OM-USB-2404-60 User's Guide
Functional Details
11
Figure 8. Passband response (typical)
Stopband bandwidth
The filter significantly attenuates all signals above the stopband frequency (0.547 ·
, where
is the sample
rate). The filter is used primarily to prevent aliasing. Therefore, the stopband frequency scales precisely with the
sample rate.
The stopband rejection (100 dB) is the minimum amount of attenuation applied by the filter to all signals with
frequencies within the stopband bandwidth.
Alias-free bandwidth
Any signal that appears in the alias-free bandwidth of the OM-USB-2404-60 is not an aliased artifact of signals
at a higher frequency. The alias-free bandwidth (0.453 ·
is defined by the ability of the filter to reject
frequencies above the stopband frequency. The alias-free bandwidth equals the sample rate minus the stopband
frequency.
Sample rates
A master timebase frequency (
) controls the OM-USB-2404-60 sample rate (
). The internal master
timebase frequency is 12.8 MHz.
The equation below provides the available sample rates of the OM-USB-2404-60:
, where
n
is any integer from 1 to 31
The sample rate must keep the device within the sample rate range. Refer to the
Specifications
chapter for more
information about the sample rate range.
Using the internal master timebase of 12.8 MHz results in sample rates of 50 kS/s, 25 kS/s, 16.67 kS/s and so on
down to 1.613 kS/s, depending on the value of
n
.
