Sparkfun spectrum shield BPM detection

hello forum

my hardware:

I have a sparkfun spectrum shield and an Arduino UNO!

the video from the roundtable (spectrum with fire) on youtube has brought me to this product from sparkfun.

in my project I want to sync two audio sources with different speeds!

like some dj sofwares with mp3.

my first idea was to take the 2 lowest bands from each source and compare these with each other.

Are similar projects already exist or has someone ideas or suggestions anyone for me?

thx for help

greets from germany

I am confused as to how you’re going to sync (in time) the signals using the Spectrum shield. It might be used to do part of that task, that is to measure the time difference between the 2 signals. But then it uses analog inputs, the “speed” (if you mean bit rate) doesn’t matter at that point. Unless of course you mean that the playback rate (for one or both pf the channels) may be wrong, in which case there will also be a spectral shift and then I’m not sure how useful the sheild will be. Perhaps you can describe in more detail the signals and the problem.

If one signal just lags or leads the other by some fixed amount of time, I can think of better ways to measure that. I’m less sure how to then sync the signals, short of re-sampling or having control of the playback.

yes i will subscribe it a little bit better when i am back at home!

my technical english is not the best!

with the shield i produce an high signal on digital out pins for each channel! for this i use the 2 lowest bands!

and then i will do an logic witch control my turntables! faster, slower etc…

i want to change the speed of my turntables with digital reststors for the pitch fader!

or with a stepper motor on the regular fader! but first i try it with digital restors

sebastian308:
yes i will subscribe it a little bit better when i am back at home!

OK, we will wait to hear what your project consists of.

Is this the video you mentioned above ?

http://www.youtube.com/watch?v=A1VySF2Rd4I

If so I would caution you to watch the part at ~ 9:30 into it again. While you might extract the beat from some music with the shield using the method described in the video, I’m doubtful it will work with all music. Other than that, it seems worth a try. Your UNO can time the difference between the detected peaks and issue some control signal. Exactly what’s needed to control your turntables (?) I don’t know without more info from you about them.