Abstract: A packet voice transceiver adapted to reside at a first end of a communication network and to send an ingress communication signal comprising voice packets to, and receive an egress communication signal comprising voice packets from, a second packet voice transceiver residing at a second end of the communication network. The packet voice transceiver includes a far-end echo canceller that reduces echo that is present in the egress communication signal. The far-end communicates with other functional components of the transceiver system and adapts its behavior based on the activity of the other functional components.

Abstract: The present invention is an information entry system comprising a touch panel monitor screen, wherein the touch panel monitor screen displays keys for information entry, which are arranged circularly in order and the keys are rotationally shifted by a random number of key units around the center of the circular arrangement without changing the order when a user touches a predetermined option key before or after the information entry. This system also has a central processing unit and a program storage unit including an Information entry Screen Generator, a Random Number Generator, a Key Moving Unit, and a PIN Information output unit. This information entry device prevents a PIN or any other information entry from being stolen by someone who glances at the finger movement, since the entire series of the entry keys are rotated before or after the PIN entry.

Abstract: A device and method for handling announcement of an incoming call in a telephone handset at least in part in accordance with a measured ambient noise level is provided. In some embodiments, the disclosed device includes an audio signaling mechanism such as a ringer whose loudness is automatically adjusted in accordance with a measured ambient noise levels. Alternatively or additionally, the present invention provides an audio speaker for outputting received voice communications, wherein the loudness of the speaker is determined at least in part in accordance with a measured ambient noise level. In some embodiments, the present invention provides methods and devices for handling announcement of an incoming call at least in part in accordance with electrical output from other sensing circuits such as location sensing circuits and environmental circuits.

Abstract: An acoustic echo canceller having an adaptive filter, a step size control unit, and (optionally) a stability control unit. The adaptive filter derives an estimate of the echo in a near-end signal using a digital filter (e.g., a FIR filter) and further cancels the echo estimate from the near-end signal to provide an output signal. The step size control unit derives step sizes to be used to adjust the coefficients of the digital filter. The step sizes are determined based on the characteristics of a reference signal and the output signal and (optionally) the characteristics of the coefficients. For example, the step size is set proportional to the reference signal amplitude, inversely proportional to the output signal amplitude, and based on a difference in the coefficient power at two different time instants. The stability control unit constrains the adjustments to the coefficients to prevent instability.

Abstract: There is disclosed an echo canceller circuit for use in a full duplex transceiver of the type comprising a line driver capable of sending analog transmit signals through a cable and comprising a line receiver capable of receiving analog receive signals from the cable. An echo canceller impedance model circuit is coupled to an output of the line driver and is coupled to an input of the line receiver. The echo canceller impedance model circuit generates an echo canceller current that is equal in magnitude and opposite in phase to a current that represents signal echoes that are present in the analog receive signals. The echo canceller impedance model circuit has a variable impedance for generating the echo canceller current. The variable impedance has at least one variable resistor and at least one variable capacitor.

Abstract: The invention includes a full duplex transceiver for transmitting and receiving communication signals. The transceiver includes 1 to N sample and hold circuits. Each sample and hold circuit receives a first signal that includes a far-end signal, and in some cases an echo signal, and in some cases alternatively or additionally cross-talk signals. The transceiver additionally includes a plurality of subtraction circuits. Each subtraction circuit receives an output of at least one of the sample and hold circuits. Each subtraction circuit subtracts at least a fraction of a replica signal from at least a fraction of the output of the at least one of the sample and hold circuits. The subtraction circuits generate an output that represent the far-end signal with substantially reduced echo and/or cross-talk interference, and is available for additional receiver processing.

Abstract: The present application provides a variety of exemplary embodiments, such as modem systems, modem devices, modem connectors, host connectors, communication systems and communication cards. For example, there is provided a modem device for use to enable a host to communicate over a communication line, wherein the host has a host connector. The modem device comprises a line side circuitry capable of interfacing with the communication line; and a digital isolation barrier (DIB) coupled to the line side circuitry, the digital isolation barrier capable of being connected to a modem connector for connection to the host connector, wherein the digital isolation barrier is capable of isolating the modem connector from the line side circuitry. Moreover, the line side circuitry may include a line side DIB interface for communication with the digital isolation barrier. Also, the modem connector may be connected to the digital isolation barrier via one or more lines.

Abstract: An equalizer for a loudspeaker telephone includes a signal generator for generating a reference signal for broadcast by a loudspeaker of the loudspeaker telephone. A filter alters the frequency response of signals prior to broadcast by the loudspeaker. During set-up, a processor processes the reference signal picked up by a microphone remote from the loudspeaker that has been convolved with the acoustical response of the environment to determine coefficients for the filter that are necessary to compensate for the environment acoustics and applies the coefficients to the filter.

Abstract: Bridge circuit for echo suppression for a reception signal of a communication device connected to a transmission line, to which can be supplied a reception signal received via the transmission line and a transmission signal to be transmitted by the communication device via the transmission line. The bridge circuit is designed such that on balancing the bridge circuit, the reception signal there can be tapped echo-compensated with a transmission signal part generated by the transmission signal being suppressed. To balance the bridge circuit a variable simulation device is provided to simulate at least one circuit section of at least one bridge branch and connect with the at least one bridge branch. By such an arrangement, the signal level in the simulation device may be reduced so far that this can be designed as an integrated circuit and to be programmable.

Abstract: The invention presents a software agent that optimizes processing resources for multiple instances of a software module that are executing simultaneously. The agent allocates and distributes processing resources, such as MIPS (millions of instruction cycles per second), to software functions executing on a core and controls resource distributions and module functions in a manner such that maximum processing capacity is utilized but not exceeded. The agent schedules the enabling and disabling of software module instance functions using a prioritization scheme that allocates MIPS to functions as the functions are enabled. An exemplary embodiment optimizes MIPS resources for multiple instances of an echo cancellation unit operating on a DSP (digital signal processor) core.

Abstract: The present invention relates to a suppression device for an arrangement for the transmission of audio signals, in particular uttered speech, having: an echo reduction unit (4), which is arranged between an input channel (1) for receiving an input audio signal (A1) coming from a remote end and an output channel (5) for outputting an output audio signal (A2), for suppressing an echo signal contained in the output audio signal (A2), a speech activity detection unit (7) for detecting a speech signal contained in the input audio signal (A1), and, a control unit (6) for setting an echo suppression factor(s) of the echo reduction unit (4) for echo suppression.

Abstract: A system for providing DC power on local telephone lines, such as telephone lines in a building or office, for powering devices and circuitry associated with communications over those telephone lines, as well as other functions. Desired voltage and power levels are supplied over local telephone lines by separating the DC power component from the central office or private branch exchange with a DC blocking filter while passing all AC telephony signals. A distinct DC power is then imposed over the telephone line for powering both the telephony service as well as other loads. Conventional telephone off-hook detection is simulated for compatibility with the central office or private branch exchange. The functions required may be integrated, partially or fully within a telephone outlet.

Abstract: The invention relates to an echo cancellation device for a full duplex communication system. The echo cancellation device utilizes a pull-up current source to increase the DC level, so as to improve the echo cancellation performance with avoiding signal distortion. And the pull-up current source used in the echo cancellation device can be implemented to a fixed current source or an adjustable current source.

Abstract: An echo cancellation device for a full duplex communications system is provided. The full duplex communication system has a transmitter for transmitting a transmit signal and a receiver for receiving a receive signal. The echo cancellation device has a filter for outputting a filter signal according to the transmit signal, an echo cancellation circuit connected to the filter for outputting an echo cancellation signal according to the filter signal, at least one echo cancellation resistor connected to the transmitter, the receiver, and the echo cancellation circuit, and an echo cancellation detection circuit for outputting a control signal according to an echo residue at the receiver to control the filter.

Abstract: An apparatus comprising a first differential output driver to provide a single ended output voltage in response to an input voltage, a second differential output driver to provide a single ended output in response to the input voltage where the first output voltage and the second output voltage are representative of the positive and inverted input voltage. The apparatus also includes a feedback circuit to monitor the first and second output voltages and apply a bias voltage to at least one of the first and second output drivers to vary the point where the first and second output voltages cross-over as the input voltage changes from a first to a second level.

Abstract: An acoustic feedback suppression apparatus according to the present invention comprises a notch filter (109) for filtering out acoustic feedback components, a plurality of first sample fast Fourier transformation means (118 to 120) for performing frequency analysis of every 512 data samples, a plurality of peak frequency detecting means (121 to 123) for detecting peak frequencies of respective channels, adding means (124) for adding signals on the respective channels, second sample fast Fourier transformation means (125) for performing frequency analysis of every 4096 data samples of the added signal, peak frequency detecting means (126) for detecting a peak frequency of the output signal outputted from the 4096 fast Fourier transformation means (125), and coefficient specifying means (129) for specifying filter coefficients of the notch filter (109).

Abstract: Techniques for enhancing the sound quality of computer telephony systems are provided. In general, digital signals including telephony sounds are converted from the time domain to the frequency domain. If noise is detected in the frequency domain conversion of the digital signals, the noise is removed utilizing a filter. The noise detection and filtering can be performed in software so that enhanced audio quality can be achieved at a relatively low cost and with flexibility for very diverse environments.

Abstract: A digital communication system includes a transmitter and a receiver and communicates on telephone line. Receipt gain of the digital communication system is controlled in accordance with the following. Initialization signals generated at the transmitter and transferred through the hybrid circuit on the telephone line are received for a predetermined time period. An average magnitude value of the initialization signal received during the time period is compared with a reference magnitude value. Receipt gain is controlled according to the difference between the average magnitude value of the receipt signal and a reference value. In this manner, when the system performance is changed according to permissible tolerance of the analog discrete components used in the ADSL system, gain of the gain amplifier is automatically controlled. Thus, the ADSL system can operate with optimal performance under given conditions.

Abstract: An affine projection or like algorithm is used to process a non-stationary signal. The affine projection algorithm creates an inverse matrix and includes a factor ? to avoid numerical instability in the inverse matrix. The factor ? is adaptively adjusted according to the characteristics of the signal.

Abstract: A self-lighting type push-button input device according to the presently disclosed subject matter can include a button base portion formed of a transparent material. Holes can be formed in predetermined positions of the button base portion, and spring portions can be formed integrally with the holes by molding transparent silicone rubber with a light diffusing agent incorporated therein. The button base portion serves as a light conducting portion, and the spring portions can uniformly diffuse the light distributed thereto by the light conducting portion, whereby lighting can be effected by a reduced number of light sources, effecting a reduction of size and cost.