excess noise on NI6023E

[kenbo]

I have been using these cards in my lab for years, but my noise level requirements have just gotten significantly more demanding. I was surprised on testing to find the noise level to be about 3 steps with the inputs grounded. The noise appears white: flat in frequency out to 500 Hz (all I care about). Is this expected behavior and is there anything I can do about it?

[johnsold]

According to the specifications the RMS noise is less than 1 LSB, so 3 LSB peak to peak sounds about right.

Averaging over multiple samples will reduce the noise.  If your signal is time varying, the averaging must either be over a time short compared to the signal variation or it must be synchronized with the period. Otherwise the averaging will reduce the signal also.

Lynn