阅读说明：本技术 一种利用上位机实时离线更新的有源噪声控制系统 (Active noise control system using upper computer for real-time off-line updating ) 是由 史创 姜南 谢荣 李会勇 于 2019-09-09 设计创作，主要内容包括：本发明公开了一种利用上位机实时离线更新的有源噪声控制系统,属于有源噪声控制技术领域。本发明利用上位机实时离线更新的有源噪声控制系统具有更好的自适应性,应对噪声环境变化有更强的再控制能力；通过本发明所提出的系统,可以将有源噪声控制系统中最占用硬件实现资源的控制滤波器更新迭代环节从控制器中分离出来,并将这一部分传递给上位机进行处理,大程度地节省了有源噪声控制系统中的硬件实现压力。从而使得源噪声控制系统利用更廉价的硬件实现平台进行实现,节约实现成本；以及将节省下来的硬件资源用于增加控制滤波器系数长度、使用计算复杂度更高的改进算法等其它需增加系统运算复杂度的部分,获得更好的噪声抑制效果。(The invention discloses an active noise control system using an upper computer to perform real-time off-line updating, and belongs to the technical field of active noise control. The active noise control system updated by the upper computer in real time and offline has better self-adaptability and stronger re-control capability in response to noise environment change; the system provided by the invention can separate the control filter updating iteration link occupying most hardware implementation resources in the active noise control system from the controller, and transmits the part to the upper computer for processing, thereby greatly saving the hardware implementation pressure in the active noise control system. Therefore, the source noise control system is realized by using a cheaper hardware realization platform, and the realization cost is saved; and the saved hardware resources are used for increasing the coefficient length of the control filter, using an improved algorithm with higher calculation complexity and other parts needing to increase the system calculation complexity, and obtaining better noise suppression effect.)

1. An active noise control system updated by an upper computer in real time and off-line is characterized by comprising an upper computer, a controller and external equipment;

the upper computer comprises a register, an update filter coefficient processing module and a secondary path model module; wherein the secondary path model module is obtained based on the secondary path modeling;

the controller comprises a register, a filter and a filter coefficient updating processing unit;

the external equipment comprises a reference microphone, an error microphone, a secondary loudspeaker, an amplifier, an analog-to-digital converter and a digital-to-analog converter;

the reference microphone is connected with the controller through an amplifier and an analog-to-digital converter; the error microphone is connected with the controller through the amplifier and the analog-to-digital converter; the controller is connected with the secondary loudspeaker through a digital-to-analog converter and an amplifier;

the controller stores a reference signal from the reference microphone as a reference signal sequence and an error signal from the error microphone as an error signal sequence; when the preset uploading condition is met, the controller uploads a reference signal sequence and an error signal sequence stored in a memory of the controller to an upper computer;

the upper computer stores the received reference signal sequence and the received error signal sequence into a memory of the upper computer, an updating filter coefficient processing module of the upper computer reads the current reference signal sequence and the current error signal sequence, updates and iterates the adaptive control filter coefficient in a noise reduction algorithm based on a secondary path model in a secondary path model module, and transmits the obtained control filter coefficient increment to a controller;

if the controller does not receive the control filter coefficient increment returned by the upper computer, the controller directly generates a control signal based on the current self-adaptive control filter coefficient and the current reference signal, outputs the control signal to an amplifier connected with a secondary loudspeaker through an analog-to-digital converter, and drives the secondary loudspeaker to sound for noise reduction; if the control filter coefficient increment returned by the upper computer is received, the filter coefficient updating processing unit of the controller adds the self-adaptive control filter coefficient existing at the local end and the received control filter coefficient increment to form the current self-adaptive control filter coefficient, the controller generates a control signal by the current self-adaptive control filter coefficient and the current reference signal, and the control signal is output to an amplifier connected with a secondary loudspeaker through an analog-to-digital converter to drive the secondary loudspeaker to sound for noise reduction processing.

2. The system of claim 1, wherein the predetermined upload conditions are: the length of the stored data reaches a threshold value or the uploading time of the periodic uploading reaches.

3. The system of claim 1, wherein the means for the host computer to communicate the obtained control filter coefficient increments to the controller comprises:

and transmitting the control filter coefficient increment updated at the last moment to the controller, transmitting the selected optimal control filter coefficient increment to the controller or transmitting the control filter coefficient increment updated at the appointed moment to the controller.

4. The system of claim 1, wherein the secondary path model in the secondary path model module is obtained by an offline update of the host computer.

Technical Field

The invention belongs to the field of active noise control, and particularly relates to an active noise control system design updated by an upper computer in an off-line mode.

Background

Noise control techniques can be divided into two categories, passive noise control and active noise control. Due to the limitations of cost, deployment mode and other limitations, the passive noise control technology has low efficiency of suppressing low-frequency noise. The human ear is sensitive to low-frequency noise, so that active noise control technology capable of effectively suppressing low-frequency noise is receiving more and more attention. The noise reduction principle of the active noise control technique is derived from the interference phenomenon of acoustic waves. After the noise to be processed is analyzed, the electroacoustic device sends an 'anti-noise' with the same amplitude and the opposite phase to the noise through the self-adaptive processing technology to offset at a specified position, and then the noise power is consumed to realize noise reduction. The active noise control system can be divided into a feedforward active noise control system and a feedback active noise control system according to the existence of a reference microphone participating in the system work.

The system operation amount in the active noise control system is closely related to the difficulty of engineering realization. On one hand, in the process of pursuing a better noise reduction effect of a single-channel or multi-channel active noise control system, the use of various improved algorithms increases the system operation amount. On the other hand, in a multi-channel active noise control system with a plurality of reference microphones (if any), a secondary speaker, an error microphone and an adaptive controller, the number of channels is increased, and the coupling in a sound field is added, so that the operation amount of the active noise control system is greatly increased, and the system is more complicated. An excessively complex active noise control system can cause excessive calculation pressure of a hardware platform, and is not beneficial to engineering implementation. Therefore, how to effectively control the computation of the active noise control system and reduce the computational pressure of the hardware implementation platform is a practical requirement for the continuous development of the active noise control technology and the promotion of commercial application.

Various solutions to this problem are provided, and mainly the algorithm for active noise control is directly improved, that is, the computational complexity of the active noise control system is attempted to be reduced from the algorithm level. Such attempts are, for example, Gonzalez, A.Albiol, S.J.Elliott.Minmization of the maximum error signal in active control, IEEETransmission on Speech and Audio Processing 1998, volume 6 (phase 3), pages 268 to 281, disclosing an active noise control minimum Algorithm, S.C.Douglas.Adaptation filters on estimating active update, IEEE Transmission on Speech and Audio Processing 1997, volume 5 (phase 4), page 378, disclosing an active noise control partial update iteration 381. For an online updating multi-channel active noise system, namely, a controller occupies own computing resource to update the adaptive filter in real time, the controller is required to have stronger computing capability, which causes higher hardware implementation cost. In order to reduce the hardware implementation pressure and cost, the existing active noise control system (e.g., active noise control headphone) usually uses an off-line update mode, i.e., an adaptive filter is trained by a computer, and after the adaptive filter is trained, the adaptive filter is stored in a controller for noise reduction. In practical application, the noise environment changes and other situations are often encountered, and the controller cannot effectively respond because the fixed filter is not updated iteratively any more, so that the robustness of the system is poor, and the noise reduction effect of the offline updating system is not as ideal as the expected noise reduction effect. At present, a system and a method for separating an adaptive control update iteration process from a hardware implementation platform do not exist.

Disclosure of Invention

The invention aims to: in order to solve the problem of overlarge system operation amount caused by using an improved algorithm, increasing the number of channels and the like in an active noise control system, a technical design method for separating a self-adaptive control updating iteration process from a noise reduction hardware realization platform is provided, so that a brand-new active noise control system utilizing an upper computer for off-line updating is provided.

The active noise control system utilizing the upper computer to perform real-time off-line updating comprises the upper computer, a controller and external equipment;

the upper computer comprises a register, an update filter coefficient processing module and a secondary path model module; wherein the secondary path model module is obtained based on the secondary path modeling;

the controller comprises a register, a filter and a filter coefficient updating processing unit;

the external equipment comprises a reference microphone, an error microphone, a secondary loudspeaker, an amplifier, an analog-to-digital converter and a digital-to-analog converter;

the reference microphone is connected with the controller through an amplifier and an analog-to-digital converter; the error microphone is connected with the controller through the amplifier and the analog-to-digital converter; the controller is connected with the secondary loudspeaker through a digital-to-analog converter and an amplifier;

the controller stores a reference signal from the reference microphone as a reference signal sequence and an error signal from the error microphone as an error signal sequence; when the preset uploading condition is met, the controller uploads a reference signal sequence and an error signal sequence stored in a memory of the controller to an upper computer;

the upper computer stores the received reference signal sequence and the received error signal sequence into a memory of the upper computer, an updating filter coefficient processing module of the upper computer reads the current reference signal sequence and the current error signal sequence, updates and iterates the adaptive control filter coefficient in a noise reduction algorithm based on a secondary path model in a secondary path model module, and transmits the obtained control filter coefficient increment to a controller;

if the controller does not receive the control filter coefficient increment returned by the upper computer, the controller directly generates a control signal based on the current self-adaptive control filter coefficient and the current reference signal, outputs the control signal to an amplifier connected with a secondary loudspeaker through an analog-to-digital converter, and drives the secondary loudspeaker to sound for noise reduction; if the control filter coefficient increment returned by the upper computer is received, the filter coefficient updating processing unit of the controller adds the self-adaptive control filter coefficient existing at the local end and the received control filter coefficient increment to form the current self-adaptive control filter coefficient, the controller generates a control signal by the current self-adaptive control filter coefficient and the current reference signal, and the control signal is output to an amplifier connected with a secondary loudspeaker through an analog-to-digital converter to drive the secondary loudspeaker to sound for noise reduction processing.

In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:

compared with the existing active noise control system for offline updating of the adaptive filter coefficient, the brand-new active noise control system for offline updating by utilizing the upper computer in real time has better adaptivity and stronger controllability for coping with noise environment changes. And secondly, by the system provided by the invention, the control filter updating iteration link which occupies most hardware implementation resources in the active noise control system can be separated from the controller. And the part is transmitted to an upper computer for processing, so that the hardware realization pressure in the active noise control system is greatly saved. On one hand, the saved hardware resources can enable the active noise control system to be realized by using a cheaper hardware realization platform, so that the realization cost can be saved, and the commercial application of the active noise control system can be better promoted; on the other hand, saved hardware resources can be used for other parts needing to increase the system operation complexity, such as increasing the control filter coefficient length, using an improved algorithm with higher calculation complexity and the like, and a better noise suppression effect is obtained.

Drawings

FIG. 1 is a block diagram of an active noise control system using an off-line update of a host computer according to the present invention;

FIG. 2 is a schematic diagram of the system components and implementation of the present invention;

FIG. 3 is a schematic diagram of the components and implementation of the sub-path modeling of the present invention;

FIG. 4 is a schematic diagram of simulation verification A of the present invention in an embodiment;

FIG. 5 is a schematic diagram B of simulation verification according to the present invention;

FIG. 6 is a schematic diagram of simulation verification C of the present invention in an embodiment.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the following embodiments and accompanying drawings.

Compared with an online updating system, the active noise control system can effectively reduce the calculation complexity and cost of the active noise control system on a controller, and can effectively adapt to the change of a noise environment. The adopted method is as follows: the active noise control system separates the self-adaptive control updating iteration process which originally consumes the most hardware resources from a hardware implementation platform, and utilizes an upper computer to perform off-line updating of the control filter coefficient on the part. Therefore, the hardware implementation platform only stores and carries the required signal information and other steps occupying little hardware resources. Further, the engineering implementation of active noise control can be realized by using cheaper hardware equipment. The implementation cost of the active noise control system is greatly reduced. Meanwhile, the upper computer actually participates in the updating iteration process of the adaptive controller, so that an improved algorithm with higher calculation complexity can be used on the premise of not increasing the pressure of hardware equipment, and the target noise reduction effect is further improved.

The active noise control system updated by the upper computer in an off-line manner can be applied to various active noise control systems such as a single channel, a multi-channel, a feedforward type, a feedback type and the like, and a schematic block diagram of the system structure is shown in fig. 1.

The active noise control system comprises an upper computer, a controller (a hardware controller) and external equipment, and the whole system can exist wholly or partially. The external equipment comprises electroacoustic devices required in an active noise control system such as a reference microphone, an error microphone and a secondary loudspeaker, and various analog-to-digital converters, digital-to-analog converters, anti-aliasing filters, power amplifiers, peripheral circuits and the like required by the system.

The upper computer of the active noise control system comprises a register, an update filter coefficient processing module and a secondary channel model module; the controller comprises a register and a filter coefficient updating processing unit; the external equipment comprises a reference microphone, an error microphone, a secondary loudspeaker, an amplifier, an analog-to-digital converter and a digital-to-analog converter; the register of the upper computer and the secondary path model module are respectively connected with the filter coefficient updating processing module; the register of the upper computer is connected with the register of the controller; the updating filter coefficient processing module of the upper computer is connected with the filter coefficient updating processing unit of the controller and used for updating the current self-adaptive filter coefficient of the controller, and the controller is connected with the secondary loudspeaker through a digital-to-analog converter and an amplifier; and the adaptive control filter coefficient and the current reference signal output by the phase secondary loudspeaker are used for generating a control signal, and the control signal is output to the power amplifier to drive the external secondary loudspeaker to sound for noise reduction. Meanwhile, the reference microphone is connected with a register of the controller through an amplifier and an analog-to-digital converter, and the error microphone is connected with the register of the controller through the amplifier and the analog-to-digital converter.

After the active noise control system updated by the upper computer in real time in an off-line mode enters a working state, a reference microphone in the external equipment picks up noise sound waves at the position of the reference microphone. Meanwhile, the error microphone picks up sound waves at the position of the error microphone, and the sound waves are used as noise reduction conditions of the monitoring system. The external equipment is connected with the controller, transmits the sound wave signals received by the external equipment and the controller at each moment to the controller, and temporarily stores the sound wave signals in a register of the controller.

The controller does not carry out the updating iterative processing part of the self-adaptive control filter coefficient in the noise reduction algorithm, only outputs a control signal, and drives the secondary loudspeaker to emit anti-noise sound waves through the power amplifier. Which is connected on the one hand to an external device, and stores the reference signals received by the reference microphone at each instant as a reference signal sequence. And storing the error signals received by the error microphone at each moment as an error signal sequence. And on the other hand, the data volume is connected with the upper computer, and when the data volume in the register reaches a certain degree or the timing is finished in a timer mode, the data volume is transmitted to the upper computer for processing, namely the data volume meets an uploading threshold or is uploaded to the upper computer periodically.

And the upper computer performs an updating iterative processing part of the adaptive control filter coefficient in the noise reduction algorithm by using a secondary path model obtained by secondary path modeling. The upper computer is only connected with the controller, and the control filter coefficient increment is transmitted to the controller to obtain the current self-adaptive control filter coefficient, so that various choices are provided, such as transmitting the control filter coefficient updated at the last moment to the controller, transmitting the selected optimal control filter coefficient to the controller, transmitting the control filter coefficient updated at the appointed moment to the controller, and the like.

The controller generates a control signal by using the current adaptive control filter coefficient and the current reference signal, outputs the control signal to the power amplifier, and drives the external secondary loudspeaker to sound for noise reduction.

Similar to the working principle of the invention when in denoising operation, the active noise control system which utilizes the off-line updating of the upper computer transfers the updating process of the secondary channel model to the upper computer for processing. In the active noise control system of the present invention, the specific number and type of each peripheral device (microphone, speaker, analog-to-digital converter, digital-to-analog converter, amplifier, peripheral circuit, etc.) is not limited, and is selected according to the specific application requirements, application scenarios, the type of the controller and the type of the upper computer. Likewise, the number and type of controllers in the system is not limited. And the number and the type of the upper computers are not limited.