Method and system for reducing undesired signals in a communication environment

• US 6,529,606 B1
• Filed: 08/23/2000
• Issued: 03/04/2003
• Est. Priority Date: 05/16/1997
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Jackson, I. Riley II, Freeburg, Thomas A.
• Primary Examiner(s): Isen, Forester W.
• Assistant Examiner(s): PENDLETON, BRIAN T
• Application Number:
  US09/644,432
• Time in Patent Office: 923 Days
• Field of Search: 381/71.1, 381/71.6, 381/71.4, 381/71.13, 381/94.1, 381/94.7, 381/94.3, 379/406.01
• US Class Current: 381/71.4
• CPC Class Codes: G10L 2021/02165 Two microphones, one receiving mainly the noise signal and the other one mainly the speech signal
• CPC Class Codes: G10L 21/0208 Noise filtering

Abstract

Methods and devices for reducing undesired signals in a communication environment. At least two distinct composite signals (X₁ and X₂) are transmitted from a first communication environment (260). A noise coefficient of the first communication environment (260) based on the at least two distinct composite signals (X₁ and X₂) is calculated. At least two noise canceling signals based on the noise coefficient are calculated. The at least two noise canceling signals are added to an incoming signal (Y₃) from a second communication environment (280) to produce at least two combined signals. The at least two combined signal are transmitted into the first communication environment (260).

Claims

1. A method for reducing an undesired signal in a first communication environment comprising:

receiving at least two distinct composite signals from the first communication environment;

separating the at least two distinct composite signals into at least a first and a second signal;

generating at least a third signal based on one of the first and the second signals;

combining the third signal with a fourth signal received from a second communication environment to form a fifth signal and a sixth signal; and

introducing the fifth signal and the sixth signal into the first communication environment.

2. The method of claim 1 wherein the third signal is 180 degrees out-of-phase with one of the first and the second signals.

3. The method of claim 2 wherein the third signal at least partially cancels one of the first and the second signals.

4. The method of claim 3 wherein the third signal has a frequency and an amplitude substantially equal to one of the first and the second signal.

5. The method of claim 1 further comprising the step of adjusting a phase of the third signal.

6. A system for reducing an undesired signal in a first communication environment comprising:

at least two receivers, located in the first communication environment, being configured to receive at least two distinct composite signals;

processing circuitry, in communication with the at least two receivers, being configured to separate the at least two distinct composite signals into at least a first signal and a second signal;

adaptive circuitry, in communication with the processor, being configured to generate at least one canceling signal based on one of the first and the second signals;

a signal combiner, in communication with the adaptive circuitry, being configured to combine the at least one canceling signal with a third signal to form a fourth signal and a fifth signal; and

at least two transmitters located in the first communication environment, being configured to introduce the fourth signal and the fifth signal into the first communication environment.

7. The system of claim 6 wherein a first communication unit in the first communication environment is in remote communication with a second communication unit in a second communication environment, the first communication unit supporting the at least two receivers, the processor, the circuitry, the signal combiner and the at least two transmitters.

8. The system of claim 6 wherein the adaptive circuitry includes an adaptive inverse filter.

9. The system of claim 8 wherein the adaptive circuitry includes a signal adjuster coupled to the adaptive inverse filter.

10. The system of claim 6 wherein each of the at least two transmitters includes one of a speaker-phone and a subscriber unit.

11. The system of claim 6 wherein each of the at least two receivers comprises a microphone.

12. The system of claim 6 wherein the processing circuitry includes a detector in communication with a processor and a second communication environment.