Abstract: Signal processing includes receiving an unknown signal having a distorted component and an undistorted component, the distorted component and the undistorted component having a nonlinear relationship; and separating from the unknown signal a reference component and a target component.

Abstract: A digital signal processor (DSP) comprises an input terminal configured to receive an input, an adaptive nonlinear phase filter coupled to the input terminal, the adaptive nonlinear phase filter having a time-varying phase response, and an adaptive nonlinear amplitude filter coupled to the input terminal, the adaptive nonlinear amplitude filter having a time-varying amplitude response. A method of processing a signal comprises receiving the signal, sending the signal to an adaptive nonlinear phase filter, the adaptive nonlinear phase filter having a time-varying phase response, and sending the signal to an adaptive nonlinear amplitude filter, the adaptive nonlinear amplitude filter having a time-varying amplitude response.

Abstract: A signal processing method includes receiving an unknown signal that includes a distorted component and an undistorted component, and performing self-linearization based at least in part on the unknown signal to obtain an output signal that is substantially undistorted, wherein performing self-linearization includes adaptively generating a replica distortion signal that is substantially similar to the distorted component, and subtracting the replica distortion signal from the unknown signal to obtain the output signal.

Abstract: A distortion correcting analog to digital converter (ADC) system includes a plurality of ADCs configured to convert an analog signal to a plurality of digital ADC outputs, wherein the plurality of ADCs are configured to generate a composite signal based on the plurality of ADC outputs, there is an offset between a first one of the plurality of ADC outputs and a second one of the plurality of ADC outputs, the offset causing distortion in the composite signal. The system further includes an adaptive self-linearizer configured to receive the composite signal, and to perform self-linearization based on the composite signal to correct for the distortion in the composite signal.

Abstract: A method of processing a signal is disclosed. The method comprises generating a digital signal, converting the digital signal to an analog signal, and generating an amplified analog signal having distortions. The method further comprises converting the amplified analog signal to a feedback digital signal at a sample rate and updating a model of the distortions based on the feedback digital signal.

Abstract: An observation system configured to observe one or more initially unknown state variables of an observed system includes an input interface configured to receive a system input, and a processing module coupled to the input interface. The processing module is configured to determine the one or more initially unknown state variables, and the determination is based at least in part on the system input, a plurality of known state variables, and a time varying mode vector that is time dependent.

Abstract: Processing an input signal that includes an input variable is disclosed. The input variable is compared to a set of ordered constants, the relative location of the input variable within a range of possible inputs is determined and a filter coefficient of a nonlinear filter is determined using the relative location of the input variable. A configurable filter includes an interface configured to receive an input signal that includes an input variable, a nonlinear filter coupled to the interface, configured to process the input signal, and a processor coupled to the nonlinear filter, configured to determine the relative location of the input variable within a range of possible inputs and to determine a filter coefficient of the nonlinear filter using the relative location of the input variable.

Abstract: A distortion correcting analog to digital converter (ADC) system includes a plurality of ADCs configured to convert an analog signal to a plurality of digital ADC outputs, wherein the plurality of ADCs are configured to generate a composite signal based on the plurality of ADC outputs, there is an offset between a first one of the plurality of ADC outputs and a second one of the plurality of ADC outputs, and the offset causing distortion in the composite signal. The distortion correcting ADC system further includes an adaptive module coupled to the plurality of ADCs, wherein the adaptive modules includes an adaptive filter having a filter response, and the adaptive module is configured to adaptively adjust the filter response to reduce the distortion in the composite signal.

Abstract: An observation system configured to observe at least one known state variable of an observed system includes a plurality of filters that are configured to receive a system input, and generate the at least one unknown state variable. Generating the unknown state variable includes processing the system input, a plurality of known state variables, and a time varying mode vector. An inverse system configured to observe at least one inverse state variable of an original system includes a plurality of filters that are configured to receive a system input, and generate the at least one inverse state variable. Generating the inverse state variable includes processing the system input, a plurality of known state variables associated with the original system, and a time varying mode vector associated with the original system.

Abstract: A system and method are disclosed for correcting for output distortion of an analog to digital converter, comprising: estimating the output distortion, providing an estimated distortion, and combining an output of the analog to digital converter with the estimated distortion to compensate for the output distortion. The compensating module for correcting output distortion of an analog to digital converter comprises a calibration module configured to estimate the output distortion and a combiner configured to combine an output of the analog to digital converter with the estimated distortion to compensate the output distortion.

Abstract: A system and method are disclosed for processing a signal propagated through a nonlinear channel. The method includes modeling the channel characteristics to produce a linearized channel model, deriving an inverse linearized channel model from the linearized channel model, and filtering the signal using the inverse linearized channel model.

Abstract: A method of processing a signal is disclosed. The method comprises generating a digital signal, converting the digital signal to an analog signal, and generating an amplified analog signal having distortions. The method further comprises converting the amplified analog signal to a feedback digital signal at a sample rate and updating a model of the distortions based on the feedback digital signal.

Abstract: A signal processing system includes a receiving terminal configured to receive a digital signal comprising a plurality of samples associated with a plurality of original sampling times, wherein the original sampling times have a period of T, and a compensation module coupled to the receiving terminal. The compensation module is configured to generate, based on the digital signal, a nominal phase shifted signal having a plurality of nominal phase shifted samples associated with a plurality of phase shifted sampling times, wherein the plurality of phase shifted sampling times correspond to fractional intervals of the original sampling times. The compensation module is further configured to generate a compensated signal based at least in part on the digital signal and the nominal phase shifted signal.

Abstract: A method of converting an input analog signal to a compensated digital signal comprises converting the input analog signal to an uncompensated digital signal, inputting the uncompensated digital signal to a distortion model, generating a modeled distortion signal based on the uncompensated digital signal, and subtracting the modeled distortion signal from the uncompensated digital signal to generate the compensated digital signal. A distortion compensating analog to digital converter (ADC) comprises an uncompensated ADC configured to convert an input analog signal to an uncompensated digital signal, and a compensation module coupled to the uncompensated ADC, configured to receive the uncompensated digital signal, generate a modeled distortion signal based on the uncompensated digital signal and subtract the modeled distortion signal from the uncompensated digital signal to generate the compensated digital signal.

Abstract: A system and method are disclosed for securely transmitting and receiving a signal. A nonlinear keying modulator is used in the transmitter to encrypt the signal using a nonlinear keying modulation technique. A nonlinear keying demodulator is used in the receiver to decrypt the signal.

Abstract: A system and a method are disclosed for converting analog signal to digital. An analog to digital converter system comprises an analog to digital converter (ADC) and an adaptive filter coupled to the ADC, wherein the adaptive filter is coupled to the ADC in a feedforward configuration. A method of generating a digital signal based on an analog signal comprises applying the analog signal to an analog to digital converter (ADC) to generate an ADC output and sending the ADC output to an adaptive filter, wherein the adaptive filter is coupled to the ADC in a feedforward configuration.

Abstract: A method of compensating for nonlinear distortions in a digital signal comprises receiving the digital signal, generating a nominal phase shifted signal based on the digital signal, generating a modeled distortion signal based on the digital signal and the nominal phase shifted signal, subtracting the modeled distortion signal from the digital signal, and generating a compensated signal. A compensating system comprises an input interface configured to receive a digital signal having nonlinear distortion, and a distortion model coupled to the interface, configured to generate a nominal phase shifted signal based on the digital signal, generate a modeled distortion signal based on the digital signal and the nominal phase shifted signal, subtract the modeled distortion signal from the digital signal, and generate a compensated signal.

Abstract: A system and method are disclosed for a nonlinear filter having a nonlinear transfer function. The nonlinear filter comprises a plurality of linear filters each having a filter output, a plurality of nonlinear elements each connected to one of the plurality of linear filters, and a combination network connected to the plurality of nonlinear elements. The nonlinear elements are used to produce nonlinear effects and generate a plurality of nonlinear outputs, and the combination network combines the nonlinear outputs.

Abstract: A method of converting an input analog signal to a compensated digital signal comprises converting the input analog signal to an uncompensated digital signal, inputting the uncompensated digital signal to a distortion model, generating a modeled distortion signal based on the uncompensated digital signal, and subtracting the modeled distortion signal from the uncompensated digital signal to generate the compensated digital signal. A distortion compensating analog to digital converter (ADC) comprises an uncompensated ADC configured to convert an input analog signal to an uncompensated digital signal, and a compensation module coupled to the uncompensated ADC, configured to receive the uncompensated digital signal, generate a modeled distortion signal based on the uncompensated digital signal and subtract the modeled distortion signal from the uncompensated digital signal to generate the compensated digital signal.

Abstract: A method of correcting for output distortion of an analog to digital converter (ADC) is disclosed. The method comprises estimating the output distortion and providing an estimated distortion. The method further comprises combining an output of the ADC with the estimated distortion to compensate for the output distortion and training a calibration module.