Why is PXIe-4481 sampling frequency Higher for Time Domain?

[jacksonmcfall@lanl.gov]

I have PXIe-4481 ADC cards that until this point, I have only used to sample at 10KHz. I now want to sample a strain gauge voltage at 4 MS/s. I see the 4481 cards can sample in the "frequency domain" at 1.25 MS/s and in the "Time Domain" at 20 MS/s. Why is this the case? What do you lose by sampling above 1.25 MS/s?

Thank you

[Henrik_Volkers]

in short: you loose ENOBs   (Resolution)

In more detail see the user manual, first 10 pages of chapter 3  (read the fantastic manual... or so 😉 )