure, a laser-based rangefinder, or sonar. These various methods have advantages and disadvantages.

[0003] The present inventors have recognized that there is a need for additional methods for determining the distance between a first device and a second device, particularly when determining the distance between devices in a device system installed within a building. Summary of the Invention

[0004] In view of the above, it is an object of the present invention to provide a method for determining the distance between a first device and a second device.

[0005] According to a first aspect, a method for determining a distance between a first networked electronic device and a second networked electronic device is provided. The first networked electronic device has a first loudspeaker and a first microphone. The second networked electronic device has a second loudspeaker and a second microphone. The method includes emitting a first audio signal using the first loudspeaker. The first audio signal has a first frequency and includes a first measurement wave carried on a first carrier wave having a first carrier frequency. The first carrier frequency is higher than the first frequency. The method further includes receiving the first audio signal using the second microphone. The method further includes determining a second audio signal at the second electronic device. The second audio signal includes a second measurement wave carried on a second carrier wave. The second measurement wave has the same frequency as the first measurement wave. Therefore, the second measurement wave has the first frequency. The second carrier wave has a second carrier frequency different from the first carrier frequency. The phase of the second measurement wave is set to simulate a reflection of the first measurement wave on the second networked electronic device. The method further includes emitting a second audio signal using a second loudspeaker. The method further includes receiving the second audio signal using the first microphone. The method further includes calculating a distance between the first networked electronic device and the second networked electronic device based on a phase shift between the emitted first measurement wave and the received second measurement wave.

[0006] In line with the above, the inventors have recognized that the characteristics of sound can be used to determine the distance between two devices each equipped with a loudspeaker and a microphone. This is done by determining the phase shift of a low-frequency, periodic measurement wave carried by an audio-based carrier wave. The low-frequency, periodic measurement wave can be less than 20 Hz. To determine distances in the range of 1 m to 50 m, the measurement wave must have a frequency between 3 and 160 Hz. This is because the wavelength of the measurement wave must be longer than half the distance between the two devices. Most loudspeakers cannot reproduce such low-frequency waves. The carrier wave emission is used to provide the low-frequency measurement wave as discussed above.

[0007] The first and second carrier waves may have a carrier frequency in the range of 200 to 20,000 Hz.

[0008] Determining the second audio signal may include setting the phase of the second measurement wave to be the same as the phase of the first measurement wave of the first audio signal received by the second microphone.

[0009] Setting the phase of the second measurement wave may include determining the phase of the second measurement wave based on a processing time of circuitry that analyzes the first audio signal at the second networked electronic device to determine the phase of the received first measurement wave.

[0010] Determining and emitting the second audio signal may include emitting a candidate second audio signal, shifting the phase of the second measurement wave of the candidate second audio signal while listening with a second microphone until the phase of the received first measurement wave and the phase of the second measurement wave of the candidate second audio signal match, and emitting the phase-matched second audio signal after the phase of the received first measurement wave and the phase of the second measurement wave of the candidate second audio signal match.

[0011] According to a second aspect, there is provided a system for determining a distance between a first networked electronic device and a second networked electronic device, the system comprising: a first networked electronic device having a first loudspeaker and a first microphone; and a second networked electronic device having a second loudspeaker and a second microphone. The first networked electronic device further comprises a first circuit configured to define a first audio signal including a first measurement wave having a first frequency and carried on a first carrier wave having a first carrier frequency higher than the first frequency, and to drive the first loudspeaker to emit the first audio signal. The second networked electronic device further comprises a second circuit configured to analyze the first audio signal after registration by the second microphone, to determine a second audio signal including a second measurement wave having a first frequency and carried on a second carrier wave having a second carrier frequency higher than the first frequency and different from the first carrier frequency, the second measurement wave having a phase set to simulate a reflection of the first measurement wave of the first audio signal on the second networked electronic device, and to drive the second loudspeaker to emit the second audio signal. The first circuit of the first networked electronic device is further configured to analyze the second audio signal after registration by the first microphone, to determine a phase shift between the emitted first measurement wave and the received second measurement wave, and to calculate a distance between the first networked electronic device and the second networked electronic device based on the determined phase shift.

[0012] The features of the method described above apply equally to this second aspect, where applicable; to avoid undue repetition, please see above.

[0013] Further areas of applicability will become apparent from the detailed description provided hereinafter. However, it should be understood that the detailed description and specific examples are given by way of example only.

[0014] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. It should be noted that, as used in this specification and the appended claims, the articles "a," "an," "the," and "said" are intended to mean that there are one or more elements, unless the context clearly dictates otherwise. Thus, for example, reference to "a unit" or "the unit" may include several devices, etc. Furthermore, the words "comprising," "including," "containing," and similar expressions do not exclude other elements or steps.

[0015] These and other aspects will now be described in more detail with reference to the accompanying drawings, which should not be considered limiting, but instead used for purposes of explanation and understanding.

[0016] As illustrated in the figures, the sizes of layers and regions may be exaggerated for illustrative purposes and are thus provided to illustrate the overall structure. Like reference numerals refer to like elements throughout. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a diagram illustrating a schematic of a system of networked electronic devices installed within a building. [Figure 2] FIG. 1 is a diagram illustrating a schematic diagram of a networked electronic device. [Figure 3] FIG. 10 is a diagram illustrating a method for using characteristics of sound to determine the distance between two networked electronic devices. [Figure 4] FIG. 1 is a block diagram of a method for determining a distance between a first electronic device and a second electronic device. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which presently preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; these embodiments are provided for thoroughness and completeness, and to fully convey the scope of the invention to those skilled in the art.

[0019] FIG. 1 illustrates a system 10 of networked electronic devices 100 installed within a building 50. Such networked electronic devices are illustrated schematically in FIG. 2. The networked electronic devices 100 each have a loudspeaker 110 and a microphone 120. Examples of such networked electronic devices 100 are networked loudspeakers, networked surveillance cameras, and / or networked access control devices. In addition to the loudspeaker 110 and the microphone 120, the networked electronic device 100 may include circuitry 130, memory 140, and a communications module 150. The communications module 150 is configured to transmit and / or receive data via a communications network to which the networked electronic device 100 is connected. The circuitry 130 is configured to exercise overall control over the functionality and operation of the networked electronic device 100. The circuitry 130 may include a processor, such as a central processing unit (CPU), a microcontroller, or a microprocessor. The processor is configured to execute program code stored in memory 140 to perform the functions and operations of networked electronic device 100. Memory 140 may be one or more of a buffer, flash memory, a hard drive, removable media, volatile memory, non-volatile memory, random access memory (RAM), or another suitable device. In a typical configuration, memory 140 may comprise non-volatile memory for long-term data storage and volatile memory that serves as system memory for networked electronic device 100. Memory 140 may exchange data with circuitry 130, loudspeaker 110, microphone 120, and / or communications module 150 via data bus 160. The functions and operations of networked electronic device 100 may be embodied in executable logic routines (e.g., lines of code, software programs, etc.) stored in a non-transitory computer-readable medium (e.g., memory 140) of networked electronic device 100 and executed by circuitry 130 (e.g., using the processor).Furthermore, the functions and operations of networked electronic device 100 may be standalone software applications or may form part of a software application that performs additional tasks related to networked electronic device 100. The functions and operations may be considered as the manner in which networked electronic device 100 is configured to perform them. Also, while the functions and operations may be implemented in software, such functionality may equally be performed by dedicated hardware or firmware, or some combination of hardware, firmware, and / or software.

[0020] In some applications, such as during commissioning of a system 10 of networked electronic devices 100, the distance between different networked electronic devices 100 will be determined. Various methods for determining distance exist today, such as tape measures, laser-based range finders, or sonar. However, none of these are optimal for determining the distance between two networked electronic devices 100 attached to a building 50.

[0021] The present inventors have recognized that characteristics of sound can be used in determining the distance between two networked electronic devices 100a and 100b, each equipped with a loudspeaker and microphone. This will now be discussed in conjunction with Figures 3 and 4. Figure 3 schematically illustrates the use of characteristics of sound to determine the distance between two networked electronic devices 100a and 100b, and Figure 4 is a block diagram of a method for determining the distance between a first electronic device 100a and a second electronic device 100b.

[0022] The first networked electronic device 100a is instructed to emit S402 by its loudspeaker a first audio signal 300 including a first measurement wave 310 having a first frequency and carried on a first carrier wave 320 having a first carrier frequency. The first audio signal 300 is illustrated along the "forward path" in Figure 3.

[0023] The second networked electronic device 100b is configured to listen for the first audio signal 300 with its microphone within the audible range of the first audio signal 300. Thus, the second networked electronic device 100b is configured to receive S404 the first audio signal.

[0024] After receiving the first audio signal 300, the second networked electronic device 100b is configured to emit S406 by its loudspeaker a second audio signal 350 having a second measurement wave 360. The second measurement wave 360 ​​has the same first frequency as the first measurement wave 310, but is carried by a second carrier wave 370 having a second carrier frequency different from the first carrier frequency. The second audio signal 350 is illustrated along the "backward path" in FIG. 3. By using a second carrier frequency different from the first carrier frequency, the second audio signal 350 can be distinguished from echoes of the first audio signal 300 from other structures.

[0025] Furthermore, the second networked electronic device 100b is configured to shift the phase of the second measurement wave 360 ​​to simulate a reflection of the first measurement wave 310 on the second networked electronic device 100b. That is, the phase of the second measurement wave 360 ​​is set to be the same as the phase of the first measurement wave 320 on the second networked electronic device 100b. Accordingly, the second networked electronic device 100b is configured to determine the second audio signal 350 such that the phase of the second measurement wave 360 ​​is set to simulate a reflection of the first measurement wave 310 on the second networked electronic device 100b. The second audio signal 350 may be determined using circuitry of the second networked electronic device 100b. Accordingly, the second networked electronic device 100b is configured to respond with a second audio signal 350 comprising the second measurement wave 360 ​​having the same phase as the first measurement wave 310 of the incoming first audio signal 300. That is, the second networked electronic device 100b is configured to simulate a reflection of the first measurement wave 310. However, to distinguish the simulated reflection from actual reflections on other structures, the second networked electronic device 100b is configured to carry the second measurement wave 360 ​​on a second carrier wave 370 having a carrier frequency different from the carrier frequency of the first audio signal 300. In other words, defining the second audio signal 350 includes setting the phase of the second measurement wave 360 ​​to be the same as the phase of the first measurement wave 310 of the first audio signal 300 received by the second microphone of the second networked electronic device 100b. Setting the phase of the second measurement wave 360 ​​may include determining the phase of the second measurement wave 360 ​​based on a processing time of a circuit that analyzes the first audio signal 300 in the second networked electronic device 100b to determine the phase of the received first measurement wave 310. By doing so, the phase of the second measurement wave 360 ​​can be synchronized with the phase of the received first measurement wave 310 .Alternatively, or in combination, determining the second audio signal 350 and emitting the second audio signal 350 may include: i) emitting a candidate second audio signal; ii) shifting the phase of the second measurement wave of the candidate second audio signal while listening with a second microphone of the second networked electronic device 100b until the phase of the received first measurement wave 310 matches the phase of the second measurement wave of the candidate second audio signal; and iii) emitting the phase-matched second audio signal 350 after the phase of the received first measurement wave 310 matches the phase of the second measurement wave of the candidate second audio signal.

[0026] The first networked electronic device 100a is then configured to listen with its microphone 120a for the second audio signal 350. Thus, the first networked electronic device 100a is configured to receive S408 the second audio signal.

[0027] The distance between the first networked electronic device 100a and the second networked electronic device 100b can then be determined based on the phase shift between the first measurement wave 310 emitted at the first networked electronic device 100a and the second measurement wave 360 ​​received at the first networked electronic device 100a, since such phase shift depends on the distance between the first networked electronic device 100a and the second networked electronic device 100b. The distance D between the first networked electronic device 100a and the second networked electronic device 100b can be calculated as: TIFF0007742869000001.tif11170, where ΔΦ is the phase shift [expressed in radians] and λ is TIFF0007742869000002.tif14170, where f is the frequency of the measurement waves 310 and 360, i.e., the first frequency discussed above. This is under the assumption that the distance between the first networked electronic device 100a and the second networked electronic device 100b is within half a wavelength. Therefore, the distance D between the first networked electronic device 100a and the second networked electronic device 100b is calculated S410 based on the phase shift between the emitted first measurement wave 310 and the received second measurement wave 360. Calculation S410 is preferably performed by circuitry in the first networked electronic device 100a. However, calculation S410 could also be performed in any other device that has computing capability and is connected to the first networked electronic device 100a, so that the phase shift, or information for calculating the phase shift, can be communicated to that device.

[0028] Assuming the operational range for the distance measurement is between 1 m and 50 m, the first frequency must be within the range of 160 Hz and 3.3 Hz. The frequencies of the first carrier wave 320 and the second carrier wave 370 must be higher than the first frequency, typically exceeding 200 Hz. The upper frequency limit for the first carrier wave 320 and the second carrier wave 370 is typically 20,000 Hz. As mentioned above, the first carrier wave 320 and the second carrier wave 370 are configured to have different carrier frequencies. By using different carrier frequencies for the different carrier waves 320 and 370, the second audio signal 350 can be distinguished from echoes of the first audio signal 300 from other structures within the building. Furthermore, the identity of the networked electronic device 100 can be encoded by assigning a specific carrier frequency to a specific networked electronic device. Typically, first audio signal 300 and second audio signal 350 are sinusoidally amplitude modulated signals, but any periodic signal that can be carried by a carrier wave will work.

[0029] Those skilled in the art will recognize that the present invention is by no means limited to that expressly described above, but rather many modifications and variations are possible within the scope of the appended claims.

[0030] For example, in some applications, the first networked electronic device and the second networked electronic device are both fixedly mounted within a building, while in other applications the first electronic device may be a portable electronic device such as a mobile phone.

[0031] Moreover, those skilled in the art, from a study of the drawings, the disclosure, and the appended claims, can understand and effect variations in practicing the claimed invention.

Claims

1. 1. A method for determining a distance between a first networked electronic device having a first loudspeaker and a first microphone and a second networked electronic device having a second loudspeaker and a second microphone, the method comprising: emitting a first audio signal using the first loudspeaker, the first audio signal having a first frequency and including a first measurement wave carried on a first carrier wave having a first carrier frequency higher than the first frequency, the first audio signal being amplitude modulated with a sine wave; receiving the first audio signal using the second microphone; defining a second audio signal at the second networked electronic device, the second audio signal having the first frequency and including a second measurement wave carried on a second carrier wave having a second carrier frequency different from the first carrier frequency, the second audio signal being sinusoidally modulated in amplitude, and defining the second audio signal including setting a phase of the second measurement wave to be the same as a phase of the first measurement wave of the first audio signal received by the second microphone, whereby the phase of the second measurement wave is set to simulate a reflection of the first measurement wave on the second networked electronic device; emitting the second audio signal using the second loudspeaker; receiving the second audio signal using the first microphone; and calculating a distance between the first networked electronic device and the second networked electronic device based on a phase shift between the emitted first measurement wave and the received second measurement wave; A method comprising:

2. 2. The method of claim 1, wherein the first frequency of the first measurement wave and the second measurement wave is in the range of 3 to 160 Hz.

3. 2. The method of claim 1, wherein the first carrier wave and the second carrier wave have a carrier frequency in the range of 200 to 20,000 Hz.

4. 2. The method of claim 1, wherein setting the phase of the second measurement wave comprises determining the phase of the second measurement wave based on a processing time of a circuit in the second networked electronic device that analyzes the first audio signal to determine the phase of the received first measurement wave.

5. defining the second audio signal and emitting the second audio signal; emitting a candidate second audio signal; Shifting the phase of the second measurement wave of the candidate second sound signal while listening with the second microphone until the phase of the received first measurement wave and the phase of the second measurement wave of the candidate second sound signal match; and After the phase of the received first measurement wave and the phase of the second measurement wave of the candidate second audio signal match, the second audio signal is emitted in phase. The method of claim 1 , comprising:

6. 1. A system for determining a distance between a first networked electronic device and a second networked electronic device, comprising: the first networked electronic device having a first loudspeaker and a first microphone; the second networked electronic device having a second loudspeaker and a second microphone; the first networked electronic device: defining a first audio signal having a first frequency and including a first measurement wave carried on a first carrier wave having a first carrier frequency higher than the first frequency, the first audio signal being amplitude modulated with a sine wave; and Driving the first loudspeaker to emit the first audio signal. and a first circuit configured to: the second networked electronic device: analyzing the first audio signal after enrollment by the second microphone; determining a second audio signal including a second measurement wave (360) having the first frequency and carried on a second carrier wave having a second carrier frequency higher than the first frequency and different from the first carrier frequency, the second audio signal being sinusoidally modulated in amplitude, wherein determining the second audio signal includes setting a phase of the second measurement wave to be the same as a phase of the first measurement wave of the first audio signal received by the second microphone, whereby the phase of the second measurement wave is set to simulate a reflection of the first measurement wave of the first audio signal on the second networked electronic device; Driving the second loudspeaker to emit the second audio signal. and a second circuit configured to: the first circuit of the first networked electronic device further comprising: analyzing the second audio signal after enrollment by the first microphone; determining a phase shift between the emitted first measurement wave and the received second measurement wave; and Calculating a distance between the first networked electronic device and the second networked electronic device based on the determined phase shift. A system configured to:

7. The system of claim 6 , wherein the first frequency of the first measurement wave and the second measurement wave is in the range of 3 to 160 Hz.

8. 7. The system of claim 6, wherein the first carrier wave and the second carrier wave have a carrier frequency in the range of 200 to 20,000 Hz.

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