From the schematics, it looks like the hardware gain is fixed. ?So I'm wondering how small a signal can be measured. ?The input range is -14V to 20V and so if 8 bit ADC is used, that would give a resolution of 34V/256 = 0.133V, which isn't that good. ?I suspect something clever is done to improve this. ?Are additional bits used? ?Or something else? ?Can low voltage signals be measured?
Thanks!

The microcontroller itself has an amplifier on the ADC, with multiple gains up to 64x.

Thanks, that explains it. I got my xminilab yesterday and I did some tests using a voltage divider driven by the AWG output./\r\n/With a signal of about 0.04V peak to peak, the waveform is quite noisy, so that seems to be about the limit of the device./\r\n/Are there any tricks for measuring a smaller AC signal?

To get a 100x increase in the gain:
1) Swap R2 (820K) and R3 (180K)./\r\n/2) Replace R7 (20K) with 110K/\r\n/3) Replace R8 (180K) with 4.7K
To understand how to calculate the gain:/\r\n/XScopes Analog Front End