Qin Li Phones & Addresses
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Bothell, WA
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Cedar Park, TX
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Austin, TX
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Ambler, PA
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State College, PA
Business Records
Name / Title
Company / Classification
Phones & Addresses
Director
China Environmental Protection, Inc
LIEP CONSULTANCY LIMITED
Publications
Us Patents
Fast Solution Of Integral Equations Representing Wave Propagation
View pageUS Patent:
7359929, Apr 15, 2008
Filed:
Nov 12, 2003
Appl. No.:
10/706605
Inventors:
Leung Tsang - Mercer Island WA, US
Dong Chen - Shanghai, CN
Qin Li - Seattle WA, US
Dong Chen - Shanghai, CN
Qin Li - Seattle WA, US
Assignee:
City University of Hong Kong - Hong Kong
International Classification:
G06F 7/38
US Classification:
708446
Abstract:
A technique for solving a set of wave equations in a region uses points arranged in a grid spanning the region or coefficients of wave expansion for objects located in the region. The grid points or the coefficients are partitioned into blocks on multiple levels, and block impedance matrices encoding the wave equations is derived for pairs of blocks. The block impedance matrix need not be calculated as it is written as the product of two non-square matrices, denoted U and V. Each of U and V have one linear dimension which is only of the order of the rank of the block impedance matrix levels. The rank is predetermined by coarse sampling. Two examples of the use of the invention are given: solving surface integral equations and Foldy Lax equations for partial waves.
Suppression Of Acoustic Feedback In Voice Communications
View pageUS Patent:
7764634, Jul 27, 2010
Filed:
Dec 29, 2005
Appl. No.:
11/275414
Inventors:
Wei Zhong - Issaquah WA, US
Chao He - Redmond WA, US
Anton W. Krantz - Kirkland WA, US
Qin Li - Seattle WA, US
Chao He - Redmond WA, US
Anton W. Krantz - Kirkland WA, US
Qin Li - Seattle WA, US
Assignee:
Microsoft Corporation - Redmond WA
International Classification:
H04B 3/20
US Classification:
370286, 327 3, 345204, 375376, 381 83, 381 86, 381 93, 381101
Abstract:
Suppressing one or more frequency ranges of a signal prevents the occurrence of feedback in a voice data communications application. A system recognizes a frequency range in a signal where feedback occurs, or anticipates a frequency range where feedback is anticipated. The signal includes a signal the input system generates or that the output system renders. The system suppresses the signal in the frequency range by disregarding one or more sampling bits representing the frequency range, or by applying one or more filters to attenuate or eliminate the signal in the frequency range. The system may monitor the signal to identify feedback resulting in different or additional frequency ranges and suppress the signal in the different or additional frequency ranges to prevent feedback from occurring.
Filter Bank Optimization For Acoustic Echo Cancellation
View pageUS Patent:
8155304, Apr 10, 2012
Filed:
Apr 10, 2007
Appl. No.:
11/784893
Inventors:
Qin Li - Redmond WA, US
Chao He - Redmond WA, US
Chao He - Redmond WA, US
Assignee:
Microsoft Corporation - Redmond WA
International Classification:
H04M 9/08
US Classification:
37940612, 37940603, 37940608
Abstract:
A communications device is presented for providing bi-directional audio communications between a near-end user and a far-end user via a bidirectional communications channel. The communications device includes an adaptive echo canceller receiving a near-end audio signal and a far-end audio signal and providing an echo-canceled near-end audio signal for transmission to the far-end user via the communications channel. The adaptive echo canceller includes a first bank of analysis filters for filtering the near-end audio signal, a second bank of analysis filters for filtering the far-end audio signal, and a bank of synthesis filters for filtering sub-band echo-canceled signals generated within the adaptive echo canceller. The first and second filter banks have a frequency response optimized to reduce echo residual gain.
Method And Apparatus For Reducing Timestamp Noise In Audio Echo Cancellation
View pageUS Patent:
8259928, Sep 4, 2012
Filed:
Apr 23, 2007
Appl. No.:
11/788939
Inventors:
Chao He - Redmond WA, US
Qin Li - Redmond WA, US
Qin Li - Redmond WA, US
Assignee:
Microsoft Corporation - Redmond WA
International Classification:
H04M 9/08
US Classification:
37940609, 3794061, 37940611, 37940613, 381 66, 702187
Abstract:
A communication end device of a two-way communication system is shown. The device includes an audio signal capture device for capturing local audio to be transmitted to another end device, an audio signal rendering device for playing remote audio received from the other end device, and buffers for buffering the captured and rendered audio signals. The device also includes an audio echo canceller operating to predict echo from the rendered audio signal at a calculated relative offset in the captured audio signal based on an adaptive filter, and subtract the predicted echo from the signal transmitted to the other end device The calculated relative offset that is used by the audio echo canceller for a current signal sample is adjusted if a difference between it and an adjusted relative offset of a preceding sample exceeds a threshold value.
Selective Glitch Detection, Clock Drift Compensation, And Anti-Clipping In Audio Echo Cancellation
View pageUS Patent:
8295475, Oct 23, 2012
Filed:
Jan 13, 2006
Appl. No.:
11/332500
Inventors:
Qin Li - Seattle WA, US
Chao He - Redmond WA, US
Mu Han - Redmond WA, US
Chao He - Redmond WA, US
Mu Han - Redmond WA, US
Assignee:
Microsoft Corporation - Redmond WA
International Classification:
H04M 9/08
US Classification:
37940608, 37940601
Abstract:
The quality and robustness of audio echo cancellation is enhanced by selectively applying glitch recovery processes based on a quality measurement of the relative offset between capture and render audio streams. For example, large and small glitch detection is enabled for low relative offset variance; large glitch detection is enabled in a medium range of relative offset variance; and neither enabled at high variance. Further, a fast glitch recovery process suspends updating the adaptive filter coefficients of the audio echo cancellation while buffers are re-aligned to recover from the glitch, so as to avoid resetting the adaptive filter. When clock drift exists between capture and render audio streams, a multi-step compensation method is applied to improve AEC output quality in case the drifting rate is low; and a resampler is used to compensate the drift in case the drifting rate is high. An anti-clipping process detects clipping of the signals, and also suspends adaptive filter updating during clipping.
Method And Apparatus For Mitigating Impact Of Nonlinear Effects On The Quality Of Audio Echo Cancellation
View pageUS Patent:
20080247535, Oct 9, 2008
Filed:
Apr 9, 2007
Appl. No.:
11/784692
Inventors:
Qin Li - Redmond WA, US
Chao He - Redmond WA, US
Chao He - Redmond WA, US
Assignee:
Microsoft Corporation - Redmond WA
International Classification:
H04M 9/08
US Classification:
37940608
Abstract:
A method is provided for reducing the adverse impact of echo on audio quality in a two-communication system. The method includes two parts. The first part begins by detecting non-linear effects (e.g. clippings and audio glitches). If a non-linear effect is detected, the system temporarily disables adaptation of the adaptive filter. In this way, filter coefficients obtained before the non-linear effect happens will not be corrupted, so the AEC can quickly recover from the non-linear effects. The second part begins by monitoring a parameter reflecting signal quality (e.g., ERLE). If the signal quality parameter falls below a given value the system switches from a full-duplex mode of operation to a half-duplex mode of operation. In this way, when a non-linear effect that is undetectable or occurs repeatedly (e.g., speaker volume changes) and which can corrupt an acoustic echo canceller (AEC) for a relatively long period of time, the system switches from full-duplex operation to half-duplex operation. In half-duplex operation, communication can only happen in one direction at a time, and thus the echo path is broken, effectively eliminating echoes. When the non-linear effect is no longer present and the quality parameter rises to a normal level, communication returns to a full-duplex mode of operation and the AEC once again removes the echoes.
Filter Bank Optimization For Acoustic Echo Cancellation
View pageUS Patent:
20120163615, Jun 28, 2012
Filed:
Mar 5, 2012
Appl. No.:
13/411865
Inventors:
Qin Li - Redmond WA, US
Chao He - Redmond WA, US
Chao He - Redmond WA, US
Assignee:
MICROSOFT CORPORATION - Redmond WA
International Classification:
G10K 11/16
US Classification:
381 711
Abstract:
A communications device is presented for providing bi-directional audio communications between a near-end user and a far-end user via a bidirectional communications channel. The communications device includes an adaptive echo canceller receiving a near-end audio signal and a far-end audio signal and providing an echo-canceled near-end audio signal for transmission to the far-end user via the communications channel. The adaptive echo canceller includes a first bank of analysis filters for filtering the near-end audio signal, a second bank of analysis filters for filtering the far-end audio signal, and a bank of synthesis filters for filtering sub-band echo-canceled signals generated within the adaptive echo canceller. The first and second filter banks have a frequency response optimized to reduce echo residual gain.
Double-Talk Detection For Audio Communication
View pageUS Patent:
20130332155, Dec 12, 2013
Filed:
Jun 6, 2012
Appl. No.:
13/490063
Inventors:
Vinod Prakash - Redmond WA, US
Xiaoqin Sun - Redmond WA, US
Warren Lam - Redmond WA, US
Qin Li - Houston TX, US
Xiaoqin Sun - Redmond WA, US
Warren Lam - Redmond WA, US
Qin Li - Houston TX, US
Assignee:
MICROSOFT CORPORATION - Redmond WA
International Classification:
G10L 21/02
G10L 21/00
G10L 21/00
US Classification:
704226, 704201, 704E21002
Abstract:
The detection of double-talk in audio communication is provided. A communication device may receive an echo signal mixed with a speech signal at a near end location. The echo signal may be generated by speech transmitted by a remote party at a far end location to a local party at the near end location. The speech signal may be received from the local party for transmission to the remote party. The communication device may then filter the echo signal and the speech signal. The communication device may then analyze the speech signal to identify speech characteristics which indicate the presence of double-talk. The communication device may then set a flag upon identifying the speech characteristics which indicate the presence of the double-talk. The communication device may then process the filtered signals to further suppress remaining echo prior to transmission of the speech signal to the remote party.