RF digital or analog transmission of audio to the prop.

J. A. Streich

I suppose I should start by describing what I'm trying to do. I want to send the analog output from an electric violin pickup to the propeller (in digital form) over RF (or other transmission medium not requiring line of site). The range of the transmission doesn't need to be too far, but it's important that both the ADC and transmission happen relatively quickly as it will be used in live performance.

I was looking to use a XBee for this as it does both ADC and transmission; but the sampling rate is too low for audio and the packetization would probably slow things down too much. So, I'm either looking to do:

Pickup -> ADC -> Transmitter )))) Receiver -> prop -> DAC -> Amp

OR

Pickup -> Transmitter )))) Receiver -> ADC -> Prop -> DAC -> Amp

I've got the protoboard, the pickup, audio jacks, pickup and amplifier. I'm looking suggestions, tips, and advice on the ADC, DAC and the transmitter. I know the Prop can do the ADC and the DAC, but I'd prefer to save the whales cogs.

Ken Peterson

What is the function of the Prop in this application?

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J. A. Streich

First, wireless osiliscope. I figgure this won't be too hard based on chip's microphone osiliscope. I can see this happening rather quickly.

Second, after that's all worked out, I want to do small audio effects similar to the Coyote-1 -- only much more basic (Coyote-1 is very impressive). I don't know much about effects, and probably won't be investing in the amount of SRAM the Coyote uses or anywhere near the time that was spent on it, when I get to this stage. So, I'll probably only do VERY minor effects at this point. Still researching what these will be.

Then digital tuner. This is more of a stepping stone than an actual stage, it leads quite quickly into the next phase. I've been thinking of using zero crossing to get started, once that works moving to try to get FFT working on a cog or two. I know others are working on FFT and might beat me to it.

Which leads to Analog to MIDI converter. Which will allow me to use my electric violin as a MIDI controller. I already have a Zeta Synthony that can do this for the Zeta pickup; but it doesn't work with my other electric violin and the while the Synthony is impressive the current delay is longer than I'd like.

Lastly, I would like display digital sheet music (haven't picked a format, and don't want to "guess and beam" MIDI) on an LCD (through VGA) mounted on a music stand, keeping rough track of where in the piece the musician is (showing if the musician is sharp of flat) and "turning the page" when the musician gets to the end of "the page". This last step is probably too ambitious for me to pull off, and may get chopped down quite a bit... but it is the current final goal.

Leon

Nordic nRF24L01 or TI CC2500 should be suitable. You'll need an MCU with an ADC, of course.

Leon

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J. A. Streich

I did some more number crunching, drawing and I think I can get away with just a pair of XBees and an ADC. The bpm should be fast enpugh, but not using the XBee's ADC functionality. I think I can send the clock and timing from the prop to ADC over XBee also, but I'm a little worried if the delay will be to large. I suppose I do have an extra propeller besides the one on the protoboard if timing becomes an issue.

Attached is a very simple version of the relevent parts of what I have on paper in my chicken-scratch in my Moleskine. Comments? Corrections? Questions? Advice?