A signal source positioning method and system based on a non-uniform linear array

Abstract

The application discloses a signal source positioning method and system based on a non-uniform linear array, which is based on a frequency domain cross-correlation algorithm, calculates a mutual power spectrum function and phase frequency characteristics of a signal, calculates an estimation of a signal time delay through an unwrapping algorithm, and further obtains an accurate estimation of a signal source position. The method designs an unwrapping algorithm according to the arraying mode of the non-uniform array, solves the phase ambiguity problem in array signal processing, and solves the periodic multi-value problem. In the case of the same number of array elements, the non-uniform arraying enables the positioning system to have a larger equivalent aperture, so as to achieve a higher-precision positioning effect; the asymmetric arraying mode also enables the system to reuse array elements and channels. The method uses the recursive idea to cyclically calculate and correct the positioning result, and further improves the positioning precision. The number of array elements and the array element spacing of the system can be flexibly changed according to requirements, so as to meet different cost and precision requirements.

Description

Technical Field

[0001] This invention relates to the field of array signal processing technology, and in particular to a method and system for locating signal sources based on a non-uniform linear array. Background Technology

[0002] In signal source localization technology, the most crucial step is calculating the Time Delay of Arrival (TDOA) of the signal reaching each receiver, which allows for the calculation of two-dimensional or three-dimensional location. The Generalized Cross Correlation (GCC) algorithm is a widely used TDOA estimation algorithm. Cross-correlation is a fundamental method for describing the temporal similarity between two signals; it describes the degree of correlation between the values ​​of two time series at any different time points. Since signals from the same source exhibit a certain degree of correlation, by calculating the cross-correlation function between the signals received by different array elements and the time independent variable corresponding to its peak value, the time difference of the signal emitted by this source reaching different receiving array elements can be estimated.

[0003] In theory, to determine the direction of a signal source, a simple binary linear array structure is sufficient to calculate the time difference between the arrival of the signal from the source at the two microphones. However, this simple structure has two problems: if the spacing between the array elements is too small, the estimation of TDOA will have a large error; if the spacing between the array elements is too large, it will lead to phase ambiguity, and the phase winding will cause periodic multi-value problems in the calculation results, resulting in inaccurate positioning. Summary of the Invention

[0004] The problem this invention aims to solve is the phase ambiguity issue in array signal estimation. This invention designs a non-uniform linear array placement method and utilizes its multi-channel signal design to implement an unwinding algorithm, achieving a higher-precision positioning system. With the same number of array elements, this system achieves a larger equivalent aperture using the non-uniform array placement method and higher positioning accuracy through an iterative approach.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] On one hand, the present invention provides a signal source localization method based on a non-uniform linear array, comprising the following specific steps:

[0007] S1. The array elements are arranged in a non-uniform linear manner, where there is a pair of receiving array elements with a spacing less than 1 / 2 of the minimum wavelength of the signal emitted by the signal source.

[0008] The resulting array receives analog signals and performs analog-to-digital conversion to obtain multiple digital sampling signals;

[0009] S2. Perform frequency domain generalized cross-correlation calculation on the sampled signals of the pair of receiving array elements described in S1 to obtain a rough estimate of the signal source location;

[0010] S3. Perform frequency domain generalized cross-correlation calculation on the other signals in S1, estimate the winding amount using the orientation obtained in S2, and dewind the signal.

[0011] S4. Using the unwound signal obtained in S3, calculate a precise estimate of the signal source's location. Repeat the iteration to obtain higher accuracy.

[0012] As a further technical solution of the present invention, each signal in S1 is sampled synchronously and analog-to-digital conversion is performed synchronously.

[0013] As a further technical solution of the present invention, in the receiving array described in S1, except for a pair of receiving array elements with an element spacing of less than 1 / 2 wavelength, the other array elements are arranged in a linear and non-uniform manner, and the arrangement does not have to be symmetrical.

[0014] As a further technical solution of the present invention, the frequency domain generalized cross-correlation algorithm in S2 is as follows: First, for a pair of receiving array elements with an element spacing of less than 1 / 2 wavelength, the cross-correlation function of the two received signals is calculated; second, the cross-power spectrum function of the two signals is calculated by applying Fast Fourier Transform (FFT), and its phase frequency characteristics are further obtained; then, based on the phase frequency characteristics of the cross-power spectrum function, a rough time delay estimation result is calculated, and a rough estimate of the signal source location is obtained.

[0015] As a further technical solution of the present invention, the dewinding algorithm in S3 is as follows: First, calculate the phase frequency characteristics of the cross power spectrum function of the signals received by other array elements; second, determine the winding amount based on the phase frequency characteristics of the signals received by array elements with an element spacing of less than 1 / 2 wavelength; then, apply the above phase frequency characteristics and calculate the phase frequency characteristics after dewinding based on the winding amount.

[0016] As a further technical solution of the present invention, S4 uses a frequency domain generalized cross-correlation algorithm to calculate an accurate estimate of the signal source location and corrects the unwound signal, repeating this step iteratively to improve the positioning accuracy.

[0017] As a further technical solution of the present invention, receiving array elements are combined to form multiple pairs of receiving array elements, wherein the receiving array elements can be repeated and do not need to be adjacent. The pairs of receiving array elements are arranged in ascending order according to the spacing between the receiving array elements, and this order is used for iteration.

[0018] On the other hand, the present invention also provides a signal source localization system based on a non-uniform linear array. The system includes multiple receiving array elements, an analog-to-digital converter, and a signal processing unit. The signal processing unit includes frequency domain generalized cross-correlation, dewinding, and time delay estimation calculation.

[0019] Compared with the prior art, the present invention, employing the above technical solution, has the following technical effects:

[0020] 1) By using a non-uniform array placement method, a larger equivalent aperture can be achieved with the same number of array elements;

[0021] 2) By adopting an asymmetric array deployment method, array elements and channels can be reused, reducing the number of basic units;

[0022] 3) By adopting a non-uniform array deployment method, the number of array elements and the spacing between each array element can be modified according to specific needs to meet the requirements of cost and accuracy;

[0023] 4) An iterative recursive approach is used to repeatedly calculate and correct the winding amount and signal source orientation, achieving a more accurate positioning effect. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a signal source localization system based on a non-uniform linear array.

[0025] Figure 2 This is a schematic diagram of the specific process of the signal processing unit in the system framework;

[0026] Figure 3 This is the non-uniform linear array layout method in the embodiment. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The measurement method of the present invention will be better understood below with reference to the accompanying drawings and specific embodiments.

[0029] This invention provides a signal source localization method based on a non-uniform linear array, comprising the following specific steps:

[0030] S1. The array elements are arranged in a non-uniform linear manner, where there is a pair of receiving array elements with a spacing less than 1 / 2 of the minimum wavelength of the signal emitted by the signal source.

[0031] The array receives analog signals and performs analog-to-digital conversion to obtain multiple digital sampling signals;

[0032] S2. Perform frequency domain generalized cross-correlation calculation on the sampled signals of the pair of receiving array elements described in S1 to obtain a rough estimate of the signal source location;

[0033] S3. Perform frequency domain generalized cross-correlation calculation on the other signals in S1, estimate the winding amount using the orientation obtained in S2, and dewind the signal.

[0034] S4. Using the unwound signal obtained in S3, calculate a precise estimate of the signal source's location. Repeat the iteration to obtain higher accuracy.

[0035] The present invention also provides a signal source localization system based on a non-uniform linear array, such as Figure 1 As shown, the system includes multiple receiving array elements 100, an analog-to-digital converter 101, and a signal processing unit 102. The multiple receiving array elements 100 synchronously sample each signal, and the analog-to-digital converter 101 digitizes the signals. Among the multiple receiving array elements, there is a pair of receiving array elements whose spacing is less than 1 / 2 of the minimum wavelength of the signal emitted by the signal source. The other array elements are arranged in a linear non-uniform manner.

[0036] The signal processing unit 102 in this invention, such as Figure 2 As shown, it includes a cross-correlation function calculation unit 200, a cross-power spectrum calculation unit 201, a GCC time delay calculation unit (rough estimation) 202, an iterative process control unit 203, an unwinding unit 204, a GCC time delay calculation unit (precise estimation) 205, and an orientation calculation unit 206.

[0037] The cross-correlation function calculation unit 200 first calculates the cross-correlation function of the two received signals for a pair of receiving array elements in 100. Next, the cross-power spectrum calculation unit 201 applies Fast Fourier Transform (FFT) to calculate the cross-power spectrum function of the two signals and further obtains its phase frequency characteristics. Then, the GCC delay calculation unit 202 calculates a rough time delay estimate based on the phase frequency characteristics of the cross-power spectrum function and obtains a rough estimate of the signal source's azimuth. Afterward, the iteration process control unit 203 determines the number of iterations and repeatedly executes the operations of the unwinding unit 204 and the GCC delay calculation unit 205. The unwinding unit 204 uses the phase frequency characteristics of a set of received array element signals obtained by 202 to determine the winding amount and calculates the phase frequency characteristics after unwinding based on the winding amount. The GCC delay calculation unit 205 obtains a precise time delay estimate based on the unwinding phase frequency characteristics. The azimuth calculation unit 206 calculates a precise estimate of the signal source's azimuth.

[0038] The technical solution of the present invention will be further illustrated below through specific embodiments:

[0039] (1) The signal emitted by the signal source is denoted as s(t), and the signal received by each receiving array is denoted as x.i (t)(i=1,2,…,N), where N is the total number of array elements, and x1(t) and x2(t) are the signals received by two array elements whose element spacing is less than 1 / 2 of the minimum wavelength of the signal emitted by the signal source. For each received signal, an analog-to-digital converter 102 converts it into a digital signal x. i (n)(i=1,2,…,N).

[0040] (2) For every two signals, the cross-correlation function calculation unit 200 is used to calculate their cross-correlation function, and the cross-power spectrum calculation unit 201 is further used to calculate the corresponding cross-power spectrum function, resulting in:

[0041]

[0042] in, and They represent x respectively i ,x j The cross-correlation function and cross-power spectrum function are given, where i,j represent the element indices, i,j = 1, 2, ..., N. Therefore, we have:

[0043]

[0044] Among them, S ss (f) represents the power spectrum function of signal s(t). Since the phase frequency characteristic of s(t) is 0, the formula for calculating the time delay Δt is as follows:

[0045]

[0046] In this embodiment, when i=1 and j=2, that is, the signals received by two array elements with a spacing less than 1 / 2 of the minimum wavelength of the signal are used to obtain a rough estimate of the time delay in the GCC time delay calculation unit 202, which is denoted as Δt0.

[0047] (3) The unwinding unit 204 iteratively calculates the precise time delay estimate Δt0 obtained in the previous step. Before the iteration begins, the cross-power spectrum calculation unit 201 calculates the output cross-power spectra of each group, and the iteration control unit 203 sorts the iteration process. In this embodiment, the sorting is based on the spacing of each group of array elements arranged from smallest to largest.

[0048] The specific steps of the iteration are as follows:

[0049] a. Define the initial winding amount k0 = 0, and the initial error as...

[0050] b. Apply the delay calculated previously. Update winding amount:

[0051]

[0052] Where T is the signal period, i.e., T = 1 / f.

[0053] c. In the i-th iteration, select the current spacing as l. i+1 A pair of signals x1(t) and x received by the pair of elements i+2 , calculate its signal phase frequency response θ (t), i (f) is:

[0054]

[0055] in

[0056] θ i (f)∈[-π,π)

[0057] The i-th time delay is calculated from this. for:

[0058]

[0059] Where, k i This is the winding amount calculated in the previous calculation.

[0060] It should be noted that the non-uniform linear array element spacing l used in this embodiment i It is not chosen arbitrarily; its value must satisfy the following:

[0061]

[0062] Only then can k be guaranteed i It was correctly solved. Among them, ε i-1 Error in delay calculation:

[0063]

[0064] d. The estimated value Return to the iterative process control unit 203 and repeat processes b to c until the iteration ends when i > N-2. After the last iteration, the output of the GCC delay calculation unit 205 is the final accurate delay estimate.

[0065] e. The precise estimated value finally output by the GCC delay calculation unit 205 is used by the azimuth calculation unit 206 to calculate the azimuth of the corresponding signal source.

[0066] This invention employs a multi-element non-uniform linear array arrangement method, combined with a generalized cross-correlation algorithm in the frequency domain, to calculate the direction of the signal source. This method and system offer the following advantages: simple array structure, high positioning accuracy, and strong real-time positioning performance; the non-uniform array arrangement allows for a larger equivalent aperture with the same number of array elements; the number of array elements and the spacing between them can be modified according to specific needs to meet cost and accuracy requirements; and the iterative recursive approach repeatedly calculates and corrects the winding amount and signal source orientation, achieving a more precise positioning effect.

[0067] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any transformations or substitutions that can be conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for locating a signal source based on a non-uniform linear array, characterized in that, The method comprises the following specific steps: S1. The array elements are arranged in a non-uniform linear manner, wherein there is a pair of receiving array elements with a spacing less than 1 / 2 of the minimum wavelength of the signal transmitted by the signal source; The obtained array receives an analog signal and performs analog-digital conversion to obtain a plurality of digital sampling signals; S2. The sampling signals of the pair of receiving array elements in S1 are subjected to frequency-domain generalized cross-correlation calculation to obtain a rough estimation of the direction of the signal source; S3. The other signals in S1 are subjected to frequency-domain generalized cross-correlation calculation, and the direction obtained in S2 is used to estimate the wrapping amount and to unwrap the signals; S4. The unwrapped signals obtained in S3 are used to calculate the accurate estimation of the direction of the signal source; the iteration is repeated to obtain higher accuracy; The iteration process is repeated as follows: a plurality of pairs of receiving array elements are combined from the receiving array elements, wherein the receiving array elements can be repeated and need not be adjacent, and each pair of receiving array elements is arranged in ascending order according to the spacing between the receiving array elements, and the iteration is performed in this order.

2. The non-uniform linear array based signal source positioning method of claim 1, wherein, The signals in S1 are synchronously sampled and subjected to analog-digital conversion processing.

3. The non-uniform linear array based signal source positioning method of claim 1, wherein, In the array in S1, except for the pair of receiving array elements with a spacing less than 1 / 2 of the wavelength, the other array elements are arranged in a linear and non-uniform manner, and the arrangement manner need not be symmetrical.

4. The non-uniform linear array based signal source positioning method of claim 1, wherein, The steps of the frequency-domain generalized cross-correlation algorithm in S2 include the following: first, the cross-correlation function of the two signals received by the pair of receiving array elements with a spacing less than 1 / 2 of the wavelength is calculated; second, the cross-power spectrum function of the two signals is calculated by using fast Fourier transform (FFT), and the phase-frequency characteristic is further obtained; then, the rough time delay estimation result is calculated according to the phase-frequency characteristic of the cross-power spectrum function, and the rough estimation of the direction of the signal source is obtained.

5. The non-uniform linear array based signal source positioning method of claim 1, wherein, The steps of the unwrapping algorithm in S3 include the following: first, the phase-frequency characteristic of the cross-power spectrum function of the signals received by the other array elements is calculated; second, the wrapping amount is determined according to the phase-frequency characteristic of the signals of the receiving array elements with a spacing less than 1 / 2 of the wavelength; and then, the unwrapped phase-frequency characteristic is calculated according to the wrapping amount by using the above phase-frequency characteristic.

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