Anti-Aliasing Filter on Analog Discovery 2 in Scopes & Instruments and the WaveForms software Posted January 7 When trying to measure white noise levels, I noticed that it was necessary to select a Sample Mode of "Average" rather than "Decimate" (under Channel Options) to avoid having spectra that were badly contaminated by aliased noise. For example, I set up the following situation: I fed C1 from the output of a low-noise 1000X preamp with 1MHz bandwidth and put a 10K ohm resistor on its input. Instead of seeing the expected 14nV/RtHz, I saw about 40nV/RtHz when in Decimate mode. I could fix this switching to Average Sample Mode. My Analog Discovery 2 came with Decimate as the default mode. When using Decimate Mode, I had to apply an analog LP filter set to about 30KHz in order to suppress all the aliasing. Other users may want to verify that they are using Average Mode if they are having problems getting good spectra.