new to Digital - a fair amount of questions

[Marc.yo]

I'm just starting to learn about digital so I have a few questions (links are accepted)

I'm looking to make something along the lines of a POG micro. After talkling to a friend who works at IBM, I got the general idea that the POG basically takes the signal, converts it into digital and uses the footprints to "trigger" the two octaves that are controlled by the pots. Don't ask me what this means, hahaha. i'm going to learn about this specific thing in depth...any responses would be wonderful


2nd of all

is it possible to do an octave through an astable 555 oscillator? I was thinking about this and I came to conclusion that you would need to use some sort of chip (uneducated on this) to translate the sound into digital, then use that info to adjust the resistance across pins 7 and 6. this would adjust the octave to match your note. to stop the sound when the note stops (which would be a problem), you would set up a digital switch that would be between the output and pin 3. The switch would be "open" when the signal stops.


would this work? what would I need to do so. Can you suggest something better? I'm sure the tracking would be far from good.

[SeanCostello]

From what I have heard in soundfiles, the POG uses pitch-shifting for its suboctaves. You can hear the standard artifacts - improved from many pitch shifters, but they are still there. The pots just mix in the different pitch shifted signals.

Sean

[SeanCostello]

Just ran across this old post and thought I would elaborate:

I bought a microPOG recently. It definitely uses pitch shifting. However, the artifacts I had heard in the MP3 files are VERY minimal. It is the cleanest pitch shifter I have yet heard (apparently the algorithm is improved from what is in the POG, possibly due to using pure integer shift ratios only).

The MicroPOG runs off of a DSP56364 Freescale DSP, a TI PMS3052A codec, and a 18F24J10 PIC.

Sean Costello