DI-2108 Hardware Manual
Controls, Indicators, and Connections
12
Low-pass Filter
Each analog channel employs a low-pass filter with automatic corner frequency selection. The filter is a CIC (cas-
caded integrator comb) type that uses as many as 512 samples per channel to calculate in real time as data is acquired.
Filter response is optimized when sampling frequency is set to ten times the highest frequency of interest.
When choosing an acquisition method in WinDaq (menu item
Edit
>
Channel Settings
) Last Point, Maximum, and
Minimum turn the filter off. The DI-2108 calculates its own Last Point, Maximum, Minimum, and Filter data making
it available at the programming level. Acquisition methods “RMS” and “Frequency” are permanently disabled for the
DI-2108, as are Input Types “Nonlinear” and “Thermocouple” and selections for “Unipolar” and “Fahrenheit.”
