Shift-invariant digital sampling rate conversion system
AssigneeST-Ericsson SA
InventorStéphan Tassart
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Abstract
There is described a method of making a linear periodically time varying system shift-invariant, comprising the following steps implemented for each input signal the sampling rate of which has to be converted: —generating a set of polyphase components based on the input signal, —feeding the generated set of polyphase components to the system, and —generating an output signal by performing interleaving, shifting and addition on signals output by the system corresponding to the generated set of polyphase components processed by the system.
Claims13
A method of converting the sampling rate of an input signal with input/output shift-invariance using a Linear Periodically Time Varying (LPTV) system, the method comprising:
- generating a set of polyphase components of the input signal wherein the LPTV system is a digital Sampling Rate Conversion (SRC) system having a fractional ratio
- R
- P
- ,
- with R and P being co-primes:
- selecting three integer numbers Q, M and q that satisfy the following equations:
- M=RQ;
- q=PQ;
- and
- MP=qR;
- feeding the generated set of polyphase components to the SRC system;
- and
- generating an output signal corresponding to the input signal with a converted sampling rate, by performing interleaving, shifting, and addition on signals output by the SRC system corresponding to the generated set of polyphase components processed by the SRC system;
- wherein the generation of each polyphase component of the set of polyphase components comprises:
- time shifting the input signal a number of times between 0 and MP;
- and
- M-fold decimating the time shifted input signals.
A computer program product stored in a computer readable medium, the computer program product comprising program instructions for converting the sampling rate of an input signal with input/output shift-invariance using a Linear Periodically Time Varying (LPTV) system, the computer program product comprising computer program code which, when run by a data-processing unit, configures the data-processing unit to:
- generate a set of polyphase components of the input signal wherein the LPTV system is a digital Sampling Rate Conversion (SRC) system having a fractional ratio
- R
- P
- ,
- with R and P being co-primes:
- select three integer numbers Q, M and q that satisfy the following equations:
- M=RQ;
- q=PQ;
- and
- MP=qR;
- feed the generated set of polyphase components to the SRC system;
- and
- generate an output signal corresponding to the input signal with a converted sampling rate, by performing interleaving, shifting, and addition on signals output by the SRC system corresponding to the generated set of polyphase components processed by the SRC system;
- wherein the generation of each polyphase component of the set of polyphase components comprises:
- time shifting the input signal a number of times between 0 and MP;
- and
- M-fold decimating the time shifted input signals.
A system for converting the sampling rate of an input signal with input/output shift-invariance comprising:
- a Linear Periodically Time Varying (LPTV) system being a Sampling Rate Conversion (SRC) system having a fractional ratio
- R
- P
- ,
- with R and P being co-primes;
- a first input port configured to receive the input signal;
- a first output port configured to output polyphase components of the input signal to the SRC system;
- a second input port configured to receive signals outputted by the SRC system corresponding to the polyphase components processed by the SRC system;
- and
- a processing unit configured to generate the polyphase components and to select three integer numbers Q, M and q that satisfy the following equations:
- M=RQ;
- q=PQ;
- and
- MP=qR;
- wherein the processing unit comprises:
- a time shifting unit configured to time shift the input signal a number of times between 0 and MP;
- and
- an M-fold decimator configured to decimate the time shifted input signals;
- the processing unit being further configured to perform interleaving, shifting and addition on the signals outputted by the SRC system for generating an output signal;
- and
- the system further comprising a second output port configured to output the generated output signal.
Dependencies are inferred from the claim text.