Mike Simmonds

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Posts posted by Mike Simmonds

  1. 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.

  2. On my Analog Discovery 2,  Using WaveForms,  I would like to synchronize  the Scope display with the signal from a Wavegen channel.  There is an old post from 2017 that described how to do something like this, but the trigger only occurred when Wavegen was first started. 

    Is there a way to repeatedly trigger the scope on each cycle of the Wavegen waveform while it is running?  

  3. Not sure if this the correct forum. Apologies if not.

    I want to generate an AM modulated wave with 200% modulation depth.  The WaveForms application appears to allow this.

    As shown in the attached file, the results are not what I expected.  I expected to have two equal lobes with the phase of the second lobe reversed from the first.

    Are my expectations incorrect or am I setting parameters incorrectly?  Or is there a bug in the Analog Discovery firmware or WaveForms application.

    200 percent AM Modulation.jpg