Echo canceler circuit and method

• US 8,238,546 B2
• Filed: 10/03/2009
• Issued: 08/07/2012
• Est. Priority Date: 12/12/2003
• Status: Active Grant

• Current Assignee: Continental Automotive Systems, Inc. (Continental AG)
• Original Assignee: Continental Automotive Systems, Inc. (Continental AG)
• Inventors: Piket, James B., Owens, Keith L., Springfield, Christopher W.
• Primary Examiner(s): Jamal, Alexander
• Application Number:
  US12/573,111
• Publication Number:
  US 20100022282A1
• Time in Patent Office: 1,039 Days
• Field of Search: 379/406.02, 379/406.06
• US Class Current: 379/406.06
• CPC Class Codes: H04M 9/082 using echo cancellers echo cancellers per se H04B3/23

Abstract

An echo canceler circuit (10) and method attenuates at least post-echo canceler uplink data (90) to produce attenuated uplink data (100) in response to uplink echo return loss based attenuation data (40). The echo canceler circuit (10) includes an echo return loss based attenuation data generator (20) and at least an uplink data attenuator (30). The echo return loss based attenuation data generator (20) produces the uplink echo return loss based attenuation data (40) in response to echo return loss data (70). The echo return loss data (70) is based on at least one of: attenuated downlink data (50), pre-echo canceler uplink data (60), and/or amplifier gain data (80). The uplink data attenuator (30) attenuates the post-echo canceler uplink data (90) to produce attenuated uplink data (100) based on the uplink echo return loss based attenuation data (40).

Claims

1. An echo canceler circuit comprising:

an uplink data attenuator operative to receive post-echo canceler uplink data and uplink echo return loss based attenuation data and in response to attenuate the post-echo canceler uplink data to produce attenuated uplink data;

a downlink data attenuator operative to receive downlink data and downlink echo return loss based attenuation data and in response to attenuate the downlink data to produce attenuated downlink data;

an echo return loss based attenuation data generator operatively coupled to the uplink data attenuator and the downlink data attenuator and operative to produce the uplink echo return loss based attenuation data and the downlink echo return loss based attenuation data in response to instantaneous echo return loss data wherein the instantaneous echo return loss data is based on at least one of;

attenuated downlink data, pre-echo canceler uplink data and amplifier gain data, wherein the echo return loss based attenuation data generator is operative to calculate the instantaneous echo return loss data based on a ratio of the attenuated downlink data and the pre-echo canceler uplink data and in response to produce the uplink echo return loss based attenuation data and the downlink echo return loss based attenuation data based on at least the instantaneous echo return loss data.

2. The echo canceler circuit of claim 1 wherein the echo return loss based attenuation data generator is operative to update standard echo return loss data based on the instantaneous echo return loss data when not in a double talk mode, such that at least one of the uplink echo return loss based attenuation data and the downlink echo return loss based attenuation data is based on the standard echo return loss data when the echo return loss based attenuation data generator determines that the standard echo return loss data indicates no problematic acoustic coupling channel.

3. The echo canceler circuit of claim 1 including:

a digital to analog converter operatively coupled to the downlink data attenuator, and operative to receive the attenuated downlink data and in response to produce a downlink audio signal;

an amplifier, operatively coupled to the digital to analog converter, and operative to receive the downlink audio signal and in response to produce an amplified downlink audio signal, wherein the amplifier has an amplifier gain;

a microphone operative to receive at least a portion of the amplified downlink audio signal and in response to produce a pre-echo canceler uplink signal; and

an analog to digital converter operatively coupled to the microphone, the uplink data attenuator and the echo return loss based attenuation generator and operative to receive the pre-echo canceler uplink signal and in response, to produce the pre-echo canceler uplink data wherein the echo return loss based attenuation data generator determines a change in the amplifier gain based on the instantaneous echo return loss data.