Synchronization method and system among multiple devices based on sound waves

Abstract

The invention provides a synchronization method and system among multiple devices based on sound waves, and relates to the field of wireless communication. Comprising the following steps: receiving a sound wave signal from first equipment; calculating to obtain a time difference according to the sound wave signal and the reference signal; and calibrating the clock of the target device according to the frequency difference. The invention provides a method for realizing multi-device time synchronization by using sound wave signals. Because the sound wave signal is not influenced by electromagnetic interference and can be effectively propagated in special environments such as underwater, the sound wave signal characteristic is utilized to generate a linear frequency modulation sound wave signal and transmit the sound wave signal to the target equipment, the time difference is obtained through processing, the clock is calibrated according to the time difference, and the target of multi-equipment high-precision time synchronization is achieved. The sound wave signal is less affected by the environment and has good anti-interference capability, so that the method provided by the invention can realize high-precision synchronous operation of multiple mobile devices in an open space, an indoor environment and other complex environments, and the interference of environmental factors on the clock synchronization process is reduced.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication, and particularly to a method and system for synchronizing multiple devices based on sound waves. Background Art

[0002] In modern wireless communication systems, time synchronization among multiple devices is crucial for enabling collaborative work and data fusion among devices. Existing device synchronization methods typically rely on electromagnetic wave signals, such as Wi-Fi, Bluetooth, and GPS. However, these methods perform poorly in environments with severe signal attenuation or high electromagnetic interference (such as underwater, inside buildings, etc.).

[0003] Particularly when synchronizing between mobile devices (such as smartphones, smartwatches, wearable devices, etc.), due to the low clock accuracy of mobile devices and the weak signal transmission and reception capabilities of devices, the clock synchronization accuracy is relatively low in an electromagnetic environment with strong electromagnetic interference. Summary of the Invention

[0004] In view of the above problems, the present invention is proposed to provide a method and system for synchronizing multiple devices based on sound waves that solve or partially solve the above problems.

[0005] In a first aspect of an embodiment of the present invention, a method for synchronizing multiple devices based on sound waves is provided. The method for synchronizing multiple devices includes:

[0006] Receiving a sound wave signal from a first device, where the sound wave signal is a chirp sound wave signal with a preset time length and a preset frequency range;

[0007] Calculating a time difference based on the sound wave signal and a reference signal, where the time difference is the time difference between the target device that generates the reference signal and the first device;

[0008] Calibrating the clock of the target device according to the time difference.

[0009] Optionally, calculating the time difference based on the sound wave signal and the reference signal includes:

[0010] Receiving and caching the sound wave signal in a preset manner;

[0011] Generating the reference signal according to a preset rule;

[0012] Calculating the frequency difference between the cached sound wave signal and the reference signal by operating on the cached sound wave signal and the reference signal;

[0013] Calculating the time difference according to the situation of the frequency difference.

[0014] Optionally, receiving and caching the acoustic wave signal in a preset manner, including:

[0015] Taking half of the preset time length as a new time length and caching the acoustic wave signal.

[0016] Optionally, generating the reference signal according to a preset rule, including:

[0017] Taking half of the preset time length as the time length of the reference signal, taking the lower limit value of the preset frequency range as the lower limit value of the reference signal, and taking the first target value of the preset frequency range as the upper limit value of the reference signal to generate the reference signal;

[0018] The first target value is half of the sum value, and the sum value is the sum of the lower limit value and the upper limit value of the preset frequency range.

[0019] Optionally, performing an operation on the cached acoustic wave signal and the reference signal to obtain the frequency difference between the cached acoustic wave signal and the reference signal, including:

[0020] Performing a fast Fourier transform on the cached acoustic wave signal to obtain a first result;

[0021] Performing a fast Fourier transform on the reference signal to obtain a second result;

[0022] Performing a cross-correlation operation on the first result and the second result using a cross-correlation function to obtain a cross-correlation result;

[0023] Extracting the maximum value from the cross-correlation result and taking the frequency corresponding to the maximum value as the frequency difference.

[0024] Optionally, calculating the time difference according to the situation of the frequency difference, including:

[0025] If the frequency difference is within a target range, calculating the time difference;

[0026] If the frequency difference is not within the target range, no calculation is performed, and the steps for the acoustic wave signal in the next time window are executed: performing an operation on the cached acoustic wave signal and the reference signal to obtain the frequency difference between the cached acoustic wave signal and the reference signal;

[0027] Wherein, the target range refers to: from 0 to a second target value, and the second target value is half of the difference value, and the difference value is the difference between the upper limit value and the lower limit value of the preset frequency range.

[0028] Optionally, if the frequency difference is within a target range, calculating the time difference, including:

[0029] Using the time difference operation formula, calculate the time difference.

[0030] Optionally, the time difference operation formula is: Δt = ΔfT / B;

[0031] Wherein, Δt represents the time difference, Δf represents the frequency difference, T represents the time length of the reference signal, and B represents the bandwidth of the reference signal.

[0032] The second aspect of the embodiments of the present invention provides a multi-device synchronization system based on sound waves, and the multi-device synchronization system includes: a plurality of devices;

[0033] Any one of the plurality of devices is used as the first device, and the remaining devices are used as target devices;

[0034] The first device includes: a signal generation unit and a signal transmission unit;

[0035] Each target device includes: a signal reception unit and a synchronization calibration unit;

[0036] The signal generation unit is configured to generate a sound wave signal, and the sound wave signal is a chirp sound wave signal with a preset time length and a preset frequency range;

[0037] The signal transmission unit is configured to transmit the sound wave signal to the target device;

[0038] The signal reception unit is configured to receive the sound wave signal;

[0039] The synchronization calibration unit is configured to calculate a time difference according to the sound wave signal and a reference signal, where the time difference is the time difference between the target device and the first device, and is also configured to calibrate the clock of the target device according to the time difference.

[0040] Optionally, the signal generation unit includes: a signal generation device;

[0041] The signal transmission unit includes: a sound wave emission device;

[0042] The signal reception unit includes: a sound wave reception device;

[0043] The synchronization calibration unit includes: a processing device.

[0044] Optionally, the synchronization calibration unit includes:

[0045] a cache sub-unit, configured to receive and cache the sound wave signal in a preset manner;

[0046] a generated signal sub-unit, configured to generate the reference signal according to a preset rule;

[0047] An operation frequency difference sub-unit, configured to perform an operation on the cached acoustic wave signal and the reference signal to obtain a frequency difference between the cached acoustic wave signal and the reference signal;

[0048] An operation time difference sub-unit, configured to calculate the time difference according to the situation of the frequency difference.

[0049] Optionally, the caching sub-unit is specifically configured to:

[0050] Use half of the preset time length as a new time length to cache the acoustic wave signal.

[0051] Optionally, the generated signal sub-unit is specifically configured to:

[0052] Use half of the preset time length as the time length of the reference signal, use the lower limit value of the preset frequency range as the lower limit value of the reference signal, and use the first target value of the preset frequency range as the upper limit value of the reference signal to generate the reference signal;

[0053] The first target value is half of the sum value, and the sum value is the sum of the lower limit value and the upper limit value of the preset frequency range.

[0054] Optionally, the operation frequency difference sub-unit is specifically configured to:

[0055] Perform a fast Fourier transform on the cached acoustic wave signal to obtain a first result;

[0056] Perform a fast Fourier transform on the reference signal to obtain a second result;

[0057] Perform a cross-correlation operation on the first result and the second result using a cross-correlation function to obtain a cross-correlation result;

[0058] Extract the maximum value from the cross-correlation result, and use the frequency corresponding to the maximum value as the frequency difference.

[0059] Optionally, the operation time difference sub-unit is specifically configured to:

[0060] If the frequency difference is within a target range, calculate the time difference;

[0061] If the frequency difference is not within the target range, do not perform an operation, and perform the following steps on the acoustic wave signal of the next time window: perform an operation on the cached acoustic wave signal and the reference signal to obtain a frequency difference between the cached acoustic wave signal and the reference signal;

[0062] Wherein, the target range refers to: from 0 to a second target value, and the second target value is half of the difference value, and the difference value is the difference between the upper limit value and the lower limit value of the preset frequency range;

[0063] If the frequency difference is within the target range, calculating the time difference includes:

[0064] Calculating the time difference by using a time difference calculation formula; the time difference calculation formula is: Δt = ΔfT / B;

[0065] Wherein, Δt represents the time difference, Δf represents the frequency difference, T represents the time length of the reference signal, and B represents the bandwidth of the reference signal.

[0066] The multi-device synchronization method based on sound waves provided by the present invention includes: first, receiving a sound wave signal from a first device; then, calculating a time difference according to the sound wave signal and a reference signal; and finally, calibrating the clock of a target device according to the frequency difference.

[0067] The multi-device synchronization method based on sound waves proposed by the present invention abandons the electromagnetic wave signals relied on by traditional device time synchronization methods, and creatively proposes to use sound wave signals to achieve multi-device time synchronization. Since a sound wave signal, as a mechanical wave, is not affected by electromagnetic interference and can effectively propagate in special environments such as underwater, the present invention utilizes its characteristics. A linear frequency-modulated sound wave signal is generated by any device and transmitted to the target device, and then the target device processes it to obtain the time difference, and finally calibrates its own clock according to the time difference, ultimately achieving the goal of high-precision time synchronization of multiple devices.

[0068] The sound wave signal is less affected by the environment and has good anti-interference ability, enabling the method proposed by the present invention to achieve high-precision synchronization operations of multiple mobile devices in open spaces, indoor environments, and other complex environments, reducing the interference of environmental factors on the clock synchronization process and having high practicability. Description of the Drawings

[0069] By reading the following detailed description of the embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. And throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0070] Figure 1 is a flowchart of a multi-device synchronization method based on sound waves according to an embodiment of the present invention;

[0071] Figure 2 is a time-amplitude image and a time-frequency image of an exemplary sound wave signal in an embodiment of the present invention;

[0072] Figure 3It is a schematic diagram of the process of calculating the frequency difference during synchronization between multiple devices based on acoustic signals in an embodiment of the present invention;

[0073] Figure 4 It is a block diagram of a multi-device synchronization system based on acoustic waves in an embodiment of the present invention. Detailed implementation manners

[0074] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific implementation manners. It should be understood that the specific embodiments described herein are only used to explain the present invention, and are only a part of the embodiments of the present invention, rather than all the embodiments, and are not used to limit the present invention.

[0075] A method for synchronizing multiple devices based on acoustic waves according to the present invention, referring to Figure 1 the flowchart of the multi-device synchronization method shown in

[0076] Step 101: Receive an acoustic signal from a first device, where the acoustic signal is a chirp acoustic signal with a preset time length and a preset frequency range.

[0077] Since electromagnetic wave signals perform poorly in environments with severe signal attenuation or a lot of electromagnetic interference, such as underwater, inside buildings, etc. Especially when performing time synchronization between mobile devices, such as smartphones, smartwatches, wearable devices, etc., due to the low clock accuracy of mobile devices and the weak signal transmission and reception capabilities of the devices, the clock synchronization accuracy in an electromagnetic environment with strong electromagnetic interference is relatively low.

[0078] As a mechanical wave, the acoustic signal is not affected by electromagnetic interference and can effectively propagate in special environments such as underwater. Based on this, the inventor creatively proposed to use acoustic signals to achieve time synchronization between multiple devices.

[0079] For multiple devices, any one device is used as the first device, and all the remaining devices are used as target devices. Among these devices, the first device generates an acoustic signal, and the acoustic signal is a chirp acoustic signal with a preset time length and a preset frequency range. The characteristic of the chirp acoustic wave is that its frequency linearly increases or decreases with time, and its characteristic is that it is less affected by the environment and has good anti-interference ability. For example, referring to Figure 2 the time-amplitude image and time-frequency image of an exemplary acoustic signal shown in Figure 2 in which the horizontal axis in the upper figure is time and the vertical axis is amplitude, and the horizontal axis in the lower figure is time and the vertical axis is frequency. From Figure 2 it can be seen that the frequency of the acoustic signal linearly increases with time, so it can be well applied to the method proposed in the present invention.

[0080] For this acoustic wave signal, in order to achieve subsequent time synchronization, it is required to have a preset time length and a preset frequency range. For example, taking the time length τ as the preset time length and the frequency range from f1 to f2 as the preset frequency range, that is, a chirp acoustic wave signal with a starting frequency of f1, an ending frequency of f2, and a modulation time of τ.

[0081] The above acoustic wave signal is transmitted from the first device to the target device, so each target device will receive this acoustic wave signal.

[0082] Step 102: Calculate the time difference based on the acoustic wave signal and the reference signal. This time difference is the time difference between the target device that generates the reference signal and the first device.

[0083] After each target device receives the acoustic wave signal sent by the first device, each target device can calculate the time difference based on the acoustic wave signal and the reference signal. This time difference is the time difference between the target device that generates the reference signal and the first device. That is, in addition to receiving the acoustic wave signal, each target device also generates a reference signal by itself, and the reference signals generated by each target device are the same, so as to ensure time synchronization.

[0084] In an embodiment of the present invention, a preferred method for calculating the time difference based on the acoustic wave signal and the reference signal includes the following steps:

[0085] Step S1: Receive and cache the acoustic wave signal in a preset manner.

[0086] When each target device receives the acoustic wave signal, it receives and caches the acoustic wave signal in a preset manner for use in subsequent time synchronization processing. Preferably, half of the preset time length can be used as the new time length to cache the acoustic wave signal. For example, if the preset time length is τ, then τ / 2 is used as the time length for caching the acoustic wave signal.

[0087] Step S2: Generate a reference signal according to a preset rule.

[0088] Each target device generates the same reference signal according to a preset rule. Preferably, half of the preset time length can be used as the time length of the reference signal. That is, the time length of the reference signal is the same as the time length of the cached acoustic wave signal.

[0089] Use the lower limit value of the preset frequency range as the lower limit value of the reference signal, and use the first target value of the preset frequency range as the upper limit value of the reference signal to generate a reference signal. Herein, the so-called first target value refers to half of the sum value, where the sum value is the sum of the lower limit value and the upper limit value of the preset frequency range. For example: if the preset frequency range is from f1 to f2, then f1 is the lower limit value of the preset frequency range, f2 is the upper limit value of the preset frequency range, and the frequency range of the reference signal is: from f1 to (f1 + f2) / 2.

[0090] Step S3: Perform an operation on the buffered acoustic wave signal and the reference signal to obtain the frequency difference between the buffered acoustic wave signal and the reference signal.

[0091] After receiving and buffering the acoustic wave signal and generating the reference signal, each target device individually performs an operation on the buffered acoustic wave signal and the generated reference signal to obtain the frequency difference between the buffered acoustic wave signal and the reference signal. A preferred method for obtaining the frequency difference through operation includes:

[0092] Perform a fast Fourier transform on the buffered acoustic wave signal to obtain a first result; perform a fast Fourier transform on the reference signal to obtain a second result. Performing fast Fourier transforms on both can convert the signals in the time domain into frequency values in the frequency domain.

[0093] After obtaining the two results, perform a cross-correlation operation on the first result and the second result using the cross-correlation function to obtain a cross-correlation result; extract the maximum value from the cross-correlation result, and use the frequency corresponding to this maximum value as the frequency difference.

[0094] Refer to Figure 3 the schematic diagram of the process of calculating the frequency difference during synchronization between multiple devices based on acoustic wave signals as shown. From Figure 3 it can be more intuitively understood that the above-mentioned fast Fourier transforms are respectively performed on the buffered acoustic wave signal and the reference signal to obtain their respective corresponding frequency-amplitude curves (corresponding to the first result and the second result), and then the two are cross-correlated to obtain a cross-correlation result. The maximum value is extracted from the cross-correlation result, and the frequency corresponding to this maximum value is used as the frequency difference Δf. Herein, the formula used for the cross-correlation operation is:

[0095]

[0096] In the above formula, R(f) and S(f) are the fast Fourier transforms of the buffered acoustic wave signal and the reference signal, and B is the bandwidth of the reference signal, B = f2 - f1.

[0097] Step S4: Calculate the time difference according to the situation of the frequency difference.

[0098] After obtaining the frequency difference, it is also necessary to calculate the time difference according to the situation of the frequency difference. Specifically:

[0099] If the frequency difference is within the target range, the time difference is calculated; if the frequency difference is not within the target range, no calculation is performed. Instead, for the acoustic wave signals in the next time window, the following steps are executed: calculate the frequency difference between the buffered acoustic wave signals and the reference signal, and subsequent steps, that is: if the frequency difference Δf is not within the target range, steps S3 to S4 are executed, and the determination of whether the frequency difference Δf is within the target range is repeated.

[0100] The so-called target range refers to: from 0 to the second target value, which is half of the difference, and the difference is the difference between the lower limit value and the lower limit value of the preset frequency range. Continuing with the previous example: the preset frequency range is from f1 to f2, then f1 is the lower limit value of the preset frequency range, f2 is the upper limit value of the preset frequency range, and the target range is: from 0 to (f2 - f1) / 2. When the frequency difference Δf is between 0 and (f2 - f1) / 2, it indicates that there is a complete segment of acoustic wave signals in the buffer. Only with this complete acoustic wave signal can the time difference be accurately calculated.

[0101] If the frequency difference is within the target range, the time difference is calculated using the time difference calculation formula. Among them, the time difference calculation formula is: Δt = ΔfT / B; where, Δt represents the time difference, Δf represents the frequency difference, T represents the time length of the reference signal, and B represents the bandwidth of the reference signal.

[0102] Step 103: Calibrate the clock of the target device according to the time difference.

[0103] After each target device obtains the time, it can calibrate its respective clock according to the time difference.

[0104] It can be known from the above method that it can better achieve high-precision synchronization operations of multiple devices in open spaces, indoor environments, and other complex environments, reduce the interference of environmental factors on the clock synchronization process, and ultimately achieve the goal of high-precision time synchronization of multiple devices.

[0105] Based on the above method for synchronizing multiple devices based on acoustic waves, an embodiment of the present invention further provides a system for synchronizing multiple devices based on acoustic waves. Refer to Figure 4 the block diagram of the system for synchronizing multiple devices shown, which includes: multiple devices; any one of the multiple devices is used as the first device, and the remaining devices are used as target devices; for example Figure 4 Target Device 1, Target Device 2,... Target Device n.

[0106] The first device includes: a signal generation unit and a signal transmission unit; each target device includes: a signal reception unit and a synchronization calibration unit.

[0107] A signal generation unit for generating an acoustic wave signal, which is a chirp acoustic wave signal with a preset time length and a preset frequency range; a signal transmission unit for transmitting the acoustic wave signal to a target device. The signal generation unit may be a signal generation device within the device, and preferably, the signal generation device includes, but is not limited to, a digital signal processor (DSP), etc.; the signal transmission unit may be an acoustic wave emission device within the device, and preferably, the acoustic wave emission device includes, but is not limited to, a speaker, etc.

[0108] A signal receiving unit for receiving an acoustic wave signal; a synchronization calibration unit for calculating a time difference based on the acoustic wave signal and a reference signal, where the time difference is the time difference between the target device and the first device, and for calibrating the clock of the target device according to the time difference. The signal receiving unit may be an acoustic wave receiving device within the device, and preferably, the acoustic wave receiving device includes, but is not limited to, a microphone, etc.; the synchronization calibration unit may be a processing device within the device, and preferably, the processing device includes, but is not limited to, a central processing unit (CPU), a microcontroller unit (MCU), etc.

[0109] Optionally, the synchronization calibration unit includes:

[0110] A cache sub-unit for receiving and caching the acoustic wave signal in a preset manner;

[0111] A generated signal sub-unit for generating the reference signal according to a preset rule;

[0112] An operation frequency difference sub-unit for operating on the cached acoustic wave signal and the reference signal to obtain the frequency difference between the cached acoustic wave signal and the reference signal;

[0113] An operation time difference sub-unit for calculating the time difference according to the situation of the frequency difference.

[0114] Optionally, the cache sub-unit is specifically used for:

[0115] Using half of the preset time length as a new time length to cache the acoustic wave signal.

[0116] Optionally, the generated signal sub-unit is specifically used for:

[0117] Using half of the preset time length as the time length of the reference signal, using the lower limit value of the preset frequency range as the lower limit value of the reference signal, and using the first target value of the preset frequency range as the upper limit value of the reference signal to generate the reference signal;

[0118] The first target value is half of the sum value, where the sum value is the sum of the lower limit value and the upper limit value of the preset frequency range.

[0119] Optionally, the operation frequency difference subunit is specifically configured to:

[0120] Perform a fast Fourier transform on the buffered acoustic wave signal to obtain a first result;

[0121] Perform a fast Fourier transform on the reference signal to obtain a second result;

[0122] Perform a cross-correlation operation on the first result and the second result using a cross-correlation function to obtain a cross-correlation result;

[0123] Extract the maximum value from the cross-correlation result, and use the frequency corresponding to the maximum value as the frequency difference.

[0124] Optionally, the operation time difference subunit is specifically configured to:

[0125] If the frequency difference is within a target range, calculate the time difference;

[0126] If the frequency difference is not within the target range, no calculation is performed, and the following steps are executed for the acoustic wave signal in the next time window: perform calculations on the buffered acoustic wave signal and the reference signal to obtain the frequency difference between the buffered acoustic wave signal and the reference signal;

[0127] Wherein, the target range refers to: from 0 to a second target value, the second target value being half of the difference, and the difference being the difference between the upper limit value and the lower limit value of the preset frequency range;

[0128] If the frequency difference is within the target range, calculating the time difference includes:

[0129] Calculate the time difference using the time difference calculation formula; the time difference calculation formula is: Δt = ΔfT / B;

[0130] Wherein, Δt represents the time difference, Δf represents the frequency difference, T represents the time length of the reference signal, and B represents the bandwidth of the reference signal.

[0131] Through the above embodiments, the method for synchronizing multiple devices based on acoustic waves provided by the present invention includes: first receiving an acoustic wave signal from a first device; then calculating a time difference according to the acoustic wave signal and the reference signal; and finally calibrating the clock of the target device according to the frequency difference.

[0132] The multi-device synchronization method based on sound waves proposed by the present invention abandons the electromagnetic wave signals relied on by traditional device time synchronization methods and creatively proposes to use sound wave signals to achieve multi-device time synchronization. Since sound wave signals, as a kind of mechanical wave, are not affected by electromagnetic interference and can effectively propagate in special environments such as underwater, the present invention utilizes its characteristics. Any device generates a chirped sound wave signal and transmits it to the target device. Then the target device processes it to obtain the time difference. Finally, the target device calibrates its own clock according to the time difference, ultimately achieving the goal of high-precision time synchronization of multiple devices.

[0133] Sound wave signals are less affected by the environment and have good anti-interference ability, enabling the method proposed by the present invention to achieve high-precision synchronization operations of multiple mobile devices in open spaces, indoor environments, and other complex environments, reducing the interference of environmental factors on the clock synchronization process and having high practicality.

[0134] Finally, it should also be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or terminal device comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article or terminal device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the existence of additional identical elements in the process, method, article or terminal device comprising the element.

[0135] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the purpose of the present invention and the scope protected by the claims. All of these fall within the protection scope of the present invention.

Claims

1. A method for synchronization between multiple devices based on sound waves, characterized in that, The multi-device synchronization method includes: Receiving an acoustic wave signal from a first device, where the acoustic wave signal is a chirp acoustic wave signal with a preset time length and a preset frequency range; Calculating a time difference based on the acoustic wave signal and a reference signal, where the time difference is the time difference between the target device that generates the reference signal and the first device; Calibrating the clock of the target device according to the time difference.

2. The multi-device synchronization method according to claim 1, wherein, Calculating the time difference based on the acoustic wave signal and the reference signal, including: Receiving and caching the acoustic wave signal in a preset manner; Generating the reference signal according to a preset rule; Performing an operation on the cached acoustic wave signal and the reference signal to obtain a frequency difference between the cached acoustic wave signal and the reference signal; Calculating the time difference according to the situation of the frequency difference.

3. The multi-device synchronization method according to claim 2, wherein Receiving and caching the acoustic wave signal in a preset manner, including: Caching the acoustic wave signal with half of the preset time length as the new time length.

4. The multi-device synchronization method according to claim 2, characterized in that, Generating the reference signal according to a preset rule, including: Generating the reference signal with half of the preset time length as the time length of the reference signal, the lower limit value of the preset frequency range as the lower limit value of the reference signal, and the first target value of the preset frequency range as the upper limit value of the reference signal; The first target value is half of the sum value, and the sum value is the sum of the lower limit value and the upper limit value of the preset frequency range.

5. The multi-device synchronization method according to claim 2, wherein Performing an operation on the cached acoustic wave signal and the reference signal to obtain a frequency difference between the cached acoustic wave signal and the reference signal, including: Performing a fast Fourier transform on the cached acoustic wave signal to obtain a first result; Performing a fast Fourier transform on the reference signal to obtain a second result; Performing a cross-correlation operation on the first result and the second result using a cross-correlation function to obtain a cross-correlation result; Extracting the maximum value from the cross-correlation result and using the frequency corresponding to the maximum value as the frequency difference.

6. The multi-device synchronization method according to claim 2, wherein, Calculating the time difference according to the situation of the frequency difference, including: If the frequency difference is within a target range, calculating the time difference; If the frequency difference is not within the target range, no calculation is performed, and the steps for the acoustic wave signal in the next time window are executed: performing an operation on the cached acoustic wave signal and the reference signal to obtain a frequency difference between the cached acoustic wave signal and the reference signal; Wherein, the target range refers to: from 0 to a second target value, and the second target value is half of the difference value, and the difference value is the difference between the upper limit value and the lower limit value of the preset frequency range.

7. The multi-device synchronization method according to claim 6, wherein If the frequency difference is within the target range, calculating the time difference, including: Calculating the time difference using a time difference calculation formula.

8. The multi-device synchronization method according to claim 7, wherein, The time difference calculation formula is: Δt = ΔfT / B; Wherein, Δt represents the time difference, Δf represents the frequency difference, T represents the time length of the reference signal, and B represents the bandwidth of the reference signal.

9. A multi-device synchronization system based on sound waves, characterized in that, The multi-device synchronization system includes: multiple devices; Any one of the multiple devices is used as the first device, and the remaining devices are used as target devices; The first device includes: a signal generation unit and a signal transmission unit; Each target device includes: a signal reception unit and a synchronization calibration unit; The signal generation unit is configured to generate an acoustic wave signal, and the acoustic wave signal is a chirp acoustic wave signal having a preset time length and a preset frequency range; The signal transmission unit is configured to transmit the acoustic wave signal to the target device; The signal reception unit is configured to receive the acoustic wave signal; The synchronization calibration unit is configured to calculate a time difference based on the acoustic wave signal and a reference signal, where the time difference is the time difference between the target device and the first device, and is also configured to calibrate the clock of the target device according to the time difference.

10. The multi-device synchronization system according to claim 9, characterized in that, The signal generation unit includes: a signal generation device; The signal transmission unit includes: an acoustic wave transmitting device; The signal reception unit includes: an acoustic wave receiving device; The synchronization calibration unit includes: a processing device.

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