On Mon, 29 Nov 2010, Sathishkumar Duraisamy wrote: > Dear all, > > I am new to the list and to the alsa library. In my application, I have to > collect data from outside world in the form of voltage, and then plot. I > have done the plotting and GUI parts of the application. Now I have to use > an ADC to collect the data. > > My question: Is it possible to use the ADC of audio input and alsa lib to > get the sample from the outside world. Have anyone tried like this. If it so > can you please guide me how I can get started? Sure. Just use the source code for arecord as a sample. But there are some limitations. Almost all audio cards do not go down to DC intpu level but have a low frequency cutoff of about 10Hz. Thus if your project requires low frequency levels, you are out of luck. Also most sound cards have a pretty hard cutoff about about 20KHz since this is the highest sound humans can hear and corresponds to the upper frequencymeasurable by a 44.1 frequncy card. If you allow in higher frequencies you get distortion int hat the high frequencies are floded over into the low frequency band. The tird problem is normaisation-- ie you really have to put in a test signal of a known voltage to calibrate your card's amplitude -voltage characteristic. > > Now I have been looking at this > http://www.alsa-project.org/main/index.php/Tutorials_and_Presentations. > > With thanks > Sathishkumar > -- William G. Unruh | Canadian Institute for| Tel: +1(604)822-3273 Physics&Astronomy | Advanced Research | Fax: +1(604)822-5324 UBC, Vancouver,BC | Program in Cosmology | unruh@xxxxxxxxxxxxxx Canada V6T 1Z1 | and Gravity | www.theory.physics.ubc.ca/ ------------------------------------------------------------------------------ Increase Visibility of Your 3D Game App & Earn a Chance To Win $500! Tap into the largest installed PC base & get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev _______________________________________________ Alsa-user mailing list Alsa-user@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-user
