Patent ID: 7164713

Claim:
An apparatus for processing data comprising: a finite impulse response (FIR) filter receiving a first sequence of first data elements at a first average rate and generating a second sequence of second data elements at a periodic second rate that is higher than the first average rate, wherein a value of each second data element is a sum of products of a value of each i th one of a corresponding set of successive ones of the first data elements and a corresponding i th filter coefficient C i of a set of filter coefficients; and a timing synchronizer for generating and providing each i th filter coefficient C i as input to the FIR filter, wherein the timing synchronizer periodically adjusts a value of each i th filter coefficient C i at the second rate such that the FIR filter both low pass filters and interpolates the first sequence to produce the second sequence wherein a value of each i th filter coefficient C i is a function C i (τ) of a variable τ that periodically changes in value at the second rate, C i (τ)= rr cos( i+τ/H ) wherein H is an integer greater than 0, and for each argument x, rr ⁢ ⁢ cos ⁡ ( x ) = sin ⁢ ⁢ π ⁢ ⁢ x ⁡ ( 1 - α ) + ( 1 - α ) ⁢ x ⁢ ⁢ cos ⁢ ⁢ π ⁢ ⁢ x ( 1 + α π ⁢ ⁢ x ⁡ [ 1 - ( 1 - α ) 2 ⁢ x 2 ] wherein α is a real number constant.