Why is random noise in DAQ mudule related to input voltage range?

[ArunJ]

The below table is from the data sheet of NI-6343 module.

What exactly is this random noise? And why does it vary with voltage range?

[Cavarval · Accepted solution]

Hello,

See this.

If a device has multiple gains, it multiplies an input signal by one of the gains to make the signal take up more of the full device range.

And this (press Ctrl+f and search for Random).

Random/System Noise—Additional system noise generated by the analog front end, measured by grounding the input channel

Essentially, each input range is related to a different gain. The Random Noise is affected by the gain. The larger the input range, the larger the gain, thus, the larger the Random Noise.

Hope it helps, 

[Hatef.fouladi]

exactly it is white noise of gain structure and you could not remove it without loosing data