Bidirectional talkback processing system
By using an audio echo cancellation chip and power amplifier module in the subway train broadcast intercom system, combined with a transformer and a bidirectional audio bus, the echo and howling problems were solved, and high-quality two-way intercom communication was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- WAYCOM TECH CO LTD
- Filing Date
- 2025-04-01
- Publication Date
- 2026-04-28
AI Technical Summary
Traditional analog bus intercom systems suffer from echo and audio feedback problems, which are particularly difficult to suppress effectively at high-power audio output, affecting communication quality and train operation.
The system employs the ML7037-003TB audio echo cancellation chip and the LM4950TS audio power amplifier module, combined with a transformer and a bidirectional audio bus, to achieve echo cancellation and feedback suppression through frequency and time domain filtering, dynamic noise suppression, and gain adjustment.
It significantly improves audio signal quality, avoids echo and feedback, ensures voice clarity, adapts to complex noise environments, and is suitable for driver-passenger intercom and emergency alarm signal processing.
Smart Images
Figure CN224178254U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of voice signal processing, and in particular to a two-way intercom processing system. Background Technology
[0002] With the rapid development of urban rail transit, the communication system of subway trains plays a vital role in ensuring passenger safety and improving service efficiency. Especially in the subway train's intercom system, the dialogue between the driver and passengers is crucial for ensuring safe and smooth operation. However, while traditional analog bus intercom systems are widely used in many projects due to their simple hardware structure, low cost, and good system stability, they also have some technical problems, particularly the tendency to produce echoes and audio feedback during communication.
[0003] In existing analog bus intercom systems, echoes typically occur because the audio signal, after being output through a speaker at one end, is re-acquired by the other end's microphone (MIC) and fed back to the speaker, creating a closed loop and causing the echo. Furthermore, the presence of this audio signal feedback loop also leads to howling, especially when the intercom volume increases. These problems become more pronounced, affecting communication quality and even disrupting normal train operations.
[0004] To address these technical challenges, researchers have proposed various techniques for audio echo cancellation and feedback suppression, one of the more common applications being echo cancellation circuits based on analog operational amplifiers. This technique attempts to reduce the impact of echo by sampling and subtracting the audio signal. However, due to the accuracy issues of the sampling resistors and transformers, as well as the length limitations of the intercom audio bus, existing solutions cannot completely solve the problems of echo and feedback. Furthermore, when the system design involves high-power audio output, the problem of audio self-oscillation feedback remains difficult to suppress effectively.
[0005] Therefore, effectively eliminating echoes and suppressing howling in subway train broadcast intercom systems has become a pressing technical challenge. Utility Model Content
[0006] This application provides a two-way intercom processing system. The application is as follows:
[0007] A two-way intercom processing system, the system comprising:
[0008] The audio input module is used to acquire audio signals from both the local and remote ends.
[0009] The audio processing module includes an audio echo cancellation chip, which is used to cancel echoes and suppress noise in the input audio signal;
[0010] The audio power amplifier module is used to amplify the power of the processed audio signal;
[0011] Transformers are used for the transmission and isolation of audio signals;
[0012] Intercom audio bus, used to transmit two-way audio signals;
[0013] The audio output module is used to output the processed audio signal.
[0014] Optionally, the audio echo cancellation chip is the dedicated audio echo cancellation chip ML7037-003TB.
[0015] Optionally, the audio amplifier module uses an LM4950TS amplifier.
[0016] Optionally, the audio input module adopts a MIC (microphone intercom) audio input method.
[0017] Optionally, the system further includes a high-frequency signal sampling circuit, which is designed with a 10Ω sampling resistor.
[0018] Optionally, the system supports two audio signal streams via a bidirectional audio bus;
[0019] The driver's intercom audio signal stream is processed by the DCP1_ML7037-003TB chip, amplified by the LM4950TS power amplifier, and transmitted to the intercom audio bus through a transformer. It is then received and processed by the DCP2 module and output through the speaker.
[0020] The passenger emergency alarm audio signal stream is processed by the DCP1_ML7037-003TB chip, amplified by the LM4950TS power amplifier, transmitted to the intercom audio bus through the transformer, and then received and processed by the PAU module before being output through the speaker.
[0021] Optionally, each end of the audio signal stream uses an ML7037-003TB dedicated audio echo cancellation processing chip, and the signal gain is adjusted by an LM4950TS audio power amplifier module to ensure high-quality audio signal output.
[0022] Optionally, the dedicated audio echo cancellation processing chip ML7037-003TB has multiple built-in echo cancellation and noise suppression algorithms, which are used to detect and eliminate echoes in real time during intercom to optimize voice quality.
[0023] The transformer and audio amplifier module are configured to support different types of audio input and output signals, including intercom between the driver and passengers, and transmission of emergency alarm signals.
[0024] The audio bus supports bidirectional audio transmission.
[0025] In this embodiment, the system integrates advanced audio processing technology, particularly utilizing an audio echo processing chip and an audio power amplifier module. Through precise echo cancellation algorithms (including frequency and time domain filtering), dynamic noise suppression, and real-time gain adjustment, the system significantly improves audio signal quality, avoids echo and feedback phenomena, and ensures speech clarity. The system's bidirectional audio signal stream design and modular structure enable it to adapt to complex noise environments and various audio application scenarios, including driver-passenger intercoms and emergency alarm signal processing. Furthermore, through audio bus transmission, audio power amplifier module amplification, and transformer isolation, stable audio signal transmission and high-quality output are guaranteed. Overall, this application improves the stability, clarity, and adaptability of audio communication systems and solves the echo problem in traditional systems. Attached Figure Description
[0026] Figure 1 This is a block diagram of a simulated bus intercom system;
[0027] Figure 2 This invention provides a schematic diagram of the structure of a two-way intercom processing system according to an exemplary embodiment of the present application.
[0028] Figure 3 This invention provides a schematic block diagram of an intercom system with two intercom ports according to an exemplary embodiment of the present application.
[0029] Figure 4 This application illustrates a corresponding embodiment of the present application. Figure 2 The circuit structure diagram of the analog bus intercom system;
[0030] Figure 5 This application illustrates a corresponding embodiment of the present application. Figure 2 Hardware schematic diagram of the intercom circuit. Detailed Implementation
[0031] To make the objectives, applications and advantages of this utility model clearer, the embodiments of this utility model will be described in further detail below with reference to the accompanying drawings.
[0032] In this article, "multiple" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.
[0033] First, such as Figure 1 The diagram shows a block diagram of an analog bus intercom system, illustrating the application background of this application. Currently, subway train PIS (Public Intercom System) systems mostly use analog bus intercom or Ethernet communication digital intercom. Analog bus intercom is widely used in many projects due to its simple hardware structure, low cost, and good system stability. However, it also has some technical problems, such as echo and howling during intercom calls. Figure 1 In this system, the intercom between DCP1 and DCP2 is for the driver, while the intercom between DCP and PAU is for passenger emergency alarms. Intercom echo occurs when the local SPK speaker outputs the sound from the local MIC input. The local MIC audio input is uploaded to the analog intercom bus, the remote end picks up the audio signal from the intercom bus and outputs it to the SPK speaker, and the output audio is then picked up by the remote end's MIC and transmitted back to the local SPK speaker. Feedback, or howling, occurs in the audio system. In a broadcast intercom system, when the feedback loop causes excessive amplification of the audio signal, a piercing scream is produced.
[0034] Therefore, in response to this problem, this application provides a new analog bus intercom implementation scheme to solve the problem of eliminating intercom echo and audio howling during intercom.
[0035] For ease of understanding, the terms used in the embodiments of this application are explained below.
[0036] ML7037-003TB Audio Echo Processing Chip: This chip is specifically designed for audio echo cancellation. It integrates multiple algorithms to process echo and noise in real-time during voice communication, ensuring clear speech. This chip is particularly important in communication devices such as telephones and walkie-talkies, as it addresses the impact of echo and noise on communication quality.
[0037] LM4950TS Audio Amplifier Module: A power amplifier (Amplifier) is used to amplify audio signals so that they can be output through devices such as speakers. The LM4950TS is a specific model of audio amplifier module suitable for amplifying audio signals.
[0038] Echo cancellation: Echo cancellation is a technique that uses electronic devices to process audio signals, thereby removing echoes caused by signal reflections or delays. This technology is primarily used in voice communication to reduce the interference of echoes on call quality.
[0039] Audio bus: An audio bus is a circuit or connection used to transmit audio signals between multiple audio devices. It is typically used to transfer audio signals from one device to another, such as from a microphone to a speaker.
[0040] Transformer: A transformer is a device used to change alternating current (AC) voltage and current. In audio systems, transformers are used for signal transmission and isolation, preventing electromagnetic interference and ensuring audio signal quality.
[0041] Adaptive filters: An adaptive filter is a filter that can automatically adjust its parameters according to changes in the input signal. In echo cancellation, it can dynamically adjust the filter parameters to adapt to environmental changes in real time, effectively removing echoes and noise.
[0042] Two-way audio signal flow: Two-way audio signal flow means that audio signals can flow simultaneously from both directions, that is, from one end (such as the driver) to the other end (such as the passenger), or in the opposite direction. This design is commonly used in intercom systems to support real-time communication between two parties.
[0043] Dynamic noise suppression: Dynamic noise suppression is a technique designed to reduce interference from ambient noise and improve the clarity of audio signals. This is especially important in noisy environments, such as intercom systems in vehicles like cars and airplanes.
[0044] In the existing design, the local MIC intercom audio signal is amplified by the LM4950TS power amplifier, and then fed onto the intercom audio bus (the intercom audio bus signal is bidirectional and has no direction) after passing through a 10R sampling resistor and a transformer. After reaching the other end, the signal passes through the transformer and a 10R sampling resistor at the other end, and then the bus audio signal is collected by an operational amplifier-based echo cancellation circuit. After passing through the LM4950TS power amplifier, the signal is output through the SPK speaker.
[0045] The peer audio acquisition circuit based on operational amplifier echo cancellation technology subtracts the signal across a 10R acquisition resistor using a sampled analog operational amplifier to eliminate the local audio signal echo during intercom communication. However, due to limitations in the accuracy of the sampling resistor, transformer, and intercom audio bus, it cannot completely eliminate intercom echo in practical applications. Furthermore, when the intercom volume is set high, it can also cause audio self-oscillation and howling. To address these issues, this application provides a two-way intercom processing system, as described in the following embodiments.
[0046] Example 1
[0047] like Figure 2 As shown, a two-way intercom processing system is provided, the system including:
[0048] The audio input module (such as DCP1_MIC, PAU_MIC) is used to acquire audio signals from both the local and remote ends; the audio processing module includes an audio echo cancellation chip, used to cancel echo and suppress noise in the input audio signals; the audio power amplifier module is used to amplify the processed audio signals; the transformer is used for the transmission and isolation of audio signals; the intercom audio bus is used to transmit bidirectional audio signals; and the audio output module (such as a speaker) is used to output the processed audio signals.
[0049] The system supports two audio signal streams via a bidirectional audio bus.
[0050] The driver's intercom audio signal stream is processed by the DCP1_ML7037-003TB chip, amplified by the LM4950TS power amplifier, and transmitted to the intercom audio bus through a transformer. After being received and processed by the DCP2 module, it is output through the speaker.
[0051] The passenger emergency alarm audio signal stream is processed by the DCP1_ML7037-003TB chip, amplified by the LM4950TS power amplifier, transmitted to the intercom audio bus through the transformer, and then received and processed by the PAU module before being output through the speaker.
[0052] Each end of the audio signal stream uses a dedicated audio echo cancellation processing chip ML7037-003TB, and the signal gain is adjusted by the LM4950TS audio power amplifier module to ensure high-quality audio signal output.
[0053] Among them, the dedicated audio echo cancellation processing chip ML7037-003TB has multiple built-in echo cancellation and noise suppression algorithms, which are used to detect and eliminate echoes in real time during intercom to optimize voice quality;
[0054] The transformer and audio amplifier module are configured to support different types of audio input and output signals, including intercom between the driver and passengers, and transmission of emergency alarm signals;
[0055] The audio bus supports bidirectional audio transmission, ensuring real-time audio signal transmission between the local and remote ends, and can flexibly adjust audio gain and signal strength to adapt to intercom needs in different environments.
[0056] Back Figure 2 Based on the specific model, the following is an analysis and explanation of each module in the diagram, including audio acquisition, echo cancellation, gain amplification, and signal output.
[0057] MIC audio input: This module represents the microphone input and is responsible for collecting audio signals from this end (such as the voice signals of the driver or passengers).
[0058] Audio power amplifier (LM4950TS): After the signal is input, it is amplified by the audio power amplifier module LM4950TS to increase the strength of the audio signal so that it can be effectively transmitted to the subsequent processing modules.
[0059] High-frequency signal sampling circuit (10Ω sampling resistor): Through the sampling resistor, a portion of the audio signal's energy is used for monitoring, feedback control, or signal sampling. This module helps the system monitor the audio signal quality in real time to make appropriate adjustments.
[0060] Transformer: A transformer is used for the transmission and electrical isolation of audio signals. It ensures that the signal can flow through the circuit and provides proper impedance matching for the next stage of processing.
[0061] Echo cancellation based on audio processing chip: This part processes the audio signal from the other end, performing echo cancellation through the audio processing chip. It uses algorithms (such as adaptive filtering technology) to remove the echo effect of the local audio signal on the other end's audio signal, ensuring clear audio during intercom.
[0062] Audio Output (Speaker): The echo-cancelled audio signal is amplified by the audio amplifier module (LM4950TS) and output to the speaker (SPK) for voice playback. Through this module, the audio signal is converted from a digital signal into audible sound, realizing voice output.
[0063] This system is designed for high-quality two-way audio transmission, with a focus on addressing echo issues in audio signals. By integrating echo cancellation algorithms and noise suppression technology, the system reduces interference from echo and noise on communication quality, improving call clarity. Furthermore, an audio amplifier module (LM4950TS) enhances the audio signal strength, ensuring clear voice transmission even in noisy environments.
[0064] like Figure 3 As shown, a block diagram of an intercom system with two intercom ports is also provided to facilitate further port expansion.
[0065] Audio input (MIC intercom audio input)
[0066] The system acquires audio signals via a microphone (MIC). This module represents the audio signals (such as the voices of the driver or passengers) captured by the microphone from this end.
[0067] Audio amplifier (LM4950TS)
[0068] After the audio input signal enters the system, it is first amplified by the audio power amplifier module (LM4950TS power amplifier). This audio power amplifier module is responsible for increasing the power of the audio signal to a suitable level for transmission and processing.
[0069] High-frequency signal sampling circuit (-10Ω sampling resistor)
[0070] After the audio signal passes through the sampling resistor (-10Ω sampling resistor), the system monitors or provides feedback on the signal strength in order to adjust subsequent signal processing according to the actual volume and quality.
[0071] Audio signal transmission (transformer)
[0072] After passing through a transformer, the signal undergoes transmission and isolation. The transformer ensures safe and stable signal transmission while preventing electrical interference.
[0073] Audio echo cancellation (echo cancellation based on audio processing chip)
[0074] The system uses an integrated audio echo processing chip (such as ML7037-003TB) to cancel the echo of the audio signal. This chip applies an echo cancellation algorithm to reduce echo interference caused by sound source reflections.
[0075] Audio output (speakers)
[0076] After processing, the audio is amplified again by a power amplifier (LM4950TS) and finally output to the speaker to ensure clear voice output.
[0077] In addition, the diagram shows two independent audio signal flow paths, namely DCP1, DCP2 and PAU, which together enable bidirectional communication of the system.
[0078] DCP1 and DCP2 signal paths: These two paths represent two intercom ports, connected to their respective microphones and speakers, and employing the same signal processing flow. After the audio signal is input from DCP1 or DCP2, it undergoes audio amplification, sampling, echo cancellation, and is finally output through the speaker. Each signal path undergoes audio gain adjustment via an amplifier (LM4950TS) and transmits the signal on the audio bus via a transformer.
[0079] PAU Signal Path: PAU stands for another signal channel used to handle passenger audio input, similar to the driver signal streams (DCP1 and DCP2). The PAU module processes passenger emergency audio signals, amplifying and canceling them through the same process, before outputting them through a speaker.
[0080] Two-way audio bus: The intercom audio bus connects all modules, ensuring bidirectional transmission of audio signals between DCP1, DCP2, and PAU. This means that drivers and passengers can communicate in real time without interruption of information transmission.
[0081] In summary, each module works in concert to ensure that the audio signal undergoes echo cancellation, gain adjustment, and amplification from acquisition to output, guaranteeing optimal sound quality. The system combines multi-channel audio signal streams with echo cancellation algorithms. Through echo cancellation and noise suppression, the system ensures clear audio signals during two-way communication, especially in noisy environments. The dual-channel audio bus and modular design guarantee system stability and flexibility, adapting to the practical application needs of different environments. The dual guarantee of gain adjustment and echo cancellation avoids self-excitation feedback during high-volume or long-duration calls, improving the user experience.
[0082] Example 2
[0083] Correspondingly, an audio echo cancellation method is also provided, characterized in that the method includes:
[0084] Acquire the input audio signal, including the local MIC signal and the remote MIC signal;
[0085] The audio signal is processed by the dedicated audio echo processing chip ML7037-003TB, which includes acoustic echo cancellation and line echo cancellation.
[0086] If the audio signal after echo cancellation meets the preset sound quality standard, the audio signal is amplified by an audio power amplifier module (such as LM4950TS) and transmitted to the other end through the audio bus.
[0087] If the audio signal after echo cancellation does not meet the preset standard, the gain of the audio signal will be further adjusted by the gain adjustment module until the audio output standard is met.
[0088] Echo cancellation processing includes:
[0089] Frequency domain-based echo cancellation algorithm;
[0090] Echo cancellation algorithm based on the time domain;
[0091] Dynamic noise suppression algorithm.
[0092] Among them, the frequency domain-based echo cancellation algorithm uses frequency domain filtering technology to suppress echoes;
[0093] The time-domain-based echo cancellation algorithm uses an adaptive filter for real-time echo cancellation.
[0094] Among them, the gain adjustment module avoids the problem of self-excitation howling caused by excessive volume when adjusting the audio signal gain, and optimizes the clarity and stability of the audio signal through a real-time feedback mechanism.
[0095] The audio signal processing flow also includes the following steps:
[0096] The audio signal is transmitted to the audio bus for bidirectional transmission to the audio processing module at the other end.
[0097] The audio processing module at the other end uses the same echo cancellation method to ensure the echo cancellation effect of the audio signal.
[0098] The audio echo cancellation process also includes a signal gain adjustment function, which is used to adjust the echo cancellation processing intensity in real time according to different environments and volume settings to avoid too much or too little echo.
[0099] Based on the above embodiments, such as Figure 4 This application illustrates a corresponding embodiment of the present application. Figure 2 The circuit structure diagram of the analog bus intercom system. Figure 5 This application illustrates a corresponding embodiment of the present application. Figure 2 Hardware schematic diagram of the intercom circuit.
[0100] like Figure 4 As shown, this two-way intercom processing system achieves high-quality audio signal processing and transmission through the collaborative work of multiple modules. The system first acquires audio signals from its local end through audio input modules (such as DCP1_MIC and PAU_MIC), which then undergo echo cancellation and noise suppression through audio processing modules (such as the ML7037-003TB echo cancellation chip). The echo cancellation process utilizes time-domain and frequency-domain algorithms combined with dynamic noise suppression to ensure the clarity of the audio signal. The processed audio signal is then amplified by an audio power amplifier module (LM4950TS) to enhance signal strength, and then electrically isolated and transmitted through a transformer. A bidirectional audio bus transmits the signal between different modules (DCP1, DCP2, and PAU), ensuring bidirectional flow and timely delivery of the audio signal between modules. Finally, the processed audio signal is output through a speaker (SPK) for the driver and passengers to hear clear voice. This system avoids echo interference and self-excited howling problems through precise echo cancellation and gain adjustment, ensuring high-quality two-way voice communication even in noisy environments, and meeting the needs of intercom systems in various usage scenarios.
[0101] like Figure 5As shown, the core component of this system is an audio processing unit based on a microcontroller (MCU). The system includes multiple modules for achieving high-quality two-way audio communication, with main functions including audio signal acquisition, echo cancellation, gain amplification, signal transmission, and output.
[0102] First, the audio input modules (such as DCP1_MIC and PAU_MIC) are used to acquire audio signals from both the local and remote ends. After the audio signals are input, they are processed by the audio processing module (as shown in the microcontroller and related circuits). The audio echo cancellation function is implemented by an audio processing chip (such as ML7037-003TB), which uses an echo cancellation algorithm to optimize the audio signal, reduce echo and noise interference, and ensure clear sound quality during intercom communication.
[0103] The processed audio signal is amplified by an audio power amplifier module (such as the LM4950TS) to ensure sufficient power for transmission. A gain adjustment module ensures the audio signal strength is moderate, avoiding feedback caused by excessive volume, while also optimizing the clarity of the audio signal.
[0104] The audio signal, after being amplified and gain-adjusted, is transmitted and electrically isolated through a transformer to ensure stable signal transmission and avoid electrical interference. The audio signal is finally output through an audio output module (such as a speaker) so that both parties can hear clear voice information.
[0105] also, Figure 5 The diagram also shows the connection between the microcontroller and various modules. Key parts of signal flow processing include audio signal sampling, filtering, and feedback control. The system design supports bidirectional audio transmission via an audio bus, ensuring real-time communication between the driver and passengers, and adjusting audio gain according to environmental and noise conditions. In conjunction with Embodiment 1, the system effectively eliminates echo interference through echo cancellation and noise suppression technologies, and enhances signal strength through an audio amplifier module, ensuring high-quality bidirectional audio communication even in noisy environments.
[0106] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. The above descriptions are merely optional embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A two-way intercom processing system, characterized in that, The system includes: The audio input module is used to acquire audio signals from both the local and remote ends. The audio processing module includes an audio echo cancellation chip, which is used to cancel echoes and suppress noise in the input audio signal; The audio power amplifier module is used to amplify the power of the processed audio signal; Transformers are used for the transmission and isolation of audio signals; Intercom audio bus, used to transmit two-way audio signals; The audio output module is used to output the processed audio signal.
2. The system according to claim 1, characterized in that, The audio echo cancellation chip is the dedicated audio echo cancellation chip ML7037-003TB.
3. The system according to claim 1, characterized in that, The audio amplifier module uses an LM4950TS amplifier.
4. The system according to claim 1, characterized in that, The audio input module uses a microphone for audio input.
5. The system according to claim 1, characterized in that, The system also includes a high-frequency signal sampling circuit, which is designed with a 10Ω sampling resistor.
6. The system according to claim 1, characterized in that, The system supports two audio signal streams via a bidirectional audio bus; The driver's intercom audio signal stream is processed by the DCP1_ML7037-003TB chip, amplified by the LM4950TS power amplifier, and transmitted to the intercom audio bus through a transformer. It is then received and processed by the DCP2 module and output through the speaker. The passenger emergency alarm audio signal stream is processed by the DCP1_ML7037-003TB chip, amplified by the LM4950TS power amplifier, transmitted to the intercom audio bus through the transformer, and then received and processed by the PAU module before being output through the speaker.
7. The system according to claim 6, characterized in that, Each end of the audio signal stream uses a dedicated audio echo cancellation processing chip ML7037-003TB, and the signal gain is adjusted by an LM4950TS audio power amplifier module to ensure high-quality audio signal output.
8. The system according to claim 7, characterized in that, The dedicated audio echo cancellation processing chip ML7037-003TB has multiple built-in echo cancellation and noise suppression algorithms, which are used to detect and eliminate echoes in real time during intercom to optimize voice quality. The transformer and audio amplifier module are configured to support different types of audio input and output signals, including intercom between the driver and passengers, and transmission of emergency alarm signals. The audio bus supports bidirectional audio transmission.