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US 7,345,600 B1Granted
Asynchronous sampling rate converter
AssigneeTexas Instruments Incorporated
InventorStephen J. Fedigan
Life of this patent
Estimating the term…
Abstract
Asynchronous sampling rate converter with input/output frequency ratio estimation and polyphase filtering uses FIFO level feedback to adaptively control frequency ratio estimation.
Claims7
A method of sampling rate conversion, comprising the steps of:
- (a) storing a block of input samples in an input FIFO, said input samples associated with an input sampling rate;
- (b) updating an input phase by the size of said block of input samples;
- (c) updating an estimate of a ratio of said input sampling rate divided by an output sampling rate;
- (d) determining the number of output samples needed to fill an output FIFO, said output FIFO emptied according to said output sampling rate;
- (e) computing output samples according to the results of step (d), said computing by filtering contents of said input FIFO;
- (f) storing said output samples from step (e) in said output FIFO;
- (g) updating an output phase by the product of said number of output samples needed multiplied by said estimate of a ratio;
- and
- (h) repeating steps (a)-(g).
6 more elements
An asynchronous sampling rate converter, comprising:
- (a) an input FIFO for input blocks of samples associated with an input sampling rate;
- (b) an output FIFO for computed output samples associated with an output sampling rate;
- (c) a ratio estimator, said ratio estimator estimating a ratio of said input sampling rate divided by said output sampling rate using an autoregression with inhomogeneous term proportional to a difference of an input phase for samples in said input FIFO and an output phase for samples in said output FIFO;
- and
- (d) an interpolator coupled to said input FIFO, to said output FIFO, and to said ratio estimator, said interpolator computing output samples to fill said output FIFO using contents of said input FIFO when said input FIFO receives an input block of samples.
2 more elements
Dependencies are inferred from the claim text.