Virtual microphones in electronic conferencing systems

• US 8,644,525 B2
• Filed: 06/02/2004
• Issued: 02/04/2014
• Est. Priority Date: 06/02/2004
• Status: Active Grant

• Current Assignee: Clearone Incorporated
• Original Assignee: ClearOne Communications Inc. (Clearone Incorporated)
• Inventors: Bathurst, Tracy A., Lambert, David, Whiteley, Wayne, Owen, Carrie L.
• Primary Examiner(s): Chin, Vivian
• Assistant Examiner(s): Tran, Con P
• Application Number:
  US10/859,911
• Publication Number:
  US 20050271220A1
• Time in Patent Office: 3,534 Days
• Field of Search: 381/92, 381/91, 381/313, 381/94.1, 381/111, 381/57, 381/56, 381/122, 381/87, 379/202.01, 379/201.01, 379/206.01, 348/14.01, 348/14.08, 348/14.09, 455/416, 700/90, 700/94, 341/122, 341/126, 341/144, 341/155
• US Class Current: 381/92
• CPC Class Codes: H04M 3/56 Arrangements for connecting several subscribers to a common circuit, i.e. affording conference facilities video conference systems H04N7/15
• CPC Class Codes: H04R 1/406 microphones

Abstract

This disclosure describes a virtual microphone for reducing common-mode noise for an individual pod in a multi-pod conferencing system that includes a base and a plurality of pods for local conference participants to communicate with remote conference participants. The described virtual microphone includes pod processor means and a loudspeaker that couples to a digital to analog converter that converts digital audio to analog audio, where the loudspeaker couples to the pod processor means. In addition, the virtual microphone includes three physical bi-polar microphones positioned at 120-degree intervals in the horizontal resting plane of the pod, where each individual physical microphone connects to a pair of audio ports with each audio port being equal distance from the loudspeaker, and where the physical microphones couple to analog to digital converting means, and further where the physical microphones couple to the pod processor means. Further, the virtual microphone includes virtual microphone means. And, the virtual microphone includes pod echo cancellation means. Further, the virtual microphone includes microphone gating means using a loudness value, a quietness counter, and a noise floor value. And further, the virtual microphone also has the individual pod using the microphone gating means to gate on or off the virtual microphone.

Claims

1. A multi-pod conferencing system for local conference participants to communicate with remote conference participants, the multi-pod conferencing system comprising;

a base unit including a base controller configured to communicate audio signals with the remote conference participates over a carrier medium; and

a plurality of pods separate from, and operably coupled to, the base unit, wherein each pod of the plurality of pods comprises;

a pod processor;

a loudspeaker operably coupled to the pod processor;

a digital to analog converter operably coupled to the loudspeaker, the digital to analog converter configured to convert digital audio to analog audio for sound reproduction by the loudspeaker;

a plurality of physical microphones connected to a pair of audio ports with each audio port being equal distance from the loudspeaker;

an analog to digital converter operably coupled with the plurality of physical microphones, the analog to digital converter configured to convert the analog audio to digital audio for processing by the pod processor; and

a plurality of virtual microphones for reducing common-mode noise, each virtual microphone of the plurality of virtual microphones formed from a combination of at least two outputs from the plurality of the physical microphones,

wherein the analog to digital converters for each pod of the plurality of pods are configured for synchronized sampling with the analog to digital converters of the other pods of the plurality of pods in the multi-pod conferencing system.

2. The multi-pod conferencing system of claim 1, wherein the carrier medium that comprises at least one of a telephone line and a voice over internet protocol network.

3. The multi-pod conferencing system of claim 2, wherein the plurality of virtual microphone further provide common-mode noise rejection.

4. The multi-pod conferencing system of claim 1, wherein pod processor is configured to support full duplex operation.

5. The multi-pod conferencing system of claim 1, wherein each pod of the plurality of pods makes a contribution to a summed audio output starting at the last pod in a chain for the plurality of pods and ending in the base unit.

6. The multi-pod conferencing system of claim 1, wherein the pod controller comprises a plurality of distributed processors that are configured to separately control audio and control functions of the pod.

7. The multi-pod conferencing system of claim 1, wherein the plurality of physical microphones are selected from the group consisting of unipolar microphones and bipolar microphones.

8. The multi-pod conferencing system of claim 1, wherein a polarity of the physical microphones are the same.

9. The multi-pod conferencing system of claim 1, wherein the base unit is configured to perform echo cancellation of local audio.

10. The multi-pod conferencing system of claim 1, wherein the pod processor is further configured to perform:

pod echo cancellation for sound between the virtual microphone and said loudspeaker; and

microphone gating for determining the best virtual microphone to gate on or off by using a loudness value, a quietness counter, and a noise floor value, wherein a constant gain is maintained by attenuation being applied to each gated microphone if more than one microphone is gated on at the same time.

11. A method of manufacturing a virtual microphone system for reducing common-mode noise for an individual pod that is part of a multi-pod conferencing system, the method comprising:

providing a base unit having a base processor for communicating audio signals to remote conference participants; and

providing a plurality of pods that are coupled to, and separate from, the base unit, wherein providing the plurality of pods comprises;

providing a pod processor for providing audio processing for various pod functions;

coupling a loudspeaker to a digital to analog converter and the pod processor, the digital to analog converter configured to convert digital audio from the pod processor to analog audio to the loudspeaker;

coupling an analog to digital converter to a plurality of physical microphones that are configured to sample analog audio in a synchronized manner with sampling performed by analog to digital converters of other pods of the virtual microphone system;

connecting the plurality of physical microphone a plurality of audio ports with each audio port being equal distance from the loudspeaker; and

coupling the physical microphones with the pod processor, such that outputs from the plurality physical microphones are combined forming a plurality of virtual microphones for reducing common-mode noise.

12. The method of claim 11, further comprising coupling the base unit with a carrier medium that comprises at least one of a telephone line and a voice over internet protocol network.

13. The method of claim 11, wherein forming the plurality of virtual microphones comprises providing common-mode noise rejection.

14. The method of claim 11, wherein providing a pod processor includes a pod processor configured to perform echo cancellation of sound between the plurality of virtual microphones and the loudspeaker, and perform determining the best virtual microphone to gate on or off by using a loudness value, a quietness counter, and a noise floor value.

15. A method of using a virtual microphone system for a multi-pod conferencing system, the method comprising:

communicating local audio to remote participants through a base unit and coupled with a plurality of pods, wherein communicating further comprises;

audio processing using a pod processor;

converting digital audio to analog audio with a loudspeaker that coupled to a digital to analog converter and the pod processor;

converting sampled analog audio to digital audio using an analog to digital converter coupled to a plurality of physical bi-polar microphones positioned in the horizontal resting plane of each individual pod of the plurality of pods, each individual physical microphone connected to a pair of audio ports with each audio port being equal distance from the loudspeaker, the physical microphones coupled to the pod processor, wherein the sampled analog audio is synchronized with sampling performed by other analog to digital converters from other pods of the virtual microphone system; and

creating a plurality of virtual microphones for reducing common-mode noise, the plurality of virtual microphones are formed by combining outputs from the plurality of physical microphones.

16. The method of claim 15, further comprising a carrier medium that comprises a telephone line, wherein the base unit comprises a base echo cancellation means for echo cancellation of local audio.

17. The method of claim 15, wherein the virtual microphone means further comprises providing common-mode noise rejection.

18. The method of claim 15, wherein audio processing using the pod processor includes:

echo cancelling sound using pod echo cancellation means for echo cancellation of sound between the virtual microphone and the loudspeaker; and

determining the best virtual microphone to gate on or off using a loudness value, a quietness counter, and a noise floor value.

19. The method of claim 15, further comprising communicating audio data between the pod and the base unit.

20. The method of claim 19, wherein communicating between the pod and the base unit employs spread spectrum techniques to the audio data.