Abstract: The magnitude processing circuit 607 non-linearly processes the received signal 2 and then outputs a non-linear processed signal. The delay processing circuit 300 further delays the non-linear processed signal and then outputs a delayed processed signal. The delayed processed signal is time-multiplexed with the non-linear processed signal. The multiplexed signal is used instead of the received signal 2. The adaptive filters 122 and 124 operate alternately with the non-linear processed signal or with the delayed processed signal obtained by non-linearly processing and then delaying the received signal 2 as the input signal. Adaptive filter coefficients can be obtained by using twice the number of conditions compared with the number is twice that for the case where only the received signal 2 is used as the input signal.

Abstract: The invention relates to an acoustic echo suppressor and a non-linear processor for an echo canceller in a 4-wire data transmission network. An echo canceller is typically controlled by comparing the power levels of the near-end and far-end signals. The transfer function of an acoustic echo path is usually very non-uniform. According to the invention, the spectrum of the far-end signal is treated, before the signal power level is calculated, with a weighted filter, which models the effect of the transfer function of acoustic echo. As a result, the double talk dynamics is improved, since high-energy vowels of far-end speech, which normally cause low-energy vowels of near-end speech to be clipped in an echo suppresseor, will be attenuated.

Abstract: A 3D sound reproducing apparatus for multiple listeners includes an inverse filter module for filtering an input sound signal such that each of the listeners can have the same virtual sound source, time multiplexing module for sequentially selecting one of the sound signals filtered by the inverse filter module at a predetermined interval, and a plurality of speakers for outputting the sound signal selected by the time multiplexing means as sound. Thus, the 3D sound reproducing apparatus for multiple listeners can concurrently present the same 3D sound effect to multiple listeners.

Abstract: The present invention relates to a system and method for providing a “lifeline” service to a VoDSL customer despite an electrical power outage or integrated access device failure at the customer premise. A bypass function is implemented in an integrated access device at the customer premise to provide the lifeline service. The bypass function is preferably a relay, which can be automatically activated to provide the lifeline service under various conditions. The bypass relay, working in conjunction with systems in the central office and the regional switching center allows the customer to obtain an active telephone line during power outages or integrated access device failures. Electrical power is also supplied to the customer's premise from the central office, thereby allowing the customer to use a telephone line in the traditional manner. The present invention can further be implemented for any number of customers and telephone lines.

Abstract: An apparatus for determining energy threshold detection values for detecting at least one tone having a known frequency and duration in an input signal. The input signal is input over a period of time that is divided into frame portions including at least an initial frame portion and a last frame portion. An energy value is determined for the at least one tone during each frame portion. A set of control flag signals are set for the at least two frame portions based on the energy values being below a threshold value in previous frame portions and the presence of noise in previous frame portions. An offset into a data table is determined based on the control word, the offset being used to retrieve a scaling coefficient and an address of an energy value for the at least two frame portions from the data table.

Abstract: In a method for determining a parameter set for a hearing aid during the computerized setting of the hearing aid, a macro call is determined, the macro call is converted into at least one setting command according to a macro definition, and the parameter set is determined dependent on the at least one setting command. Such a method is high-performance and nonetheless flexible and easy to manipulate.

Abstract: The Least Mean Square (LMS) and Normalized LMS (NLMS) algorithms commonly employed in adaptive filters of echo cancelers are further optimized. Finite impulse response (FIR) filters are used to estimate a transfer function of an echo channel in a communications link. The LMS and NLMS algorithms are used to adapt the filter coefficients of the estimated transfer functions. By including the echo channel energy gain in the LMS or NLMS update equation, adaptation speed is increased by making adaptation responsive to the channel energy gain. An algorithm for estimating the echo channel energy gain adapts the estimate based on measured system parameters, such as a measured instantaneous channel gain and a near-end voice level. By considering in the NLMS algorithm, the average energy of either the microphone signal or the error signal, as well as the standard reference signal, a higher nominal update gain can be used. With a higher nominal update gain, the NLMS algorithm will converge more quickly.

Abstract: A ring trip detector circuit and method for use with a plurality of subscriber line interface circuits each having at least one telephone unit connected to it, having a ring generator for feeding a ringing voltage to the subscriber line interface circuits, and which detects when at least one of the subscriber units goes off-hook. The voltage level of the ringing voltage is compared with a predetermined level so as to detect when any one of the ringing subscriber telephone units goes off-hook. Thereafter, each of the plurality of subscriber line interface circuits is sequentially disconnected from the ring generator, and reconnected only in the absence of an off-hook condition in the disconnected subscriber telephone unit. The ringing voltage thereby remains fed to all ringing subscriber lines for which all connected equipment is on-hook.

Abstract: A method and apparatus for the detection of one or more telephone off-hook conditions using an analog-to-digital converter to detect voltage changes between tip and ring lines of a telephone network loop. An isolation network provides substantial electrical isolation for a detection device from voltage surges on the tip and ring lines of a “plain old telephone system” (POTS) network. The isolation network also provides a minimal load on the POTS wiring system, so as not to cause a false detection of an off-hook condition by central office equipment. A gain amplifier is used to scale the tip and ring voltage to a suitable range for an analog-to-digital converter (ADC). The ADC outputs a digital voltage value to a decision-making element, such as a microprocessor, a digital signal processor, or a state machine. The decision-making element can detect when multiple POTS devices coupled to the network wiring loop go into an off-hook state.

Abstract: A system for processing an input signal communicated on a telephone line includes an input node to receive the input signal. The input signal comprises a first component associated with a first frequency band, a second component associated with a second frequency band higher than the first frequency band, and a third component associated with a third frequency band higher than the second frequency band. A first filter coupled to the input node receives the input signal, attenuates the first and third components, and communicates a first signal substantially comprising the second component. A second filter coupled to the input node receives the input signal, attenuates the second component, and communicates a second signal substantially comprising the first and third components. A third filter coupled to the second filter receives the second signal, attenuates the third component, and communicates a third signal substantially comprising the first component.

Abstract: Method and apparatus for alternately providing positive and negative direct current voltages to a single twisted pair includes a power source configured to provide a first signal and a second signal, the first and second signals having different polarities, a controller configured to provide a control signal in accordance with a predetermined timing signal, and a voltage alternating switch circuit having first and second output terminals, the voltage alternating switch circuit coupled to the power source configured to receive the first and second signals, the voltage alternating switch circuit further coupled to the controller configured to receive the control signal, and in accordance thereto, providing first and second signals alternately to first and second output terminals, such that the adverse corrosive effect of positive voltage line powering is minimized.

Abstract: A surge reset circuit used to automatically reset a surge protection circuit within a telephone line interface circuit. A sensor (e.g., a zenering device) advantageously generates a voltage level representing current draining out of the transient voltage suppression portion of the surge protection circuit after a transient energy surge. If the current is draining, which may indicate a potential lockup situation, feedback circuitry generates a reset feedback signal that is provided to a cutoff device. The cutoff device, in response to receiving the feedback signal, disables a current limiter portion of the surge protection circuit to reduce the current draining from the transient voltage suppression portion. As the current level is reduced, the transient voltage suppression portion will reset when the current drops below a threshold value or is substantially eliminated. As a result, the feedback circuitry removes the reset feedback signal from the cutoff device to re-enable the current limiter.

Abstract: Echo is canceled in a communication device including at least one microphone and a loudspeaker. Signals directed to the loudspeaker are filtered through at least one first filter. The filtered signals are subtracted from signals received by the microphone. At least one second filter filters the subtracted results to produce a signal corresponding to speech signals received by the microphone. At least one third filter filters the subtracted results to produce a signal corresponding to echo from the loudspeaker. The output from the third filter is subtracted from the output from the second filter to produce an echo-canceled signal. The device may include a number of microphones, and the first, second, and third filters may each include a number of filters equal to the number of microphones. The outputs from the second filter may be added, the outputs from the third filter may be added, and the sum of the outputs from the third filter may be subtracted from the sum of the outputs of the second filter.

Abstract: Methods and apparatus for broadcasting high quality audio “studio direct” with the same digital information employed in the studio by the video producer with AC-3 digital audio signals for broadcast to individual receiver decoders (IRD) include a method for altering meta data bits with minimum recalculation of cyclical redundancy check values. Control over individual data bits such as copyright bits is maintained by determining the bit status, comparing it to a preferred status, changing the status if it does not comply with the preferred status, and reevaluating cyclical redundancy check value in each data packet to avoid disruption in the data transmission. The calculation according to the present invention simplifies the hardware, storage and processing demands of previously known calculation techniques by forward and reverse comparisons of partial packet cyclic redundancy check (CRC) values.

Abstract: The invention relates to a MOS transistors substitutive circuit having a transformer/data interface function, in particular for ISDN networks, comprising first (11a) and second (11b) power supply/transmitter blocks, the first power supply/transmitter block (11a) being connected between a voltage reference (V) and a first data interface (RX), and the second power supply/transmitter block (11b) being connected between a ground potential reference (GND) and a second data interface (TX), both power supply/transmitter blocks being connected to a supply voltage reference (VDD). The MOS transistors substitutive circuit according to the invention comprises first (12) and second (12′) MOS transistor pairs connected to the voltage reference (V), the MOS transistors being diode configured and held in their saturation range, so as to have a high A.C. impedance and virtually zero D.C. impedance, thereby minimizing power dissipation through the substitutive circuit.

Abstract: In methods and apparatus for echo cancellation, a noise estimate is selectively added to a downlink communications signals to improve the convergence speed and stability of an echo-canceling adaptive filter. The added signal content enables the echo-canceling adaptive filter to more quickly track echo path changes during user communications and prevents divergence of the adaptive filter during periods in which the downlink signal does not contain information (e.g., speech) sufficient to develop a quality echo path estimate. To prevent performance degradation from a user perspective, the added noise is made to resemble existing system noise (e.g., either near-end or far-end background noise). In exemplary embodiments, filter convergence speed and stability are further improved by whitening the spectrum and increasing the power level of the added noise whenever a near-end user is active and masking the added noise.

Abstract: A method of for canceling echos at a first end of a telephone call marks every other byte of a first digital representation of a first analog signal originating at the first end of the call with a signature. A second digital representation of a second analog signal from the second end of the call is received at the first end and split into a stream of odd number bytes and a stream of even number bytes. The streams of bytes are analyzed for the presence of the signature and one of the streams of bytes is converted to a third analog signal if the signature is detected.

Abstract: A portable spa including an audio system designed to use the spa shell as the sound generating device. Transducer devices are mounted within an enclosure which is bonded to the spa shell so as couple the sound vibration energy to the shell so that sound can be heard when using the spa.

Abstract: In a subscriber line control device connected to a plurality of subscriber circuits, there is a memory circuit for recording signal data indicating the states of subscriber lines, and hardware for displaying flags denoting changes in the signal data indicating the states of the subscriber lines, as well as firmware for monitoring periodically the flags displayed by the hardware.

Abstract: A signal detector for detecting at least a first signal having a first frequency includes a matched transform unit and an energy level threshold unit. The matched transform unit is adapted to receive at least a first frame of time domain input samples at a sampling frequency and generate at least a first frequency energy value for the first frame based on at least a first subset of the time domain input samples and a first matched filter coefficient. The sampling frequency is a non-integral multiple of the first frequency, and the first matched filter coefficient depends on the first frequency. The energy level threshold unit is adapted to compare the first frequency energy value to a threshold energy value to determine the presence of the first signal. A method for detecting at least a first signal having a first frequency is provided. The method includes receiving at least a first frame of time domain input samples at a sampling frequency.