Abstract: A signal coding technique for switching amplifiers includes quantizing the amplitude A(t) of an input signal to produce a time series Â(t) having M levels; modulating a clock signal in response to Â(t), thereby to produce a control signal; switching among at least three different power supply output levels in response to the control signal, thereby to generate an output pulse stream; and filtering the output pulse stream to produce an output signal for transmission.

Abstract: An endpoint or other communication device of a communication system includes a clock recovery loop having a phase error estimator. The communication device is operative as a slave device relative to another communication device that is operative as a master device. The clock recovery loop is configured to control a slave clock of the slave device responsive to a phase error estimate generated by the phase error estimator so as to synchronize the slave clock with a master clock of the master device. The phase error estimator comprises a plurality of filters each configured to generate a different estimate of master clock phase using at least a subset of a plurality of packets received from the master device, and control logic for adaptively selecting at least a particular one of the plurality of filters for use in generating the phase error estimate to be processed in the clock recovery loop.

Abstract: A signal coding technique for switching amplifiers includes quantizing the amplitude A(t) of an input signal to produce a time series Â(t) having M levels; modulating a clock signal in response to Â(t), thereby to produce a control signal; switching among at least three different power supply output levels in response to the control signal, thereby to generate an output pulse stream; and filtering the output pulse stream to produce an output signal for transmission.

Abstract: The present invention relates to a method of wideband RF detection. The method may include transmitting a signal from a plurality of transmit positions along a drive path. Reflections of the transmitted signal are received at a plurality of receive positions along the drive path. A signature is formed based on arrival angles of the reflections at each of the receive positions. The signature includes the arrival angles of the reflections at each of the receive positions with respect to a distance along the drive path of a corresponding transmit position and a corresponding receive position of each of the reflections.

Abstract: The present invention relates to a method of wideband RF detection. The method may include transmitting a signal from a plurality of transmit positions along a drive path. Reflections of the transmitted signal are received at a plurality of receive positions along the drive path. A signature is formed based on arrival angles of the reflections at each of the receive positions. The signature includes the arrival angles of the reflections at each of the receive positions with respect to a distance along the drive path of a corresponding transmit position and a corresponding receive position of each of the reflections.

Abstract: An endpoint or other communication device of a communication system includes a clock recovery loop having a phase error estimator. The communication device is operative as a slave device relative to another communication device that is operative as a master device. The clock recovery loop is configured to control a slave clock of the slave device responsive to a phase error estimate generated by the phase error estimator so as to synchronize the slave clock with a master clock of the master device. The phase error estimator comprises a plurality of filters each configured to generate a different estimate of master clock phase using at least a subset of a plurality of packets received from the master device, and control logic for adaptively selecting at least a particular one of the plurality of filters for use in generating the phase error estimate to be processed in the clock recovery loop.

Abstract: A repeater and methods thereof are provided. The example repeater first receives a donor signal (e.g., from a base station for repeating in a downlink direction, from a mobile station for repeating in an uplink direction, etc.) and a transmitted version of an internally generated pilot signal. The repeater configures an adaptive filter signal to cancel the received transmitted version of the internally generated pilot signal. In an example, the first receiving and configuring steps may be performed during a first mode of operation (e.g., a “training” mode). The repeater second receives the donor signal and a retransmitted version of the donor signal (e.g., retransmitted from the repeater). The repeater cancels the retransmitted donor signal based on the configured adaptive filter signal.

Abstract: A Doppler radar signal processing system and method and a Doppler radar employing the system or the method. In one embodiment, the system includes: (1) an input configured to receive at least one radar output signal representing a reflected Doppler radar signal, (2) signal processing circuitry coupled to the input and configured to produce an arc-length cardiopulmonary signal from the at least one radar output signal and employ a respiration fundamental frequency estimate to extract a heart rate signal from the arc-length cardiopulmonary signal and (3) an output coupled to the signal processing circuitry and configured to provide the heart rate signal.

Abstract: A Doppler radar signal processing system and method and a Doppler radar employing the system or the method. In one embodiment, the system includes: (1) an input configured to receive at least one radar output signal representing a reflected Doppler radar signal, (2) signal processing circuitry coupled to the input and configured to produce an arc-length cardiopulmonary signal from the at least one radar output signal and employ a respiration fundamental frequency estimate to extract a heart rate signal from the arc-length cardiopulmonary signal and (3) an output coupled to the signal processing circuitry and configured to provide the heart rate signal.

Abstract: A repeater and methods thereof are provided. The example repeater first receives a donor signal (e.g., from a base station for repeating in a downlink direction, from a mobile station for repeating in an uplink direction, etc.) and a transmitted version of an internally generated pilot signal. The repeater configures an adaptive filter signal to cancel the received transmitted version of the internally generated pilot signal. In an example, the first receiving and configuring steps may be performed during a first mode of operation (e.g., a “training” mode). The repeater second receives the donor signal and a retransmitted version of the donor signal (e.g., retransmitted from the repeater). The repeater cancels the retransmitted donor signal based on the configured adaptive filter signal.

Abstract: The present invention typically involves the use of a compressed blocking area to assist in sealing a filter element and avoiding channeling in a wound fibrous tissue filtering system. It may involve the use of multiple, spaced, interstitial rings. It may involve the intentional wasting of a portion of the filter element to create a compressed blocking area. It may also involve the use of different heights of the rings and may include the use of compression and secondary tapers on the rings. The heights and spacing of the rings with respect to the other ring or rings may vary in a certain ratio.

Abstract: The present invention typically involves the use of a compressed blocking area to assist in sealing a filter element and avoiding channeling in a wound fibrous tissue filtering system. It may involve the use of multiple, spaced, interstitial rings. It may involve the intentional wasting of a portion of the filter element to create a compressed blocking area. It may also involve the use of different heights of the rings and may include the use of compression and secondary tapers on the rings. The heights and spacing of the rings with respect to the other ring or rings may vary in a certain ratio.

Abstract: The present invention typically involves the use of a compressed blocking area to assist in sealing a filter element and avoiding channeling in a wound fibrous tissue filtering system. It may involve the use of multiple, spaced, interstitial rings. It may involve the intentional wasting of a portion of the filter element to create a compressed blocking area. It may also involve the use of different heights of the rings and may include the use of compression and secondary tapers on the rings. The heights and spacing of the rings with respect to the other ring or rings may vary in a certain ratio.

Abstract: A method and apparatus for providing a differential microphone with a desired frequency response are disclosed. The desired frequency response is provided by operation of a filter, having an adjustable frequency response, coupled to the microphone. The frequency response of the filter is set by operation of a controller, also coupled to the microphone, based on signals received from the microphone. The desired frequency response may be determined based upon the distance between the microphone and a source of sound, and may comprise both a relative frequency response and absolute output level. The frequency response of the filter may comprise the substantial inverse of the frequency response of the microphone to provide a flat response. Furthermore, the filter may comprise a Butterworth filter.

Abstract: A signal processing method and apparatus including a digital finite impulse response filter wherein the error caused by slow asymptotic convergence of the filter's adaptive coefficients is reduced. A first input signal is provided to an adaptive FIR filter including a coefficient calculator, finite impulse response FIR filter and a summation device. The filter also receives a second input signal, which may, for example, be the echo of the first input signal. The first input signal and the second input signal have a first bandwidth. The adaptive FIR filter then provides an output signal to a filter, which then filters the output signal to a second bandwidth which is less than the first bandwidth. The processed signal will have less error caused by the slow asymptotic convergence of the filter than previously possible because the error-concentrated frequency components near the band edge of the first frequency band have been filtered or removed.

Abstract: A subband adaptive filter is disclosed that retains the computational and convergence speed advantages of subband processing while eliminating delay in the signal path. The technique has applications in active noise control where delay seriously limits cancellation performance and in acoustic echo cancellation where transmission delay specifications may limit the use of conventional subband designs. A reference signal and a residual error signal are each decomposed into a plurality of subband signals, and a set of adaptive weighting coefficients is generated for each of these subbands by a conventional complex LMS (least-mean-squared) technique. These sets of subband weighting coefficients are then transformed into the frequency domain, appropriately stacked and inverse transformed back into the time domain to obtain wideband filter coefficients for a programmable filter.

Abstract: A method and apparatus for providing a differential microphone with a desired frequency response are disclosed. The desired frequency response is provided by operation of a filter, having an adjustable frequency response, coupled to the microphone. The frequency response of the filter is set by operation of a controller, also coupled to the microphone, based on signals received from the microphone. The desired frequency response may be determined based upon the distance between the microphone and a source of sound, and may comprise both a relative frequency response and absolute output level. The frequency response of the filter may comprise the substantial inverse of the frequency response of the microphone to provide a flat response. Furthermore, the filter may comprise a Butterworth filter.

Abstract: Signal processing apparatus having the capability to perform simultaneous space-time processing of sonar, radar and similar time-varying signals, and to effect the Fourier transform of multiple time-varying signals through electro-optical photoelastic means, photoconductive means, or photoemissive means.