Method of implementing a variable number of filter sections for digital signal processing
View Patent ↗A DSP-based equalization system which uses a jump and lookup table stored in volatile memory to execute a variable number of equalization structures stored in nonvolatile memory for the equalization of a data signal. The system and method of design provide minimal nonvolatile memory allocation.
1. A method of equalizing an input signal for a digital signal processor (DSP) which produces an output signal having a desired frequency response, comprising the steps of:
transferring a jump and lookup table from nonvolatile memory to volatile memory, said jump and lookup table containing addresses to execute equalization structures of the DSP;
transferring a plurality of filter coefficients from said nonvolatile memory to said volatile memory, said plurality of filter coefficients provide optimum equalization structures to obtain said desired frequency response;
retrieving one of said addresses by use of a first pointer to execute a first equalization structure;
retrieving a corresponding set of filter coefficients by use of a second pointer to provide a first equalization structure;
producing an intermediate result in response to filtering said input signal;
incrementing said first pointer to next said addresses of said jump and lookup table to execute a subsequent equalization structure;
incrementing said second pointer to next said corresponding set of filter coefficients to provide a subsequent equalization structure;
transferring said intermediate signal to said subsequent equalization structure for additional filtering,
incrementing said first pointer and said second pointer to provide next said subsequent equalization structure for additional filtering;
transferring said intermediate result as an equalized output signal when said first pointer indicates filtering is complete.
2. The method of claim 1 wherein said frequency response includes a set of separate frequency bands.
3. The method of claim 1 wherein said equalization structure uses a plurality of equalization structures.
4. The method of claim 3 wherein a first equalization structure has a first equalization characteristic and a second filter structure has a second filter characteristic.
5. The method of claim 1 wherein said equalization structure uses one equalization structure repeatedly.
6. The method of claim 1 , wherein said input data signal is an audio signal and said jump and lookup table and said sets of filter coefficients are adapted to provide predetermined equalization according to a plurality of frequency bands customized to acoustical characteristics of a predetermined automobile interior.