Multi-point active noise reduction device

Abstract

The invention provides a multi-point active noise reduction device. The device is characterized by comprising a voiceprint demodulation module, a connecting optical fiber, an optical fiber pickup module, a vibration sensing module, a feedback control module and a loudspeaker module. The distributed optical fiber voiceprint demodulation technology is utilized, the optical fiber probe is used for collecting noise signals of all point positions, and the sound source vibration sensor and the differential feedback control algorithm are combined, so that multi-point active noise reduction is achieved. The invention provides a distributed multi-point active noise reduction solution under a complex scene, so that the distributed multi-point active noise reduction solution can meet noise reduction requirements of various scenes such as spinning, printing, building, railway and aviation.

Description

(I) Technical field

[0001] The present invention relates to a multi-point active noise reduction device, mainly to the field of active noise reduction, and more specifically to a multi-point active noise reduction device based on optical fiber acoustic wave sensing technology. Based on distributed optical fiber voiceprint collection and high-fidelity voiceprint demodulation method, a low-latency, multi-point, simplified noise reduction device can be realized. (II) Background technology

[0002] Noise reduction technology is widely used in the fields of construction, transportation, aerospace, electronic communications, and industrial production. Common noise reduction technologies currently include passive noise reduction and active noise reduction. Passive isolation noise reduction solutions require the use of sound-absorbing materials to achieve noise elimination or isolation, with high implementation costs, and are suitable for noise reduction in indoor confined spaces. Active noise reduction technology can offset noise that cannot be physically isolated in real time by outputting an inverted waveform with equal amplitude to the noise signal. It is suitable for confined or open spaces and has more flexible application scenarios. Existing active noise reduction technologies are mainly based on electrical voiceprint collection solutions, which require the collection of field signals in advance for inverted output. When the ambient sound field changes, there are problems such as poor environmental adaptability and unstable noise reduction effects. In addition, in a complex open environment, when multi-point noise reduction is required, electrical technology is difficult to achieve low-latency transmission and real-time feedback of noise signals at different points. Point coverage can only be achieved by increasing the number of noise reduction devices, and the system is complex and costly.

[0003] For example, Chinese patent CN201480046581.0 discloses a noise reduction method, device and mobile terminal. The device determines the terminal vibration waveform by collecting the acceleration signal of the sound source, and then inverts the vibration waveform to obtain a noise reduction signal and superimposes it on the audio output device. This technology can be applied to noise reduction headphones to reduce and eliminate the noise generated by bone vibration and improve the audio-visual effect. However, due to the working range of the electrical sound wave acquisition system, the system is only suitable for noise reduction in a closed environment near the human ear, and cannot achieve multi-point noise reduction function.

[0004] Chinese patent CN201610382317.5 discloses a method for inverse noise reduction of textile machinery. The method first uses a sound intensity probe to obtain a noise signal and obtain its spectrum. Then, the inverse noise spectrum required for noise reduction is obtained based on the noise spectrum and a slicing result is obtained. Finally, the number and position of speakers are determined based on the slicing result, and an inverse noise signal is sent through the speaker to cancel the noise. This method cancels noise by applying inverse noise with an inverse phase of the noise spectrum, which can achieve the working requirement of reducing noise during the operation of textile machinery. However, due to the limitations of the electrical transmission frequency band, rate and synchronization accuracy, the number of noise reduction points that can be supported is less than 4, and the number of speakers and wires and cables increases rapidly with the number of points. The system is complex and the cost is high.

[0005] In order to realize the multi-point active noise reduction function in a complex environment, the present invention proposes a multi-point active noise reduction device. Based on distributed optical fiber sensing technology, communication optical fiber is used as a voiceprint collection device, and voiceprint demodulation technology is used to restore the environmental noise waveform collected by optical fiber probes at different points in real time. Combined with the sound source signal collected by the vibration sensor, the differential and feedback algorithm is introduced to realize the multi-point active suppression function of environmental noise. Compared with the traditional active noise reduction scheme, the technical advantages of the device include: using communication optical fiber as a voiceprint collection device, it can realize the real-time collection of noise voiceprint signals in a complex environment, and the noise signal is transmitted back to the voiceprint demodulator at the speed of light, which significantly reduces the transmission delay and improves the real-time performance and noise reduction effect of the system; the voiceprint demodulation module based on optical fiber technology can support hundreds of noise reduction points to output anti-phase sound waves at the same time, greatly increasing the number of noise reduction points, and realizing distributed multi-point noise reduction function; the optical fiber probe device has a simple and compact structure, has strong robustness to external electromagnetic disturbances, and does not require wires and cables, which greatly reduces the complexity and cost of the system. The technical advantages of the device proposed in the present invention enable it to be applicable to the noise reduction needs of many scenarios such as textiles, printing, construction, railways, and aviation. (III) Summary of the invention

[0006] The purpose of the present invention is to overcome the problems of poor environmental adaptability and unstable noise reduction effect in the prior art, and to provide a distributed multi-point active noise reduction device. The device is based on distributed optical fiber sensing technology, uses communication optical fiber as a voiceprint collection device, and uses voiceprint demodulation technology to restore the environmental noise waveform collected by optical fiber probes at different points in real time. Combined with the sound source signal collected by the vibration sensor, a differential and feedback algorithm is introduced to achieve the active suppression function of multi-point environmental noise.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A multi-point active noise reduction device consists of a voiceprint demodulation module, a connecting optical fiber, an optical fiber pickup module, a vibration sensing module, a feedback control module, and a speaker module.

[0009] Specifically speaking, the voiceprint demodulation module is composed of a laser, a modulator, a circulator, a photodetector, a digital acquisition card, a demodulation unit, and a sending unit.

[0010] The laser in the voiceprint demodulation module outputs a laser beam, which is modulated into an optical pulse signal by the modulator and then injected into the connecting optical fiber through the circulator. The laser output wavelength needs to match the transmission loss of the connecting optical fiber to ensure that the transmission loss of the laser beam in the transmission optical fiber is no more than 20dB / km. By setting the pulse width of the optical pulse signal, the spatial resolution of the device for sound wave collection can be controlled. The shorter the pulse width, the higher the spatial resolution.

[0011] The optical pulse signal enters the optical fiber probe in the optical fiber pickup module through the connecting optical fiber to realize the collection of environmental noise signals. The collected environmental noise signal is then transmitted back through the connecting optical fiber to the photoelectric detector, digital acquisition card, and demodulation unit in the voiceprint demodulation module for sound wave demodulation to obtain the environmental noise waveform at different positions.

[0012] The demodulation unit in the voiceprint demodulation module can solve the sound wave signals at different positions from the light intensity and phase changes carried by the backscattered light beam. By setting the filtering parameters in the demodulation unit, it can be ensured that the demodulation dynamic range parameters of the demodulation unit match the sound intensity range of the ambient noise. By setting the pulse repetition frequency of the modulator, the detection bandwidth of the photodetector, the sampling frequency of the digital acquisition card and other parameters, it can be ensured that the sound wave acquisition frequency range of the device covers the ambient noise frequency band.

[0013] Specifically speaking, the fiber optic pickup module consists of a fiber optic probe and a fixed frame.

[0014] By setting the length of the optical fiber included in the optical fiber probe in the optical fiber pickup module, the device's collection sensitivity and spatial resolution to the ambient noise at each point can be controlled, ensuring that the length of the optical fiber included in the optical fiber probe in the optical fiber pickup module matches the pulse width parameter set by the modulator.

[0015] Specifically speaking, the vibration sensing module consists of a sensing unit and a transmission unit.

[0016] The sensing unit in the vibration sensing module is installed at the sound source position, and is used to collect the vibration waveform of the sound source, and transmit the vibration waveform of the sound source from the transmission unit to the differential unit in the feedback control module. The vibration waveform of the sound source is used as a reference signal to correct the ambient noise waveform at each point. By setting the sensing parameters of the vibration sensing module, the response frequency range of the vibration sensing module to the vibration of the sound source can be controlled to ensure that the response frequency range of the vibration sensing module covers the ambient noise frequency band.

[0017] From a specific analysis, the feedback control module consists of a differential unit, a feedback unit, and a drive unit.

[0018] The function of the differential unit of the feedback control module is to compare the ambient noise waveform collected by the optical fiber probe with the sound source vibration waveform collected by the sensing unit, obtain an error waveform after performing a differential operation, and then transmit the error waveform and the ambient noise waveform collected by the optical fiber probe to the feedback unit.

[0019] The feedback unit minimizes the error waveform by the least square method based on the error waveform and the ambient noise waveform transmitted by the differential unit, thereby correcting the ambient noise waveform. The corrected ambient noise waveform is then inverted to form a drive waveform and transmitted to the drive unit. To ensure the real-time active noise reduction function of the device, the response time of the feedback control module must be no longer than 0.1 seconds.

[0020] The drive unit transmits the drive waveform transmitted by the feedback unit to the speaker module for sound wave amplification and playback, thus realizing the active noise reduction function. The output frequency range of the selected speaker module must cover the ambient noise frequency band.

[0021] Compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects:

[0022] 1. Compared with the prior art, the multi-point active noise reduction device provided by the present invention uses communication optical fiber as a voiceprint collection device, which can realize real-time collection of noise signals in complex environments. The noise signal is transmitted back to the voiceprint demodulator at the speed of light, which significantly reduces the transmission delay and improves the real-time performance and noise reduction effect of the system.

[0023] 2. The voiceprint demodulation module used in the solution of the present invention can support hundreds of noise reduction points to output anti-phase sound waves at the same time, greatly increasing the number of noise reduction points and realizing distributed multi-point noise reduction function.

[0024] 3. The optical fiber probe device of the present invention has a simple and compact structure, is highly robust to external electromagnetic disturbances, and does not require wires and cables, which greatly reduces the complexity and cost of the system. It has broad application prospects in the fields of textiles, printing, construction, railways, aviation, etc. (IV) Description of the drawings

[0025] Figure 1 It is a multi-point active noise reduction device, which consists of a voiceprint demodulation module, a connecting optical fiber, an optical fiber pickup module, a vibration sensing module, a feedback control module, and a speaker module.

[0026] Figure 2 It is the time domain diagram and spectrum diagram of the environmental noise waveform collected by the fiber optic probe.

[0027] Figure 3 It is the vibration waveform of the sound source collected by the vibration sensor module.

[0028] Figure 4 It is a comparison chart of the sound intensity at the probe position before and after noise reduction. (V) Specific implementation methods

[0029] The present invention is further described below with reference to the accompanying drawings and examples.

[0030] like Figure 1 As shown, a multi-point active noise reduction device is composed of a soundprint demodulation module (1), a connecting optical fiber (2), an optical fiber pickup module (3), a vibration sensor module (4), a feedback control module (5), and a speaker module (6).

[0031] In the device, the voiceprint demodulation module (1) is composed of a laser (101), a modulator (102), a circulator (103), a photoelectric detector (104), a digital acquisition card (105), a demodulation unit (106), and a sending unit (107); the optical fiber pickup module (3) is composed of an optical fiber probe (301) and a fixed frame (302); the vibration sensing module (4) is composed of a sensing unit (401) and a transmission unit (402); and the feedback control module (5) is composed of a differential unit (501), a feedback unit (502), and a driving unit (503).

[0032] The laser (101) in the voiceprint demodulation module (1) outputs a laser beam, which is modulated into an optical pulse signal (7) by a modulator (102) and then injected into the connecting optical fiber (2) via a circulator (103).

[0033] The optical pulse signal (7) enters the optical fiber probe (301) in the optical fiber pickup module (3) through the connecting optical fiber (2) to collect the environmental noise signal, and then is transmitted back through the connecting optical fiber (2) to the photoelectric detector (104), the digital acquisition card (105), and the demodulation unit (106) in the voiceprint demodulation module (1) for sound wave demodulation to obtain the environmental noise waveform (8) at different positions, and then the environmental noise waveform (8) is transmitted to the differential unit (501) in the feedback control module (5) through the sending unit (107).

[0034] The sensing unit (401) in the vibration sensing module (4) is installed at the sound source position, collects the sound source vibration waveform (9), and transmits the sound source vibration waveform (9) to the differential unit (501) in the feedback control module (5) through the transmission unit (402).

[0035] The differential unit (501) compares the environmental noise waveform (8) collected by the optical fiber probe (301) with the sound source vibration waveform (9) collected by the sensing unit (401), and performs a differential operation to obtain an error waveform (10), and then transmits the error waveform (10) and the environmental noise waveform (8) collected by the optical fiber probe (301) to the feedback unit (502).

[0036] The feedback unit (502) corrects and inverts the environmental noise waveform according to the error waveform (10) and the environmental noise waveform (8) transmitted by the differential unit (501) to form a driving waveform (11), which is then transmitted to the driving unit (503).

[0037] The driving unit (503) transmits the driving waveform (11) transmitted by the feedback unit (502) to the speaker module (6) for sound wave amplification and playback, thereby realizing an active noise reduction function.

[0038] The laser (101) is a continuous light laser with a laser wavelength of 1550.11 nm, an output power of 20 mW, and an output connector that is a FC / APC standard optical fiber connector.

[0039] The modulator (102) is an acousto-optic modulator with a frequency shift of 40 MHz, a pulse width of 50 ns and a modulation frequency of 200 kHz.

[0040] The circulator (103) is a single-mode optical fiber circulator, and the output connector is an FC / APC standard optical fiber connector.

[0041] The photoelectric detector (104) is a laser diode with a response wavelength range of 800nm-1800nm ​​and a response bandwidth of 80MHz.

[0042] The sampling rate of the digital acquisition card (105) is 200 MHz.

[0043] The filter used in the demodulation unit (106) is a bandpass filter with a passband frequency range of 10 Hz to 600 Hz, and the sound wave demodulation algorithm used is a PGC demodulation algorithm.

[0044] The connecting optical fiber (2) is a G652 single-mode optical fiber, and the loss at a wavelength of 1550.11 nm is about 0.19 dB / km.

[0045] The optical fiber included in the optical fiber probe (301) in the optical fiber pickup module (3) is 30 meters long, and the material of the fixed frame (302) is aluminum alloy.

[0046] The sensing unit (401) in the vibration sensing module (4) is a point-type acceleration sensor with a frequency range of 10-500 Hz, and the transmission unit (402) is an ordinary copper stranded wire.

[0047] The differential unit (501) in the feedback control module (5) performs a linear differential operation on the ambient noise waveform collected by the optical fiber probe (301) and the sound source vibration waveform collected by the sensor unit (401), thereby obtaining an error waveform. Based on the obtained error waveform, the feedback unit (502) uses a least squares algorithm to minimize the error waveform to obtain a corrected ambient noise waveform. The ambient noise waveform is then shifted by π phase to achieve an inverted phase operation. The output impedance of the drive unit (503) matches the input impedance of the speaker module (6).

[0047] The output frequency range of the corresponding loudspeaker module (6) is 10-500 Hz.

[0048] To facilitate understanding of the present invention, the present invention is further described below in conjunction with specific embodiments. The present invention can be implemented in many different forms and is not limited to the embodiments described in this specification.

[0049] Step 1. Turn on the power of the voiceprint demodulation module (1), set the pulse width in the voiceprint demodulation module (1) to 50ns, the output power to 20mW, and set the length of the connecting optical fiber (2) to 1km; connect the connecting optical fiber (2) to the voiceprint demodulation module (1) through the FC / APC interface; connect the connecting optical fiber (2) to the optical fiber pickup module (3) through the FC / APC interface. Place the optical fiber pickup module (3) at the noise reduction point and fix it with the fastening screws. Connect the feedback control module (5) to the speaker module (6) through an audio cable. The time domain diagram of the collected environmental noise waveform and its spectrum diagram collected by the optical fiber probe (301) are shown as follows. Figure 2 shown.

[0050] Step 2: Install the vibration sensor module (4) at the sound source position by magnetic attraction, and connect the transmission unit (402) to the BNC interface of the feedback control module (5). Turn on the power of the vibration sensor module (4). The vibration waveform of the sound source collected by the vibration sensor module (4) is as follows: Figure 3 shown.

[0051] Step 3: Perform a linear difference operation on the ambient noise waveform collected by the optical fiber probe (301) and the sound source vibration waveform collected by the sensor unit (401) to obtain an error waveform, and use the least square method to minimize the error waveform to obtain a corrected ambient noise waveform. Then, the ambient noise waveform is shifted by π phase to achieve an inverted waveform.

[0052] Step 4: Turn on the power of the speaker module (6) to output an inverted waveform to achieve the noise reduction function. Figure 4 shown.

Claims

1. A multi-point active noise reduction device, characterized by: The device comprises a voiceprint demodulation module (1), a connecting optical fiber (2), an optical fiber pickup module (3), a vibration sensing module (4), a feedback control module (5), and a speaker module (6); the voiceprint demodulation module (1) in the device comprises a laser (101), a modulator (102), a circulator (103), a photoelectric detector (104), a digital acquisition card (105), a demodulation unit (106), and a sending unit (107); the optical fiber pickup module (3) comprises an optical fiber probe (301) and a fixed frame (302); the vibration sensing module (4) comprises a sensing unit (401) and a transmission unit (402); and the feedback control module (5) comprises a differential unit (501), a feedback unit (502), and a driving unit (503). The laser (101) in the voiceprint demodulation module (1) outputs a laser beam, which is modulated into an optical pulse signal (7) by the modulator (102) and then injected into the connecting optical fiber (2) through the circulator (103). The optical pulse signal (7) enters the optical fiber probe (301) in the optical fiber pickup module (3) through the connecting optical fiber (2) to collect the environmental noise signal. The backscattered light beam in the optical fiber probe (301) is transmitted back through the connecting optical fiber (2) to the photoelectric detector (104), the digital acquisition card (105), and the demodulation unit (106) in the voiceprint demodulation module (1) for sound wave demodulation to obtain the environmental noise waveform (8) at different positions. The environmental noise waveform (8) is then transmitted to the differential unit (501) in the feedback control module (5) through the transmission unit (107). The sensing unit (401) in the vibration sensing module (4) is installed at the sound source position to collect the sound source vibration waveform (9), and the sound source vibration waveform (9) is transmitted to the differential unit (501) in the feedback control module (5) through the transmission unit (402). The differential unit (501) compares the ambient noise waveform (8) collected by the optical fiber probe (301) with the sound source vibration waveform (9) collected by the sensing unit (401), and performs a differential operation to obtain an error waveform (10), and then transmits the error waveform (10) and the ambient noise waveform (8) collected by the optical fiber probe (301) to the feedback unit (502). The feedback unit (502) corrects and inverts the ambient noise waveform according to the error waveform (10) and the ambient noise waveform (8) transmitted by the differential unit (501) to form a driving waveform (11), and transmits it to the driving unit (503). The driving unit (503) transmits the driving waveform (11) transmitted by the feedback unit (502) to the speaker module (6) for sound wave amplification and playback, thereby realizing an active noise reduction function.

2. A multi-point active noise reduction device according to claim 1, characterized in that: The voiceprint demodulation module can solve the sound wave signals at different positions from the changes in light intensity, phase, and polarization state carried by the backscattered light beam, and the frequency range needs to cover the ambient noise frequency band.

3. The multi-point active noise reduction device according to claim 1, characterized in that: The connecting optical fiber can transmit the laser beam and the backscattered light beam with low loss, and the transmission loss is not higher than 20dB / km.

4. The multi-point active noise reduction device according to claim 1, characterized in that: The length of the optical fiber in the optical fiber pickup module matches the pulse width parameter of the modulator.

5. The multi-point active noise reduction device according to claim 1, characterized in that: The response frequency range of the vibration sensor module to the vibration of the sound source covers the ambient noise frequency band.

6. The multi-point active noise reduction device according to claim 1, characterized in that: The response time of the feedback control module is no longer than 0.1 second.

7. The multi-point active noise reduction device according to claim 1, characterized in that: The output frequency range of the loudspeaker module covers the ambient noise frequency band.

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