Vector estimation system, method and associated encoder

A vector estimation system for processing a sequence of input vectors, said input vectors each comprising a plurality of elements, and said system comprising:

• a digital filter with a filter vector input for receiving said sequence of input vectors and an observation noise variance input for controlling characteristics of said filter, said digital filter also having a current slowly evolving filter estimate output, a predictor error variance output and a previous slowly evolving filter estimate output, said current slowly evolving filter estimate output providing a current filtered estimate value of a slowly evolving component of said sequence of input vectors, said predictor error variance output providing a current predictor error variance value and said previous slowly evolving filter estimate output providing a previous filtered estimate value of said slowly evolving component of said sequence of input vectors;
• and
• a parameter estimator having an estimator vector input for receiving said sequence of input vectors and a previous slowly evolving filter estimate input coupled to said previous slowly evolving filter estimate output, said parameter estimator further includes a observation noise variance output coupled to said observation noise variance input,
• wherein when said vector estimation system receives a current input vector that is one of said sequence of said input vectors, said parameter estimator provides a current observation noise variance value at said observation noise variance output thereby modifying said current filtered estimate value at said current slowly evolving filter estimate output, said current observation noise variance value being dependent upon said current input vector, said current predictor error variance value, and said previous filtered estimate value.

A method for processing a sequence of input vectors each comprising a plurality of elements, said vectors being applied to a vector estimation system having a parameter estimator coupled to a digital filter, said method comprising the steps of:

• receiving said sequence of input vectors at inputs of said filter and said parameter estimator;
• determining a current predictor gain value from a current input vector that is one of said sequence of said input vectors, said determining being effected by said parameter estimator;
• and
• applying said current predictor gain value to said digital filter to thereby modify a current filtered estimate value provided at an output of said digital filter, said current predictor gain value being dependent upon a previous filtered estimate value from said filter and said current input vector.

A method for processing a sequence of input vectors each comprising a plurality of elements, said vectors being applied to a vector estimation system having a parameter estimator coupled to a digital filter, said method comprising the steps of:

• receiving said sequence of input vectors at inputs of said filter and said parameter estimator;
• determining a current observation noise variance value from a current input vector that is one of said sequence of said input vectors, said determining being effected by said parameter estimator;
• and
• applying said current observation noise variance value to said digital filter to thereby modify a current filtered estimate value provided at an output of said digital filter, said current observation noise variance value being dependent upon said current input vector, a current predictor error variance value from said filter, and a previous filtered estimate value from said filter.

An encoder for processing a speech signal each comprising a plurality of elements, and said encoder comprising:

• a signal normalization module for processing the speech signal to provide a sequence of input vectors each comprising a plurality of elements;
• a digital filter with a filter vector input coupled to an output of the signal normalization module for receiving said sequence of input vectors, the digital filter also having an observation noise variance input for controlling characteristics of said filter, said digital filter also having a current slowly evolving filter estimate output, a predictor error variance output and a previous slowly evolving filter estimate output, said current slowly evolving filter estimate output providing a current filtered estimate value of a slowly evolving component of said sequence of input vectors, said predictor error variance output providing a current predictor error variance value and said previous slowly evolving filter estimate output providing a previous filtered estimate value of said slowly evolving component of said sequence of input vectors;
• a parameter estimator having an estimator vector input for receiving said sequence of input vectors and a previous slowly evolving filter estimate input coupled to said previous slowly evolving filter estimate output, said parameter estimator further includes a observation noise variance output coupled to said observation noise variance input;
• and
• a slowly evolving component encoder with an input coupled to said slowly evolving filter estimate output, wherein when said vector estimation system receives a current input vector that is one of said sequence of said input vectors, said parameter estimator provides a current observation noise variance value at said observation noise variance output thereby modifying said current filtered estimate value at said current slowly evolving filter estimate output, said current observation noise variance value being dependent upon said current input vector, said current predictor error variance value, and said previous filtered estimate value.