Directional broadcasting method based on beam forming and constant wave width

Abstract

The invention discloses a directional broadcasting method based on beam forming and constant wave width, which comprises a linear array, a DSP module and an FPGA module, the linear array comprises a plurality of loudspeaker units, and the method comprises the following steps: obtaining a directional broadcasting target, performing simulation bending on the linear array by the DSP module, and calculating a first time delay of each loudspeaker unit; the DSP module calculates the delay of beam forming of each loudspeaker unit; the FPGA module calculates the total time delay and the amplitude beam control quantity of each loudspeaker unit in parallel; and each loudspeaker unit outputs a signal, and the FPGA module performs weighting processing on the output signal in parallel according to the amplitude beam control quantity of each loudspeaker unit to synthesize a beam signal. According to the invention, the DSP and the FPGA are combined, the DSP module carries out beam forming algorithm design according to the target position, and the FPGA module carries out parallel computing processing, so that the problems of limited range, low efficiency and high cost of the existing directional broadcast are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of audio beam control, and in particular to a directional broadcasting method based on beam synthesis and constant beam width. Background Art

[0002] At present, directional broadcast speakers are mainly based on phased array or ultrasonic technology to achieve directional propagation of sound. Although the current technology has initially met the basic needs of directional broadcasting, the following problems still exist:

[0003] (1) Limited coverage: Most existing technologies are only targeted at small areas, making it difficult to achieve multi-area broadcasting or flexibly adjust coverage.

[0004] (2) Significant sidelobe interference: Phased array technology has difficulty effectively suppressing side lobes while forming the main beam, causing sound to leak into non-target areas.

[0005] (3) Insufficient environmental adaptability: Unable to dynamically adjust sound field parameters according to environmental noise and reflection conditions, and the sound quality is easily affected by external interference.

[0006] (4) High control complexity: Existing systems mostly rely on complex professional settings and are not suitable for ordinary users to operate.

[0007] (5) High cost: Ultrasonic technology equipment is expensive and difficult to popularize, and general users may not be able to use it on a large scale.

[0008] Therefore, there is a need for a method for performing directional broadcasting that is flexible, efficient and has a wide coverage. Summary of the invention

[0009] To solve the above problems, the present invention provides a directional broadcasting method based on beam synthesis and constant bandwidth. By combining DSP with FPGA, the DSP module designs the beam synthesis algorithm according to the target position, and the FPGA module performs parallel computing and processing, which solves the problems of limited range, low efficiency and high cost of existing directional broadcasting.

[0010] To achieve the above object, the present invention provides the following technical solutions:

[0011] A directional broadcasting method based on beam synthesis and constant beam width includes a linear array, a DSP module and an FPGA module, wherein the linear array includes a plurality of speaker units, and the method includes the following steps:

[0012] S1. Obtain a directional broadcast target, the DSP module simulates the bending of the linear array according to the directional broadcast target, generates a virtual arc, and calculates the first delay of each speaker unit according to the offset of each speaker unit from the linear array to the virtual arc;

[0013] S2. The DSP module calculates the delay of beam synthesis of each speaker unit according to the directional broadcast target direction, and calculates the second delay of each speaker unit according to the delay weight of each speaker unit;

[0014] S3. The DSP module sends the virtual arc and the first delay and the second delay of each speaker unit to the FPGA module. The FPGA module calculates the total delay of each speaker unit in parallel according to the first delay and the second delay of each speaker unit, and calculates the amplitude beam control amount of each speaker unit according to the virtual arc.

[0015] S4. Each speaker unit outputs a signal, and the FPGA module performs weighted processing on the output signals of each speaker unit in parallel according to the amplitude beam control amount of each speaker unit, and then adds them together to synthesize the beam signal and output the beam signal.

[0016] Furthermore, in step S1, the first time delay of each speaker unit is calculated according to the offset of each speaker unit from the linear array to the virtual arc, and the specific implementation method is: the number of speaker units in the linear array is M, and the spacing between adjacent speaker units is d, then the radius R of the virtual arc is:

[0017]

[0018] Among them, the total length of the array is H T =(M-1)d, θ0 is half of the virtual arc angle, and the offset of each speaker unit from the linear array to the virtual arc is calculated according to the virtual arc radius, and the first time delay T of each speaker unit is calculated according to the offset i .

[0019] Furthermore, in step S2, the delay of beam synthesis of each speaker unit is calculated, and its specific implementation method is: the angle between the central axis of the virtual arc and the horizontal axis is α, and the path difference between adjacent array elements is dsin(α), then for the i-th speaker unit, the second delay t i for

[0020]

[0021] Where C is the speed of sound, i=1,2,3,…,M-1.

[0022] Further, in step S3, the FPGA module calculates the total delay of each speaker unit in parallel according to the first delay and the second delay of each speaker unit, and its specific implementation method is: the FPGA module calculates the total delay of each speaker unit through a distributed pipeline method.

[0023] Furthermore, in step S3, the amplitude beam control amount of each speaker unit is calculated according to the virtual arc, and the specific implementation method is: for the i-th speaker unit, the amplitude beam control amount U i The calculation formula is:

[0024]

[0025] Among them, x i is the normalized angle, θ s is the elevation angle of the i-th speaker unit in the spherical coordinates of the virtual arc.

[0026] Further, in step S4, the FPGA module performs weighted processing on the output signals of each speaker unit in parallel according to the amplitude beam control amount of each speaker unit and then adds them up. The specific implementation method is as follows:

[0027] The FPGA module performs fast Fourier transform on the output signal of each speaker unit in parallel to obtain the frequency domain signal of each speaker unit. The FPGA module performs weighted phase compensation on the frequency domain signal of each speaker unit in parallel according to the total delay of each speaker unit and then adds them to obtain the beam frequency domain signal. The FPGA module performs inverse Fourier transform on the beam frequency domain signal to obtain the beam signal.

[0028] Further, in step S4, the frequency domain signal of each speaker unit is weighted phase compensated according to the total delay of each speaker unit and then added, and the specific calculation method is:

[0029]

[0030] Among them, τ i is the total delay of the ith speaker unit, f i is the frequency domain signal of the i-th speaker unit, U i is the amplitude beam control value of the i-th speaker unit.

[0031] Furthermore, the DSP module and the FPGA module exchange data via an I2S communication interface.

[0032] Furthermore, before step S1, the method further includes: setting a sensor to detect environmental noise, and the DSP module adjusting the beam gain according to the environmental noise.

[0033] Furthermore, it also includes: connecting the DSP module with the FPGA module, and testing the communication efficiency and data exchange delay between the DSP module and the FPGA module.

[0034] Through the above technical scheme, the present invention has the following beneficial effects: the DSP module and the FPGA module are used to work together, the FPGA module performs parallel processing and accelerated calculation according to the DSP module design algorithm, and adjusts the gain in real time according to the environmental noise, ensuring accurate coverage of the target area broadcast, thereby improving the flexibility and efficiency of directional broadcasting. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The present invention is a schematic diagram of the overall process of a directional broadcasting method based on beam synthesis and constant bandwidth. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] Example 1

[0039] See also Figure 1 A directional broadcasting method based on beam synthesis and constant beam width includes a linear array, a DSP module and an FPGA module, wherein the linear array includes a plurality of speaker units, and the method includes the following steps:

[0040] S1. Obtain a directional broadcast target, the DSP module simulates the bending of the linear array according to the directional broadcast target, generates a virtual arc, and calculates the first delay of each speaker unit according to the offset of each speaker unit from the linear array to the virtual arc;

[0041] S2. The DSP module calculates the delay of beam synthesis of each speaker unit according to the directional broadcast target direction, and calculates the second delay of each speaker unit according to the delay weight of each speaker unit;

[0042] S3. The DSP module sends the virtual arc and the first delay and the second delay of each speaker unit to the FPGA module. The FPGA module calculates the total delay of each speaker unit in parallel according to the first delay and the second delay of each speaker unit, and calculates the amplitude beam control amount of each speaker unit according to the virtual arc.

[0043] S4. Each speaker unit outputs a signal, and the FPGA module performs weighted processing on the output signals of each speaker unit in parallel according to the amplitude beam control amount of each speaker unit, and then adds them together to synthesize the beam signal and output the beam signal.

[0044] Adaptive beamforming is an advanced signal processing technology that is widely used in wireless communications, radar, sonar, acoustic equipment, etc. By dynamically adjusting the weights of array antennas or sensors, adaptive beamforming can enhance signals in specific directions while suppressing interference and noise, thereby improving the system's signal-to-noise ratio (SNR) and anti-interference capabilities.

[0045] In a specific embodiment, it also includes: repeating steps S1-S5 according to different requirements of the number, width, direction, etc. of beams to generate multiple beams in real time.

[0046] The DSP module is responsible for implementing the basic beamforming algorithm, including delay calculation and weighting coefficient allocation. After the algorithm design is completed, the delay calculation and weighting process are assigned to the FPGA module, and the parallel computing capability of the FPGA is used to quickly calculate the weighted delay of each speaker unit. At the same time, when the FPGA module processes multiple beams in parallel, it can simultaneously calculate the directivity and gain of multiple beams to ensure the real-time generation of multiple beams.

[0047] Specifically, the linear array includes 16 speaker units, the frequency response range of the speaker units is 80Hz to 16kHz, and the spacing between adjacent speaker units is set to 5.33cm to meet the requirement that the spacing is less than half the wavelength of the highest operating frequency. The DSP module is a DSP chip, which belongs to the RK3308 or Analog Devices SHARC series, and the FPGA module model is GW5A-EV25.

[0048] In an optional embodiment, in step S1, the first time delay of each speaker unit is calculated according to the offset of each speaker unit from the linear array to the virtual arc, and the specific implementation method is: the number of speaker units in the linear array is M, and the distance between adjacent speaker units is d, then the radius R of the virtual arc is:

[0049]

[0050] Among them, the total length of the array is H T =(M-1)d, θ0 is half of the virtual arc angle, and the offset of each speaker unit from the linear array to the virtual arc is calculated according to the virtual arc radius, and the first time delay T of each speaker unit is calculated according to the offset i .

[0051] An arc array is formed to form a beam in a specified direction. The angle of the virtual arc determines the beam width of the sound beam emitted from the array. The actual beam is generally 60-70% of the virtual arc angle.

[0052] Specifically, the first time delay T of each speaker unit is calculated according to the sound speed: i .

[0053] In an optional embodiment, in step S2, the delay of beam synthesis of each speaker unit is calculated, and its specific implementation method is: the angle between the central axis of the virtual arc and the horizontal axis is α, and the path difference between adjacent array elements is dsin(α), then for the i-th speaker unit, the second delay t i for

[0054]

[0055] Among them, C is the speed of sound, generally 340m / s, i=1,2,3,…,M-1.

[0056] Specifically, the first speaker unit usually refers to the speaker unit numbered 1 in the array, which is the leftmost or topmost unit in the array. The first array unit is regarded as a reference point, and its delay or received signal is used as a benchmark for other array units.

[0057] In addition, the speaker units may be numbered according to the central axis of the virtual arc, with the speaker unit closest to the central axis of the virtual arc being the first array unit, and the speaker units farther away from the central axis of the virtual arc having larger numbers and higher delays.

[0058] In an optional embodiment, in step S3, the FPGA module calculates the total delay of each speaker unit in parallel based on the first delay and the second delay of each speaker unit, and the specific implementation method is: the FPGA module calculates the total delay of each speaker unit through a distributed pipeline method.

[0059] Distributed pipeline computing is based on pipeline computing, further distributing computing tasks to multiple parallel subcircuits, each of which processes a portion of the input data. This method not only improves computing efficiency, but also makes the computing process more flexible and scalable.

[0060] In an optional embodiment, in step S3, the amplitude beam control amount of each speaker unit is calculated according to the virtual arc, and the specific implementation method is: for the i-th speaker unit, the amplitude beam control amount U i The calculation formula is:

[0061]

[0062] Among them, xi is the normalized angle, θ s is the elevation angle of the i-th speaker unit in the spherical coordinates of the virtual arc.

[0063] The amplitude of each speaker unit is controlled by the Legendre beam control function to eliminate the sidelobe effect within a certain frequency range and produce a relatively constant beam width.

[0064] Furthermore, the weighting coefficients may also adopt a Hamming window, a Chebyshev window, a Blackman window or other suitable weighting functions to ensure that the main lobe of the beam is maximized and the side lobes are suppressed.

[0065] In an optional embodiment, in step S4, the FPGA module performs weighted processing on the output signals of each speaker unit in parallel according to the amplitude beam control amount of each speaker unit and then adds them up. The specific implementation method is as follows:

[0066] The FPGA module performs fast Fourier transform on the output signal of each speaker unit in parallel to obtain the frequency domain signal of each speaker unit. The FPGA module performs weighted phase compensation on the frequency domain signal of each speaker unit in parallel according to the total delay of each speaker unit and then adds them to obtain the beam frequency domain signal. The FPGA module performs inverse Fourier transform on the beam frequency domain signal to obtain the beam signal.

[0067] Frequency domain analysis can decompose complex signals into a superposition of simple sinusoidal signals, so as to understand the structure of the signal more accurately. At the same time, it can more easily identify and remove noise signals in the frequency domain, and can enhance or suppress signals with specific frequency components to meet the needs of amplitude beam control.

[0068] In an optional embodiment, in step S4, the frequency domain signal of each speaker unit is weighted phase compensated according to the total delay of each speaker unit and then added, and the specific calculation method is:

[0069]

[0070] Among them, τ i is the total delay of the ith speaker unit, f i is the frequency domain signal of the i-th speaker unit, U i is the amplitude beam control value of the i-th speaker unit.

[0071] In an optional embodiment, the DSP module and the FPGA module exchange data via an I2S communication interface.

[0072] In an optional embodiment, before step S1, the method further includes: setting a sensor to detect environmental noise, and the DSP module adjusting the beam gain according to the environmental noise.

[0073] Specifically, the environment is monitored by setting up a noise sensor or a microphone.

[0074] In an optional embodiment, the method further includes: connecting the DSP module to the FPGA module, and testing the communication efficiency and data exchange delay between the DSP module and the FPGA module.

[0075] Specifically, the communication between the DSP module and the FPGA module is established through IIS (Internet Information Service), and an efficient data transmission format and timing are defined, which can improve the calculation efficiency of beamforming and ensure the flexibility of directional broadcasting.

[0076] The embodiment disclosed in this specification is only an example of a unilateral feature of the present invention, and the protection scope of the present invention is not limited to this embodiment, and any other functionally equivalent embodiments fall within the protection scope of the present invention. For those skilled in the art, various other corresponding changes and deformations can be made according to the technical solutions and concepts described above, and all of these changes and deformations should fall within the protection scope of the claims of the present invention.

Claims

1. A directional broadcasting method based on beamforming and constant beamwidth, characterized in that: The method comprises a linear array, a DSP module and an FPGA module, wherein the linear array comprises a plurality of speaker units, and the method comprises the following steps: S1. Obtain a directional broadcast target, the DSP module simulates the bending of the linear array according to the directional broadcast target, generates a virtual arc, and calculates the first delay of each speaker unit according to the offset of each speaker unit from the linear array to the virtual arc; S2. The DSP module calculates the delay of beam synthesis of each speaker unit according to the directional broadcast target direction, and calculates the second delay of each speaker unit according to the delay weight of each speaker unit; S3. The DSP module sends the virtual arc and the first delay and the second delay of each speaker unit to the FPGA module. The FPGA module calculates the total delay of each speaker unit in parallel according to the first delay and the second delay of each speaker unit, and calculates the amplitude beam control amount of each speaker unit according to the virtual arc. S4. Each speaker unit outputs a signal, and the FPGA module performs weighted processing on the output signals of each speaker unit in parallel according to the amplitude beam control amount of each speaker unit, and then adds them together to synthesize the beam signal and output the beam signal.

2. A directional broadcasting method based on beamforming and constant beamwidth according to claim 1, characterized in that: In step S1, the first time delay of each speaker unit is calculated according to the offset of each speaker unit from the linear array to the virtual arc. The specific implementation method is: the number of speaker units in the linear array is M, and the distance between adjacent speaker units is d, then the radius R of the virtual arc is: Among them, the total length of the array is H T =(M-1)d, θ0 is half of the virtual arc angle, and the offset of each speaker unit from the linear array to the virtual arc is calculated according to the virtual arc radius, and the first time delay T of each speaker unit is calculated according to the offset i .

3. A directional broadcasting method based on beamforming and constant beamwidth according to claim 2, characterized in that: In step S2, the delay of beam synthesis of each speaker unit is calculated, and its specific implementation method is: the angle between the central axis of the virtual arc and the horizontal axis is α, and the path difference between adjacent array elements is dsin(α). Then for the i-th speaker unit, the second delay t i for Where C is the speed of sound, i=1,2,3,…,M-1.

4. A directional broadcasting method based on beamforming and constant beamwidth according to claim 3, characterized in that: In step S3, the FPGA module calculates the total delay of each speaker unit in parallel according to the first delay and the second delay of each speaker unit. The specific implementation method is: the FPGA module calculates the total delay of each speaker unit through a distributed pipeline method.

5. A directional broadcasting method based on beamforming and constant beamwidth according to claim 4, characterized in that: In step S3, the amplitude beam control amount of each speaker unit is calculated according to the virtual arc, and the specific implementation method is: for the i-th speaker unit, the amplitude beam control amount U i The calculation formula is: Among them, x i is the normalized angle, θ s is the elevation angle of the i-th speaker unit in the spherical coordinates of the virtual arc.

6. A directional broadcasting method based on beamforming and constant beamwidth according to claim 5, characterized in that: In step S4, the FPGA module performs weighted processing on the output signals of each speaker unit in parallel according to the amplitude beam control amount of each speaker unit and then adds them up. The specific implementation method is as follows: The FPGA module performs fast Fourier transform on the output signal of each speaker unit in parallel to obtain the frequency domain signal of each speaker unit. The FPGA module performs weighted phase compensation on the frequency domain signal of each speaker unit in parallel according to the total delay of each speaker unit and then adds them to obtain the beam frequency domain signal. The FPGA module performs inverse Fourier transform on the beam frequency domain signal to obtain the beam signal.

7. A directional broadcasting method based on beamforming and constant beamwidth according to claim 6, characterized in that: In step S4, the frequency domain signal of each speaker unit is weighted phase compensated according to the total delay of each speaker unit and then added. The specific calculation method is: Among them, τ i is the total delay of the ith speaker unit, f i is the frequency domain signal of the i-th speaker unit, U i is the amplitude beam control value of the i-th speaker unit.

8. The directional broadcasting method based on beamforming and constant beamwidth according to claim 1, characterized in that: The DSP module and the FPGA module exchange data via the I2S communication interface.

9. The directional broadcasting method based on beamforming and constant beamwidth according to claim 1, characterized in that: Also includes: The sensor is set to detect the environmental noise, and the DSP module adjusts the beam gain according to the environmental noise.

10. The directional broadcasting method based on beamforming and constant beamwidth according to claim 1, characterized in that: Before step S1, the method further includes: connecting the DSP module to the FPGA module, and testing the communication efficiency and data exchange delay between the DSP module and the FPGA module.

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