Device for inhibiting grating lobes of acoustic transducer array and application method

Abstract

The invention discloses a device for inhibiting grating lobes of an acoustic transducer array and an application method. The device comprises an upper computer, an acoustic host and an acoustic transducer array which are connected in sequence, the acoustic host comprises a logic control circuit, N signal generation units connected with the logic control circuit and N linear amplification circuits connected with the N signal generation units in a one-to-one correspondence mode, and N channels are formed; the signal generation unit comprises a summing circuit and M single-frequency sine wave oscillation circuits connected with the summing circuit; the acoustic transducer array is a linear regular arrangement array and comprises N transducer array elements which are connected with the N linear amplification circuits in a one-to-one correspondence manner, the width of each transducer array element is L, the spacing distance between the adjacent transducer array elements is dL, the resonance center frequency of each transducer array element is F, and the relative bandwidth is B. According to the invention, a good grating lobe suppression effect can be obtained with relatively low technical cost.

Description

Technical Field

[0001] This invention relates to the field of acoustic application technology, and in particular to a device and application method for suppressing the grating lobes of an acoustic transducer array. Background Technology

[0002] Acoustic transducer arrays are widely used in sonar, medical ultrasound imaging, and power ultrasound. In sonar systems, arrays use beamforming to detect and track underwater targets; medical ultrasound utilizes the array's transmitting and receiving capabilities to acquire high-resolution images of human tissues; and in power ultrasound, the directional transmission of sound wave energy is controlled to achieve applications such as acoustic chemical reactions and microbial treatment. In addition, acoustic transducer array technology is also used in noise control, geological exploration, and consumer electronics, such as beamforming speaker arrays in smart speakers. With the development of MEMS and flexible electronics technologies, miniaturized arrays have further expanded their application prospects in wearable devices and the Internet of Things. It can be said that acoustic transducer arrays cover almost all acoustic application scenarios.

[0003] When the element spacing of an array exceeds half a wavelength, the transmitted signal will form grating lobes in non-target directions, causing energy dispersion and interference. In sonar applications, grating lobes can lead to false target detection; in medical ultrasound, they can degrade image quality and introduce artifacts. Furthermore, grating lobes can also cause sensitive signal leakage or interfere with adjacent frequency bands.

[0004] To suppress grating lobes, it is usually necessary to optimize the array design (such as sparse arrangement) or adopt amplitude weighting methods (such as Gaussian weighting). However, current common suppression methods often come at the cost of increased beamwidth, decreased signal gain, or higher complexity and computational power in the array control system. Overall, while existing technical solutions can reduce grating lobe effects to some extent, most require sacrificing certain aspects of system performance or increasing implementation difficulty. For example, Chinese invention patent "A device for suppressing grating lobes of acoustic transducer array using a bandpass drive signal" (202510760672.0) proposes a method for suppressing grating lobes using a bandpass drive signal, which can effectively reduce the circuit cost of the system. However, generating the bandpass drive signal requires the transmitting circuit to have arbitrary waveform generation capabilities (generally using direct digital synthesis circuits), and its circuit cost remains high. Therefore, finding a method to achieve better grating lobe suppression at a lower cost has high scientific and engineering value for various acoustic applications. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a device and application method for suppressing grating lobes in acoustic transducer arrays, achieving good grating lobe suppression with a relatively simple technical solution. This achieves a good balance between system cost and grating lobe suppression effectiveness.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A device for suppressing grating lobes in an acoustic transducer array includes a host computer, an acoustic host, and an acoustic transducer array connected sequentially. The acoustic host includes a logic control circuit, N signal generation units all connected to the logic control circuit, and N linear amplifier circuits connected one-to-one with the N signal generation units, forming N channels. The acoustic transducer array is a linearly arranged array, including N transducer elements connected one-to-one with the N linear amplifier circuits. The width of each transducer element is L, the spacing between adjacent transducer elements is dL, the resonant center frequency of each transducer element is F, and the relative bandwidth is B.

[0008] The host computer is used to calculate the drive signal parameters for each channel and send them to the logic control circuit.

[0009] The logic control circuit is used to receive the drive signal parameters of each channel sent by the host computer, convert them into specific circuit parameters, and then send them to the corresponding signal generation unit. The signal generation unit consists of M single-frequency sine wave oscillation circuits and 1 adder circuit, which can generate a composite drive signal composed of the sum of sine waves of multiple frequencies. The waveform, amplitude, and phase of the composite drive signal conform to the parameters sent by the host computer. The linear amplifier circuit is used to amplify the power of the composite drive signal.

[0010] The acoustic transducer array is used to generate different sound fields through different composite drive signals.

[0011] Preferably, the circuit structures and circuit parameters of the N signal generation units are all the same; the circuit structures and circuit parameters of the N linear amplifier circuits are all the same.

[0012] Preferably, the logic control circuit is an FPGA or a CPLD.

[0013] The application method of the device for suppressing acoustic transducer array grating lobes as described above includes the following steps:

[0014] The center distance P between adjacent transducer elements is calculated based on the transducer element width L and the transducer element spacing dL of the acoustic transducer array.

[0015] The wavelength of the sound wave in the medium is calculated as λ = C / F based on the resonant center frequency F of the transducer array element and the sound velocity C in the medium to be emitted.

[0016] If P < λ / 2, then grating lobe suppression is not required; otherwise, grating lobe suppression is required. 1) Waveform The calculation formula is as follows:

[0017] (1)

[0018] Where M is the number of single-frequency oscillation circuits in the signal generation unit, P0 is the amplitude of the driving signal, and f i The signal frequency for each single-frequency oscillator circuit;

[0019] 2) Amplitude: The composite drive signals of N channels are all set to the same signal amplitude;

[0020] 3) Phase: If the acoustic transducer array is non-focused, the composite drive signals of the N channels are directly set to be in phase; if the acoustic transducer array is focused, the phase calculation formula for the composite drive signal of each channel is:

[0021] (2)

[0022] Where D represents the vertical distance from the focal point to the acoustic transducer array; n represents the nth element; τ n This represents the transmission delay of the composite drive signal for the nth array element.

[0023] Based on the above technical solution, the beneficial effects of this invention are: when using a transducer array with a regular arrangement of single-frequency drive signals, grating lobes will inevitably be generated when the center distance between array elements is greater than half the wavelength of the sound wave, especially in the case of a focused sound field. Furthermore, the position and amplitude of the grating lobes are calculable. If the frequency of the drive signal is changed, the position and amplitude of the grating lobes will change accordingly.

[0024] Replacing a single-frequency drive signal with a drive signal containing multiple different frequency components disperses the energy across these components, resulting in numerous distinct grating lobes. These grating lobes have relatively low energy and are located at different positions. Overall, the sound field no longer contains a single, concentrated energy lobe, effectively suppressing grating lobes. Therefore, by adding several sine waves of different frequencies to create a new drive signal, the energy at the grating lobe can be dispersed to different spatial locations, thus suppressing the grating lobe.

[0025] This invention provides a device for suppressing grating lobes in an acoustic transducer array. The acoustic transducer array used is a regularly arranged array, which is relatively easy to manufacture and has low cost. The logic control circuit is a conventional FPGA or CPLD, with low usage and development costs. The single-frequency sinusoidal oscillator circuit and the adder circuit are mature and inexpensive technologies. The linear amplifier circuit is also a conventional circuit, requiring no special design or fabrication. The only control measure is the calculation and parameter setting of the drive waveform, which is slightly more complex than a single-frequency drive signal, achieving a relatively good grating lobe suppression effect with very little system cost. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of a device for suppressing the grating lobes of an acoustic transducer array in one embodiment;

[0027] Figure 2 This is a schematic diagram illustrating the calculation of the transmitted waveform parameters of an acoustic transducer array in one embodiment.

[0028] Figure 3 This is an operation flowchart of a device for suppressing grating lobes of an acoustic transducer array in one embodiment;

[0029] Figure 4 This is a comparison diagram of the sound field distribution generated by single-frequency and multi-frequency composite driving signals in one embodiment, wherein (a) is the full sound field distribution diagram generated by a single-frequency sinusoidal wave driving signal; (b) is the focal plane distribution diagram generated by a single-frequency sinusoidal wave driving signal; (c) is the full sound field distribution diagram generated by a two-frequency sinusoidal wave composite driving signal; and (d) is the focal plane distribution diagram generated by a two-frequency sinusoidal wave composite driving signal. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0031] like Figures 1 to 4 As shown, this embodiment provides a device for suppressing grating lobes of an acoustic transducer array, comprising a host computer, an acoustic host, and an acoustic transducer array connected in sequence. The acoustic host includes one logic control circuit, N signal generation units all connected to the logic control circuit, and N linear amplifier circuits connected one-to-one with the N signal generation units, forming N channels. The acoustic transducer array is a linearly arranged array, including N transducer elements connected one-to-one with the N linear amplifier circuits. The width of each transducer element is L, the spacing between adjacent transducer elements is dL, the resonant center frequency of each transducer element is F, and the relative bandwidth is B.

[0032] The host computer is used to calculate the driving signal parameters of each channel based on the parameters of the acoustic host and the parameters of the medium from which the sound waves are to be emitted, and then send them to the logic control circuit.

[0033] The acoustic host is used to control the emission of sound waves, and to control the waveform, amplitude, and phase of the drive signal for each channel, thereby achieving good suppression of grating lobes in the sound field generated by the transducer array. Specifically, it receives the drive signal parameters for each channel sent by the host computer, converts them into specific circuit parameters, and then sends them to the corresponding signal generation unit. The signal generation unit consists of M single-frequency sine wave oscillation circuits and one adder circuit, which can generate a composite drive signal composed of the sum of sine waves of multiple frequencies, the waveform, amplitude, and phase of which conform to the parameters sent by the host computer. The linear amplifier circuit is used to amplify the power of the composite drive signal.

[0034] Acoustic transducer arrays are used to generate different sound fields through different composite drive signals.

[0035] In one embodiment of a device for suppressing grating lobes of an acoustic transducer array, the acoustic host includes one logic control circuit, N signal generation units, and N linear amplifier circuits. The logic control circuit is connected to each single-frequency sinusoidal oscillator circuit in all the signal generation units and is connected to a host computer via a communication interface. Each signal generation unit includes several single-frequency sinusoidal oscillator circuits and an adder circuit, with all single-frequency sinusoidal oscillator circuits serving as input signals to the adder circuit. The signal generation circuits are connected to corresponding linear amplifier circuits, and the logic control circuit uniformly controls which single-frequency sinusoidal oscillator circuits participate in the generation of the transmission drive signal to generate a composite drive signal with the required waveform, amplitude, and phase. The linear amplifier circuits are connected to corresponding transducer elements, and linearly amplify the composite drive signal sent from the corresponding direct digital synthesis circuit, then use it to drive the transducer elements to emit sound waves.

[0036] The signal generation unit and the linear amplifier circuit have the same circuit structure and parameters. The difference lies in the different transducer array elements connected to them, and the different driving signals generated by receiving different instructions from the logic control circuit.

[0037] In one embodiment of an apparatus for suppressing the grid lobes of an acoustic transducer array, the logic control circuit is generally an FPGA or CPLD. It receives the waveform, amplitude, and phase of the signal to be transmitted by each channel from the host computer, and parses and converts the instructions sent by the host computer into specific instructions that can be executed by the signal generation unit and the linear amplifier circuit according to the parameter settings of the subsequent circuits. It then sends these instructions one by one to each circuit of the signal generation unit and the linear amplifier circuit.

[0038] One embodiment provides an application method for a device to suppress the grating lobes of an acoustic transducer array. First, based on the parameters of the acoustic host and the parameters of the medium from which the sound wave is to be emitted, the host computer calculates the driving signal parameters for each channel and sends them to the logic control circuit. Then, the logic control circuit calculates the specific control parameters for the single-frequency sinusoidal oscillation circuit and the linear amplifier circuit for each channel, sends them to each channel one by one, and activates the transmission, driving the acoustic transducer array to generate a sound field. The specific process includes the following steps:

[0039] The center distance P between adjacent transducer elements is calculated based on the transducer element width L and the transducer element spacing dL of the acoustic transducer array.

[0040] The wavelength of the sound wave in the medium is calculated as λ = C / F based on the resonant center frequency F of the transducer array element and the sound velocity C in the medium to be emitted.

[0041] If P < λ / 2, then grating lobe suppression is not required; otherwise, grating lobe suppression is required. 1) Waveform The calculation formula is:

[0042] (1)

[0043] Where M is the number of single-frequency oscillation circuits in the signal generation unit, P0 is the amplitude of the driving signal, and f i The signal frequency for each single-frequency oscillator circuit;

[0044] 2) Amplitude: The composite drive signals of N channels are all set to the same signal amplitude;

[0045] 3) Phase: If the acoustic transducer array is non-focused, then the composite drive signals of the N channels are directly set to be in phase; if the acoustic transducer array is focused, then the phase calculation formula for the composite drive signal of each channel is:

[0046] (2)

[0047] Where D represents the vertical distance from the focal point to the acoustic transducer array; n represents the nth element; τ n This represents the transmission delay of the composite drive signal for the nth array element.

[0048] Example

[0049] Set a such Figure 2The acoustic transducer array shown has an element width L = 1.5 mm, an adjacent element spacing dL = 1.0 mm, an element number N = 64, an element resonant center frequency of 1 MHz, a relative bandwidth of 40% (±0.2 MHz), and a vertical distance D = 100 mm between the sound field focal point and the transducer array. A single-frequency sine wave of 1 MHz was used to drive the transducer array to emit sound waves, and the sound field distribution at the focal plane and the overall sound field distribution were recorded. The waveform obtained by combining frequencies of 0.8 MHz and 1.2 MHz and calculating according to formula (1) was used again to drive the transducer array to emit sound waves, and the sound field distribution at the focal plane and the overall sound field distribution were recorded.

[0050] Compare the full sound field and the sound field at the focal plane generated by the two driving signals, for example... Figure 4 As shown, (a) is the full sound field distribution diagram generated by a single-frequency sinusoidal wave driving signal; (b) is the focal plane distribution diagram generated by a single-frequency sinusoidal wave driving signal; (c) is the full sound field distribution diagram generated by a composite sinusoidal wave driving signal of two frequencies; and (d) is the focal plane distribution diagram generated by a composite sinusoidal wave driving signal of two frequencies. Figure 4 As can be seen, after adopting a dual-frequency sinusoidal composite driving signal, the grating lobe energy in the sound field is dispersed to different spatial locations, resulting in a decrease in normalized sound pressure. This reduction in the maximum sound pressure outside the main lobe effectively improves the effectiveness and safety of the ultrasonic system. Thus, by changing the driving signal, effective suppression of the grating lobes in the sound field generated by a regularly arranged transducer array is achieved.

[0051] The above are merely preferred embodiments of this application and are not intended to limit the scope of protection of the embodiments in this specification. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the embodiments in this specification should be included within the scope of protection of the embodiments in this specification.

[0052] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. An apparatus for suppressing grating lobes of an acoustic transducer array, the apparatus comprising: It comprises a host computer, an acoustic host and an acoustic transducer array connected in sequence, the acoustic host comprises one logic control circuit, N signal generating units each connected with the logic control circuit, and N linear amplification circuits each connected with one of the N signal generating units, forming N channels; The acoustic transducer array is a linearly arranged array, comprising N transducer elements each connected with one of the N linear amplification circuits, the width of each transducer element is L, the interval distance between adjacent transducer elements is dL, the resonant center frequency of each transducer element is F, and the relative bandwidth is B, wherein, The host computer is configured to calculate the driving signal parameters of each channel and send them to the logic control circuit; The logic control circuit is configured to receive the driving signal parameters of each channel sent by the host computer and convert them into specific circuit parameters before sending them to the corresponding signal generating unit; the signal generating unit comprises M single-frequency sine wave oscillation circuits and one adder circuit, and can generate a composite driving signal composed of sine waves of multiple frequencies, the waveform, amplitude and phase of the composite driving signal conform to the parameters issued by the host computer; the linear amplification circuit is configured to amplify the power of the composite driving signal; The acoustic transducer array is configured to generate different sound fields through different composite driving signals.

2. A device for suppressing grating lobes of an acoustic transducer array according to claim 1, characterized in that The circuit structure and circuit parameters of the N signal generating units are the same; the circuit structure and circuit parameters of the N linear amplification circuits are the same.

3. The apparatus of claim 1, wherein, The logic control circuit is FPGA or CPLD.

4. Use of a device for suppressing grating lobes of an acoustic transducer array according to any one of claims 1 to 3, characterized in that, The method comprises the following steps: According to the width L and the interval distance dL of the transducer elements of the acoustic transducer array, the center distance P = L + dL of the adjacent transducer elements is calculated; According to the resonant center frequency F of the transducer elements and the sound speed C in the medium to be emitted, the wavelength λ = C / F of the sound wave in the medium is calculated; If P < λ / 2, no grating lobe suppression is needed; otherwise, grating lobe suppression is needed. 1) Waveform The calculation formula is shown as follows: （1） Wherein, M is the number of single frequency oscillation circuits in the signal generating unit, P0 is the amplitude of the driving signal, f i is the signal frequency of each single frequency oscillation circuit; 2) Amplitude, the composite driving signals of the N channels are all set to the same signal amplitude; 3) Phase, if the acoustic transducer array is non-focusing emission, the composite driving signals of the N channels are directly set to the same phase; if the acoustic transducer array is focusing emission, the phase calculation formula of the composite driving signal of each channel is: （2） where D represents the vertical distance of the focal point from the acoustic transducer array; n represents the nth element; τ n represents the complex drive signal emission delay of the nth element.

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