[sdiy] Four new lectures up

[Aaron Lanterman]

users.ece.gatech.edu/~lanterma/ece4803

3/29 expo conversion (I prepared this right before class, and class was 
about to start just as I was figuring about tempco stuff - so take 
anything I say regarding tempco with a grain of salt - see Ian's page for 
the Real Deal)

4/3 sample playback and the dangers of aliased digial oscillators (I make 
lots of obnoxious noises with my Mac)

4/5 alias-free synthesis of classic analog waveforms (based on the 
Stilson+Smith paper); digital state variable filters

4/12 Digital emulation of a SSM2040/Prophet 5-style filter, including 
Antti style tanh nonlinearities - I did an OTA instead of a ladder stage 
since I think the OTA version is easier to understand.

Near the end of lecture, I ran out of note material so I decided to start 
freewheeling. I decided to see if I could find the filter coefficient to 
get a particular half-power point, figuring it would be an easy 
calculation like a one-pole analog filter. It wasn't and I wound up 
floundering and spinning into a black hole of confused oblivion...

...I fixed it in next lecture (after I discovered "impulse invariant" 
techniques), but the distance learning people haven't posted that to our 
server yet, so I can't link to yet.

Today's lecture was on some demos of my Prophet 5 emulation in MATLAB, 
along with a brief discussion and demo of Chebychev waveshaping. I'll get 
that up when I can.

- Aaron

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Dr. Aaron Lanterman, Asst. Prof.
and Demetrius T. Paris Junior Prof.    Voice:  404-385-2548
School of Electrical and Comp. Eng.    Fax:    404-894-8363
Georgia Institute of Technology        E-mail: lanterma at ece.gatech.edu
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