System and method for controlling gain and timing phase in a presence of a first least mean square filter using a second adaptive filter

An information communication system, comprising:

• a variable gain amplifier (VGA) means for amplifying an input signal of the information communication system;
• analog-to-digital converter (ADC) means for converting an output of the VGA means;
• first filter means for filtering an output of said ADC means,
• wherein tap weight coefficients of the first filter means are updated according to a first least mean square (LMS) engine means,
• wherein the first filter means is responsive to an output of the ADC means, and
• wherein at least two tap weight coefficients of the first filter means are constrained;
• second filter means for filtering an output of said first filter means,
• wherein tap weight coefficients of the second filter means are updated according to adaptation engine means for updating a tap weight coefficient,
• wherein the second filter means is responsive to an output of the first filter means,
• wherein a number of tap weight coefficients of the second filter means comprises one of less than and equal to a number of the tap weight coefficients of the first filter means,
• wherein the second filter means comprises a three-tap filter means,
• wherein tap weight coefficients of the three-tap filter means comprise “a”, “1+b”, and “−a”, respectively,
• wherein a value of tap weight coefficient “a” of the second filter means is updated to provide a timing phase of the second filter means that is associated with a change in timing phase error introduced by the first filter means,
• wherein the tap weight coefficient “a” is updated according to equation:
• a[n+1]=a[n]−α*Δθ,
• wherein a[n+1] comprises a value of the tap weight coefficient “a” for a next sampling time of the input signal,
• wherein a[n] comprises a value of the tap weight coefficient “a” for a current sampling time of the input signal,
• wherein α comprises a first gain constant, and
• wherein Δθ comprises a change in timing phase error associated with the first filter means,
• wherein a value of tap weight coefficient “b” of the second filter means is updated to provide a gain of the second filter means that is associated with a change in gain error from the first filter means,
• wherein the tap weight coefficient “b” is updated according to equation:
• b[n+1]=b[n]β*ΔΓ,
• wherein b[n+1] comprises a value of the tap weight coefficient “b” for a next sampling time of the input signal,
• wherein b[n] comprises a value of the tap weight coefficient “b” for a current sampling time of the input signal,
• wherein β comprises a second gain constant, and
• wherein ΔΓ comprises a change in gain error from the first filter means;
• gain controller means for controlling gain of the VGA means,
• wherein the gain controller means is in communication with the VGA means and responsive to the output of the second filter means,
• wherein the gain of the second filter means is configured to cause the gain controller means to modify a gain of the VGA means to compensate for the change in gain error from the first filter means;
• and
• timing phase controller means for controlling timing phase of the ADC means,
• wherein the timing phase controller means is in communication with the ADC means and responsive to an output of the second filter means,
• wherein the timing phase of the second filter means is configured to cause the timing phase controller means to modify a timing phase of the ADC means to compensate for the change in timing phase error introduced by the first filter means.

An information communication system, comprising:

• a variable gain amplifier (VGA), wherein the VGA is responsive to an input signal of the information communication system;
• an analog-to-digital converter (ADC), wherein the ADC is responsive to an output of the VGA;
• a first filter,
• wherein tap weight coefficients of the first filter are updated according to a first least mean square (LMS) engine,
• wherein the first filter is responsive to an output of the ADC, and
• wherein at least one tap weight coefficient of the first filter is constrained;
• a second filter,
• wherein the second filter is responsive to an output of the first filter, and
• wherein a number of tap weight coefficients of the second filter comprises one of less than and equal to a number of the tap weight coefficients of the first filter;
• a reconstruction filter that is responsive to the output of the first filter;
• and, at least one of:
• a gain controller for controlling gain of the VGA, wherein the gain controller is in communication with the VGA and responsive to the output of the second filter and an output of the reconstruction filter;
• and
• a timing phase controller for controlling timing phase of the ADC, wherein the timing phase controller is in communication with the ADC and responsive to an output of the second filter and an output of the reconstruction filter;
• and
• an error generator that signals the at least one of the gain controller and the timing phase controller based on the output of the second filter and an output of the reconstruction filter.

A method for controlling at least one of gain and timing phase of a communication system, comprising the steps of:

• a.) amplifying an input signal to generate an amplified signal;
• b.) converting the amplified signal into a digital signal to generate a converted signal;
• c.) filtering the converted signal to generate a first filtered signal in accordance with a first plurality of filter coefficients,
• wherein the first plurality of filter coefficients are updated according to a first least mean square (LMS) process, and
• wherein at least one filter coefficient of the first plurality of filter coefficients is constrained;
• d.) filtering the first filtered signal to generate a second filtered signal in accordance with a second plurality of filter coefficients,
• wherein a number of filter coefficients of the second plurality of filter coefficients comprises one of less than and equal to a number of the filter coefficients of the first plurality of filter coefficients;
• e.) generating a reconstruction filter output in response to the first filtered signal;
• f.) controlling at least one of a gain of step (a.) and a timing phase of step (b.) in response to the second filtered signal and the reconstruction filter output;
• and
• g.) controlling the at least one of the gain of step (a.) via a gain controller and the timing phase of step (b.) based on a signal that is generated by an error generator and based on the second filtered signal and the reconstruction filter output.

A method for controlling at least one of gain and timing phase of a communication system, comprising the steps of:

• a.) amplifying an input signal to generate an amplified signal;
• b.) converting the amplified signal into a digital signal to generate a converted signal;
• c.) filtering the converted signal to generate a first filtered signal in accordance with a first plurality of filter coefficients,
• wherein the first plurality of filter coefficients are updated according to a first least mean square (LMS) process, and
• wherein at least one filter coefficient of the first plurality of filter coefficients is constrained;
• d.) filtering the first filtered signal to generate a second filtered signal in accordance with a second plurality of filter coefficients,
• wherein a number of filter coefficients of the second plurality of filter coefficients comprises one of less than and equal to a number of the filter coefficients of the first plurality of filter coefficients;
• and
• e.) controlling at least one of a gain of step (a.) via a gain controller and a timing phase of step (b.) in response to the second filtered signal,
• wherein at least two filter coefficients of the first plurality of filter coefficients are constrained, and wherein the method further comprises the steps of:
• f.) updating a value of at least one filter coefficient of the second plurality of filter coefficients to provide a gain of step (d.) that is associated with a change in gain error from step (c.);
• and
• g.) modifying the gain of step (a.) based upon the gain of step (d.), to compensate for the change in gain error from step (c.).

A method for controlling at least one of gain and timing phase of a communication system, comprising the steps of:

• a.) amplifying an input signal to generate an amplified signal;
• b.) converting the amplified signal into a digital signal to generate a converted signal;
• c.) filtering the converted signal to generate a first filtered signal in accordance with a first plurality of filter coefficients,
• wherein the first plurality of filter coefficients are updated according to a first least mean square (LMS) process, and
• wherein at least one filter coefficient of the first plurality of filter coefficients is constrained;
• d.) filtering the first filtered signal to generate a second filtered signal in accordance with a second plurality of filter coefficients,
• wherein a number of filter coefficients of the second plurality of filter coefficients comprises one of less than and equal to a number of the filter coefficients of the first plurality of filter coefficients;
• and
• e.) controlling at least one of a gain of step (a.) via a gain controller and a timing phase of step (b.) in response to the second filtered signal,
• wherein at least two filter coefficients of the first plurality of filter coefficients are constrained, and where the method further comprises the steps of:
• f.) updating a value of at least one filter coefficient of the second plurality of filter coefficients to provide a timing phase of step (d.) that is associated with a change in timing phase error introduced by step (c.);
• and
• g.) modifying a timing phase of step (b.) based upon the timing phase of step (d.), to compensate for the change in timing phase error introduced by step (c.).

An information communication system, comprising:

• a variable gain amplifier (VGA), wherein the VGA is responsive to an input signal of the information communication system;
• an analog-to-digital converter (ADC), wherein the ADC is responsive to an output of the VGA;
• a first filter,
• wherein tap weight coefficients of the first filter are updated according to a first least mean square (LMS) engine,
• wherein the first filter is responsive to an output of the ADC, and
• wherein at least one tap weight coefficient of the first filter is constrained;
• a second filter,
• wherein the second filter is responsive to an output of the first filter, and
• wherein a number of tap weight coefficients of the second filter comprises one of less than and equal to a number of the tap weight coefficients of the first filter;
• and, at least one of:
• a gain controller for controlling gain of the VGA, wherein the gain controller is in communication with the VGA and responsive to the output of the second filter;
• and
• a timing phase controller for controlling timing phase of the ADC, wherein the timing phase controller is in communication with the ADC and responsive to an output of the second filter,
• wherein at least two tap weight coefficients of the first filter are constrained,
• wherein a value of at least one tap weight coefficient of the second filter is updated to provide a gain of the second filter that is associated with a change in gain error from the first filter, and
• wherein the gain of the second filter is configured to cause the gain controller to modify a gain of the VGA to compensate for the change in gain error from the first filter.

An information communication system, comprising:

• a variable gain amplifier (VGA), wherein the VGA is responsive to an input signal of the information communication system;
• an analog-to-digital converter (ADC), wherein the ADC is responsive to an output of the VGA;
• a first filter,
• wherein tap weight coefficients of the first filter are updated according to a first least mean square (LMS) engine,
• wherein the first filter is responsive to an output of the ADC, and
• wherein at least one tap weight coefficient of the first filter is constrained;
• a second filter,
• wherein the second filter is responsive to an output of the first filter, and
• wherein a number of tap weight coefficients of the second filter comprises one of less than and equal to a number of the tap weight coefficients of the first filter;
• and, at least one of:
• a gain controller for controlling gain of the VGA, wherein the gain controller is in communication with the VGA and responsive to the output of the second filter;
• and
• a timing phase controller for controlling timing phase of the ADC, wherein the timing phase controller is in communication with the ADC and responsive to an output of the second filter,
• wherein at least two tap weight coefficients of the first filter are constrained,
• wherein a value of at least one tap weight coefficient of the second filter is updated to provide a timing phase of the second filter that is associated with a change in timing phase error introduced by the first filter, and
• wherein the timing phase of the second filter is configured to cause the timing phase controller to modify a timing phase of the ADC to compensate for the change in timing phase error introduced by the first filter.

An information communication system, comprising:

• means for amplifying an input signal received by the information communication system to generate an amplified signal;
• means for converting the amplified signal into a digital signal to generate a converted signal;
• first means for filtering the converted signal to generate a first filtered signal,
• wherein tap weight coefficients of the first means for filtering are updated according to a first least mean square (LMS) adaptation means,
• wherein at least one tap weight coefficient of the first means for filtering is constrained;
• second means for filtering the first filtered signal to generate a second filtered signal,
• wherein a number of tap weight coefficients of the second means for filtering comprises one of less than and equal to a number of the tap weight coefficients of the first means for filtering;
• reconstruction means for generating a reconstruction filter output in response to the first filtered signal;
• means for controlling at least one of a gain of the means for amplifying;
• and a timing phase of the means for converting in response to the second filtered signal and the reconstruction filter output;
• and
• error generating means for signaling the means for controlling based on the second filtered signal and the reconstruction filter output.

An information communication system, comprising:

• a variable gain amplifier (VGA), wherein the VGA is responsive to an input signal of the information communication system;
• an analog-to-digital converter (ADC), wherein the ADC is responsive to an output of the VGA;
• a first filter,
• wherein tap weight coefficients of the first filter are updated according to a first least mean square (LMS) engine,
• wherein the first filter is responsive to an output of the ADC, and
• wherein at least one tap weight coefficient of the first filter is constrained;
• a second filter,
• wherein the second filter is responsive to an output of the first filter, and
• wherein a number of tap weight coefficients of the second filter comprises one of less than and equal to a number of the tap weight coefficients of the first filter;
• at least one of:
• a gain controller for controlling gain of the VGA, wherein the gain controller is in communication with the VGA and responsive to an output of the second filter;
• and
• a timing phase controller for controlling timing phase of the ADC, wherein the timing phase controller is in communication with the ADC and responsive to an output of the second filter;
• and
• a first error generator that is responsive to said output of the second filter and an output of a reconstruction filter that is connected between said first filter and said first error generator,
• wherein said at least one of said gain controller and said timing phase controller is responsive to said first error generator.

An information communication system, comprising:

• means for amplifying an input signal received by the information communication system to generate an amplified signal;
• means for converting the amplified signal into a digital signal to generate a converted signal;
• first means for filtering the converted signal to generate a first filtered signal,
• wherein tap weight coefficients of the first means for filtering are updated according to a first least mean square (LMS) adaptation means,
• wherein at least one tap weight coefficient of the first means for filtering is constrained;
• second means for filtering the first filtered signal to generate a second filtered signal,
• wherein a number of tap weight coefficients of the second means for filtering comprises one of less than and equal to a number of the tap weight coefficients of the first means for filtering;
• at least one of:
• means for controlling a gain of the means for amplifying in response to the second filtered signal;
• means for controlling a timing phase of the means for converting in response to the second filtered signal;
• and
• error generating means for generating an output signal in response to said output of the second filter and an output of a reconstruction filter that is connected between said first means for filtering and said error generating means,
• wherein said at least one of means for controlling a gain and means for controlling a timing phase is responsive to said error generating means.

A computer readable medium that stores a computer program, said computer program when executed by a processor, causes the processor to control at least one of gain and timing phase of a communication system by performing the steps of:

• a.) filtering an input signal to generate a first filtered signal in accordance with a first plurality of filter coefficients;
• b.) updating the first plurality of filter coefficients according to a first least mean square (LMS) process;
• c.) constraining at least one filter coefficient of the first plurality of filter coefficients;
• d.) filtering the first filtered signal to generate a second filtered signal in accordance with a second plurality of filter coefficients,
• wherein a number of filter coefficients of the second plurality of filter coefficients comprises one of less than and equal to a number of the filter coefficients of the first plurality of filter coefficients;
• e.) generating a reconstruction filter output in response to the first filtered signal;
• and
• f.) generating an error generator output in response to the second filtered signal and said reconstruction filter output;
• g.) outputting at least one of a gain control signal and a timing phase control signal in response to the error generator output from step (f.).