National Instruments NI 9229, NI 9239 Understanding NI 9229/9239 Data Rates

The filter significantly attenuates all signals above the stopband

frequency. The primary goal of the filter is to prevent aliasing.

Therefore, the stopband frequency scales precisely with the data

rate. The stopband rejection is the minimum amount of attenuation

applied by the filter to all signals with frequencies within the

stopband.

Any signal that appears in the alias-free bandwidth of the

NI9229/9239 is not an aliased artifact of signals at a higher

frequency. The alias-free bandwidth is defined by the ability of the

filter to reject frequencies above the stopband frequency and equals

the data rate minus the stopband frequency.

Understanding NI 9229/9239 Data Rates

The frequency of a master timebase (fM) controls the data rate (fs)

of the NI 9229/9239. The NI 9229/9239 includes an internal master

timebase with a frequency of 12.8 MHz, but the module also can

accept an external master timebase or export its own master

timebase. To synchronize the data rate of an NI 9229/9239 with

other modules that use master timebases to control sampling, all of