Patent ID: 8693601
Filing Date: 2014-04-08
Classification: H03H

Abstract:
1. A method of implementing a multirate filter for sampling a data stream from a first clock frequency to a second clock frequency, the method comprising: measuring a current phase relationship between a current resampling filter input clock signal and a current multirate output clock signal; identifying an initial polyphase filter coefficient index corresponding to the measured phase relationship using a mapping of the measured phase relationship within a pre-generated quantized mapping table, wherein the pre-generated quantized mapping table comprises an association of each of a plurality of sets of different values of measured phase relationships with one initial polyphase filter coefficient index that identifies a particular polyphase filter component of the multirate filter, and wherein the multirate filter comprises a plurality of polyphase filter components each uniquely identified by a different polyphase filter coefficient index and each capable of being individually selected to generate a different output data sample from processing received data; selecting a corresponding polyphase filter component from within the multirate filter using the initial polyphase filter coefficient index identified; configuring the multirate filter to pass data from the data stream through the corresponding polyphase filter component, wherein the corresponding polyphase filter component selected generates an initial output data sample from data of the data stream inputted to the multirate filter, and wherein the initial output data sample is derived utilizing sampling functions specific to that corresponding polyphase filter component; and in response to a request for generation of a next output data sample, updating the initial polyphase filter coefficient index to a calculated next polyphase filter coefficient index value.