Adjusting coefficients of a filter
Demodulation apparatus includes a transversal filter characterized by coefficients adjusted by a coefficient determiner responsive to a constant modulus error signal and variable mode error signal related to the output of a spectral mean frequency detector having its input coupled to the output of the transversal filter.
1. A method for adjusting the coefficients of a transversal filter comprising
partitioning the coefficients into a first subset and a second subset,
adjusting the coefficients in the first subset based on a first criterion, and
adjusting the coefficients in the second subset based on a second criterion.
2. The method of claim 1 wherein the first criterion is constant.
3. The method of claim 1 wherein the second criterion is variable.
4. The method of claim 2 wherein the first constant criterion tends to minimize a first constant error cost function.
5. The method of claim 3 wherein the second variable criterion tneds to minimize a second variable error cost function.
6. The method of claim 1 wherein the first subset is adjusted based on a conventional constant modulus algorithm.
7. The method of claim 5 wherein the second variable error cost function is adjusted over time.