Method and apparatus for reducing echo feedback in a communication system

• US 6,741,874 B1
• Filed: 04/18/2000
• Issued: 05/25/2004
• Est. Priority Date: 04/18/2000
• Status: Expired due to Fees

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Grube, Gary, Ziolko, Eric, Novorita, Robert
• Primary Examiner(s): Trost, William
• Assistant Examiner(s): Ferguson, Keith
• Application Number:
  US09/552,466
• Time in Patent Office: 1,498 Days
• Field of Search: 455/570, 455/550.1, 455/517, 455/422.1, 455/426.1, 455/403, 379/406.01, 379/406.02, 379/406.05, 379/406.07, 379/390.02, 379/392.01, 379/406.03, 379/406.04, 379/406.06, 379/406.08, 379/406.09, 379/406.1, 379/406.11, 379/406.12, 379/406.13, 379/406.14, 379/406.15, 379/406.16, 379/388.04, 379/388.07, 370/282, 370/286, 370/289, 370/288, 370/287, 381/318
• US Class Current: 455/570
• CPC Class Codes: H04M 9/082 using echo cancellers echo cancellers per se H04B3/23

Abstract

A method and apparatus for reducing echo feedback in a wireless communication system (10) is accomplished when a receiving communication unit (24) senses a feedback signal, or echo, via an ancillary communication path. The receiving communication unit is a targeted recipient of an original audio signal generated by a transmitting communication unit (22), where the original audio signal (42) is conveyed to the receiving communication unit. Upon detecting the feedback signal and determining that it exceeds a feedback threshold, the receiving communication unit attenuates an audible output of the original signal to reduce echo to the transmitting communication unit. In addition, the receiving communication unit, and/or the transmitting communication unit include echo canceller to further minimize the echo within the digital communication system.

Claims

1. A method comprising the steps of:

sensing, by a receiving communication unit of a plurality of communication units, a feedback signal via an ancillary communication path, wherein a transmitting communication unit transmits an original signal to the receiving communication unit, and wherein the feedback signal is representation of the original signal that is produced as a result of physical proximity of the transmitting and receiving communication units; and

attenuating, by the receiving communication unit, an audible output to reduce echo to the transmitting communication unit when the feedback signal exceeds a feedback threshold.

2. The method of claim 1, further comprising the step of receiving the feedback signal via an ancillary receiver within the receiving communication unit, wherein the ancillary path is established between the ancillary receiver and an ancillary transmitter within the transmitting communication unit when the ancillary receiver and the ancillary transmitter are within proximal limitations of each other.

3. The method of claim 1, further comprising the step of determining when the feedback signal exceeds the feedback threshold by at least one of determining when a bit error rate of the feedback signal is less than a bit error rate threshold-and determining when a signal strength of the feedback signal is less than a signal strength threshold.

4. The method of claim 1, further comprising the step of receiving the feedback signal via a microphone of the receiving communication unit.

5. The method of claim 1, further comprising the step of combining, by the receiving communication unit, the original signal with a delayed representation of the feedback signal to provide echo cancellation.

6. The method of claim 1, further comprising the steps of:

discontinue reception of the original signal when the feedback signal is sensed; and

utilizing the feedback signal as the original signal.

7. The method of claim 1, further comprising the step of verifying that the feedback signal corresponds to the original signal by at least one of identification code verification and signal mapping.

8. A communication unit comprising:

a receiver operably coupled to receive a digitally encoded original signal from a transmitting communication unit;

a decoder operably coupled to the receiver, wherein the decoder decodes the digitally encoded original signal to produce a decoded original signal;

an audible converter operably coupled to the decoder, wherein the audible converter converts the decoded original signal into an audible signal, wherein the audible signal is attenuated based on an attenuation signal; and

an echo detector, operably coupled to the audible converter, wherein the echo detector detects a feedback signal via an ancillary communication path, generates the attenuation signal based on the feedback signal, and provides the attenuation signal to the audible converter, wherein the feedback signal is representation of the digitally encoded original signal that is produced as a result of physical proximity of the transmitting communication unit and the communication unit.

9. The communication unit of claim 8, further comprising an ancillary receiver that receives the feedback signal, wherein the ancillary communication path is established between the ancillary receiver and an ancillary transmitter within the transmitting communication unit when the ancillary receiver and the ancillary transmitter are within proximal limitations of each other.

10. The communication unit of claim 8, further comprising a signal detector operably coupled to detect presence of the feedback signal, wherein the signal detector detects the presence of the feedback signal based on at least one of bit error rate of the feedback signal being less than a bit error rate threshold and signal strength of the feedback signal being less than a signal strength threshold.

11. The communication unit of claim 8, further comprising a combiner that combines the original decoded signal with a delayed representation of the feedback signal to provide echo cancellation.

12. A communication unit comprising:

a processing unit; and

memory operably coupled to the processing unit, wherein the memory stores programming instructions that, when read by the processing unit, cause the processing unit to sense a feedback signal via an ancillary communication path, wherein a transmitting communication unit transmits an original signal to the receiving communication unit, and wherein the feedback signal is representation of the original signal that is produced as a result of physical proximity of the transmitting and receiving communication units; and

to attenuate an audible output to reduce echo to the transmitting communication unit when the feedback signal exceeds a feedback threshold.

13. The communication unit of claim 12, arranged and constructed to receive the feedback signal via an ancillary receiver, wherein the ancillary path is established between the ancillary receiver and an ancillary transmitter within the transmitting communication unit when the ancillary receiver and the ancillary transmitter are within proximal limitations of each other.

14. The communication unit of claim 12, arranged and constructed to determine the feedback signal exceeds the feedback threshold by at least one of determining when bit error rate of the feedback signal is less than a bit error rate threshold and determining when signal strength of the feedback signal is less than a signal strength threshold.

15. The communication unit of claim 12, arranged and constructed to combine the original signal with a delayed representation of the feedback signal to provide echo cancellation.

16. The communication unit of claim 12, arranged and constructed to:

discontinue reception of the original signal when the feedback signal is sensed; and

utilize the feedback signal as the original signal.

17. The communication unit of claim 12, arranged and constructed to verify that the feedback signal corresponds to the original signal by at least one of identification code verification and signal mapping.