Audio transmission system based on tree topology structure

Abstract

The present invention relates to the technical field of in-vehicle audio. Disclosed is an audio transmission system based on a tree topology structure. The system comprises: a host, which is used for acquiring topology information of an audio transmission network and establishing a routing table; the audio transmission network, which comprises a plurality of audio transmission nodes forming a tree topology structure, wherein the audio transmission nodes are used for acquiring and parsing data frames sent by other audio transmission nodes, transmitting the data frames to a target node on the basis of the routing table, and further used for generating, on the basis of acquired audio data and control information, a data frame to be sent, and querying the routing table to transmit the data frame until the data frame reaches the target node; and a peripheral device, which is used for processing the audio data by applying the target node connected to the peripheral device, and used for collecting the audio data and the control information. In the present invention, a tree topology system is constructed, and the same routing protocol is used for control information and audio data, thereby realizing the transfer of the audio data and control information between any nodes, and improving the data transmission efficiency and system flexibility.

Description

An audio transmission system based on a tree topology Technical Field

[0001] This invention relates to the field of vehicle audio technology, and in particular to an audio transmission system based on a tree topology. Background Technology

[0002] In the field of automotive audio, with the continuous increase of in-vehicle audio acquisition and playback devices, there is an urgent need for a high-efficiency, low-cost transmission solution that can transmit audio data to various locations in the vehicle for playback as needed and collect audio data from various locations in the vehicle and transmit it to the audio processor. While transmitting audio data, the audio processor also needs to control the audio playback and acquisition devices according to the requirements. This requires the transmission solution to support the transmission and response of control information at the same time. The current system mainly adopts a daisy chain topology, which only supports half-duplex transmission mode. It can only control other slave nodes through the audio processor docked at the master node, resulting in low transmission efficiency. In scenarios with multiple audio processors, this single system topology cannot meet the control requirements. Summary of the Invention

[0003] In view of the above-mentioned defects or deficiencies in the prior art, the present invention provides an audio transmission system based on a tree topology. By constructing a tree topology, the present invention covers the application scenarios of daisy chain topology. Audio data and control information adopt the same routing transmission protocol, which can realize the transmission of control information between any nodes.

[0004] This invention provides an audio transmission system based on a tree topology.

[0005] Host equipment, audio transmission network, and peripheral devices;

[0006] The audio transmission network includes multiple audio transmission nodes forming a tree topology, wherein the root node is connected to the host and at least one child node, and each child node is connected to the peripheral device.

[0007] The host is used to obtain the topology information of the audio transmission network and establish corresponding routing tables in the root node and each level of child nodes according to the obtained topology information.

[0008] The audio transmission node is used to acquire data frames sent by other audio transmission nodes, query the routing table based on the parsing result of the data frames to obtain the transmission path of the target node, and transmit the data frames to the target node according to the transmission path of the target node; and to generate data frames to be sent based on the acquired audio data and control information, query the routing table to obtain the transmission path corresponding to the target node, and transmit the data frames to be sent to the next audio transmission node according to the transmission path.

[0009] The peripheral device is used to process audio data based on the audio data and control information obtained from the target node it is connected to; and to collect audio data and control information and input them to the child node it is connected to.

[0010] Furthermore, the non-leaf nodes in the child nodes include an uplink communication interface, at least two downlink communication interfaces, a peripheral interface, and a data processing and routing module;

[0011] The uplink communication interface is used to receive downlink data frames from the previous audio transmission node and send the downlink data frames to the data processing and routing module.

[0012] The downlink communication interface is used to receive uplink data frames from the next-level audio transmission node and send the uplink data frames to the data processing and routing module.

[0013] The data processing and routing module is used to parse the data frame, output the data in the data frame from the peripheral interface according to the settings of the control register, add the data input from the peripheral interface to the uplink data frame or the downlink data frame, and then send it to the next audio transmission node through the uplink communication interface or the downlink communication interface.

[0014] Furthermore, the data frame includes a preamble, a synchronization subframe, several data segments, and a tail frame arranged in sequence.

[0015] The preamble uses a sequence that does not conform to the Manchester coding rules, while the synchronization subframe uses a sequence that conforms to the Manchester coding rules.

[0016] The synchronization subframe includes a synchronization control subframe and a synchronization response subframe. The root node periodically sends the synchronization control subframe at a predetermined frequency. The child node generates its own operating clock based on the synchronization control subframe sent by the root node and the phase-locked loop, and sends the synchronization control subframe to the next level child node through the downlink communication interface. After the leaf node receives the synchronization control subframe, it returns the synchronization response subframe through the uplink communication interface.

[0017] Furthermore, the plurality of data segments include simple data segments, control information data segments, and routing data segments; wherein, the simple data segment includes transmitted audio data and a first checksum; the control information data segment includes segment type, source node information, target node information, control information, and a second checksum; and the routing data segment includes segment type, target node information, audio data, and a third checksum.

[0018] Furthermore, the data processing and routing module is also used to control which simple data segments in the received data frame are used by the current audio transmission node through the control register, and to indicate in which simple data segments the received audio data is stored for transmission to the next level audio transmission node.

[0019] Furthermore, the data processing and routing module is also used to parse the received control information data segment to obtain target node information;

[0020] If the current audio transmission node is the target node, the data processing and routing module operates according to the control information, inserts the response information into the reverse transmission data frame according to the format of the control information data segment, and takes the current audio transmission node as the source node and the node that initiates the control information as the target node.

[0021] If the current audio transmission node is not the target node, the data processing and routing module queries the routing table to determine which output port the control information data segment will be transmitted to the next-level audio transmission node.

[0022] Furthermore, the data processing and routing module is also used to parse the received routing data segment to obtain target node information;

[0023] If the current audio transmission node is the target node, the data processing and routing module will output the audio data in the received routing data segment through the peripheral interface of the current audio transmission node.

[0024] If the current audio transmission node is not the target node, the data processing and routing module queries the routing table to determine which output port the routed data segment should be transmitted to the next-level audio transmission node.

[0025] Furthermore, when at least two downlink communication interfaces in the audio transmission node receive uplink data frames, the data processing and routing module merges the two uplink data frames and then sends them to the next-level audio transmission node through the uplink communication interface.

[0026] Furthermore, the leaf nodes in the child nodes have an uplink communication interface but no downlink communication interface. When the leaf node receives a synchronization control subframe, it sends a synchronization response subframe to the next higher-level audio transmission node through the uplink communication interface.

[0027] Furthermore, the root node is configured as a node with both uplink and downlink communication interfaces. The root node sends a data frame containing a synchronization control subframe through the downlink communication interface. If a synchronization response subframe is received from the downlink communication interface within a predetermined time, it is determined that the downlink communication interface is connected to a next-level node.

[0028] The next-level node of the root node is configured to have both uplink and downlink communication interfaces by using a synchronization control subframe. The next-level node of the root node continues to send the synchronization control subframe from the previous level to the next-level node through the downlink communication interface. If the downlink communication interface receives a synchronization response subframe within a predetermined time, it is determined that the downlink communication interface is connected to a next-level node. If it does not receive a synchronization response subframe within a predetermined time, it is determined that the downlink communication interface does not have a next-level node.

[0029] Repeat the above steps until no lower-level nodes can be found. Assign a unique number to each found node to obtain the topology information of the audio transmission network, and establish a corresponding routing table in each audio transmission node based on the obtained topology information.

[0030] This invention provides an audio transmission system based on a tree topology, which has the following advantages: The invention constructs a tree topology audio transmission system, covering daisy-chain system application scenarios. It adopts a full-duplex transmission mode, allowing uplink and downlink data frames to be transmitted simultaneously, supporting higher audio sampling frequencies and a larger number of nodes. It constructs routing tables for each node, introducing routing data segments on top of simple data segments, balancing audio data transmission efficiency and flexibility. Audio data and control information use the same routing transmission protocol, enabling the transmission of audio data and control information between any nodes. This eliminates the limitation in current daisy-chain systems where only the audio processor docked at the master node can control other slave node peripheral devices. Attached Figure Description

[0031] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0032] Figure 1 is a schematic diagram of an audio transmission system based on a tree topology according to an embodiment of the present invention;

[0033] Figure 2 is a schematic diagram of the structure of an audio transmission node in an audio transmission system based on a tree topology according to an embodiment of the present invention;

[0034] Figure 3 is an example of an audio transmission system based on a tree topology according to an embodiment of the present invention;

[0035] Figure 4 is a routing representation of an example of an audio transmission system based on a tree topology provided by an embodiment of the present invention;

[0036] Figure 5 is a flowchart illustrating an audio transmission method based on a tree topology according to an embodiment of the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0039] It should be understood that although the terms first, second, third, etc., may be used to describe the acquisition modules in the embodiments of the present invention, these acquisition modules should not be limited to these terms. These terms are only used to distinguish the acquisition modules from each other.

[0040] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0041] It should be noted that the directional terms such as "upper," "lower," "left," and "right" used in the embodiments of the present invention are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of the present invention. Furthermore, in the context, it should be understood that when it is mentioned that an element is formed "upper" or "lower" of another element, it can not only be formed directly "upper" or "lower" of the other element, but also indirectly "upper" or "lower" of the other element through an intermediate element.

[0042] Referring to Figure 1, this embodiment of the invention provides an audio transmission system based on a tree topology, which includes a host, an audio transmission network, and peripheral devices;

[0043] The audio transmission network comprises multiple audio transmission chips forming a tree-like topology, with each chip serving as an audio transmission node in the system. These audio transmission nodes are connected via a coaxial cable or twisted-pair cable, with the root node connected to the host and at least one child node, and each child node connected to the peripheral device.

[0044] Referring to Figure 2, a schematic diagram of an audio transmission node structure is provided. The non-leaf nodes in the child nodes include an uplink communication interface, at least two downlink communication interfaces, a peripheral interface, and a data processing and routing module. The peripheral interface includes an audio data interface conforming to the I2S / TDM / PDM protocol for connecting audio devices, and an I2C interface for connecting to a controller. The uplink communication interface receives downlink data frames from the previous-level audio transmission node and sends them to the data processing and routing module. The downlink communication interface receives uplink data frames from the next-level audio transmission node and sends them to the data processing and routing module. The data processing and routing module parses the data frames to obtain audio data and control information. Based on the settings of the control register, it outputs the audio data from the corresponding audio data interface for playback via an audio device such as a speaker. It also adds audio data collected by an audio device such as a microphone and control information input by the controller to the uplink or downlink data frames, and then sends them to the next audio transmission node via the uplink or downlink communication interface. Specifically, when at least two downlink communication interfaces in an audio transmission node receive uplink data frames, the data processing and routing module merges the two uplink data frames and then sends them to the next-level audio transmission node through the uplink communication interface. The transmission of downlink and uplink data frames between audio transmission nodes uses the same transmission medium, and transmission in both directions can occur simultaneously.

[0045] The data frame includes a preamble, a synchronization subframe, several data segments, and a tail frame arranged sequentially. The preamble uses a sequence that does not conform to the Manchester encoding rules, and the synchronization subframes use a sequence that conforms to the Manchester encoding rules. When the data frame receiver detects the preamble sequence, it prepares to receive the synchronization subframe. The first codeword that conforms to the Manchester encoding rules indicates the start of the synchronization subframe. The synchronization subframe includes a synchronization control subframe and a synchronization response subframe. The root node periodically sends the synchronization control subframe at a predetermined frequency, which is usually the audio data sampling frequency of the system. The child nodes generate their own operating clock based on the synchronization control subframe sent by the root node and the phase-locked loop, and send the synchronization control subframe to the next level child node through the downlink communication interface. This continues until the leaf node receives the synchronization control subframe and returns the synchronization response subframe through the uplink communication interface, thereby realizing the synchronization and control of the entire system. The leaf node is the last level child node that has an uplink communication interface but no downlink communication interface.

[0046] Several data segments include simple data segments, control information data segments, and routing data segments. Each data segment in a data frame is of equal size. The simple data segment includes the transmitted audio data and a first checksum. Preferably, this embodiment uses a CRC (Cyclic Redundancy Check) value as the checksum. The sender calculates the CRC value when loading the audio data and appends it to the end of the audio data to form a simple data segment. After receiving a simple data segment, the receiver calculates the CRC value and compares it with the received CRC value to check data integrity. On one hand, the data processing and routing module of the audio transmission node uses a control register to control which simple data segments in the received data frame will be used by the current audio transmission node. On the other hand, the control register also indicates which simple data segments the received audio data should be placed in before being sent to the next-level audio transmission node. The number of simple data segments in the data frame is fixed and can be set through the control register of the audio transmission node; each audio transmission node in the system needs to use the same setting. Since the simple data segment only contains audio data and its corresponding CRC value, and does not contain information such as the destination node, it has higher bandwidth utilization and higher audio data transmission efficiency. However, in the tree topology system of this embodiment, the simple data segment cannot flexibly realize data transmission between arbitrary nodes, especially dynamically changing the transmission path between nodes. If you want to change the target node of data transmission, you can only do so by setting the control register of the target node.

[0047] Therefore, based on the simple data segment transmission, this embodiment also introduces a control information data segment and a routing data segment to further realize the transmission of control information and audio data between any nodes, taking into account both the efficiency and flexibility of audio data transmission. The control information data segment and the routing data segment are placed after the simple data segment. After receiving the simple data segment, the audio transmission node can directly process the audio data. After receiving the control information data segment and the routing data segment, it needs to parse to obtain the segment type before performing corresponding processing.

[0048] The control information data segment includes segment type, source node information, target node information, control information, and a second checksum. This segment is used to transmit control information between audio transmission nodes according to the routing table. Each audio transmission node needs to parse the control information data segment through the data processing and routing module to obtain source and target node information. This allows them to determine if the current node is the target node. If it is, they operate according to the control information, such as writing the control information into a control register for subsequent processing of the received audio data, and inserting the response information into the reverse transmission data frame according to the control information data segment format. The response information is then sent back using the current audio transmission node as the source node and the node that initiated the control information as the target node. If the current audio transmission node is not the target node, the data processing and routing module queries the routing table to determine which output port the control information data segment should be transmitted to the next-level audio transmission node.

[0049] The routing data segment includes the segment type, target node information, audio data, and a third checksum. The routing data segment is used to transmit audio data between audio transmission nodes according to the routing table. The current audio transmission node obtains the target node information by parsing the routing data segment through the data processing and routing module. If the current node is the target node, the audio data in the received routing data segment is output through the peripheral interface of the current audio transmission node. If the current node is not the target node, the routing table is queried to determine which output port the routing data segment should be transmitted to the next-level audio transmission node.

[0050] The host is used to acquire the topology information of the audio transmission network and establish corresponding routing tables in the root node and each level of child nodes based on the acquired topology information. Specifically, the host performs a preorder traversal starting from the root node, configuring the root node as a node with both uplink and downlink communication interfaces. The root node then sends a data frame containing a synchronization control subframe through the downlink communication interface. If a synchronization response subframe is received from the downlink communication interface within a predetermined time, it is determined that the downlink communication interface is connected to a next-level node. The host then configures the next-level node of the root node to have both uplink and downlink communication interfaces through the synchronization control subframe. The node at the port, the next level node of the root node continues to send the synchronization control subframes from the previous level to the next level node through the downlink communication interface. If the downlink communication interface receives a synchronization response subframe within a predetermined time, it is determined that the downlink communication interface is connected to a next level node. If it does not receive a synchronization response subframe within the predetermined time, it is determined that the downlink communication interface does not have a next level node. The above steps are repeated until no next level node can be found. Each found node is assigned a unique number to obtain the topology information of the audio transmission network, and a corresponding routing table is established in each audio transmission node according to the obtained topology information.

[0051] For example, referring to Figure 3, an audio transmission system based on a tree topology is described. The host obtains the topology information of the audio transmission network of the system, designates the root node as master, and the child nodes as slave0, slave1, slave2, slave3, and slave4. Based on the topology information of the audio transmission network, a routing table is constructed for each audio transmission node as shown in Figure 4. Each node can query the routing table to determine which interface to use to transmit to the next node. Audio data and control information use the same routing transmission protocol, enabling the transmission of data and control information between any nodes. For example, when master sends a data frame to slave3, each node can query the routing table to find the transmission path as: master.B0, slave0.B0, slave1.B1, slave3; as another example, when slave4 sends a data frame to slave3, each node can query the routing table to find the transmission path as: slave4.A, slave2.A, slave0.B0, slave1.B1, slave3.

[0052] The audio transmission node acts as an intermediate node for audio transmission. It acquires data frames sent by other audio transmission nodes, queries the routing table based on the parsing results of the data frames to obtain the transmission path to the target node, and transmits the data frames to the target node according to the transmission path. For example, after the current node slave0 acquires a data frame containing audio data and control information sent by the master, it parses the data frame through the data processing and routing module. The parsing result reveals that the target node is slave3. The routing table is then queried to obtain the transmission path from the current node to the target node slave3, which is slave0.B0. Data frames are transmitted to slave1 via communication interface B0. Similarly, slave1 parses the data frames and queries the routing table, then transmits the data frames to slave3 via its communication interface B1. Slave3 parses the data frames to obtain control information and audio data, and determines that the current node is the target node. The data processing and routing module then transmits the audio data to the corresponding audio device through the required audio data interface according to the control information, and inserts the response information into the reverse transmission data frame according to the format of the control information data segment. With slave3 as the source node and master as the target node, the response information is sent back to master.

[0053] The audio transmission node is also used as a source node for audio transmission, generating a data frame to be sent based on the acquired audio data and control information, querying the routing table to obtain the transmission path corresponding to the target node, and transmitting the data frame to be sent to the next audio transmission node according to the transmission path.

[0054] Specifically, the source node acquires audio data and control information in the following ways: 1. It acquires control information from other nodes and acquires audio data locally. For example, the root node acquires control information from the connected host or the child node acquires control information from the connected controller. Then, it packages the control information into a control information fragment format and transmits it to the current audio transmission node. The current audio transmission node receives and parses the control information fragment to acquire the control information and writes it into the control register. The current audio transmission node acquires local audio data through the audio data interface. Using the current audio transmission node as the source node, it transmits the control information and audio data in a data frame format to the target node according to the control information. For example, in the system shown in Figure 3, the host writes the command "transfer the audio data collected by node slave4 to the target node slave3" to the master via the I2C bus. After obtaining the control information, the master transmits it to node slave4 in the form of control information fragments. The current node slave4 parses the control information fragments through the data processing and routing module, writes the control information to the control register, and obtains the audio data collected by the audio device such as the microphone through its audio data interface according to the control information. According to the routing table, to transmit the data frame to the target node slave3, the current node slave4's transmission path is slave4.A. The control information and audio data are then transmitted together. Data is transmitted in data frame format to the next node slave2 via its uplink communication interface A. Node slave2 parses the data frame through its data processing and routing module. Based on the target node information, it is confirmed that the current node slave2 is not the target node. According to the routing table query, slave2 needs to continue transmitting data frames to the next node slave0 via its uplink communication interface A until it is transmitted to node slave3. When it is transmitted to node slave3, slave3 parses the data frame through its data processing and routing module. Based on the target node information, it is confirmed that the current node slave3 is the target node. After processing the audio data according to the control information, it is transmitted to the designated audio playback device for playback through the audio data interface.

[0055] 2. Directly acquiring local control information and audio data: When the root node acts as the source node, it acquires control information and audio data through the connected host; when a child node acts as the source node, it acquires control information and audio data through the connected controller. For example, child node slave4 acts as the source node. The user can input commands through the controller it is connected to. The controller directly writes the command-related control information into slave4's control register via the I2C bus. After slave4 acquires the control information and local audio data transmitted via the audio data interface, it acts as the source node and transmits the control information and audio data in data frame format to the target node.

[0056] The peripheral devices include audio devices and controllers. For example, the audio devices include power amplifiers, speakers, and microphones. For instance, the speakers are used to receive audio data processed and sent by the connected audio transmission node, convert it into sound signals, and play it. The microphones are used to collect audio data and transmit it to the connected audio transmission node. The controllers are used to write control information to the connected audio transmission node via the I2C bus.

[0057] Referring to Figure 5, another embodiment of the present invention also provides an audio transmission method based on a tree topology, applied to an audio transmission method based on a tree topology shown in Figure 1, the method comprising:

[0058] Step S101: The host obtains the topology information of the audio transmission network and establishes corresponding routing tables in the root node and each level of child nodes according to the obtained topology information.

[0059] Step S102: The root node obtains audio data and control information from the host to generate a data frame to be sent, queries the routing table to obtain the transmission path corresponding to the target node, and transmits the data frame to be sent to the next audio transmission node according to the transmission path.

[0060] In step S103, the next audio transmission node parses the data frame through the data processing and routing module, queries the routing table based on the parsing result of the data frame to obtain the transmission path of the target node, and transmits the data frame to the target node according to the transmission path of the target node.

[0061] This invention provides an audio transmission system based on a tree topology. The tree topology covers daisy-chain system application scenarios and employs full-duplex transmission, allowing simultaneous transmission of uplink and downlink data frames. It supports higher audio sampling frequencies and a larger number of nodes. A routing table is constructed for each node, introducing control information data segments and routing data segments on top of simple data segments. This balances audio data transmission efficiency and flexibility. Audio data and control information use the same routing transmission protocol to enable the transmission of audio data and control information between any nodes, eliminating the limitation of current daisy-chain systems where only the audio processor docked at the master node can control other slave node peripheral devices.

[0062] The above description is merely a preferred embodiment of the present invention. Those skilled in the art should understand that the scope of disclosure involved in the present invention is not limited to the technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions disclosed in the present invention.

Claims

1. A tree topology based audio transmission system, characterized in that, include: Host equipment, audio transmission network, and peripheral devices; The audio transmission network includes multiple audio transmission nodes forming a tree topology, wherein the root node is connected to the host and at least one child node, and each child node is connected to the peripheral device. The host is used to obtain the topology information of the audio transmission network and establish corresponding routing tables in the root node and each level of child nodes according to the obtained topology information. The audio transmission node is used to obtain data frames sent by other audio transmission nodes, query the routing table based on the parsing result of the data frames to obtain the transmission path of the target node, and transmit the data frames to the target node according to the transmission path of the target node. In addition, a data frame to be sent is generated based on the acquired audio data and control information, the routing table is queried to obtain the transmission path corresponding to the target node, and the data frame to be sent is transmitted to the next audio transmission node according to the transmission path; The peripheral device is used to process the audio data based on the audio data and control information obtained from the target node it is connected to. And, it is used to collect audio data and control information input to the child nodes connected to it.

2. The audio transmission system based on a tree topology according to claim 1, characterized in that: The non-leaf nodes in the child nodes include an uplink communication interface, at least two downlink communication interfaces, a peripheral interface, and a data processing and routing module. The uplink communication interface is used to receive downlink data frames from the previous audio transmission node and send the downlink data frames to the data processing and routing module. The downlink communication interface is used to receive uplink data frames from the next-level audio transmission node and send the uplink data frames to the data processing and routing module. The data processing and routing module is used to parse the data frame, output the data in the data frame from the peripheral interface according to the settings of the control register, add the data input from the peripheral interface to the uplink data frame or the downlink data frame, and then send it to the next audio transmission node through the uplink communication interface or the downlink communication interface.

3. The audio transmission system based on a tree topology according to claim 2, characterized in that: The data frame includes a preamble, a synchronization subframe, several data segments, and a tail frame arranged in sequence. The preamble uses a sequence that does not conform to the Manchester coding rules, while the synchronization subframe uses a sequence that conforms to the Manchester coding rules. The synchronization subframe includes a synchronization control subframe and a synchronization response subframe. The root node periodically sends the synchronization control subframe at a predetermined frequency. The child node generates its own operating clock based on the synchronization control subframe sent by the root node and the phase-locked loop, and sends the synchronization control subframe to the next level child node through the downlink communication interface. After the leaf node receives the synchronization control subframe, it returns the synchronization response subframe through the uplink communication interface.

4. The audio transmission system based on a tree topology according to claim 3, characterized in that: The data segments include simple data segments, control information data segments, and routing data segments; wherein, the simple data segment includes transmitted audio data and a first checksum; the control information data segment includes segment type, source node information, target node information, control information, and a second checksum; and the routing data segment includes segment type, target node information, audio data, and a third checksum.

5. The audio transmission system based on a tree topology according to claim 4, characterized in that: The data processing and routing module is also used to control which simple data segments in the received data frame are used by the current audio transmission node through the control register, and to indicate in which simple data segments the received audio data is stored for transmission to the next level audio transmission node.

6. The audio transmission system based on a tree topology according to claim 4, characterized in that: The data processing and routing module is also used to parse the received control information data segment to obtain target node information; If the current audio transmission node is the target node, the data processing and routing module operates according to the control information, inserts the response information into the reverse transmission data frame according to the format of the control information data segment, and takes the current audio transmission node as the source node and the node that initiates the control information as the target node. If the current audio transmission node is not the target node, the data processing and routing module queries the routing table to determine which output port the control information data segment will be transmitted to the next-level audio transmission node.

7. The audio transmission system based on a tree topology according to claim 4, characterized in that: The data processing and routing module is also used to parse the received routing data segment to obtain target node information; If the current audio transmission node is the target node, the data processing and routing module will output the audio data in the received routing data segment through the peripheral interface of the current audio transmission node. If the current audio transmission node is not the target node, the data processing and routing module queries the routing table to determine which output port the routed data segment should be transmitted to the next-level audio transmission node.

8. An audio transmission system based on a tree topology according to claim 2, characterized in that: When at least two downlink communication interfaces in the audio transmission node receive uplink data frames, the data processing and routing module merges the two uplink data frames and then sends them to the next-level audio transmission node through the uplink communication interface.

9. An audio transmission system based on a tree topology according to claim 3, characterized in that: The leaf nodes in the child nodes have an uplink communication interface but no downlink communication interface. When the leaf node receives a synchronization control subframe, it sends a synchronization response subframe to the next higher-level audio transmission node through the uplink communication interface.

10. The tree topology based audio transmission system as claimed in claim 4, wherein, The host is further used for: Configure the root node as a node with both uplink and downlink communication interfaces. The root node sends a data frame containing a synchronization control subframe through the downlink communication interface. If a synchronization response subframe is received from the downlink communication interface within a predetermined time, it is determined that the downlink communication interface is connected to a next-level node. The next-level node of the root node is configured to have both uplink and downlink communication interfaces by using a synchronization control subframe. The next-level node of the root node continues to send the synchronization control subframe from the previous level to the next-level node through the downlink communication interface. If the downlink communication interface receives a synchronization response subframe within a predetermined time, it is determined that the downlink communication interface is connected to a next-level node. If it does not receive a synchronization response subframe within a predetermined time, it is determined that the downlink communication interface does not have a next-level node. Repeat the above steps until no lower-level nodes can be found. Assign a unique number to each found node to obtain the topology information of the audio transmission network, and establish a corresponding routing table in each audio transmission node based on the obtained topology information.

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