©
National Instruments Corp.
15
NI 9234 Operating Instructions and Specifications
Stopband
The filter significantly atten
u
ates all signals above the stopband
freq
u
ency. The primary goal of the filter is to prevent aliasing.
Therefore, the stopband freq
u
ency scales precisely with the data
rate. The stopband rejection is the minim
u
m amo
u
nt of atten
u
ation
applied by the filter to all signals with freq
u
encies within the
stopband.
Alias-Free Bandwidth
Any signal that appears in the alias-free bandwidth of the NI 9234
is not an aliased artifact of signals at a higher freq
u
ency. The
alias-free bandwidth is defined by the ability of the filter to reject
freq
u
encies above the stopband freq
u
ency, and it is eq
u
al to the
data rate min
u
s the stopband freq
u
ency.