EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: Circlotron on August 20, 2016, 11:55:20 am
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Say I set the scope to average 256 traces. During the accumulation of these traces, say a square wave, the waveform gets sharper and sharper and the horizontal sections get down to only 1 pixel wide. Then when the 256 count is reached the horizontal sections of the trace are dithered between adjacent pixels! While this may be mathematically correct is just makes the waveform look fuzzy - the very thing you are trying to avoid by using averaging mode. Looks great while the average count is going up, but not as good once the average count is reached. Very annoying! Is this your experience on your scope? Software version 00.01.01 Hardware version 2.0 All options enabled.
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Not in front of my scope (DS4k) so this is just a theory:
During averaging the scope takes time to build up a single trace and so it displays what is calculated so far.
Once the average is complete then every refresh displays a new trace - albeit with a tiny difference from the previous one due to the averaging. That tiny difference is displayed as 'dithering' based on the persistence setting. If you faff around with that setting you should be able to make the dithering go away and sharpen up the line.