Re: SNR in sigma delta
Well, it really depends on what 'order' of SD adc you have.
The SNR is related to the resolution of the convertor and the amount of quantization noise.
Here's the way of calculating it:
I was always told in university that whenever you double the samping frequency, its like adding another bit and a half to the resolution.
But thats only for first order, where, if you want 16-bits, then 15/1.5 = 10. So its 2^10 = 1024, stupid number :x .
The equation, off the top of my head :roll: is (L+0.5) bits added to the resolution for every doubling of the sampling frequency, where L is the order of the convertor. Most people nowadays use 2nd to 4th order. Say for now, you want a second order SD convertor, resolution 16 bits, and a sampling rate of 48Khz.
16 bits needed, how many added bits do we need = 16-1 = 15.
L is 2 (2nd order), so for every doubling of the sampling frequency = 2.5 bits.
So 15/2.5 = 6.
2^6 = 64. (For sampling rate of 48Khz, 48 *64 = 3.072Mhz Ouch 8O)
In your terms, thats Fs = 64 * Fn.
Well, I know that doesn't really help you, but at least theres something on SD convertors for you
For experimental readings, I'm not too up on fft. I found this ages ago when doing research into convertors:
**broken link removed**
Hope this isn't a waste of your time
regards,
BuriedCode.