Hi Rob, This can also help you. In this project (...EmbeddedSDK\src\dsp56824evm\nos\applications\nbfilter) data is received by codec, IIR filtered and then sent back to codec. Hope this helps. Best regards, Fabio Estevam -----Original Message----- From: rwolfbrandt [mailto:] Sent: ter-feira, 29 de outubro de 2002 19:54 To: Subject: [motoroladsp] IIR filter usage with DSP56858EVM Hello, I am new to the group as well as to the Motorola DSP56858EVM. I am trying to implement a simple IIR filter, but it is not working properly (i.e. the cutoff frequency is not where it is supposed to be). If someone could help I would very much appreciate it and hope to repay the favor in the future. Here are the specifics. Lowpass IIR, second order, Fc = 200 Hz. Coefficients from Matlab: b092, b1384, b292, a02767, a1=- 32768, a2&241 relevant code: //initializations const Frac16 LP_io_filter[5] = {26241, -16384, 8192, 16384, 8192}; UInt16 nbiq=1, block_size; dfr16_tIirStruct *pIIR_lp; int i = 0; //processing //input is read from codec void process(Frac16 *input_buffer, Frac16 *output_buffer) { if(i==0) { this++; pIIR_lp = dfr16IIRCreate ((Frac16 *)&LP_io_filter[0],nbiq); } dfr16IIR (pIIR_lp, input_buffer, output_buffer, block_size); } //output is written to codec I know it isn't working properly because I injected white noise into the codec and viewed the output spectrum with Cool Edit Pro to see that Fc appeared to be around 1000 Hz. I've been struggling with this isssue for a few days now and could really use a hand. Thank you! Rob _____________________________________ Note: If you do a simple "reply" with your email client, only the author of this message will receive your answer. You need to do a "reply all" if you want your answer to be distributed to the entire group. _____________________________________ About this discussion group: To Join: To Post: To Leave: Archives: http://www.yahoogroups.com/group/motoroladsp More Groups: http://www.dsprelated.com/groups.php3 ">http://docs.yahoo.com/info/terms/ | |||
|