Measurement Computing USB-2404-10 - Manual (Page 14)

USB-2404-10 User's Guide Functional Details
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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 USB-2404-10 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 USB-2404-10 sample rate ( ). The internal master timebase
frequency is 12.8 MHz.
The equation below provides the available sample rates of the USB-2404-10:
, 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.