A method for directional broadcasting based on beam synthesis and constant beamwidth

Abstract

The application discloses a directional broadcasting method based on beam synthesis and constant wave width, comprising a linear array, a DSP module and an FPGA module, the linear array comprises a plurality of speaker units, and the method comprises the following steps: obtaining a directional broadcasting target, the DSP module simulates bending of the linear array, and calculates a first time delay of each speaker unit; the DSP module calculates a delay of beam synthesis of each speaker unit; the FPGA module parallelly calculates a total time delay and an amplitude beam control quantity of each speaker unit; each speaker unit outputs a signal, and the FPGA module parallelly performs weighting processing on the output signal according to the amplitude beam control quantity of each speaker unit to synthesize a beam signal. Through combination of the DSP and the FPGA, the DSP module is designed according to a beam synthesis algorithm of a target position, and the FPGA module is parallelly calculated and processed, so that the problems of a limited range and low efficiency and high cost of the existing directional broadcasting are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of audio beam control technology, and particularly relates to a directional broadcasting method based on beam synthesis and constant beam width. BACKGROUND

[0002] The current directional broadcasting loudspeaker is mainly based on phased array or ultrasonic technology to realize the directional propagation of sound. Although the current technology has initially met the basic needs of directional broadcasting, there are still the following problems:

[0003] (1) Limited coverage: Most existing technologies are only for small areas, and it is difficult to realize multi-area broadcasting or flexible adjustment of coverage.

[0004] (2) Significant sidelobe interference: Phased array technology is difficult to effectively suppress sidelobes while forming the main beam, resulting in sound leakage to non-target areas.

[0005] (3) Insufficient environmental adaptability: unable to dynamically adjust the sound field parameters according to environmental noise and reflection conditions, and the sound quality is easily disturbed by the outside world.

[0006] (4) High control complexity: existing systems rely on complex professional settings, which are not suitable for ordinary users.

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

[0008] Therefore, there is currently a need for a directional broadcasting method that is flexible, efficient and has a wide coverage. SUMMARY

[0009] To solve the above problems, the present application provides a directional broadcasting method based on beam synthesis and constant beam width, which combines DSP and FPGA. The DSP module designs the beam synthesis algorithm according to the target position, and the FPGA module performs parallel computation and processing, solving the problems of limited range and low efficiency of existing directional broadcasting, and high cost.

[0010] To achieve the above purpose, the present application provides the following technical solutions:

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

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

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

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

[0016] Further, 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 manner is that: the number of speaker units in the linear array is M, the spacing between adjacent speaker units is d, and the radius R of the virtual arc is:

[0017]

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

[0019] Further, in step S2, the delay of beamforming of each speaker unit is calculated, and the specific implementation manner is that: the angle between the axis of the virtual arc and the horizontal axis is α, the wave path difference of adjacent elements is dsin(α), and for the i-th speaker unit, the second time delay t i is

[0020]

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

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

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

[0024]

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

[0026] Further, in step S4, the FPGA module performs weighted processing and addition on the output signals of each speaker unit in parallel according to the amplitude beam control quantity of each speaker unit, and the specific implementation manner is that:

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

[0028] Further, in step S4, the specific calculation manner of performing weighted phase compensation and addition on the frequency domain signals of each speaker unit according to the total time delay of each speaker unit is that:

[0029]

[0030] Wherein, τ i is the total time delay of the i-th speaker unit, f i is the frequency domain signal of the i-th speaker unit, and U i is the amplitude beam control quantity of the i-th speaker unit.

[0031] Further, the DSP module and the FPGA module exchange data through the I2S communication interface.

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

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

[0034] By the technical scheme, the following beneficial effects are achieved: the DSP module and the FPGA module work cooperatively, the FPGA module performs parallel processing and accelerates calculation according to the algorithm designed by the DSP module, and the gain is adjusted in real time according to the environmental noise, so that the target area is accurately covered by broadcasting and the flexibility and efficiency of the directional broadcasting are improved. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 A schematic diagram of a whole process of a directional broadcasting method based on beam synthesis and constant beam width. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

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

[0038] Example 1

[0039] Reference Figure 1 A directional broadcasting method based on beam synthesis and constant beam width, comprising a linear array, a DSP module and an FPGA module, the linear array comprising a plurality of loudspeaker units, the method comprising the following steps:

[0040] S1. obtaining a directional broadcasting target, the DSP module simulating bending of the linear array according to the directional broadcasting target to generate a virtual arc, and calculating a first time delay of each loudspeaker unit according to an offset of each loudspeaker unit from the linear array to the virtual arc;

[0041] S2. the DSP module calculating a delay of beam synthesis of each loudspeaker unit according to a direction of the directional broadcasting target, and calculating a second time delay of each loudspeaker unit according to a delay weighting of each loudspeaker unit;

[0042] S3. the DSP module sending the virtual arc and the first time delay and the second time delay of each loudspeaker unit to the FPGA module, the FPGA module calculating a total time delay of each loudspeaker unit in parallel according to the first time delay and the second time delay of each loudspeaker unit, and calculating an amplitude beam control amount of each loudspeaker unit according to the virtual arc;

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

[0044] Adaptive beamforming is an advanced signal processing technique widely used in fields such as wireless communication, radar, sonar, and acoustic devices. By dynamically adjusting the weights of array antennas or sensors, adaptive beamforming can enhance signals in a specific direction while suppressing interference and noise, improving the signal-to-noise ratio (SNR) and anti-interference capability of the system.

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

[0046] The DSP module is responsible for implementing basic beamforming algorithms, including delay calculation and weight coefficient distribution, etc. After the algorithm design is completed, the delay calculation and weighting process are distributed to the FPGA module, and the parallel computing capability of the FPGA is used to quickly calculate the weighting delay of each speaker unit. At the same time, the FPGA module can calculate the directivity and gain of multiple beams simultaneously when processing multiple beams in parallel, ensuring 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 interval is less than half the wavelength of the highest operating frequency. The DSP module is a DSP chip, which belongs to RK3308 or Analog Devices SHARC series, and the FPGA module is of GW5A-EV25 type.

[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 is as follows: 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:

[0049]

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

[0051] The angle of the virtual arc determines the beam width of the sound beam emitted from the array, and the actual machine beam is generally 60-70% of the angle of the virtual arc.

[0052] Specifically, the first time delay T i .

[0053] In an optional embodiment, in step S2, the delay of each loudspeaker unit beam synthesis is calculated, and the specific implementation manner is: the angle between the axis of the virtual arc and the horizontal axis is α, and the wave path difference of adjacent elements is dsin(α), so for the i th loudspeaker unit, the second time delay t i

[0054]

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

[0056] Specifically, the first loudspeaker unit generally refers to the loudspeaker unit numbered 1 in the array, which is the leftmost or uppermost unit in the array. The first array unit is regarded as the reference point, and its time delay or received signal is used as the reference of other array units.

[0057] In addition, the number of loudspeaker units can also be defined according to the axis of the virtual arc. The loudspeaker unit closest to the axis of the virtual arc is the first array unit, and the farther the loudspeaker unit is from the axis of the virtual arc, the higher the delay.

[0058] In an optional embodiment, in step S3, the FPGA module calculates the total time delay of each loudspeaker unit according to the first time delay and the second time delay of each loudspeaker unit in parallel, and the specific implementation manner is: the FPGA module calculates the total time delay of each loudspeaker unit by the distributed pipeline method.

[0059] Distributed pipeline calculation is further distributing the calculation task to multiple parallel sub-circuits on the basis of pipeline calculation, and each sub-circuit processes a part of the input data. This method not only improves the calculation efficiency, but also makes the calculation process more flexible and scalable.

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

[0061]

[0062] Where x​​i for normalizing the angle, θ s is the elevation angle of the i-th loudspeaker unit in the spherical coordinates in the virtual arc.

[0063] Each loudspeaker unit is amplitude beam controlled by a Legendre beam control function to eliminate the sidelobe effect and produce a more constant beam width in a certain frequency range.

[0064] Further, the weighting coefficient can also adopt a Hamming window, a Chebyshev window, a Blackman window or other suitable weighting functions to ensure the main lobe of the beam to be maximized and the sidelobes to be suppressed.

[0065] In an optional embodiment, in step S4, the FPGA module adds the weighted signals of each loudspeaker unit after parallel processing of the amplitude beam control of each loudspeaker unit, and the specific implementation manner is as follows:

[0066] The FPGA module performs a fast Fourier transform on the output signals of each loudspeaker unit in parallel to obtain the frequency domain signals of each loudspeaker unit, and adds the frequency domain signals of each loudspeaker unit after weighted phase compensation according to the total time delay of each loudspeaker unit to obtain a beam frequency domain signal, and the FPGA module performs an inverse Fourier transform on the beam frequency domain signal to obtain a beam signal.

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

[0068] In an optional embodiment, in step S4, the frequency domain signals of each loudspeaker unit are added after weighted phase compensation according to the total time delay of each loudspeaker unit, and the specific calculation manner is as follows:

[0069]

[0070] wherein τ i is the total time delay of the i-th loudspeaker unit, f i is the frequency domain signal of the i-th loudspeaker unit, and U i is the amplitude beam control amount of the i-th loudspeaker unit.

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

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

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

[0074] In an optional embodiment, further comprising: 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.

[0075] Specifically, the communication between the DSP module and the FPGA module is established by IIS (Internet Information Service), a high-efficiency data transmission format and timing are defined, the calculation efficiency of the beam synthesis is improved, and the flexibility of the directional broadcast is ensured.

[0076] The embodiments disclosed in the specification are only an example of the one-sided features of the present application, and the protection scope of the present application is not limited to this embodiment. Any other functionally equivalent embodiments fall within the protection scope of the present application. For those skilled in the art, other various corresponding changes and modifications can be made according to the above-described technical solutions and concepts, and all these changes and modifications should belong to the protection scope of the claims of the present application.

Claims

1. A method for directional broadcasting based on beam synthesis and constant beamwidth, characterized in that, The method comprises the following steps: S1. obtaining a directional broadcast target, the DSP module simulates bending of the linear array according to the directional broadcast target, generates a virtual arc, and calculates a first time delay of each speaker unit according to an offset of each speaker unit from the linear array to the virtual arc; S2. the DSP module calculates a delay of beam synthesis of each speaker unit according to a direction of the directional broadcast target, and calculates a second time delay of each speaker unit according to a delay weighting of each speaker unit; S3. the DSP module sends the virtual arc and the first time delay and the second time delay of each speaker unit to the FPGA module, the FPGA module calculates a total time delay of each speaker unit in parallel according to the first time delay and the second time delay of each speaker unit, and calculates an amplitude beam control amount of each speaker unit according to the virtual arc; S4. each speaker unit outputs a signal, the FPGA module performs weighting processing on the output signal of each speaker unit in parallel according to the amplitude beam control amount of each speaker unit, and then adds the output signals to synthesize a beam signal and output the beam signal, In step S3, the FPGA module calculates the total time delay of each speaker unit in parallel according to the first time delay and the second time delay of each speaker unit, and the specific implementation manner is that the FPGA module calculates the total time delay of each speaker unit by using a distributed pipeline method, In step S4, the FPGA module performs weighting processing on the output signal of each speaker unit in parallel according to the amplitude beam control amount of each speaker unit, and then adds the output signals, and the specific implementation manner is that: The FPGA module performs fast Fourier transform on the output signal of each speaker unit in parallel to obtain a frequency domain signal of each speaker unit, the FPGA module performs weighting phase compensation on the frequency domain signal of each speaker unit according to the total time delay of each speaker unit, and then adds the frequency domain signals to obtain a beam frequency domain signal, and the FPGA module performs inverse Fourier transform on the beam frequency domain signal to obtain a beam signal.

2. The method of claim 1, wherein, 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 manner is that the number of speaker units in the linear array is M, the spacing between adjacent speaker units is d, and the radius R of the virtual arc is: Wherein, the total length of the array , is half of the virtual arc angle, the offset between the bending of each loudspeaker unit from the linear array to the virtual arc is calculated according to the virtual arc radius, and the first time delay of each loudspeaker unit is calculated according to the offset .

3. The method of claim 2, wherein, In step S2, the delay of each loudspeaker unit beam synthesis is calculated, which is specifically implemented as: the angle between the axis of the virtual arc and the horizontal axis is Then the wave path difference of adjacent elements is Then the second time delay for the i-th loudspeaker unit is ​ Wherein, C is the speed of sound, i = 1, 2, 3, …, M-1.

4. The method of claim 2, wherein, In step S3, the amplitude beam steering amount of each loudspeaker unit is calculated according to the virtual arc, and the specific implementation manner is: for the i-th loudspeaker unit, the amplitude beam steering amount The calculation formula is: wherein is the normalized angle, , is the elevation angle in the spherical coordinates of the i-th loudspeaker unit in the virtual arc.

5. The method of claim 1, wherein, In step S4, the frequency domain signal of each speaker unit is added after weighting phase compensation according to the total time delay of each speaker unit, and the specific calculation manner is that: wherein, is the total time delay for the i-th speaker unit, is the frequency domain signal for the i-th speaker unit, is the amplitude beam steering amount for the i-th speaker unit.

6. The method of claim 1, wherein, The DSP module and the FPGA module exchange data through an I2S communication interface.

7. The method of claim 1, wherein, Further comprising: A sensor is arranged to detect environmental noise, and the DSP module adjusts the beam gain according to the environmental noise.

8. The method of claim 1, wherein, Before step S1, further comprising: connecting the DSP module and the FPGA module, and testing the communication efficiency and data exchange delay between the DSP module and the FPGA module.

Images