System for dynamically adapting the length of a filter

A method of dynamically adjusting the length of an adaptive digital filter (ADF) having an adaptation procedure and a plurality of taps, said ADF utilized in a system wherein said system has at least one measurable quality criteria Q, said method comprising the steps of:

• waiting for said adaptation procedure of said ADF to converge;
• measuring said at least one measurable quality criteria in said system, wherein said measurable quality criteria is derived fom any point within said system other than from said adaptive digital filter or from said plurality of taps therein;
• comparing said measured at least one quality criteria against a predetermed threshold;
• removing M taps from said ADF and repeating said steps of measuring and comparing if said measured at least one quality criteria is above said predetermined threshold;
• and
• adding M taps to said ADF if said measured at least one quality criteria is below said predetermined threshold.

A method of dynamically adjusting of an adaptive digital filter (ADF) having a plurality of taps, said plurality of taps having an associated set of filter coefficients, said ADF utilized in a system wherein said system has a measurable signal to noise ratio (SNR), said method comprising the steps of:

• waiting for said ADF to converge;
• measuring said SNR at a suitable point in said system other than within said adaptive digital filter from said plurality of tops therein;
• storing said filter coeffcients;
• comparing said measured SNR against a predtermined threshold;
• removing M taps from said ADF and repeating said steps of measuring and comparing if said measured SNR is above said predetermined theshold;
• and
• restoring said filter coefficients previously stored if said measured SNR is below said predetermined threshold.

A method of dynamically adjusting the length of a least mean squares (LMS) echo canceler initially having L.sub.max number of taps, said echo canceler utilized in a system wherein said system as at least one measurable quality criteria Q, said method comprising the steps of:

• waiting for said echo canceler to converge, said echo canceler utilizing said L.sub.max ;
• number of taps;
• measuring said at least one measurable quality criteria in said system, wherein said measurable quality criteria is derived from any point within said system other than from said echo canceler or from said taps therein;
• comparing said measured at least one quality criteria against a predetermined threshold;
• removing M taps from said echo canceler and repeating said steps of waiting, measuring and comparing if said measured at least one quality criteria is above said predeterined threshold;
• and
• adding M taps to said echo canceler if said measured at least one quality criteria is below said predetermined threshold.

A method of dynamically adjusting the length of an adaptive echo canceler initially having L.sub.max number of taps, said taps having an associated set of filter coefficlents, said echo canceler utilized in a system wherein said system comprises a measurable signal to noise ratio (SNR) and echo to signal ratio (ESR), said method comprising the steps of:

• waiting for said echo canceler to converge, said echo canceler utilizing said L.sub.max number of taps;
• measuring an initial SNR, called SNR.sub.old, at a suitable point within said system;
• measuring the ESR at a second suitable point within said system;
• calculating a percentage of energy that can be removed from said echo canceler utilizing said SNR.sub.old and said ESR;
• and
• removing M taps from said echo canceler in accordance with said calculated percentage of energy.

In a digital filter having a length fir.sub.-- len representing both the number of taps and associated coefficients, a pointer to the first coefficient represented by fir.sub.-- coefs.sub.-- ptr, said filter having a head and a tail, said filter processing a set of data samples wherein a pointer data.sub.-- ptr points to the next sample to be processed, said digital filter utilized in a system wherein said system has at least one measurable quality criteria Q, a method of removing M taps from said head of said filter, said method comprising the steps of:

• measuring said at least one measurable quality criteria in said system, wherein said measurable quality criteria is derived from any point within said system other than from said digital filter or from said plurality of taps therein;
• comparing said measured at least one quality criteria against a predetermined threshold;
• decrementing said filter length fir.sub.-- len by M;
• incrementing said pointer to the first coefficient fir.sub.-- coefs.sub.-- ptr by M;
• incrementing said data pointer data.sub.-- ptr by M;
• and
• repeating said steps of measuring and comparing if said measured at least one quality criteria is above said predetermined threshold.

In a digital filter having a length fir.sub.-- len representing both the number of taps and associated coefficients, a pointer to the first coefficient represented by fir.sub.-- coefs.sub.-- ptr, said filter having a head and a tail, said filter processing a set of data samples wherein a pointer data.sub.-- ptr points to the next sample to be processed, said digital filter utilized in a system wherein said system has at least one measurable quality criteria Q, a method of adding M taps to said head of said filter, said method comprising the steps of:

• measuring said at least one measurable quality criteria in said system, wherein said measurable quality criteria is derived from any point within said system other than from said digital filter or from said plurality of taps therein;
• comparing said measured at least one quality criteria against a predetermined threshold;
• incrementing said filter length fir.sub.-- len by M;
• decrementing said pointer to the first coefficient fir.sub.-- coefs.sub.-- ptr by M;
• and
• decrementing said data pointer data.sub.-- ptr by M.
• repeating said steps of measuring and comparing if said measured at least one quality criteria is below said predetermined threshold.

In a digital filter having a length fir.sub.-- len representing both the number of taps and associated coefficients, said filter having a head associated with a first coefficient and a tail associated with the last coefficient, a pointer to said first coefficient represented by fir.sub.-- coefs.sub.-- ptr, a pointer to the next sample to be processed represented by data.sub.-- ptr, a method of realizing a digital filter with M taps removed from said head of said filter, said method comprising the steps of:

• decrementing said filter length fir.sub.-- len by M;
• incrementing said pointer to the first coefficient fir.sub.-- coefs.sub.-- ptr by M;
• incrementing said data pointer data.sub.-- ptr by M thereby reducing the number of data samples to be filtered by M;
• and
• executing the digital filter utilizing the remaining number of taps and coefficients represented by the value (fir.sub.-- len-M) and the set of data samples reduced in number by M.

In a digital filter having a length fir.sub.-- len representing both the number of taps and associated coefficients, said filter having a head associated with a first coefficient and a tail associated with the last coefficient, a pointer to said first coefficient represented by fir.sub.-- coefs.sub.-- ptr, a pointer to the next sample to be processed represented by data.sub.-- ptr, a method of realizing a digital filter with M taps added to said head of said filter, said method comprising the steps of:

• incrementing said filter length fir.sub.-- len by M;
• decrementing said pointer to the first coefficient fir.sub.-- coefs.sub.-- ptr by M;
• decrementing said data pointer data.sub.-- ptr by M thereby increasing the number of samples to be filtered by M;
• and
• executing the digital filter utilizing the increased number of taps and coefficients represented by the value (fir.sub.-- len+M) and the set of data samples increased in number by M.