Motorola Corporation

Freescale Semiconductor,inc.

General Dynamics Decision Systems, Inc.

William Chunhung Yip

David L Barron

James Brian Piket

James A Stephens

Steven Peter Allen

Timothy Gerard Hall

Sean S You

Gerald V Piosenka

David T Gustafson

Paul R Kennedy

Christopher W Springfield

Marc Alan Newman

Bruce Edward Geren

Ernest Pei-Ching Chen

Steven Pater Allen

Paul Lopez Kennedy

Daryl Leslie Bergstrom

Thomas Gerard Callaghan

Thomas Nall

Donald Fong Gee

Lance Foreman Amos

Paul Roy Kennedy

Holly Elizabeth Hall

Methods and apparatus are provided for an echo cancellation system. The echo cancellation system comprises an automatic gain control (AGC), a first scalar, a second scalar, a signal summing stage, and an adaptive filter. The AGC is responsive to a first signal in a reference path and a second signal in a near end path. The signal summing stage is between the first and second scalar in the near end path and the first and second scalars are responsive to the AGC. The adaptive filter is responsive to the first signal and provides a third signal to the signal summing stage that corresponds to an echo signal and is subtracted from a signal in the near end path. The second scalar has a scale rate that is the inverse of the scale rate of the first scalar such that unity scaling occurs on the near end path.

Automatic gain control for an adaptive finite impulse response and method therefore

An echo canceling system receives and transmits audio signals between a far end and a near end. During single talk, which is when only one end is originating audio, the path back to the originator is impeded by echo cancellation and attenuation. When there is double talk, which is when both ends are originating audio, the attenuation is removed, or at least significantly reduced. This is achieved by using ERLE, which itself is a known signal used for other purposes in an echo cancellation system, to provide information as to when double talking is occurring. This allows for stopping the attenuation for the double talk situation, which is the desired result.

Controlling attenuation during echo suppression

A speech recognition system () having a sampler block () and a feature extractor block () for extracting time domain and spectral domain parameters from a spoken input speech into a feature vector. A polynomial expansion block () generates polynomial coefficients from the feature vector. A correlator block (), a sequence vector block (), an HMM table () and a Viterbi block () perform the actual speech recognition based on the speech units stored in a speech unit table () and the HMM word models stored in the HMM table (). The HMM word model that produces the highest probability is determined to be the word that was spoken.

Speech recognition using polynomial expansion and hidden markov models

A bi-directional hands-free communication device includes a microphone for transmitting a signal along a transmit path and a speaker receiving a signal transmitted along a receive path and outputting a corresponding output signal. An echo canceller, positioned in the transmit path and the receive path, cancels echo signals induced by the microphone from the speaker and outputs a corresponding cancelled signal along the transmit path, and a transparency circuit distributes state-dependent additional loss derived from the noise floor margin to the transmit path and the receive path to reduce residual echo signals output from the echo canceller. The transparency circuit measures a noise floor and inserts an artificial noise signal to the transmit path, and optionally to the receive path, at a predetermined level in relation to the measured noise floor, and dynamically adjusts the speaker to compensate for changing environmental conditions by dividing a range of an expected ambient noise power into adjacent consecutive bins, and controlling a volume of the speaker responsive to ambient noise changes only when measured noise power moves into an adjacent bin.

Full-duplex hands-free transparency circuit and method therefor

The step sizes for tap positions of an adaptive filter ( ) in an echo canceller ( ) for canceling an echo signal are individually selected based upon a profile of the echo environment. A training signal ( ) is injected into the echo canceller and to the echo path during a training interval, or period. The adaptive filter profiles the echo path during the training interval. Respective step sizes &agr;&lsqb;k&rsqb; for the tap positions are generated as a function of the echo profile so generated.

Method and apparatus for setting a step size for an adaptive filter coefficient of an echo canceller

A voice decoder detects channel errors and loss of cryptographic synchronization using the change in spectral energy between sequential frames. The change in energy between frames is determined between corresponding LSP's of said successive frames and summed together. A running average of the change in energy for a predetermined number of frames is maintained. Current voice frames are eliminated based on the difference between the change in energy associated with the current frame and the running average. Accordingly, offensive audio associated with such channel errors or cryptographic synchronization loss is eliminated.

Voice decoder and method for detecting channel errors using spectral energy evolution

A hands-free communications unit employs a downlink peak power memory element ( , FIG. ), a downlink voice activity detector ( ), and an uplink voice activity detector ( ). The downlink voice activity detector ( ) evaluates the incoming signal to determine if the signal includes voice. In a similar manner, the uplink voice activity detector ( ) determines if an outgoing signal includes voice. In the event that the incoming signal includes voice and the energy of the outgoing signal exceeds a threshold calculated from the peak power of the incoming signal, the uplink voice activity detector ( ) indicates that a double-talk condition exists ( , FIG. ). In the event that the incoming signal does not include voice, the uplink voice activity detector ( ) compares the uplink signal to a voice threshold above a noise floor to determine if the outgoing signal includes voice.

Echo canceler and double-talk detector for use in a communications unit

A technique and method that efficiently and simultaneously transfers both voice and data information over a single communications link (11). The technique and method utilizes a multi-rate vocoder (12) for providing voice information at a plurality of different rates. Accordingly, the vocoder may be dynamically adjusted during transfer of information to meet channel bandwidth requirements. The technique and method also utilizes a bit-control protocol for inserting voice information within a stream of data information by the use of inserting flags having predetermined bitstreams. Accordingly, voice information is dynamically inserted into an existing bitstream of data information such that voice information is transferred only upon demand and when needed. This prevents the transfer of useless information, such as voice information when a speaker is silent and, thus, allows for very efficient utilization of system bandwidth.

Simultaneous transfer of voice and data information using multi-rate

Apparatus and a method are described for providing a security token. The security token may be used for numerous applications, but is particularly useful in conjunction with radiotelephone devices having secure functions. In accordance with the invention the user must insert a PIN and utter sounds. The radiotelephone device will activate the secure functions only if the PIN is correct and the sounds uttered are authenticated against voice feature vectors stores it the token.

Radio telecommunication device and method of authenticating a user with

A method and system simplifies and accomplishes the programming of a PED (12), such as a cellular telephone (22), via the use of a personal computer (PC). The present invention includes software (52, 54) within the PC (14) for providing a graphical user interface (GUI) to the user for ease and simplicity of selecting various programming features and settings associated with the cellular telephone to be programmed. The software further includes a translator (56) for translating these user selected features/settings into specific key depresses to be sent to the cellular telephone, via software and hardware interfaces (58, 18, 20), for accomplishing the programming of such features/settings. Additionally, the software includes the capability to monitor the data being displayed on the cellular telephone because such data may be required to accomplish various programming features.

Method and system for programming a cellular phone

A two-wire line and a four-wire line telephone system interface with each other through a hybrid (12). After a connection between the two and four-wire line systems is made, an echo canceler (10) provides training signals to the hybrid on the transmit path an generates echo cancellation signals on the receive path. An adaptive filter (16) is employed to provide the proper echo cancellation signals, while a controller (22) provides filter coefficients based on an error signal. The training signals include the convolution of an impulse function with a sin(x)/x function. Once the filter coefficients are determined for the particular call, the transmit path of the four-wire line system is switched in and voice data between the two systems my commence.

Multi-channel echo canceler and method using convolution of two training

An echo canceller (500) utilizes a central control unit (502) (CCU) and at least one convolution processing unit (504) (CPU) to perform echo cancellation on one or more channels. A method for operating the echo canceller (500) controls reading (706) one or more reference signals (510) and reflected signals (512), convolution and adaptive processing (11, 21, 31, 41) using the CPUs (504), and post-processing (702) to produce one or more echo cancelled signals (514). Convolution and adaptive processing for multiple channels can be performed simultaneously (11, 31) by multiple CPUs (504), or in a time-multiplexed manner (11, 21) by a single CPU (504), or a combination (11, 21, 31, 41) of simultaneous and time-multiplexing by multiple CPUs (504). CCU (502) is able to perform processing functions (702-730) while CPUs (504) perform convolution and adaptive processing (11, 21, 31, 41).

Multi-channel echo cancellation method and apparatus

A quadrant detector circuit (400) has a comparator (442) having a pair of inputs (438, 440). A first (438) of the pair of inputs (438, 440) is coupled to an in-phase signal (434) and a second (440) of the pair of inputs (438, 440) is coupled to a quadrature phase signal (436). A sample counter (448) has a reset (446) coupled to an output (444) of the comparator (442). A controllable switch (456) has a selection input (454) coupled to an output (452) of the sample counter (448). The controllable switch (456) is capable of switching between a local oscillator signal (458) and an inverse local oscillator signal (460).

Balance differential receiver

A balanced differential radio receiver (100) has an antenna (64) operative for receiving a modulated signal. A first pair of mixers (110, 112) each having an input that receives an output (106, 108) of the antenna (64) and each of the first pair of mixers (110, 112) having an output (118, 120). A second pair of mixers (114, 116) each having an input that receives an inverse output (108, 106) of the antenna (64). A resistive adding circuit (122, 124) having a pair of inputs (118, 120). The inputs (118, 120) coupled to the output of the first pair of mixers (110, 112).

Balanced differential radio receiver and method of operation

A technique and method that efficiently and simultaneously transfers both voice and data information over a single communications link (11). The technique and method utilizes a multi-rate vocoder (12) for providing voice information at a plurality of different rates. Accordingly, the vocoder may be dynamically adjusted during transfer of information to meet channel bandwidth requirements. The technique and method also utilizes a byte-control protocol for inserting voice information within a stream of data information by the use of a data link escape (DLE) byte command (34). Accordingly, voice information is dynamically inserted into an existing stream of data information such that voice information is transferred only upon demand and when needed. This prevents the transfer of useless information, such as voice information when a speaker is silent and, thus, allows for very efficient utilization of system bandwidth.

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Scottsdale, AZ, United States of America

William Chunhung Yip