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Hello I am trying to work on CODEC. 1. when i tried to run the eg program of codec given by the TI it ran successfuly and i checked out that i am getting a sine wave on pin 23 of TLC320AD50 chip. when i halted the program the CLKMD changes to 4007 which is 100MHZ which should be 1007 i.e 40MHZ because my DIP switches 5 & 6 are up. 2. when i increase the number of points in lookup table(in the eg program the lookup table is 256) like 512,1024,2048,4096 the amplitude of the sine wave goes on decreasing and the period of the sine wave also increases can anyone tell me why? thanks |
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Regarding codec
Started by ●May 15, 2002
Reply by ●May 15, 20022002-05-15
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>2. when i increase the number of points in lookup >table(in the eg program the lookup table is 256) like >512,1024,2048,4096 the amplitude of the sine wave goes >on decreasing and the period of the sine wave also >increases can anyone tell me why? When you increase the size of the table the period of the wave increases ie the frequency of the wave decreases as the sampling rate (or the rate at which you are reading out the data) is fixed. Meaning that doubling the table size means it takes twice as long to output the entire waveshape resulting in a frequency/period change. As for the change in amplitude the only thing that comes to mind at the moment is there might be a high pass filter in the codec thats attenuating your signal the lower you go, but thats just a shot in the dark. Polyhex |
Reply by ●May 15, 20022002-05-15
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1. Are you using DSP BIOS? If so the DSP Bios might have changed the speed through the Bios tool 2. How are you increasing the size of the lookup table? Are you just recopying the first 256 bytes over and over? Or are you spreading it out among the new larger tables? Carl Chipman Nomadics, Inc. http://www.nomadics.com -----Original Message----- From: sahana rao [mailto:] Sent: Wednesday, May 15, 2002 4:14 AM To: Subject: [c54x] Regarding codec Hello I am trying to work on CODEC. 1. when i tried to run the eg program of codec given by the TI it ran successfuly and i checked out that i am getting a sine wave on pin 23 of TLC320AD50 chip. when i halted the program the CLKMD changes to 4007 which is 100MHZ which should be 1007 i.e 40MHZ because my DIP switches 5 & 6 are up. 2. when i increase the number of points in lookup table(in the eg program the lookup table is 256) like 512,1024,2048,4096 the amplitude of the sine wave goes on decreasing and the period of the sine wave also increases can anyone tell me why? thanks _____________________________________ 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: Send an email to To Post: Send an email to To Leave: Send an email to Archives: http://www.yahoogroups.com/group/c54x Other Groups: http://www.dsprelated.com ">http://docs.yahoo.com/info/terms/ |
