Time focus based pulse time of arrival difference estimation method

Abstract

This invention discloses a time-focusing-based method for estimating the time difference of arrival (TDOA) of impulse sound, comprising the following steps: a low-altitude target transmits an acoustic signal to a reference microphone and other microphones, wherein the acoustic signal received by the microphones is an impulse sound signal; the short-time cross-power spectrum function of the reference microphone signal and the other microphone array is calculated, and then time-focusing processing is performed; a discrete inverse Fourier transform is performed on the time-focused short-time cross-power spectrum function to obtain the time-focused cross-correlation function; based on the maximum value of the cross-correlation function, the TDOA of the signal received by the reference microphone and the other microphones is calculated. This invention improves the accuracy of impulse sound TDOA estimation under low signal-to-noise ratio conditions through the time-focusing method.

Description

Technical Field

[0001] This invention belongs to the field of sound source localization technology, and in particular to a method for estimating the time difference of arrival of pulse sound based on time focusing. Background Technology

[0002] Target detection and monitoring are primary prerequisites for air defense, especially the identification of various low-altitude, slow-moving, and small targets, which presents significant challenges. In recent years, passive acoustic detection technology has been widely applied in research on countering low-altitude targets. Location methods based on time difference of arrival (TDOA) offer advantages such as low computational complexity, high real-time performance, and low hardware cost, and are widely used in modern sound source localization systems. Extracting the TDOA parameter from the acoustic signal becomes the primary problem. The most commonly used TDOA estimation method is the cross-correlation method. The cross-correlation function can quickly solve for the TDOA parameter, but its accuracy decreases significantly under high noise conditions. Summary of the Invention

[0003] The purpose of this invention is to provide a pulse sound arrival time difference estimation method based on time focusing, addressing the problems existing in the prior art.

[0004] The technical solution to achieve the objective of this invention is: a pulse sound time difference estimation method based on time focusing, the method comprising the following steps:

[0005] Step 1: The target sends a pulsed acoustic signal to the reference microphone and other microphone arrays;

[0006] Step 2: Calculate the short-time cross-power spectral function of the reference microphone and other microphone arrays;

[0007] Step 3: Perform time focusing on the short-time cross-power spectral function;

[0008] Step 4: Perform inverse Fourier transform on the short-time cross-power spectrum function after time focusing to obtain the cross-correlation function;

[0009] Step 5: Calculate the arrival time difference between the reference microphone received signal and the other microphone received signal based on the maximum value of the cross-correlation function.

[0010] Furthermore, the signals received by the reference microphone and other microphones in step 1 are as follows:

[0011] i represents the reference microphone, and j represents other microphones;

[0012] Reference microphone received sound wave signal x i Represented as:

[0013] x i [n] = a i s[n-τ i ]+wi [n] (1)

[0014] Other microphones receive sound wave signals x j Represented as:

[0015] x j [n] = a j s[n-τ j ]+w j [n] (2)

[0016] Where n represents the number of sampling points, n = 0, 1, ..., N-1, and N represents the signal length. The pulse acoustic discrete signal is represented as s[n], x i [n]、x j [n] represents the sound wave signal received by the reference microphone and the sound wave signal received by other microphones, respectively. i ]、s[n-τ j [a] represents the sound source signal received by the reference microphone and the sound source signal received by other microphones, respectively. i and a j These are the attenuation coefficients of the sound source pulse signal after it reaches microphone i and microphone j, respectively. i [n] and w j [n] represents the additive noise received by microphones i and j in addition to the sound source pulse signal, and is independent of the signal s[n]; τ i and τ j Let τ be the propagation time from the sound source to microphone i and microphone j, respectively. ij =τ j -τ i The time difference of arrival (TDOA) is the delay between the signals received by the two microphones.

[0017] Further, step 2, calculating the short-time cross-power spectral function of the reference microphone and other microphone arrays, specifically includes:

[0018] Step 2-1: Calculate the discrete short-time Fourier transform of the signals received by each microphone, and obtain:

[0019]

[0020]

[0021] Where h represents the window function, k represents the frequency (k = 0, 1, ..., N-1), and l represents the window shift (k = 0, 1, ..., N-1). Indicates the reference microphone received signal x i Discrete short-time Fourier transform calculated using the window function h, This indicates that other microphones receive signal x.j Discrete short-time Fourier transform calculated using the window function h;

[0022] Step 2-2, calculate the sound wave signal x received by the reference microphone. i Sound wave signals received by other microphones x j short-time cross-power spectrum function

[0023]

[0024] Furthermore, step 3, which involves time focusing the short-time cross-power spectral function, specifically includes:

[0025] Step 3-1, in At the maximum value, that is:

[0026]

[0027] Where, kp represents The frequency at which the maximum value is located, p represents The timeline position where the maximum value is located;

[0028] Within a window length centered on column p containing the maximum value, sum the time-frequency points whose phase satisfies formula (7):

[0029]

[0030] Where S represents the restriction domain, H is the length of the window function h, phase(·) represents the phase value of the complex number, and θ represents the phase difference threshold; This represents the phase difference between a time-frequency point with time position l and frequency position k, and a time-frequency point with time position p and frequency position k.

[0031] Step 3-2, perform time rearrangement, that is:

[0032]

[0033] in, Represented as x i and x j Short-time cross power spectrum Cross-power spectrum after time rearrangement.

[0034] Further, step 4 involves performing an inverse Fourier transform on the time-focused short-time cross-power spectral function to obtain the cross-correlation function, as shown in the formula:

[0035]

[0036] in, The cross-correlation function after time focusing. This represents the inverse Fourier transform.

[0037] Further, step 5, which involves calculating the arrival time difference between the reference microphone received signal and the other microphone received signal based on the maximum value of the cross-correlation function, specifically includes:

[0038] Find the index of the maximum value of the cross-correlation function:

[0039]

[0040] Obtain the time difference of arrival estimation

[0041] Compared with existing technologies, the significant advantages of this invention are as follows: The time-focused pulse signal arrival time difference estimation method disclosed in this invention uses time focusing to rearrange the short-time cross-power spectrum along the time axis based on the phase difference, thereby enhancing signal energy and reducing noise interference. This results in a more pronounced correlation peak in the rearranged cross-correlation function. Compared with cross-correlation algorithms, this invention effectively solves the problem of low signal-to-noise ratio arrival time difference estimation in sound source localization, and also has the advantages of low computational complexity and high accuracy.

[0042] The present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0043] Figure 1 This is a flowchart of the pulse signal arrival time difference estimation method based on time focusing according to the present invention.

[0044] Figure 2 This is a diagram of the explosion point signal.

[0045] Figure 3 This is a performance comparison chart of the pulse signal arrival time difference estimation method based on time focusing according to the present invention. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0047] It should be noted that if the embodiments of the present invention involve descriptions such as "first" and "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" and "second" may explicitly or implicitly include at least one of those features. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0048] In one embodiment, combined Figure 1 This paper provides a method for estimating the time difference of arrival of pulse sound based on time focusing, which includes the following steps:

[0049] S1, low, slow, small target, transmits sound wave signals to a reference microphone and other microphones, sound wave pulse signals such as Figure 2 As shown;

[0050] S2, calculate the short-time cross-power spectrum function of the reference microphone signal and other microphone arrays, and then perform time-focusing processing on the short-time cross-power spectrum function;

[0051] S3. Perform an inverse Fourier transform on the short-time cross-power spectrum function after time focusing to obtain the cross-correlation function after time focusing. Based on the maximum value of the cross-correlation function, obtain the arrival time difference between the reference microphone received signal and the other microphone received signal.

[0052] Furthermore, in one embodiment, in S1 the target transmits a pulsed sound wave signal to a reference microphone and other microphones, which receive the signal as follows:

[0053] i represents the reference microphone, and j represents other microphones;

[0054] Reference microphone received sound wave signal x i Represented as:

[0055] x i [n] = a i s[n-τ i ]+w i [n] (11)

[0056] Other microphones receive sound wave signals x j Represented as:

[0057] x j [n] = a j s[n-τ j ]+wj [n] (12)

[0058] Where n represents the number of sampling points, n = 0, 1, ..., N-1, and N represents the signal length. The pulse acoustic discrete signal is represented as s[n], x i [n]、x j [n] represents the sound wave signal received by the reference microphone and the sound wave signal received by other microphones, respectively. i ]、s[n-τ j [a] represents the sound source signal received by the reference microphone and the sound source signal received by other microphones, respectively. i and a j These are the attenuation coefficients of the sound source pulse signal after it reaches microphone i and microphone j, respectively. i [n] and w j [n] represents the additive noise received by microphones i and j in addition to the sound source pulse signal, and is independent of the signal s[n]; τ i and τ j Let τ be the propagation time from the sound source to microphone i and microphone j, respectively. ij =τ j -τ i The time difference of arrival (TDOA) is the delay between the signals received by the two microphones.

[0059] Further, in one embodiment, S2 calculates the short-time cross-power spectrum function of the reference microphone and other microphone arrays, and performs time focusing on the short-time cross-power spectrum function, specifically including:

[0060] S2-1, calculate the discrete short-time Fourier transform of the signals received by each microphone, and obtain:

[0061]

[0062]

[0063] Where h represents the window function, k represents the frequency (k = 0, 1, ..., N-1), and l represents the window shift (k = 0, 1, ..., N-1). Indicates the reference microphone received signal x i Discrete short-time Fourier transform calculated using the window function h, This indicates that other microphones receive signal x. j Discrete short-time Fourier transform calculated using the window function h;

[0064] S2-2, Calculate the acoustic signal x received by the reference microphone. i Sound wave signals received by other microphones x j short-time cross-power spectrum function

[0065]

[0066] S2-3, in At the maximum value, that is:

[0067]

[0068] Where, kp represents The frequency at which the maximum value is located, p represents The timeline position where the maximum value is located;

[0069] Within a window length centered on column p containing the maximum value, sum the time-frequency points whose phases satisfy formula (17):

[0070]

[0071] Where S represents the restriction domain, H is the length of the window function h, phase(·) represents the phase value of the complex number, and θ represents the phase difference threshold; This represents the phase difference between a time-frequency point with time position l and frequency position k, and a time-frequency point with time position p and frequency position k.

[0072] S2-4, perform time rearrangement, that is:

[0073]

[0074] in, Represented as x i and x j Short-time cross power spectrum Cross-power spectrum after time rearrangement.

[0075] Furthermore, in one embodiment, S3 specifically includes:

[0076] S3-1, Perform an inverse Fourier transform on the short-time cross-power spectral density function after time focusing to obtain the cross-correlation function, the formula of which is:

[0077]

[0078] in, The cross-correlation function after time focusing. Indicates the inverse Fourier transform;

[0079] S3-2, Based on the maximum value of the cross-correlation function, calculate the arrival time difference between the reference microphone received signal and the other microphone received signal, specifically including:

[0080] Find the index of the maximum value of the cross-correlation function:

[0081]

[0082] Obtain the time difference of arrival estimation

[0083] In one embodiment, a time-focused pulse sound time difference estimation system is provided, the system comprising:

[0084] The first module is used to enable the target to send pulsed acoustic wave signals to the reference microphone and other microphone arrays;

[0085] The second module is used to calculate the short-time cross-power spectrum function of the reference microphone and other microphone arrays;

[0086] The third module is used to perform time focusing on the short-time cross-power spectrum function;

[0087] The fourth module is used to perform inverse Fourier transform on the short-time cross-power spectrum function after time focusing to obtain the cross-correlation function;

[0088] The fifth module is used to calculate the time difference of arrival between the reference microphone received signal and the other microphone received signal based on the maximum value of the cross-correlation function.

[0089] Specific limitations regarding the time-focused pulse sound arrival time difference estimation system can be found in the limitations of the time-focused pulse sound arrival time difference estimation method described above, and will not be repeated here. Each module in the aforementioned time-focused pulse sound arrival time difference estimation system can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the memory of a computer device as software, so that the processor can call and execute the corresponding operations of each module.

[0090] In one embodiment, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements:

[0091] Step 1: The target sends a pulsed acoustic signal to the reference microphone and other microphone arrays;

[0092] Step 2: Calculate the short-time cross-power spectral function of the reference microphone and other microphone arrays;

[0093] Step 3: Perform time focusing on the short-time cross-power spectral function;

[0094] Step 4: Perform inverse Fourier transform on the short-time cross-power spectrum function after time focusing to obtain the cross-correlation function;

[0095] Step 5: Calculate the arrival time difference between the reference microphone received signal and the other microphone received signal based on the maximum value of the cross-correlation function.

[0096] For specific limitations on each step, please refer to the limitations on the pulse sound arrival time difference estimation method based on time focusing mentioned above, which will not be repeated here.

[0097] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, the computer program being implemented when executed by a processor:

[0098] Step 1: The target sends a pulsed acoustic signal to the reference microphone and other microphone arrays;

[0099] Step 2: Calculate the short-time cross-power spectral function of the reference microphone and other microphone arrays;

[0100] Step 3: Perform time focusing on the short-time cross-power spectral function;

[0101] Step 4: Perform inverse Fourier transform on the short-time cross-power spectrum function after time focusing to obtain the cross-correlation function;

[0102] Step 5: Calculate the arrival time difference between the reference microphone received signal and the other microphone received signal based on the maximum value of the cross-correlation function.

[0103] For specific limitations on each step, please refer to the limitations on the pulse sound arrival time difference estimation method based on time focusing mentioned above, which will not be repeated here.

[0104] To better demonstrate the algorithm performance of this method, a simulation experiment is designed as follows: Simulation signal 1 is as follows: Figure 2 As shown, simulation signal 1 is time-delayed to obtain simulation signal 2. Simulation signal 1 is the reference microphone received signal, and simulation signal 2 is the signal received by other microphones. Random white noise is added to simulation signal 1 and simulation signal 2. 1000 time-of-arrival (TOA) estimation experiments are conducted on simulation signal 1 and simulation signal 2 at different signal-to-noise ratios. The root mean square error (RMSE) curves of the cross-correlation algorithm and the TOA estimation of this invention are obtained, as shown in the figure. Figure 3 As shown.

[0105] Depend on Figure 3 It can be seen that the pulse signal arrival time difference estimation method based on time focusing of the present invention has a root mean square error smaller than that of the cross-correlation algorithm under different signal-to-noise ratios, thus achieving accuracy in estimating the pulse signal arrival time difference under low signal-to-noise ratio.

[0106] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention without departing from its spirit and scope should be included within the protection scope of the present invention.

Claims

1. A method for estimating the time difference of arrival (TDOA) of pulsed sound based on time focusing, characterized in that, The method includes the following steps: Step 1: The target sends a pulsed acoustic signal to the reference microphone and other microphone arrays; Step 2: Calculate the short-time cross-power spectral function of the reference microphone and other microphone arrays; Step 3: Perform time focusing on the short-time cross-power spectral function; Step 4: Perform inverse Fourier transform on the short-time cross-power spectrum function after time focusing to obtain the cross-correlation function; Step 5: Calculate the time difference of arrival between the reference microphone received signal and the other microphone received signal based on the maximum value of the cross-correlation function. Step 2, calculating the short-time cross-power spectral function of the reference microphone and other microphone arrays, specifically includes: Step 2-1: Calculate the discrete short-time Fourier transform of the signals received by each microphone, and obtain: （1） （2） in, This represents the window function, where k represents the frequency. , l indicates window shift, , Indicates the reference microphone received signal Window function The discrete short-time Fourier transform of the calculation This indicates that other microphones are receiving signals. Window function Calculate the discrete short-time Fourier transform; Step 2-2: Calculate the sound wave signal received by the reference microphone. Sound wave signals received by other microphones short-time cross-power spectrum function : （3） Step 3, which involves time focusing the short-time cross-power spectral function, specifically includes: Step 3-1, in At the maximum value, that is: （4） in, express The frequency at which the maximum value is located express The timeline position where the maximum value is located; Column containing the maximum value Within a window length centered at a given point, sum the time-frequency points for which the phase satisfies formula (5): （5） in, Indicates the restricted domain. For window functions Length, Represents the phase value of a complex number. Indicates the phase difference threshold; This represents the phase difference between a time-frequency point with time position l and frequency position k, and a time-frequency point with time position p and frequency position k. Step 3-2, perform time rearrangement, that is: （6） in, Represented as and Short-time cross power spectrum Cross-power spectrum after time rearrangement.

2. The pulse sound arrival time difference estimation method based on time focusing according to claim 1, characterized in that, The signals received by the reference microphone and other microphones in step 1 are as follows: Indicates the reference microphone. Indicates other microphones; Reference microphone received sound wave signal Represented as: （7） Sound signals received by other microphones Represented as: （8） Where n represents the number of sampling points, N represents the signal length, and the pulse acoustic discrete signal is represented as: , , These represent the sound wave signals received by the reference microphone and the sound wave signals received by other microphones, respectively. , These are the sound source signals received by the reference microphone and the sound source signals received by other microphones, respectively. and The sound source pulse signal arrives at the microphone. and microphone The attenuation coefficient after that, and microphones and microphone The received additive noise, in addition to the sound source pulse signal, is compared with the signal. They are independent of each other; and The sound source reaches the microphone. and microphone The propagation time, The time difference of arrival (TDOA) is the delay between the signals received by the two microphones.

3. The pulse sound arrival time difference estimation method based on time focusing according to claim 1, characterized in that, Step 4 involves performing an inverse Fourier transform on the short-time cross-power spectral density function after time focusing to obtain the cross-correlation function, as shown in the formula: （9） in, The cross-correlation function after time focusing. , This represents the inverse Fourier transform.

4. The pulse sound arrival time difference estimation method based on time focusing according to claim 3, characterized in that, Step 5, which calculates the time difference of arrival between the reference microphone received signal and the other microphone received signal based on the maximum value of the cross-correlation function, specifically includes: Find the index of the maximum value of the cross-correlation function: （10） Obtain the time difference of arrival estimation .

5. A pulse acoustic time-of-arrival difference estimation system based on time-focusing according to any one of claims 1 to 4, characterized in that, The system includes: The first module is used to enable the target to send pulsed acoustic wave signals to the reference microphone and other microphone arrays; The second module is used to calculate the short-time cross-power spectrum function of the reference microphone and other microphone arrays; The third module is used to perform time focusing on the short-time cross-power spectrum function; The fourth module is used to perform inverse Fourier transform on the short-time cross-power spectrum function after time focusing to obtain the cross-correlation function; The fifth module is used to calculate the time difference of arrival between the reference microphone received signal and the other microphone received signal based on the maximum value of the cross-correlation function.

6. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the method according to any one of claims 1 to 4.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the method of any one of claims 1 to 4.

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