WO2012174790A1

WO2012174790A1 - Noise reducing method and mobile terminal

Info

Publication number: WO2012174790A1
Application number: PCT/CN2011/078637
Authority: WO
Inventors: 秦世军; 周加品
Original assignee: 中兴通讯股份有限公司
Priority date: 2011-06-24
Filing date: 2011-08-19
Publication date: 2012-12-27
Also published as: CN102223428A

Abstract

A noise reducing method and a mobile terminal. The mobile terminal comprises: an inverting circuit, a superimposer and a receiver. The inverting circuit is configured to invert a collected noise signal synchronous with environment noise. The superimposer is configured to superimpose a noise signal obtained after the inverting circuit performs inverting on a voice signal received by the mobile terminal. The receiver is configured to output a signal obtained after the superimposer performs superimposition. The foregoing technical solution not only effectively solves the problem of noise reducing in a noisy environment, but also takes account of the voice transmission quality.

Description

Method for reducing noise and mobile terminal

Technical field

The present invention relates to a technique for reducing noise of a mobile terminal, and more particularly to a method for reducing noise and a mobile terminal.

Background technique

At present, mobile terminals have become an indispensable communication tool in people's lives, and their applications are very common. The application environment is very different and will inevitably be used in more noisy environments, such as large dining halls, public transportation, downtown and roadside.

The existing noise reduction mobile phones on the market are all performing noise reduction processing on the uplink. The implementation methods are mainly divided into hardware noise reduction and digital signal processing (DSP) noise reduction.

Among them, the hardware noise reduction scheme, the implementation method is simple, and a single microphone (Mic) can realize the noise reduction function. However, it has the disadvantage that while the noise is being reduced, the attenuation of the speech is also very large, and the distortion is severe, and the speech is empty and flickering. Especially when the background noise is relatively large, the strong noise reduction mode must be used, so that the voice becomes very small, and the other party sounds very difficult.

DSP noise reduction scheme is divided into single Mic and dual Mic; single Mic scheme, hardware implementation is simple, and DSP operation is more flexible; the disadvantage is that the effect of noise reduction is limited, especially for non-stationary noise (such as Caf noise). Did not achieve the desired results. Dual Mic scheme, through DSP parameter control, the operation is more flexible, the noise reduction effect is obvious, and the fidelity of the voice is higher, and the volume attenuation is smaller.

Mobile terminals are increasingly used in noisy environments, such as construction sites, subways, buses, etc., but the uplink noise reduction function is far from satisfying the needs of users, because it can only ensure that the caller can hear the voice more clearly. The caller is in a noisy environment around, even if the volume of the handset is large, it is difficult to hear the contents of the other party's voice.

Summary of the invention

Embodiments of the present invention provide a method for reducing noise and a mobile terminal to solve existing mobile When the terminal answers the call in a noisy environment, the caller cannot hear the voice content of the other party. The embodiment of the invention provides a method for reducing noise, which is applied to a downlink of a mobile terminal, and the method includes:

Inverting the noise signal that is collected in synchronization with the environmental noise;

The inverted noise signal is superimposed with the voice signal received by the mobile terminal, and the superposed signal is output.

Wherein: the step of inverting the noise signal synchronized with the ambient noise is: performing amplification and analog-to-digital conversion on the collected noise signal, and correlating the analog-to-digital converted noise signal with the environmental noise. Synchronous processing, and inverting the correlated and synchronized processed noise signals.

Wherein: the steps of outputting the superimposed signal include:

The superimposed signal is subjected to digital-to-analog conversion and amplification processing, and then output.

An embodiment of the present invention further provides a mobile terminal, where the mobile terminal includes: an inverting processing circuit, an adder, and an earpiece, where:

The inverting processing circuit is configured to: invert the noise signal that is collected in synchronization with the environmental noise;

The adder is configured to: superimpose a noise signal inversely processed by the inversion processing circuit with a voice signal received by the mobile terminal;

The earpiece is configured to: output a signal superimposed by the adder.

The inverting processing circuit includes: a reference microphone, an adaptive filter, and an inverter, wherein:

The reference microphone is configured to: collect a noise signal;

The adaptive filter is configured to: correlate and synchronize the noise signal collected by the reference microphone with the ambient noise;

The inverter is configured to: perform inverse processing on the adaptive filter correlation and the synchronized processed noise signal.

Wherein: the inverting processing circuit further includes a serial connection in series and the reference microphone and the self An amplifier and an analog-to-digital converter that are adapted between the filters, where:

The amplifier is configured to: amplify a noise signal of the reference microphone set; the analog-to-digital converter is configured to: perform analog-to-digital conversion on the amplified noise signal of the amplifier, and convert the analog-to-digital converted noise A signal is sent to the adaptive filter.

The mobile terminal further includes: a digital-to-analog converter and an amplifier connected in series and located between the adder and the earpiece, wherein:

The digital-to-analog converter is configured to: perform digital-to-analog conversion on the superimposed signal of the adder, and send the digital-to-analog converted signal to the amplifier;

The amplifier is configured to: amplify the signal sent by the digital-to-analog converter and output the signal to the earpiece.

The above method for reducing noise and the mobile terminal not only effectively solve the problem of noise reduction in a noisy environment, but also take into account the transmission quality of the voice. BRIEF abstract

1 is a block diagram showing the principle of an uplink noise reduction function according to an embodiment of the present invention;

2 is a schematic block diagram of a downlink noise reduction function according to an embodiment of the present invention;

3 is a schematic diagram of signals of main mic and reference mic reception in an uplink according to an embodiment of the present invention; FIG. 4 is a schematic diagram of an environmental noise signal based on reference mic extraction in FIG. 3 according to an embodiment of the present invention; FIG. Input the schematic diagram of the uplink voice signal of the baseband chip;

6 is a schematic diagram of a noise signal and an environmental noise signal output by the earpiece of the embodiment of the present invention. Preferred embodiment of the invention

In order to make the objects, the technical solutions and the advantages of the present invention more clearly, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, in the case of no conflict, the features in the embodiments and the embodiments of the present application may be arbitrarily combined with each other.

Embodiments of the present invention provide a mobile terminal, where the mobile terminal is in uplink and downlink. Both have the function of reducing noise; wherein, on the uplink, the uplink-based dual is used.

The DSP scheme of Mic, as shown in FIG. 1 , is a block diagram of the uplink noise reduction function of the embodiment of the present invention. To ensure good noise reduction effect, two Mic are generally used, one is the main Mic, which is used for normal Receive speech with noise at the same time; One is reference Mic (or sub-Mic), which is mainly used to collect ambient noise. If the consistency of the Mic cells and the distance between the two Mics (for example, greater than 8 cm) can be properly extended, the noise reduction effect will be better. Since this scheme is the same as the prior art, it will not be described in detail here.

An embodiment of the present invention also introduces an improved noise reduction scheme on the downlink. The mobile terminal includes: an inversion processing circuit, an adder, and an earpiece, where:

The adder is configured to: superimpose the noise signal reversely processed by the inversion processing circuit and the voice signal received by the mobile terminal;

The earpiece is configured to: output a signal superimposed by the adder.

The inverting processing circuit may include: a reference microphone, an adaptive filter, and an inverter, where:

The reference microphone is configured to: collect a noise signal;

The inverting processing circuit may further include an amplifier and an analog to digital converter connected in series and between the reference microphone and the adaptive filter, wherein:

In addition, the mobile terminal may further include: a digital-to-analog converter and an amplifier connected in series and located between the adder and the earpiece, wherein: The digital-to-analog converter is configured to: perform digital-to-analog conversion on the superimposed signal of the adder, and send the digital-to-analog converted signal to the amplifier;

The amplifier is configured to: amplify the signal sent by the digital-to-analog converter and output the signal to the earpiece. The specific structure is shown in Figure 2.

The working principle of noise reduction is to generate a noise signal with the same phase but opposite phase, and superimpose it with the electrical signal or the acoustic signal, so that the noise cancels or attenuates each other, thereby reducing the noise. The purpose of noise. The uplink and downlink denoising is slightly different in implementation. The following describes the noise reduction process of the uplink and downlink respectively.

Uplink noise reduction is the mutual cancellation or attenuation of electrical signals. As shown in Figure 3, the main Mic and the reference Mic simultaneously receive the speech signal (electrical signal) accompanied by noise and the environmental noise signal. Since the reference mic is far from the mouth of the caller, the amplitude of the speech signal is smaller than that of the main mic. It is generally required that there is more than 6dB of sound attenuation between the main mic and the reference mic. The signal processing technology is relatively mature. The output signals of the main Mic and the reference Mic are processed by an adaptive filter to extract ambient noise. The signal is shown in Figure 4, and then inverted by the inverter. Then, the noise signal of the inverted output is superimposed on the voice link of the main mic, thereby canceling the noise component in the uplink voice signal, and the uplink voice signal entering the baseband is a relatively pure voice signal, and the signal is as shown in FIG. 5; This achieves the purpose of reducing noise by the uplink voice.

Downlink noise reduction is the mutual cancellation or attenuation of acoustic signals. The ambient noise is first collected by reference to Mic. Then, the noise signal passes through the amplifier and the A/D converter to the adaptive filter. The adaptive filter performs the spectrum analysis of the noise in real time and correlates and synchronizes with the surrounding ambient noise. The processing is superimposed on the downlink voice link by the inverter, and is output by the handset together with the voice. Thus, the processed noise output from the handset is opposite to the surrounding ambient noise, and the amplitude is similar. As shown in Fig. 6, the two noise sound waves are superimposed in space, and the noise energy is attenuated. In contrast, the signal-to-noise ratio of speech will be greatly improved, and the clarity of speech will be significantly improved to achieve the purpose of noise reduction.

The embodiment of the invention further provides a method for reducing noise, the method comprising:

Step 1: Perform reverse phase processing on the noise signal synchronized with the ambient noise collected by the ;; The step may include: performing amplification and analog-to-digital conversion on the collected noise signal, correlating and synchronizing the analog-to-digital converted noise signal with the ambient noise, and performing inverse processing on the correlated and synchronized processed noise signals. ;

The correlation process is to describe the degree of correlation between the values of two random signals at any two different times tl, t2. Synchronization is to ensure the accuracy of the relevant processing. The two signals only make sense when they are related in time.

Step 2: superimposing the inversely processed noise signal with the voice signal received by the mobile terminal, and outputting the superposed signal.

The output superimposed signal includes: performing digital-to-analog conversion and amplification processing on the superimposed signal, and then outputting by the earpiece.

The above method for reducing noise not only effectively solves the problem of noise reduction in noisy environments, but also takes into account the transmission quality of speech.

One of ordinary skill in the art will appreciate that all or a portion of the above steps may be accomplished by a program that instructs the associated hardware to be stored in a computer readable storage medium, such as a read only memory, a magnetic disk, or an optical disk. Alternatively, all or part of the steps of the above embodiments may also be implemented using one or more integrated circuits. Correspondingly, each module/unit in the above embodiment may be implemented in the form of hardware or in the form of a software function module. The invention is not limited to any specific form of combination of hardware and software.

The above embodiments are only intended to illustrate the technical solutions of the present invention and are not to be construed as limiting the invention. It should be understood by those skilled in the art that the present invention may be modified or equivalently substituted without departing from the spirit and scope of the invention.

Industrial applicability

The above method for reducing noise and the mobile terminal not only effectively solve the problem of noise reduction in a noisy environment, but also take into consideration the transmission quality of speech, and therefore have strong industrial applicability.

Claims

Claim

A method for reducing noise, which is applied to a downlink of a mobile terminal, the method comprising: performing inverse processing on a noise signal synchronized with ambient noise collected by the ;;

2. The method according to claim 1, wherein: the step of inverting the collected noise signal synchronized with the environmental noise comprises:

Amplifying and analog-to-digital conversion of the collected noise signal, correlating and synchronizing the analog-to-digital converted noise signal with the ambient noise, and inverting the correlated and synchronized processed noise signals.

3. The method according to claim 1 or 2, wherein: the step of outputting the superimposed signal comprises:

4. A mobile terminal, comprising: an inverting processing circuit, an adder, and an earpiece, wherein:

The earpiece is configured to: output a signal superimposed by the adder.

The mobile terminal according to claim 4, wherein the inverting processing circuit comprises: a reference microphone, an adaptive filter, and an inverter, wherein:

The reference microphone is configured to: collect a noise signal;

The inverter is configured to: correlate and synchronize the processed noise signal to the adaptive filter Perform reverse phase processing.

6. The mobile terminal of claim 5, wherein: the inverting processing circuit further comprises an amplifier and an analog to digital converter connected in series and between the reference microphone and the adaptive filter, wherein:

The mobile terminal according to claim 6, wherein the mobile terminal further comprises: a digital-to-analog converter and an amplifier connected in series and located between the adder and the earpiece, wherein: