A long-distance wireless public broadcasting directional sound box array method and system

Abstract

The application discloses a long-distance wireless public broadcasting directional sound box array method and system, and directional sound box arrays and a management host are connected through WIFI-Mesh technology to form a network structure, the management host is a root node of the network structure, and each directional sound box of the directional sound box array is a sub-node of the network structure, and the method comprises the following steps: the management host sends a network-wide synchronization TFS timestamp to each directional sound box of the directional sound box array at a fixed time, so that all the directional sound boxes are network-wide time synchronized based on the network-wide synchronization TFS timestamp; and a target directional sound box receives an audio data packet sent by the management host and synchronously plays the audio data packet. Through WIFI-Mesh beacon absolute synchronization time, the application solves the problem that public broadcasting sound is not synchronized and not continuously played due to network transmission jitter, playing buffer and other reasons when an internet intelligent sound box downloads a music file on the market.

Description

Technical Field

[0001] This invention relates to the field of wireless broadcasting technology, and specifically to a method and system for a long-distance wireless public broadcasting directional speaker array. Background Technology

[0002] Currently, public address systems not only have complex wiring, but also suffer from problems such as asynchronous broadcasting from multiple points, significant delays, and auditory echoes, as detailed below:

[0003] Traditional wired public address speakers undoubtedly increase the complexity of site construction;

[0004] Traditional UHF wireless speakers are limited by short range (around 50 meters), building obstructions, and interference from co-channel and adjacent-channel signals, making it impossible to create large-area public address speaker arrays, such as those used in schools, parks, communities, and multi-story production workshops.

[0005] Bluetooth smart network speakers, limited by the short-range indoor transmission of Bluetooth, cannot meet the application scenarios of long-range outdoor transmission.

[0006] Because traditional public address speakers are far apart, the time difference between the sound waves from adjacent speakers reaching the listener is often greater than 50 milliseconds. This results in the Haas effect, where listeners can clearly hear the delayed sound source, like an echo, creating an uncomfortable auditory experience. Summary of the Invention

[0007] To overcome the shortcomings of the prior art, the purpose of this invention is to provide a method and system for a long-range wireless public address directional speaker array. This system uses WIFI-Mesh beacons for absolute time synchronization to solve the problem of asynchronous and discontinuous playback of public address audio caused by network transmission jitter and playback buffering when downloading music files on smart speakers on the market.

[0008] To address the aforementioned problems, the first aspect of this invention discloses a method for using a long-range wireless public address directional speaker array. The directional speaker array and a management host form a network structure using WIFI-Mesh technology. The management host serves as the root node of the network structure, and each directional speaker in the array serves as a child node of the network structure. The method includes the following steps:

[0009] The management host periodically sends a network-wide synchronization TFS timestamp to each directional speaker in the directional speaker array so that all directional speakers can synchronize their time across the network based on the network-wide synchronization TFS timestamp.

[0010] The target-oriented speaker receives audio data packets sent by the management host and plays the audio data packets synchronously;

[0011] or,

[0012] When the management host sends audio data packets to each target directional speaker in the directional speaker array, it carries a network-wide synchronized TFS timestamp.

[0013] After receiving the audio data packet, the target directional speaker obtains the network-wide synchronized TFS timestamp, performs network-wide time synchronization based on the network-wide synchronized TFS timestamp, and then plays the audio data packet synchronously.

[0014] As a preferred embodiment, in the first aspect of the present invention, the network-wide synchronized TFS timestamp is generated by the router node or by the WIFI wireless module of the management host; and / or the management host performs digital encoding compression on the input audio signal, adds forward error correction redundancy packets, and forms the audio data packet. After receiving the audio data packet, the target directional speaker performs wireless packet loss detection on the audio data packet. If packet loss exists, it performs an XOR operation through forward error correction redundancy technology to restore the audio data packet.

[0015] In a preferred embodiment, in the first aspect of the present invention, the method further includes:

[0016] The positions of each directional speaker in the directional speaker array are set so that the sound heard by the listener within the coverage area of ​​the directional speaker is perceived as coming from the same directional speaker.

[0017] As a preferred embodiment, in the first aspect of the present invention, the position of each directional speaker in the directional speaker array is set, including:

[0018] Each directional speaker is set to have the same coverage radius. Any three adjacent directional speakers that are not on the same straight line form an equilateral triangle. The sound of any two adjacent directional speakers has an overlapping coverage area, which is denoted as the overlapping area.

[0019] The coverage radius of each directional speaker is determined based on the maximum width of the overlapping area of ​​two adjacent directional speakers and the voltage difference.

[0020] The coordinates of each directional speaker are determined based on the coverage radius and the height of the equilateral triangle.

[0021] As a preferred embodiment, in the first aspect of the present invention, determining the coverage radius of each directional speaker based on the maximum width of the overlapping area of ​​two adjacent directional speakers and the voltage difference includes:

[0022] Let two adjacent directional speakers be labeled as the first directional speaker and the second directional speaker, respectively. Let the line connecting the first directional speaker and the second directional speaker be labeled as the first connecting line, and let the intersection of the first connecting line with the first directional speaker and the second directional speaker be labeled as the first intersection point and the second intersection point, respectively. Let the distance between the first intersection point and the first directional speaker be labeled as the first distance, and let the distance between the first intersection point and the second intersection point be labeled as the second distance. The second distance is the maximum width of the overlapping area of ​​any two adjacent directional speakers.

[0023] The maximum width and voltage difference of the overlap region between the two adjacent directional speakers are determined based on the Haas effect:

[0024] D≤V*t (1)

[0025]

[0026] r = r1 + D (3)

[0027] The coverage radius of each directional speaker is obtained according to the above formulas (1), (2) and (3):

[0028]

[0029] Where D is the maximum width, V is the speed of sound in the air, t is the time difference between the direct sound and the early reflected sound in the same space, ΔL is the pressure difference between the direct sound and the early reflected sound in the same space, t and ΔL are both set values, r is the coverage radius of the directional speaker, and r1 is the first distance.

[0030] As a preferred embodiment, in a first aspect of the present invention, determining the coordinates of each directional speaker based on the coverage radius and the height of the equilateral triangle includes:

[0031] Define the coordinates of the directional speaker corresponding to the i-th row and j-th column as (X... i Y j Given that the coordinates of the directional speaker in the first row and first column are (0, 0), then:

[0032]

[0033] Y j = (j-1)*H (5)

[0034] Where i≥1, j≥1, MOD() is the modulo operation, H is the height of the equilateral triangle, and:

[0035]

[0036] The coordinates of all directional speakers are determined based on the above formulas (4), (5) and (6).

[0037] The second aspect of this invention discloses a long-range wireless public address directional speaker array system, which includes a directional speaker array composed of multiple directional speakers and a management host. The directional speaker array and the management host form a network structure through WIFI-Mesh technology. The management host serves as the root node of the network structure, and each directional speaker in the directional speaker array serves as a child node of the network structure.

[0038] The management host periodically sends a network-wide synchronization TFS timestamp to each directional speaker in the directional speaker array, so that all the directional speakers can synchronize their time across the network based on the network-wide synchronization TFS timestamp; after receiving the audio data packets sent by the management host, the target directional speaker plays the audio data packets synchronously.

[0039] or,

[0040] When the management host sends an audio data packet to each target directional speaker in the directional speaker array, it carries a network-wide synchronized TFS timestamp. After receiving the audio data packet, the target directional speaker obtains the network-wide synchronized TFS timestamp, performs network-wide time synchronization based on the network-wide synchronized TFS timestamp, and then plays the audio data packet synchronously.

[0041] As a preferred embodiment, in the second aspect of the present invention, the network-wide synchronized TFS timestamp is generated by the router node or by the WIFI wireless module of the management host; and / or the management host performs digital encoding compression on the input audio signal, adds forward error correction redundancy packets, and forms the audio data packet. After receiving the audio data packet, the target directional speaker performs wireless packet loss detection on the audio data packet. If packet loss exists, it performs an XOR operation through forward error correction redundancy technology to restore the audio data packet.

[0042] As a preferred embodiment, in a second aspect of the present invention, the positions of each directional speaker in the directional speaker array are set so that the sound heard by the listener within the coverage area of ​​the directional speaker is perceived as being emitted from the same directional speaker.

[0043] As a preferred embodiment, in a second aspect of the present invention, the position of each directional speaker in the directional speaker array is set, including:

[0044] Each directional speaker is set to have the same coverage radius. Any three adjacent directional speakers that are not on the same straight line form an equilateral triangle. The sound of any two adjacent directional speakers has an overlapping coverage area, which is denoted as the overlapping area.

[0045] Let two adjacent directional speakers be labeled as the first directional speaker and the second directional speaker, respectively. Let the line connecting the first directional speaker and the second directional speaker be labeled as the first connecting line, and let the intersection of the first connecting line with the first directional speaker and the second directional speaker be labeled as the first intersection point and the second intersection point, respectively. Let the distance between the first intersection point and the first directional speaker be labeled as the first distance, and let the distance between the first intersection point and the second intersection point be labeled as the second distance. The second distance is the maximum width of the overlapping area of ​​any two adjacent directional speakers.

[0046] The maximum width and voltage difference of the overlap region between the two adjacent directional speakers are determined based on the Haas effect:

[0047] D≤V*t (7)

[0048]

[0049] r = r1 + D (9)

[0050] The coverage radius of each directional speaker is obtained according to the above formulas (7), (8) and (9):

[0051]

[0052] Where D is the maximum width, V is the speed of sound in the air, t is the time difference between the direct sound and the early reflected sound in the same space, ΔL is the pressure difference between the direct sound and the early reflected sound in the same space, t and ΔL are both set values, r is the coverage radius of the directional speaker, and r1 is the first distance.

[0053] Define the coordinates of the directional speaker corresponding to the i-th row and j-th column as (X... i Y j Given that the coordinates of the directional speaker in the first row and first column are (0, 0), then:

[0054]

[0055] Y j = (j-1)*H (11)

[0056] Where i≥1, j≥1, MOD() is the modulo operation, H is the height of the equilateral triangle, and:

[0057]

[0058] Based on the above formulas (10), (11) and (12), the coordinates of all directional speakers are determined, thus completing the setting of the position of each directional speaker in the directional speaker array.

[0059] Compared with existing technologies, its advantages are as follows:

[0060] 1. This invention solves the problem of asynchronous public address system audio, which sounds like an echo and is discontinuous, caused by network transmission jitter and playback buffering when downloading music files on smart speakers on the market, through absolute synchronization of time via WIFI-Mesh beacons.

[0061] 2. WIFI-Mesh networking meets the usage range of a wider area, such as the public broadcasting needs of schools, parks, communities and multi-story production workshops. The management host supports the push of sound from mobile phones and computers using the Internet DLNA protocol, supports downloading broadcast content from the cloud, and supports microphone input. It solves the wiring problem of the original wired network public broadcasting speakers and the problem of short distance of UHF wireless speakers and Bluetooth smart speakers.

[0062] 3. By setting the position coordinates of the directional speakers, we can create a more convenient, more comfortable, and wire-free long-distance public address directional speaker array product for customers, thereby enhancing the product's competitiveness and commercial value in the same industry market. Attached Figure Description

[0063] Figure 1 This is a flowchart illustrating the long-distance wireless public address directional speaker array method disclosed in Embodiment 1 of the present invention;

[0064] Figure 2 This is a schematic diagram showing the placement of the two directional speakers disclosed in an embodiment of the present invention;

[0065] Figure 3 This is a schematic diagram showing the placement of multiple directional speakers as disclosed in an embodiment of the present invention;

[0066] Figure 4 This is a flowchart illustrating the long-distance wireless public address directional speaker array method disclosed in Embodiment 2 of the present invention;

[0067] Figure 5 This is a schematic diagram of the structure of the long-distance wireless public address directional speaker array system disclosed in Embodiment 3 of the present invention. Detailed Implementation

[0068] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

[0069] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0070] The term "comprising" and any variations thereof in the specification and claims of this application are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product or device.

[0071] In embodiments of the present invention, the terms "exemplarily" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplarily" or "for example" in embodiments of the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the terms "exemplarily" or "for example" is intended to present the relevant concepts in a specific manner.

[0072] The following is a detailed description in conjunction with the accompanying drawings.

[0073] Example 1

[0074] The long-range wireless public address system in this embodiment of the invention refers to a network structure formed by a management host and N directional speakers within a predetermined area of ​​a certain large area. This network structure can be a tree structure, a mesh structure, or a star structure, etc., and its form is not limited here. The management host serves as the root node of this network structure, and each directional speaker serves as a child node of the network structure. The directional speakers can be arranged in each corner of the predetermined area, with N directional speakers forming a directional speaker array.

[0075] The management host has a built-in WIFI wireless module to establish the root node of the WIFI-Mesh wireless network. The management host also has a built-in wired network module to access the Internet, and can also have a built-in sound card to support microphone input.

[0076] Therefore, the management host can acquire audio media resources through the LAN protocol, the cloud, and microphone input. The management host performs digital encoding and compression on the input audio media, adds forward error correction redundancy packets, and packages the full network synchronization TFS timestamp of the WIFI-Mesh into the audio data packet. It then multicasts the data to all wireless public address speaker devices that have joined the WIFI-Mesh network.

[0077] Directional speakers have directional sound propagation, which can limit the sound to propagate within a local area and has a clear sound boundary. When installing, they can be suspended from poles at the same height, and a sound cover can be used to further limit the sound propagation within a local area. Within a certain height range, the sound propagation range of each directional speaker can be considered approximately circular.

[0078] The directional speaker has a built-in WIFI wireless module. When powered on, it automatically joins the WIFI-Mesh network established by the management host, receives beacon frames of the WIFI-Mesh network, and participates in calculating the full network operation synchronization TFS time of the WIFI-Mesh.

[0079] Specifically, please refer to Figure 1 As shown, a method for a long-range wireless public address directional speaker array may include the following steps:

[0080] S110. The management host periodically sends a network-wide synchronization TFS timestamp to each directional speaker in the directional speaker array so that all directional speakers can synchronize their time across the network based on the network-wide synchronization TFS timestamp.

[0081] According to the WIFI standard, each WIFI chip has a 64-bit counter that increments by 1 every microsecond and overflows after 585,000 years. This counter is called the TSF (Timing Synchronization Function) counter in the WIFI standard. At the same time, the value of this counter can be used as a unique timestamp, which is recorded as the TFS timestamp.

[0082] According to the 802.11 standard, when a Wi-Fi device (referring to the management host) establishes a data transmission link between a site and an access point, the router (AP) periodically sends beacon frames. The frames carry the corresponding 64-bit timestamp information. The Wi-Fi device synchronizes the 64-bit timestamp of the received beacon frame to its local TSF (Timing Synchronization Function) counter to keep the local TSF time value consistent with the access point's time, thereby achieving time synchronization.

[0083] After receiving the TFS timestamp periodically sent by the router AP, the management host sends the TFS timestamp to each directional speaker in the directional speaker array. Therefore, the TFS timestamp here can be called the network-wide synchronization TFS timestamp based on its function. Each directional speaker receives the network-wide synchronization TFS timestamp and participates in calculating the network-wide synchronization TFS time of the WIFI-Mesh, thereby synchronizing the time of the entire network structure. This is the basis for listeners in the preset area to hear comfortable sound. Here, comfortable sound means that the sound feels like it is coming from a single directional speaker, rather than from multiple different directional speakers.

[0084] In other embodiments, the beacon frame carrying the corresponding 64-bit calculator timestamp information, i.e., the network-wide synchronized TFS timestamp, can also be generated by the WIFI module of the management host and sent to each directional speaker.

[0085] S120. The target-oriented speaker receives the audio data packet sent by the management host and plays the audio data packet synchronously.

[0086] Target-oriented speakers refer to directional speakers that receive audio data packets according to the multicast method of the management host. In a preferred embodiment of the present invention, they refer to all directional speakers that are powered on and running.

[0087] The management host can acquire audio media resources through the DLNA protocol, the cloud, and microphone input. Then, it digitally encodes and compresses the input audio media to form audio data packets, adds forward error correction redundancy packets, and packages the full network synchronization TFS timestamp of the WIFI-Mesh into the audio data packets. The data packets are then multicast to all target directional speakers that have joined the WIFI-Mesh network.

[0088] The target-oriented speaker receives WIFI-Mesh multicast audio data packets from the management host and can also perform wireless packet loss detection. If packet loss occurs, it uses Forward Error Correction (FEC) to perform an XOR operation to restore the data packets. Testing showed that with 100% redundancy (10% to 20% of media packets), it can resolve data restoration issues.

[0089] Therefore, the WIFI-Mesh network composed of directional speakers and management host has the characteristics of high speed and low latency, with a bus speed of up to 20Mbps, and can set up 1024 directional speaker nodes.

[0090] S130. The positions of each directional speaker in the directional speaker array are set so that the sound heard by the listener within the coverage area of ​​the directional speaker is perceived as coming from the same directional speaker.

[0091] The positioning of each directional speaker in the directional speaker array in this embodiment of the invention is based on the Haas effect of human hearing.

[0092] The Haas effect essentially explains the relationship between direct sound and early reflections in the same space. The conclusion is that as long as the time difference between the early reflections (the sound obtained after one, two, or multiple reflections of the direct sound) and the direct sound (the sound that reaches the listener directly from the directional speaker) is less than t (t is a set value, which can be set from 20ms to 50ms, depending on the scenario requirements; for example, if the scenario requires high precision, it can be set to 25ms, and if the precision requirement is low, it can be set to 40ms, etc.), and the sound pressure difference remains within ΔL (D is a set value, which can be set from -5dB to -20dB, depending on the scenario requirements; for example, if the scenario requires high precision, it can be set to -8dB, and if the precision requirement is low, it can be set to -15dB, etc.), then the two sounds will be perceived as the same sound.

[0093] For example, taking t = 35 ms as an example, given that the speed of sound in air V is approximately 340 m / s, the distance D that the sound travels is:

[0094] D=V*t=340*0.035=11.9m.

[0095] In other words, when two directional speakers play sound sources simultaneously, and the sound pressure difference is kept within ΔL, and the distance difference between them reaching the human ear is less than 11.9 meters, the human ear will perceive them as the same sound.

[0096] like Figure 2 The two dots in the diagram represent the placement positions of the two directional speakers, and the two circles represent the sound coverage areas of the directional speakers. The maximum width (D) of the overlapping area of ​​their coverage areas is controlled within 11.9 meters to ensure that the time difference between the sound source of the two directional speakers and the overlapping area is within 35 milliseconds. Simultaneously, the sound pressure difference between points r1 and r must be less than 10 dB to ensure that the two directional speakers are perceived as the same sound.

[0097] Based on the above principle, the position of each directional speaker in the directional speaker array can be set, which may include the following steps:

[0098] Assume that all directional speakers have the same coverage radius, and that any three adjacent directional speakers that are not on the same straight line form an equilateral triangle, with any two adjacent directional speakers having overlapping coverage areas, denoted as the overlapping region. Figure 3 As shown.

[0099] Let two adjacent directional speakers be designated as the first directional speaker and the second directional speaker, respectively. Let the line connecting the first directional speaker and the second directional speaker be designated as the first connecting line, and let the intersections of the first connecting line with the first directional speaker and the second directional speaker be designated as the first intersection point and the second intersection point, respectively. Let the distance between the first intersection point and the first directional speaker be designated as the first distance, and let the distance between the first intersection point and the second intersection point be designated as the second distance. The second distance is the maximum width of the overlapping area of ​​any two adjacent directional speakers.

[0100] The maximum width and voltage difference of the overlap region between the two adjacent directional speakers are determined based on the Haas effect:

[0101] D≤V*t (1)

[0102]

[0103] r = r1 + D (3)

[0104] The coverage radius of each directional speaker is obtained according to the above formulas (1), (2) and (3):

[0105]

[0106] Where D is the maximum width, V is the speed of sound in the air, t is the time difference between the direct sound and the early reflected sound in the same space, ΔL is the pressure difference between the direct sound and the early reflected sound in the same space, t and ΔL are both set values, r is the coverage radius of the directional speaker, and r1 is the first distance.

[0107] Assuming t = 35ms and 0 > ΔL > -10dB, we can obtain r > 17.4m. Therefore, when arranging a directional speaker array, the coverage range of the selected directional speakers needs to be greater than 17.4m.

[0108] Based on the above conclusions, the coordinate layout of the two-dimensional directional speakers can be derived from the one-dimensional placement scheme as follows: Figure 3 As shown.

[0109] Define the coordinates of the directional speaker corresponding to the i-th row and j-th column as (X... i Y j Given that the coordinates of the directional speaker in the first row and first column are (0, 0), then:

[0110]

[0111] Y j = (j-1)*H (5)

[0112] Where i≥1, j≥1, MOD() is the modulo operation, H is the height of the equilateral triangle, and:

[0113]

[0114] Based on the above formulas (4), (5) and (6), the coordinates of all directional speakers are determined, thus completing the setting of the position of each directional speaker in the directional speaker array.

[0115] Since the directional speakers are suspended from poles at the same height, the coordinates of the directional speakers here refer to planar coordinates within the same plane.

[0116] If directional speakers are arranged according to the above coordinates and all directional speakers play synchronously at the same volume, then a sound can be heard in any corner of a large preset area.

[0117] Example 2

[0118] Please refer to Figure 4 As shown, a method for a long-range wireless public address directional speaker array may include the following steps:

[0119] S210. When the management host sends audio data packets to each target directional speaker in the directional speaker array, it carries a network-wide synchronized TFS timestamp.

[0120] S220. After receiving the audio data packet, the target directional speaker obtains the network-wide synchronized TFS timestamp, performs network-wide time synchronization based on the network-wide synchronized TFS timestamp, and then plays the audio data packet synchronously.

[0121] S230. The positions of each directional speaker in the directional speaker array are set so that the sound heard by the listener within the coverage area of ​​the directional speaker is perceived as coming from the same directional speaker.

[0122] The difference between Embodiment 2 and Embodiment 1 lies in that Embodiment 1 performs network-wide time synchronization first, followed by multicasting of audio data packets, while Embodiment 2 carries a network-wide synchronized TFS timestamp with each audio data packet transmission. Relatively speaking, Embodiment 1 improves efficiency and reduces the number of time synchronization operations, but its time synchronization accuracy may not be as precise as Embodiment 2. Embodiment 2 improves time synchronization accuracy, but because it requires carrying a network-wide synchronized TFS timestamp with each audio data packet transmission, and each directional speaker also needs to perform calculations to achieve time synchronization, its efficiency is relatively low, and there is a possibility of network congestion.

[0123] Example 3

[0124] Please refer to Figure 5As shown, a long-range wireless public address directional speaker array system includes a directional speaker array composed of multiple directional speakers (each circle in the figure represents a directional speaker) and a management host. The directional speaker array and the management host form a network structure through WIFI-Mesh technology. The management host serves as the root node of the network structure, and each directional speaker in the directional speaker array serves as a child node of the network structure.

[0125] The management host periodically sends a network-wide synchronization TFS timestamp to each directional speaker in the directional speaker array, so that all the directional speakers can synchronize their time across the network based on the network-wide synchronization TFS timestamp; after receiving the audio data packets sent by the management host, the target directional speaker plays the audio data packets synchronously.

[0126] or,

[0127] When the management host sends an audio data packet to each target directional speaker in the directional speaker array, it carries a network-wide synchronized TFS timestamp. After receiving the audio data packet, the target directional speaker obtains the network-wide synchronized TFS timestamp, performs network-wide time synchronization based on the network-wide synchronized TFS timestamp, and then plays the audio data packet synchronously.

[0128] Preferably, the network-wide synchronized TFS timestamp is generated by the router node or by the WIFI wireless module of the management host; or / and, the management host performs digital encoding and compression on the input audio signal, adds forward error correction redundancy packets, and forms the audio data packet. After receiving the audio data packet, the target directional speaker performs wireless packet loss detection on the audio data packet. If packet loss exists, it performs an XOR operation through forward error correction redundancy technology to restore the audio data packet.

[0129] Preferably, the positions of each directional speaker in the directional speaker array are set so that the sound heard by a listener within the coverage area of ​​the directional speakers appears to be emitted from the same directional speaker. Specifically, this may include:

[0130] Setting the position of each directional speaker in the directional speaker array includes:

[0131] Each directional speaker is set to have the same coverage radius. Any three adjacent directional speakers that are not on the same straight line form an equilateral triangle. The sound of any two adjacent directional speakers has an overlapping coverage area, which is denoted as the overlapping area.

[0132] Let two adjacent directional speakers be labeled as the first directional speaker and the second directional speaker, respectively. Let the line connecting the first directional speaker and the second directional speaker be labeled as the first connecting line, and let the intersection of the first connecting line with the first directional speaker and the second directional speaker be labeled as the first intersection point and the second intersection point, respectively. Let the distance between the first intersection point and the first directional speaker be labeled as the first distance, and let the distance between the first intersection point and the second intersection point be labeled as the second distance. The second distance is the maximum width of the overlapping area of ​​any two adjacent directional speakers.

[0133] The maximum width and voltage difference of the overlap region between the two adjacent directional speakers are determined based on the Haas effect:

[0134] D≤V*t (7)

[0135]

[0136] r = r1 + D (9)

[0137] The coverage radius of each directional speaker is obtained according to the above formulas (7), (8) and (9):

[0138]

[0139] Where D is the maximum width, V is the speed of sound in the air, t is the time difference between the direct sound and the early reflected sound in the same space, ΔL is the pressure difference between the direct sound and the early reflected sound in the same space, t and ΔL are both set values, r is the coverage radius of the directional speaker, and r1 is the first distance.

[0140] Define the coordinates of the directional speaker corresponding to the i-th row and j-th column as (X... i Y j Given that the coordinates of the directional speaker in the first row and first column are (0, 0), then:

[0141]

[0142] Y j = (j-1)*H (11)

[0143] Where i≥1, j≥1, MOD() is the modulo operation, H is the height of the equilateral triangle, and:

[0144]

[0145] Based on the above formulas (10), (11) and (12), the coordinates of all directional speakers are determined, thus completing the setting of the position of each directional speaker in the directional speaker array.

[0146] The present invention has provided a detailed description of a long-range wireless public address directional speaker array method and system. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for using a long-range wireless public address directional speaker array, characterized in that, The directional speaker array and the management host form a network structure using WIFI-Mesh technology. The management host serves as the root node of the network structure, and each directional speaker in the directional speaker array serves as a child node of the network structure. The process includes the following steps: The positions of each directional speaker in the directional speaker array are set; The management host periodically sends a network-wide synchronization TFS timestamp to each directional speaker in the directional speaker array so that all directional speakers can synchronize their time across the network based on the network-wide synchronization TFS timestamp. The target-oriented speaker receives audio data packets sent by the management host and plays the audio data packets synchronously; or, When the management host sends audio data packets to each target directional speaker in the directional speaker array, it carries a network-wide synchronized TFS timestamp. After receiving the audio data packet, the target directional speaker obtains the network-wide synchronized TFS timestamp, performs network-wide time synchronization based on the network-wide synchronized TFS timestamp, and then plays the audio data packet synchronously. The setting of the position of each directional speaker in the directional speaker array includes: Each directional speaker is set to have the same coverage radius. Any three adjacent directional speakers that are not on the same straight line form an equilateral triangle. The sound of any two adjacent directional speakers has an overlapping coverage area, which is denoted as the overlapping area. The coverage radius of each directional speaker is determined based on the maximum width of the overlapping area of ​​two adjacent directional speakers and the voltage difference. The coordinates of each directional speaker are determined based on the coverage radius and the height of the equilateral triangle; The coverage radius of each directional speaker is determined based on the maximum width of the overlap area between two adjacent directional speakers and the voltage difference, including: Let two adjacent directional speakers be labeled as the first directional speaker and the second directional speaker, respectively. Let the line connecting the first directional speaker and the second directional speaker be labeled as the first connecting line, and let the intersection of the first connecting line with the first directional speaker and the second directional speaker be labeled as the first intersection point and the second intersection point, respectively. Let the distance between the first intersection point and the first directional speaker be labeled as the first distance, and let the distance between the first intersection point and the second intersection point be labeled as the second distance. The second distance is the maximum width of the overlapping area of ​​any two adjacent directional speakers. The maximum width and voltage difference of the overlap region between the two adjacent directional speakers are determined based on the Haas effect: （1） （2） （3） The coverage radius of each directional speaker is obtained according to the above formulas (1), (2) and (3): Where D is the maximum width, V is the speed of sound in the air, t is the time difference between the direct sound and the early reflected sound in the same space, ΔL is the pressure difference between the direct sound and the early reflected sound in the same space, t and ΔL are both set values, r is the coverage radius of the directional speaker, and r1 is the first distance.

2. The method for long-distance wireless public address directional speaker array according to claim 1, characterized in that, The network-wide synchronized TFS timestamp is generated by the router node or by the WIFI wireless module of the management host; and / or the management host performs digital encoding and compression on the input audio signal, adds forward error correction redundancy packets, and forms the audio data packet. After receiving the audio data packet, the target directional speaker performs wireless packet loss detection on the audio data packet. If packet loss exists, it performs an XOR operation through forward error correction redundancy technology to restore the audio data packet.

3. The method for long-distance wireless public address directional speaker array according to claim 1, characterized in that, The coordinates of each directional speaker are determined based on the coverage radius and the height of the equilateral triangle, including: Define the coordinates of the directional speaker corresponding to the i-th row and j-th column as (X... i Y j Given that the coordinates of the directional speaker in the first row and first column are (0, 0), then: （4） （5） Where i≥1, j≥1, MOD() is the modulo operation, H is the height of the equilateral triangle, and: （6） The coordinates of all directional speakers are determined based on the above formulas (4), (5) and (6).

4. A long-range wireless public address directional speaker array system, characterized in that, It includes a directional speaker array consisting of multiple directional speakers and a management host. The directional speaker array and the management host form a network structure through WIFI-Mesh technology. The management host serves as the root node of the network structure, and each directional speaker in the directional speaker array serves as a child node of the network structure. The positions of each directional speaker in the directional speaker array are set; The management host periodically sends a network-wide synchronization TFS timestamp to each directional speaker in the directional speaker array, so that all the directional speakers can synchronize their time across the network based on the network-wide synchronization TFS timestamp. After receiving the audio data packet sent by the management host, the target directional speaker synchronously plays the audio data packet; or, When the management host sends audio data packets to each target directional speaker in the directional speaker array, it carries a network-wide synchronized TFS timestamp. After receiving the audio data packet, the target directional speaker obtains the network-wide synchronized TFS timestamp, performs network-wide time synchronization based on the network-wide synchronized TFS timestamp, and then plays the audio data packet synchronously. The setting of the position of each directional speaker in the directional speaker array includes: Each directional speaker is set to have the same coverage radius. Any three adjacent directional speakers that are not on the same straight line form an equilateral triangle. The sound of any two adjacent directional speakers has an overlapping coverage area, which is denoted as the overlapping area. Let two adjacent directional speakers be labeled as the first directional speaker and the second directional speaker, respectively. Let the line connecting the first directional speaker and the second directional speaker be labeled as the first connecting line, and let the intersection of the first connecting line with the first directional speaker and the second directional speaker be labeled as the first intersection point and the second intersection point, respectively. Let the distance between the first intersection point and the first directional speaker be labeled as the first distance, and let the distance between the first intersection point and the second intersection point be labeled as the second distance. The second distance is the maximum width of the overlapping area of ​​any two adjacent directional speakers. The maximum width and voltage difference of the overlap region between the two adjacent directional speakers are determined based on the Haas effect: （7） （8） （9） The coverage radius of each directional speaker is obtained according to the above formulas (7), (8) and (9): Where D is the maximum width, V is the speed of sound in the air, t is the time difference between the direct sound and the early reflected sound in the same space, ΔL is the pressure difference between the direct sound and the early reflected sound in the same space, t and ΔL are both set values, r is the coverage radius of the directional speaker, and r1 is the first distance.

5. The long-range wireless public address directional speaker array system according to claim 4, characterized in that, The network-wide synchronized TFS timestamp is generated by the router node or by the WIFI wireless module of the management host; and / or the management host performs digital encoding and compression on the input audio signal, adds forward error correction redundancy packets, and forms the audio data packet. After receiving the audio data packet, the target directional speaker performs wireless packet loss detection on the audio data packet. If packet loss exists, it performs an XOR operation through forward error correction redundancy technology to restore the audio data packet.

6. The long-range wireless public address directional speaker array system according to claim 4, characterized in that, Define the coordinates of the directional speaker corresponding to the i-th row and j-th column as (X... i Y j Given that the coordinates of the directional speaker in the first row and first column are (0, 0), then: （10） （11） Where i≥1, j≥1, MOD() is the modulo operation, H is the height of the equilateral triangle, and: （12） Based on the above formulas (10), (11) and (12), the coordinates of all directional speakers are determined, thus completing the setting of the position of each directional speaker in the directional speaker array.

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