I was inspired by this recent SolderSmoke Blog post -->
ZL2CTM Teensy SDR about using a
Teensy Microcontroller as a software Intermediate Frequency (IF) stage for a direct conversion receiver.
I had seen some of the DSP capabilities of the Teensy and have done some simple tone generation test but that is it. I noticed that the PJRC site has been updated
HERE and there is a very nice Audio Tutorial that I watched and enjoyed.
Just to start out, and to look at the filter capabilities, I used the web-based Audio Design Tool on the PJRC site to create the following:
This is just to have two Audio Sine-wave sources and a noise source in an attempt to experiment with the Biquad filter. I then take the output of the teensy audio shield and feed it into a PC with a audio spectrum analyzer to see the shape of the filtering. So far I have not built a sharp skirt filter but it is possible per Charlie ZL2CTM.
When I get more time I would like to duplicate Charlie's results using my NE612/Si5351 DC receiver.
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