Bus addressing type four-wire system cascade long-distance microphone gating acquisition system

Abstract

The invention provides a bus addressing type four-wire system cascade long-distance microphone gating acquisition system, and the system comprises an edge processing module which is used for generating and transmitting a return-to-zero code control signal containing a self-checking mode code or a polling mode code; the plurality of gating acquisition modules are serially cascaded through a four-wire system bus; each gating acquisition module is composed of a pure hardware circuit without a calculation unit, and comprises a return-to-zero code chip used for receiving the return-to-zero code control signal, transmitting the return-to-zero code control signal to the next-level gating acquisition module step by step, and outputting a control signal to an analog switch; the analog switch array is used for switching paths according to the control signal of the return-to-zero code chip and gating a microphone or a self-checking signal; the relay amplification chip is used for following and amplifying the audio signal to compensate for long-distance transmission attenuation; and the edge processing module is only provided with one analog-to-digital converter, and the analog switch is gated in a time-sharing manner, so that the time-sharing acquisition of the audio signals of all the cascade gating acquisition modules is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of application system design of sound-electricity conversion devices (microphones), and particularly relates to a bus-addressable four-wire cascaded long-distance microphone gating acquisition system. Background Art

[0002] In industrial scenarios such as mines, power plants, and ports, to ensure the stable operation of long-distance belt conveyor systems, it is necessary to monitor the operating status of belt rollers and other related components through multi-point sound acquisition and recognition technologies. As shown in the attached Figure 1 description, the current multi-point sound acquisition system adopts a tree-like forest structure and consists of multiple processing nodes. Each node includes an AI edge processing device and a limited number of acquisition pickups. The pickups are responsible for collecting audio signals and transmitting them for processing. However, the current monitoring solution has certain drawbacks. First, for the acquisition system with a tree-like topology, wiring is difficult in a complex industrial equipment environment, and it is difficult to flexibly adjust the wiring method according to the monitoring sample acquisition requirements. Second, since each node processes a limited number of pickup signals, multiple AI edge processing devices need to be configured, which leads to redundancy in device resources and thus a significant increase in system costs. Finally, considering the impact of dust and vibration on the long-term reliability of pickups and edge devices, the maintenance of an edge system using multiple complex computing chips is difficult.

[0003] Figure 1 The implementation difficulties of the corresponding tree-like topology + parallel computing scheme include: The wiring problem of the tree-like topology; Too few faulty samples; Interference from different ambient sounds; Real-time backhaul of multi-point sounds; The impact of dust and vibration on the long-term reliability of pickups and edge devices. Summary of the Invention

[0004] Aiming at the defects and deficiencies of the existing tree-like topology microphone acquisition system, such as complex wiring, device redundancy (requiring multiple edge processing devices), and high maintenance difficulty (multiple computing chips are affected by dust and vibration), the present invention provides a bus-addressable four-wire cascaded long-distance microphone gating acquisition system.

[0005] The present invention achieves a technological breakthrough through the following innovative designs: using a serial bus cascade topology to replace the traditional tree structure, and realizing long-distance flexible wiring through a four-wire bus (power positive / negative, control line, audio line); designing a pure hardware selection acquisition module (without MCU and other computing units), which is composed of a return-to-zero code chip (such as SM16703P), a low on-resistance analog switch (such as TS5A3359DCUR) and a low-noise relay amplifier (such as OPA2335AID), and transmitting control signals step by step through the return-to-zero code protocol, without node handshake or software programming, and supporting theoretically unlimited levels cascade; innovative dynamic address allocation mechanism (address is automatically determined by access sequence and detected by self-test mode) to achieve flexible replacement and expansion of modules; only a single AD converter is configured to complete the audio acquisition of all cascade nodes through time-sharing selection of analog switches, greatly reducing equipment cost and redundancy; combined with anti-interference designs such as shielded twisted pair, common-mode filter capacitors and differential input and output modules to ensure the integrity of long-distance (200-meter cascade) audio signals; supports self-test and polling dual-mode operation (self-test mode detects valid nodes, polling mode time-sharing acquisition) to improve system reliability and monitoring efficiency.

[0006] The present invention effectively solves the wiring, cost and maintenance problems of the microphone acquisition system in industrial long-distance belt monitoring scenarios, and has the advantages of high scalability, low redundancy and strong reliability.

[0007] The technical solution specifically adopted by the present invention to solve the technical problem is: A bus-addressable four-wire cascaded long-distance microphone gating acquisition system, comprising: An edge processing module, used for generating and sending a return-to-zero code control signal including a self-check mode code or a polling mode code; A plurality of strobe acquisition modules are serially cascaded via a four-wire bus, wherein the four-wire bus includes a positive power line, a negative power line, a control line, and an audio line; Each of the gating acquisition modules is composed of a pure hardware circuit without a computing unit, and the pure hardware circuit includes: A return-to-zero code chip is used to receive the return-to-zero code control signal and transmit it step by step to the next-level selection acquisition module, and output the control signal to the analog switch; An analog switch array, used for switching paths according to the control signal of the return-to-zero code chip, and selecting a microphone or a self-test signal; Relay amplifier chip, used to follow and amplify audio signals to compensate for long-distance transmission attenuation; The edge processing module is only equipped with one analog-to-digital converter, and the audio signal time-sharing acquisition of all cascaded acquisition modules is realized by time-sharing gating the analog switch.

[0008] Further, the address of the gating acquisition module is automatically determined by the access order. The address of the first accessed gating acquisition module is 0, and the addresses of the subsequently accessed gating acquisition modules increase sequentially. The address information is obtained by dynamically detecting through the self-check mode.

[0009] Further, the code length of the return-to-zero control signal is 24 bits, where: The self-check mode code includes a first set of control bits for the gating module to generate a self-check signal, a second set of reserved bits, and a third set of switchable self-check signal bits; the self-check signal bits are alternating level bits for generating a test audio signal; The polling mode code includes a first set of reserved bits, a second set of control bits for the gating module to switch to the microphone acquisition path, and a third set of reserved bits.

[0010] Further, the relay amplification chip is a low-noise operational amplifier, which is used to compensate for the signal attenuation in long-distance transmission, so that the amplitude loss of the audio signal is controllable when the cascaded transmission distance is not less than 200 meters.

[0011] Further, the gating acquisition module further includes a microphone pre-amplification circuit composed of an operational amplifier, a resistor voltage-dividing network, and a negative feedback resistor, and the amplitude of the output audio signal is adjusted to be lower than 1.2V by adjusting the negative feedback resistor.

[0012] Further, each cascaded module of the power positive line independently sets a self-resetting fuse, which is used to automatically disconnect the lower-level power supply when a short circuit or overload occurs in the cascaded module.

[0013] Further, the audio cable uses shielded twisted pair, and the cascaded interface is configured with a common-mode filtering capacitor, or a differential input / output module is connected to suppress external coupled voltage interference.

[0014] Further, the edge processing module supports two operating modes: Self-check mode, dynamically detecting the number of effective gating acquisition modules by sending a self-check mode code; Polling mode, sending a polling mode code according to the effective number, and gating the microphone to collect audio signals node by node; Among them, the self-check mode is executed prior to the polling mode.

[0015] Further, the gating acquisition module adopts a detachable cascaded structure, which supports dynamically increasing or decreasing the number of modules.

[0016] Further, the amplitude of the output of the pre-amplification circuit is adjusted to 1V to relatively reduce the noise amplitude.

[0017] Compared with the prior art, the present invention and its preferred solutions at least include the following beneficial effects: First, by replacing the traditional tree structure with a serial bus cascading topology, the problem of difficult wiring in complex industrial scenarios is solved. It supports flexible long-distance arrangement of sound pickup points, greatly improving the convenience of system installation and maintenance. Second, by adopting a pure hardware gating acquisition module (without computing units such as MCUs) combined with a return-to-zero code control protocol, the step-by-step transmission of control signals and hardware gating are realized, avoiding handshaking or software programming between nodes, and significantly improving the system response speed and long-term operation reliability. Finally, through a single AD time-sharing acquisition mechanism, only one analog-to-digital converter needs to be configured to complete the audio acquisition of all cascaded nodes, effectively reducing equipment redundancy and lowering the hardware cost and maintenance difficulty.

[0018] The dynamic address allocation mechanism (the address is automatically determined by the access order and detected through the self-check mode) avoids the cumbersome operations of physically or software setting addresses, supports flexible replacement and expansion of modules; the detachable cascading structure allows the number of nodes to be dynamically increased or decreased according to actual needs, further enhancing the adaptability of the system; the anti-interference design (such as shielded twisted pair, differential input and output modules, etc.) ensures the integrity of audio signals during long-distance transmission and enhances the stability in complex industrial environments; the dual-mode operation mechanism (detecting valid nodes in the self-check mode and time-sharing acquisition in the polling mode) realizes the reliable management of the entire process from node status verification to signal acquisition, further improving the monitoring efficiency and accuracy. Brief Description of the Drawings

[0019] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments: Figure 1 Schematic diagram of the existing technical solution; Figure 2 Basic concept diagram designed and developed for the present invention; Figure 3 Schematic diagram of the hardware connection of the present invention; Figure 4 Structure diagram of the edge processing module of the present invention; Figure 5 Structure diagram of the gating acquisition module of the present invention; Figure 6 Example diagram of data transmission of the present invention; Figure 7 Overall system structure diagram of the present invention; Figure 8 Acquisition subsystem diagram of the present invention; Figure 9 Flowchart of the path self-check mode of the present invention; Figure 10 Flowchart of the polling acquisition mode of the present invention; Figure 11 Principle diagram of the cascading structure of the present invention; Figure 12 Circuit diagram of the cascading structure of the present invention; Figure 13 This is the circuit schematic diagram of the cascade acquisition module of the present invention; Figure 14 This is the schematic diagram of the microphone preamplifier circuit of the present invention; Figure 15 This is the schematic diagram of the long-distance multi-stage cascade circuit of the present invention. Specific embodiments

[0020] To make the features and advantages of the present invention more obvious and understandable, specific embodiments are given below for detailed description as follows: It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in this specification have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0021] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0022] In view of the problems of difficult wiring and equipment redundancy in the current multi-point sound acquisition and recognition system, the embodiment of the present invention provides an audio acquisition system based on a serial polling bus, called a "bus addressing four-wire cascade long-distance microphone gating acquisition system". The acquisition system adopts a serial bus topology instead of a tree-shaped parallel connection, which is easier to install, wire, debug and maintain in engineering applications. The basic concept of its design and development is as Figure 2 shown.

[0023] Feasibility analysis of the serial acquisition structure: Assume that during the operation of a long-distance belt conveyor system, a belt idler fails, and the serial acquisition system is used to collect the audio signal generated when the fault occurs. Considering that in a long-distance belt conveyor system, the abnormal audio signal of the belt idler will persist for a certain period of time after the fault occurs. Therefore, the real-time requirement of the monitoring and recognition task for the acquisition system is relatively low, and the abnormal signal can be monitored by polling at regular intervals on the serial bus. In addition, the belt idler and other belt-related sound signals are all periodic signals, and the signal period is short, the amount of collected data is small, and the single acquisition time is short. During the bus polling process, single-point acquisition will not take too much time, thus ensuring the efficient operation of the system.

[0024] To this end, in the basic design provided by the embodiments of the present invention, the system mainly includes two parts: a gating acquisition module and an edge processing module. Among them, the gating acquisition module is composed of a pure hardware circuit without software, and the edge processing module serves as the control host in the system to drive the gating acquisition module. Working process: The edge processing module first sends a working signal to the gating acquisition module. After the hardware circuit of the gating acquisition module receives the signal, it immediately executes the corresponding action.

[0025] The schematic diagram of the hardware connection is as Figure 3 shown. The bus consists of four lines, including two lines for power supply, one line for the user to send control acquisition signals, and one line for receiving the electrical analog signal of the sound.

[0026] Among them, the main functions of each part are described as follows: 1. The edge processing module, as a processing module connecting the backend server and the frontend gating acquisition module, is mainly responsible for controlling the acquisition module to poll and acquire the audio signals of the belt transmission system or perform self-check audio signal acquisition of the acquisition module, and after processing the acquired signals, transmit them to the backend server through the network protocol, as Figure 4 shown.

[0027] 2. The gating acquisition module is composed of a pure hardware circuit, as Figure 5 shown, and is responsible for receiving and responding in real time to the control signals from the edge processing module. It is composed of a four-wire cascade and is connected to the edge processing module, respectively: (1). Positive power supply: Responsible for the positive power supply of the module, providing power signals for circuits such as chips (2). Negative power supply: Responsible for the negative power supply of the module. In the designed circuit, the negative electrode is grounded and used as the ground wire for circuits such as chips.

[0028] (3). Control signal line: Responsible for transmitting the control signals from the edge processing module, adopting the unipolar return-to-zero code protocol, and sequentially sending control signal codewords, and the corresponding cascaded modules receive them in sequence.

[0029] (4). Audio receiving line: Responsible for periodically transmitting the analog audio signals of each microphone cascading node back to the system and returning the acquired sound information according to the change of the control signal line.

[0030] In the gating acquisition module, each control circuit and the MIC head form an independent minimum receiving unit module. These unit modules form a complete gating acquisition module through a serial cascade method. Each unit module can be disassembled, so that the number of receiving units in the gating acquisition module can be flexibly adjusted to meet different application requirements.

[0031] The composition description of each part of the unit module is as follows: (1). U1 uses the SM16703P return-to-zero code transmission chip. The distance between two chips can reach 30m, meeting the wiring requirements for monitoring long-distance belt conveyor systems. The RGB three pins of U1 can receive communication codes to emit different currents, and different voltages can be obtained through voltage conversion of the currents. The current of the R pin of U1 is changed into a voltage through a resistor or optocoupler to control the analog switch U2. An example of data transmission is as Figure 6 shown: DIN input data format: Trst + 24-bit grayscale data of the first chip + 24-bit grayscale data of the second chip +... + 24-bit grayscale data of the Nth chip.

[0032] (2). U2 analog switch selects a three-way electronic analog switch.

[0033] (3). The relay can be selected as a chip with audio green wave shaping ability, or composed of a single operational amplifier. This enables the module to adapt to long-distance audio signal transmission.

[0034] (4). The MIC can be an active or passive MIC. For a passive MIC, a driving circuit for the MIC needs to be added separately.

[0035] The overall system constructed based on the above modules consists of a remote server, an edge cabinet, n edge processing modules, and n cascaded acquisition modules. Each detection path is set to be composed of an edge processing module and n cascaded acquisition modules, as Figure 7 shown.

[0036] Its core part is an acquisition subsystem composed of an edge processing module for one path and n cascaded acquisition modules, as Figure 8 shown.

[0037] Its main design points include: (1). The cascade is a physically sequential gating, rather than a digital communication method relying on MCU digital coding quantization: In this embodiment, the minimum controllable acquisition unit designed for the edge processing module is composed of three chips, such as U1 - U3 in the dashed box in Figure 5 . The minimum acquisition unit does not contain computing units such as MCU. This control unit can be cascaded one by one. Since the single-line return-to-zero code data protocol is used, the control data is transmitted to each module step by step through the return-to-zero code, and the analog switch is controlled to select different paths through the output pins of the return-to-zero code chip. Therefore, in the designed control acquisition scenario, theoretically, an unlimited number of connections can be made.

[0038] (2). In this embodiment, the shaping and filtering of analog signals are transmitted step by step without handshaking and without being converted into a specific encoded digital signal: The control data is transmitted through the return-to-zero code transmission chip. The return-to-zero code chip will latch the control signal of the output switch step by step according to the return-to-zero (RESET) signal, as Figure 6As shown in the figure, the processing module sends a control signal of 24 * n bits. The cascaded return-to-zero code transmission chips will gradually decrease and follow the output. When the zero-level signal is received, the states of each chip are latched and output. Therefore, as long as the 24-bit control data is sent in sequence, that is, the data of the high address bits is sent first and the data of the low address bits is sent later, when the zero level is received, it can be confirmed that the chips corresponding to the address bits have received and latched the corresponding control signals for output.

[0039] Meet the signal transmission of the edge processing module to each control unit.

[0040] Therefore, there is no need for handshaking between each acquisition strobe. Only the edge processing module needs to perform a certain encoding and sending, and the analog switch can be controlled through the transmission chip to return the audio-electric signal.

[0041] Since the transmission and response between acquisition modules are signal transmissions of pure digital circuits, the response is rapid, no setting and programming are required, and the reliability is good.

[0042] (3), There is no need to program specific nodes and physically set the phase address, and it can be replaced arbitrarily: Due to the use of the return-to-zero code control method, the control signal is transmitted step by step. Therefore, once the module is connected to the system, each module will be encoded with an address one by one. That is, the address of the acquisition module closer to the edge processing module is lower. The address of the first acquisition module is 0, and it increases by 1 one by one. This address encoding does not need to be stored. When the system starts, through the self-check mode, the available modules are detected, and the actual number of connected modules can be detected accordingly.

[0043] (4), The inter-stage connection is in series, suitable for long-distance linear series connection: The designed module connection method is in series one by one. Since the number of connections is not limited, it is convenient for flexible long-distance wiring. In this embodiment, an intermediate shaping chip is designed in the module unit to follow and amplify the signal to ensure reliable transmission and feedback.

[0044] (5), The acquisition system only needs one AD to realize the time-sharing audio acquisition of all pickups on the linear long-distance line: In the above logic, due to the time-sharing acquisition method, only an AD converter and an MCU need to be configured in the edge module, which saves equipment costs. The time-sharing acquisition is controlled by the edge processing module according to the above return-to-zero code method. Each chip U1 is controlled to output and control the analog switch to release the audio acquisition signal of the corresponding node for feedback.

[0045] This embodiment designs that the acquisition system has two operating mechanisms, the path self-check mode and the polling acquisition mode: (1) Path self-check mode: During self-check, the specified module U1_R needs to be 0, and U1_G needs to be 1 to enable this path of self-check. If the module is not specified, U1_R is 1, U1_G is 0, and U1_B is the corresponding self-check voltage. The edge processing module compiles the cyclic traversal control information with a length of N * 24 bits according to Figure 4 the transmission rules, and sends it to the acquisition module one by one. The acquisition module then generates a specific self-check voltage signal accordingly and directly returns it to the AD sampling and sound recognition system of the main control system.

[0046] More specifically, the control process is as follows: ① The edge processing module generates cyclic traversal control information with a length of N * 24 bits, and this information is called a control token. The initial N is set to 10, and then the number detected subsequently increases one by one. The processing module sends control signals one by one through the return-to-zero code. The 24-bit self-check control code format of the selected module is: ([00000000][11111111][00000000 / 11111111]), and the 24-bit self-check control code format of the non-selected module is: ([11111111][00000000][00000000]).

[0047] ② The acquisition module node receives the token selection signal and performs latching and output transfer. In the self-check mode, the binary code 01 is output through the U1_R and U1_G pins of the selected module to the U2 analog switch, thereby enabling the self-check path of this module. U1_B outputs alternating high and low levels to generate a test audio signal or a specific DC signal. For the remaining modules, U1_R is at a high level, and U1_G and U1_B are at a low level.

[0048] ③ The switch switches channels according to the status of the RGB control line, connects the acquisition line to the generated self-check audio signal or specific DC signal, and returns it to the AD sampling and sound recognition system of the main control system through relay amplification, thereby performing cyclic self-check.

[0049] The pseudocode is as follows: N = 10 checkedN = 0 Start: i = checkedN for i in N: sendOnePointCheck(i) # Send the self-check control code of the specified address bit if(checkPointEnable()): CheckedN ++ else: return CheckedN if(CheckedN > N) goto Start The process is as Figure 9 shown.

[0050] (2)Polling acquisition mode: During the acquisition work, the specified modules U1_R and U1_G need to be set to 1, that is, this MIC path is selected. If module U1_R is not specified as 1 and U1_G is 0. The edge processing module prepares the polling traversal control information with a length of N * 24 bits according to Figure 6 the transmission rules and sends it to the acquisition module one by one. The acquisition module then controls the analog switch to select the MIC one by one according to the status of U1_R, collects the signals accordingly, and directly returns to the AD sampling and voice recognition system of the main control system.

[0051] More specifically, the control process is as follows: ① The edge processing module generates a polling traversal control token with a length of N * 24 bits. N is set to the number of valid channels obtained in the self-check mode. The processing module sends the control signal through the return-to-zero code. In the polling acquisition mode, the 24-bit acquisition control code format for the selected module is: ([11111111][11111111][00000000]), and the 24-bit acquisition control code format for the non-selected module is: ([11111111][00000000][00000000]).

[0052] ② The acquisition module node receives the token selection signal and performs latching and output transfer. In the acquisition mode, the binary code 11 is output to the U2 analog switch through the U1_R and U1_G pins of the selected module, thereby enabling the third path of the analog switch of this module, that is, the acquisition audio path, and thus switching the receiving route to the pickup. For the remaining modules, U1_R is at a high level, and U1_G and U1_B are at a low level.

[0053] ③ The acquisition module then collects the audio electrical signals generated by the pickup accordingly, returns them to the AD sampling and voice recognition system of the main control system through relay amplification, and thus performs cyclic acquisition.

[0054] The pseudocode is as follows: N = checkPointsNum() for i in N: sendOnePointSample(i) # Send the acquisition control code of the specified address bit saveOnePointToCache() processCacheVoice() The flowchart is as Figure 10 shown.

[0055] The prominent features and advantages of the above design in this embodiment include: 1. The MIC pick-up heads are connected in series. The number of pick-up heads can be arbitrarily specified according to actual needs, and the spacing between the pick-up heads can also be flexibly configured. In addition, the installation positions of the pick-up points can be flexibly arranged according to the application scenarios, facilitating installation and wiring operations, and improving the applicability and convenience of the system.

[0056] 2. According to the working mode of this system, in application scenarios within a range of 200 meters, regardless of the number of MIC acquisition heads, the edge device only needs to be configured with one analog-to-digital converter (AD), one voice recognition system, and one four-core serial bus. This design greatly reduces the system equipment cost, reduces the system redundancy, improves the operation reliability, and reduces the maintenance cost, as Figure 11 , Figure 12 shown.

[0057] 3. After being installed in the monitoring environment, this acquisition system can communicate with the backend processing server to realize the functions of collecting, processing, and transmitting the audio information of the working state of the long-distance belt conveyor system.

[0058] 4. This system can collect on-site audio information and perform analysis and processing. Through the feature recognition and judgment of the sound signal, it can give real-time warnings to on-site personnel about the operating state of the long-distance belt conveyor system. At the same time, the system can accurately locate and report potential problem points and their relevant information, providing timely and accurate basis for equipment maintenance and management.

[0059] Finally, this embodiment further demonstrates and introduces an optimal implementation solution for the circuit implementation details of the key cascaded acquisition module as shown in Figure 5 : In the cascaded acquisition module with three chips as the core, U1-SM16703P is a return-to-zero code chip, which transmits control signals, controls the switching path of the switch circuit, and outputs a self-check signal through pin U1_B; U2 is a three-channel switching analog switch; U3 is a follower amplifier.

[0060] The circuit principle it realizes is as shown in Figure 13 : Upper-level access terminals: Power supply 24V, power supply ground GNDI, cascaded analog signal output AOUT, return-to-zero code signal input DIN; Lower-level input terminals: Power supply 24VO, power supply ground GNDO, cascaded analog signal input AIN, return-to-zero code signal output DOUT; Chip selection: U1-SM16703 is a return-to-zero code LED control chip. Through return-to-zero code single-wire communication, it can simultaneously control the current magnitudes of OUTR, OUTG, and OUTB of U1, which are converted into voltage control via R2, R3, and R4.

[0061] The voltages of the OUTR and OUTG signals serve as the channel selection signals for analog switch U2. OUT_B serves as the path self-check voltage signal. By setting different voltages, the conduction voltage drop of the entire cascaded path can be measured, and thus it can be determined whether there is a connection fault in the entire cascaded path. The return-to-zero code signal is connected through DIN and transmitted to the next-level module through the DOUT port of U1.

[0062] U2-TS5A3359DCUR is a bidirectional single-channel single-pole triple-throw analog switch with low on-resistance characteristics, and the path is selected through the input two-wire pins.

[0063] U3-OPA2335AID is a dual-channel operational amplifier chip with characteristics such as low noise, low input bias current, and high precision, which is used to follow and amplify the audio signal in the cascaded link to ensure the integrity of the output signal.

[0064] Power supply It is powered by 24V and connected to the next-level power supply 24VO through a 50V / 1A self-resetting fuse to automatically cut off the power of the next level when a short circuit or overload fault occurs in the next level. The 24V is converted to 5V through a switching power supply as the module power supply.

[0065] The principle of the microphone preamplifier circuit is as Figure 14 shown: U4 is a dual-channel single-supply rail-to-rail operational amplifier OPA2335AID.

[0066] C5 filters the sound signal, and signals above 20KHz will be attenuated. MIC_IN can be connected to an electret microphone or an active microphone. R16 serves as the bias resistor for the electret microphone. If an active microphone is connected, there is no need for the pull-up bias of R16 and it can be directly connected to C5; U4B is an emitter follower, and its positive terminal is connected to 2.5V through voltage division by two resistors, serving as the power supply midpoint of the U4A amplifier; U4A and the surrounding power supply form a proportional amplifier. R11 and R12 form a DC voltage bias of 1.25V. At the same time, R13 and R14 also form a DC voltage bias of 1.25V. R19 is the negative feedback resistor. Its AC amplification factor is (R19 + R13 / / R14) / (R13 / / R14) = (R19 + 5000) / 5000. Adjust R19 so that the maximum output signal amplitude is lower than 1.2V.

[0067] Circuit simulation experiment Long-distance multi-stage cascade: As Figure 15 shown, by cascading multiple modules, the long-distance signal transmission is tested. A variable resistor is set between cascades to test the signal attenuation. The test steps are as follows: 1. Set a sine wave signal input in the MIC part of the rightmost cascade module, with a signal amplitude of 20 mV and a frequency of 5 kHz; 2. Set an oscilloscope at the AOUT output part of the leftmost cascade module; 3. Control the access of the MIC signal to the last-stage module through the simulated return-to-zero code cascade; 4. Control the remaining stage modules to be in the signal transmission mode through the simulated return-to-zero code cascade; 5. Adjust the variable resistor between cascades to test the signal attenuation; 6. Observe the collected audio signal in the oscilloscope at the leftmost end.

[0068] Since a relay following amplifier module is set in the cascade module and the analog switch in the module is a low on-resistance switch, the signal integrity can be maintained during inter-stage transmission, and the signal amplitude of the first-stage output can be maintained.

[0069] Signal-to-noise ratio under multi-node cascade: The system maintains a certain signal-to-noise ratio through the following strategies: 1. Adjust the output amplitude of the microphone preamplifier circuit to about 1 V, so that the interference noise amplitude is relatively small compared to the output signal amplitude.

[0070] 2. During the transmission process, since the signal path only includes the emitter follower of the operational amplifier and the analog switch, there is no other noise source, and at the same time, the emitter follower has sufficient load-carrying capacity, effectively improving the signal-to-noise ratio.

[0071] 3. Use shielded wires during the transmission process to shield external coupled voltage interference.

[0072] 4. According to the specific application scenario, a differential input / output module can be connected to AOUT and AIN to further improve the signal-to-noise ratio.

[0073] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention should have the ordinary meanings understood by those with ordinary skills in the field to which the present invention belongs. The "first", "second" and similar words used in the present invention do not denote any order, quantity or importance, but are only used to distinguish different components. Words such as "including" or "comprising" mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Upper", "lower", "left", "right", etc. are only used to indicate relative position relationships, and when the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0074] The above are only the preferred embodiments of the present invention, and are not limitations on the present invention in other forms. Any person skilled in the art may use the technical content disclosed above to make changes or modifications into equivalent embodiments with equivalent changes. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the technical solution content of the present invention still fall within the protection scope of the technical solution of the present invention.

[0075] The present invention is not limited to the above best mode. Anyone inspired by the present invention can obtain various other forms of bus addressing four-wire cascaded long-distance microphone gating acquisition systems. All equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope covered by the present invention.

Claims

1. A bus addressing four-wire cascaded long-distance microphone gating acquisition system, characterized in that Including: An edge processing module for generating and sending a zero-code control signal containing a self-check mode code or a polling mode code; A plurality of gated acquisition modules serially cascaded through a four-wire bus, the four-wire bus including a positive power line, a negative power line, a control line, and an audio line; Each of the gated acquisition modules is composed of a pure hardware circuit without a calculation unit, and the pure hardware circuit includes: A zero-code chip for receiving the zero-code control signal and transmitting it to the next-level gated acquisition module step by step, and outputting a control signal to the analog switch; An analog switch array for switching paths according to the control signal of the zero-code chip to gate a microphone or a self-check signal; A relay amplification chip for following and amplifying the audio signal to compensate for long-distance transmission attenuation; The edge processing module is only configured with one analog-to-digital converter, and by time-division gating the analog switch, time-division acquisition of the audio signals of all cascaded gated acquisition modules is realized.

2. The bus addressing four-wire cascaded long-distance microphone gating acquisition system according to claim 1, characterized in that: The address of the gated acquisition module is automatically determined by the access order. The address of the first accessed gated acquisition module is 0, and the addresses of the subsequent accessed gated acquisition modules increase sequentially. The address information is obtained by dynamically detecting the self-check mode.

3. The bus-addressing four-wire cascaded long-distance microphone gated acquisition system according to claim 1, wherein: The code length of the zero-code control signal is 24 bits, wherein: The self-check mode code includes a first set of control bits for the gating module to generate a self-check signal, a second set of reserved bits, and a third set of switchable self-check signal bits; the self-check signal bits are alternating level bits for generating a test audio signal; The polling mode code includes a first set of reserved bits, a second set of control bits for the gating module to switch to the microphone acquisition path, and a third set of reserved bits.

4. The bus addressing four-wire cascaded long-distance microphone gating acquisition system according to claim 1, wherein: The relay amplification chip is a low-noise operational amplifier for compensating the signal attenuation of long-distance transmission, so that the amplitude loss of the audio signal is controllable when the cascaded transmission distance is not less than 200 meters.

5. The bus addressing four-wire cascaded long-distance microphone gating acquisition system according to claim 1, characterized in that: The gated acquisition module further includes a microphone pre-amplification circuit composed of an operational amplifier, a resistor voltage-dividing network, and a negative feedback resistor, and the output audio signal amplitude is adjusted to be lower than 1.2V by adjusting the negative feedback resistor.

6. The bus addressing four-wire cascaded long-distance microphone gating acquisition system according to claim 1, wherein: Self-resetting fuses are independently set for each cascaded module of the positive power line to automatically disconnect the power supply of the lower level when a short circuit or overload occurs in the cascaded module.

7. The bus addressing four-wire cascaded long-distance microphone gating acquisition system according to claim 1, characterized in that: The audio line uses shielded twisted pair, and the cascaded interface is configured with a common-mode filtering capacitor, or a differential input / output module is connected to suppress external coupled voltage interference.

8. The bus-addressing four-wire cascaded long-distance microphone gated acquisition system according to claim 1, wherein: The edge processing module supports two operating modes: Self-check mode, dynamically detecting the number of valid gated acquisition modules by sending a self-check mode code; Polling mode, sending a polling mode code according to the valid number, and gating the microphone to acquire audio signals node by node; Among them, the self-check mode is executed prior to the polling mode.

9. The bus-addressing four-wire cascaded long-distance microphone gating acquisition system according to claim 1, wherein: The gated acquisition module adopts a detachable cascaded structure and supports dynamically increasing or decreasing the number of modules.

10. The bus addressing four-wire cascaded long-distance microphone gating acquisition system according to claim 5, wherein: The output amplitude of the pre-amplification circuit is adjusted to 1V to relatively reduce the noise amplitude.

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