How many ways can you process a PI target signal with a Micro ?

[6666]

Thanks for all the replies, there is another variable as well, some ccts use +- 5 volt on the preamp, some others use only + and ground, what effect does this have on the micro looking at the target signal ?

[F117]

The Microchip PIC needs an analog signal between 0 and 5 V ( it will be clipped by internal diodes ) both for the ADC and the analog comparator.
So, if it is AC coupled, it should be superimposed on a 2.5V DC level.
When DC coupled between -5 and +5V, it will only see the positive part.

[green]

More averages => less noise,
More averages => larger dynamic range.

The noise floor of a PI is the sum of the noise of the damping and limiting resistors. For a carefully designed, standard PI a noise floor of 3uV is already a feat. If you want to directly sample this then your 3dB signal above noise is 6uV, you need an ADC resolution of 19 bits. You spend $50 on a 24bit ADC to waste 21% of its resolution.

I'm guessing the chart says I need 70,000 averages for 24bits. Maybe 100 averages for 20bits. 100 averages is closer to what's needed. Maybe I'm looking at it wrong.