ADC and time Stamping

GNU Radio
1

Hi,

  1. How is the scaling of input voltages to the ADC is done? If i see a
    10 or some number as voltage level at output what does it mean?

  2. What does time stamping exactly mean in case of USRP2 ? My
    understanding is that the time stamp is the difference of time and not
    the
    Absolute time since board doesn’t have any source to get absolute
    timestamp.

Regards
Subodh