Monday, February 18, 2013

LFO Noise Spectra

Well a bit of a break again but we are back into about 3 old projects. I have decided not to start anything new unitl at least 5 of the old modules get finished and panelized! This is from the Forbin LFO that I started ages ago that uses a dsPIC to generate the waveforms. Along with the usual suspects, Sine, Saw, Ramp, Triangle, Pulse I have put in noise and it will be brownian noise and the frequency control will also effect it. I have done a reasonable amount of work on it and at the momement is seems to work after a fashion. I seem to have a bit of a problem with the dc offset in the noise sources causing the integrated signal to run to a rail reasonably quickly. I am looking at ways of overcoming this at the moment. The rest of it seems quite good. This is the spectra of the white noise source that drives the brownian integrator. It is based upon some code from the internet. My other noise source is based upon a shift register approach but the spectra is even less flat than this one... I think that I will have to incorporate some sort of AC coupling of the signal in a digital sort of way... basically a high pass filter.
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