Method of eliminating background noise and a device using the same

1. A method of eliminating background noise, comprising steps of:

(a) detecting an effective value of a received audio signal, and generating an average power signal of the received audio signal using a detecting unit, wherein the receive audio signal includes noise and a voice signal;

(b) generating a noise eliminating control signal by comparing the average power signal from the detecting unit with a first threshold using a first signal generating unit, the first signal generating unit including a first comparison module, a second comparison module, a compensation module and a second logic processing module, the generating further comprising:

(b1) extracting a first control signal for an effective voice signal by comparing the average power signal from the detecting unit with a second threshold using the first comparison module;

(b2) generating a second control signal by compensating the first control signal from the first comparison module using the compensation module;

(b3) extracting a third control signal for an excessive audio signal by comparing the average power signal from the detecting unit with a third threshold using the second comparison module; and

(b4) processing the second control signal from the compensation module and the third control signal from the second comparison module using exclusive logic OR, and generating the noise eliminating control signal using the second logic processing module; and

(c) eliminating the noise in the received audio signal, and amplifying the voice signal in the received audio signal in accordance with the noise eliminating control signal from the second logic processing module using an amplifying unit;

wherein the first threshold is determined based on the difference between an average power of the voice signal and an average power of the noise.

2. The method of eliminating background noise according to claim 1 , wherein the step (a) comprises steps of:

(a1) determining whether the received audio signal is a voice signal;

(a2) generating a trigger signal for detecting the effective value, based on the determination result and the noise eliminating control signal generated in a preceding elimination cycle; and

(a3) detecting the effective value in response to the trigger signal, and generating the average power signal of the received audio signal.

3. The method of eliminating background noise according to claim 2 , further comprises a step of pre-amplifying the received audio signal.

4. The method of eliminating background noise according to claim 2 , wherein the step (a1) comprises steps of:

(a11) generating a forward comparison result by comparing the received audio signal with a second threshold;

(a12) generating an inverse comparison result by comparing the received audio signal with a third threshold;

(a13) processing the forward comparison result and the inverse comparison result using a logic OR operation to determine whether the received audio signal is a voice signal; and

(a14) processing the result of step (a13) and the noise eliminating control signal generated in a preceding elimination cycle, and generating the trigger signal.

5. The method of eliminating background noise according to claim 1 , further comprises steps of:

generating an attenuation control signal by comparing the average power signal with a fourth threshold; and

attenuating an excessive audio signal properly using the attenuation control signal.

6. A device of eliminating background noise, comprising:

a detecting unit, which is configured to detect an effective value of a received audio signal, and generate an average power signal of the received audio signal, wherein the receive audio signal includes noise and a voice signal;

a first signal generating unit, which is configured to generate a noise eliminating control signal by comparing the average power signal from the detecting unit with a first threshold, the first signal generating unit including a first comparison module, a second comparison module, a compensation module and a second logic processing module, wherein:

the first comparison module is configured to extract a first control signal for an effective voice signal by comparing the average power signal from the detecting unit with a second threshold;

the compensation module is configured to generate a second control signal by compensating the first control signal from the first comparison module;

the second comparison module is configured to extract a third control signal for an excessive audio signal by comparing the average power signal from the detecting unit with a third threshold; and

the second logic processing module is configured to process the second control signal from the compensation module and the third control signal from the second comparison module using exclusive logic OR, and generating the noise eliminating control signal; and

an amplifying unit, which is configured to eliminate the noise in the received audio signal, and amplify the voice signal in the received audio signal in accordance with the noise eliminating control signal from the second logic processing module;

wherein the first threshold depends, at least in part, on the difference between an average power of the voice signal and an average power of the noise.

7. The device of eliminating background noise according to claim 6 , wherein the detecting unit further comprises:

a determining circuit, which is configured to determine whether the received audio signal is a voice signal;

a control circuit, which is configured to generate a trigger signal for detecting the effective value of the received audio signal, after processing the determination result and the noise eliminating control signal generated in a preceding elimination cycle; and

a detecting circuit, which is configured to detect the effective value in response to the trigger signal, and generate the average power signal of the received audio signal.

8. The device of eliminating background noise according to claim 7 , wherein the detecting unit further comprises:

a pre-amplifying circuit, which is configured to pre-amplify the received audio signal, wherein the output terminals of the pre-amplifying unit are configured to connected to the determining circuit and the detecting circuit, respectively.

9. The device of eliminating background noise according to claim 7 , wherein the determining circuit further comprises:

a forward determining module, which is configured to generate a forward comparison result by comparing the received audio signal with a second threshold;

an inverse determining module, which is configured to generate an inverse comparison result by comparing the received audio signal with a third threshold; and

a first logic processing module, which is configured to process the forward comparison result and the inverse comparison result, and determine whether the received audio signal is a voice signal.

10. The device of eliminating background noise according to claim 9 , wherein the forward determining module and the inverse determining module comprise a plurality of comparators and Schmitt inverters.

11. The device of eliminating background noise according to claim 7 , wherein the control circuit further comprises a logic OR gate and a two-to-one switch, wherein an output terminal of the logic OR gate is configured to be connected to the two-to-one switch.

12. The device of eliminating background noise according to claim 6 , wherein the compensation module further comprises:

a multi-frequency oscillator, which is configured to detect a first pulse from the first comparison module, and generate a second pulse with a certain bandwidth when a descending slope in the first pulse is detected; and

a logic OR gate, which is configured to broaden the second pulse using the second control signal.

13. The device of eliminating background noise according to claim 6 , further comprises:

a second signal generating unit, which is configured to generate an attenuation control signal by comparing the average power audio signal with a fourth threshold; and

an audio attenuation unit, which is configured to attenuate an excessive audio signal properly using the attenuation control signal.

14. The device of eliminating background noise according to claim 6 , wherein the amplifying unit further comprises:

a first inverse phase follower;

a controllable inverter;

a second inverse phase follower;

an inverse phase adder; and

a low pass filter;

wherein an output terminal of the controllable inverter is configured to connect to the second inverse phase follower, and

the inverse phase adder is configured to connect to the first inverse phase follower, the second inverse phase follower, and the low pass filter, respectively.