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Support Forums => General Board => Topic started by: Douglas McDonald on August 06, 2010, 05:46:26 PM

Title: Soundcard amplitude
Post by: Douglas McDonald on August 06, 2010, 05:46:26 PM
I have a program that mixes two frequencies and plays them just like DTMF but not telephone freq's. That works great. Now I need to control the amplitude to .07,.15,1.4,2.07,3.07 and 3.37 volts rms. Is there away to do this on code?

Thank you
Doug
Title: Re: Soundcard amplitude
Post by: Peter House on August 06, 2010, 10:56:51 PM
I am sure there is a way to control the voltages RELATIVELY.  I am pretty sure you will not be able to control the absolute amplitude without some type of calibration procedure.
Title: Re: Soundcard amplitude
Post by: Robert Eaton on August 06, 2010, 11:07:55 PM
Quote from: Peter House on August 06, 2010, 10:56:51 PM
I am sure there is a way to control the voltages RELATIVELY.  I am pretty sure you will not be able to control the absolute amplitude without some type of calibration procedure.

Or with some kind of fancy sound card like this one:
http://www.renkus-heinz.com/easera/easeragateway.html (http://www.renkus-heinz.com/easera/easeragateway.html)
Title: Re: Soundcard amplitude
Post by: Douglas McDonald on October 16, 2010, 01:32:45 PM
I keep coming back to this. I really want to use a pc sound card and a geniric built in one, AC97 type. but for now I've moved to a hardware solution. Using a dsPIC MCU I can do every thing I need in firmware as the dsp part has some great active filtering. The DTMF stuff is easy its the amplitude at different frequencies thats was killing me. With DSP and the filters I can make them all exact for DAC output.

Thanks
Doug