Method and apparatus for efficient implementation of a multirate LMS filter

摘要

An efficient implementation of a multirate filter with delayed error feedback prevents an instruction processing rate requirement from increasing by performing interpolation and decimation in a LMS filter element at the same time. The multirate filter calculates an ith coefficient value, wherein i is a set of consecutive integers, by obtaining an (i-1)th error value, obtaining an (i-1)th data value, multiplying the (i-1)th error value and the (i-1)th data value to obtain an ith coefficient product, obtaining Mth coefficient value from a coefficient register, wherein M is a predetermined integer, adding the Mth coefficient value to the ith coefficient product to obtain an ith coefficient value calculating an ith data value by multiplying the (i-1)th data value and the Mth coefficient value to produce ith convolution product, and adding an (i-1)th convolution sum to the ith convolution product to produce an ith convolution sum. Obtaining of the Mth coefficient value decimates the convolution product by M and interpolates the error value by M. Obtaining of the (i-1)th data value further includes incrementing a data register by one when new data is not written into the data register.