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Electronics => Beginners => Topic started by: herbkanis on March 10, 2018, 02:52:54 am

Title: What are the dark rectangles on the logic analyzer waveform?
Post by: herbkanis on March 10, 2018, 02:52:54 am

Hi,
Has anyone seen dark rectangles like the ones in the waveform capture I’ve attached?
The logic is from an Epson Printer and I’m using a Diligent Discovery 2 to get the waveforms.

Thanks for any help,

Title: Re: What are the dark rectangles on the logic analyzer waveform?
Post by: MarginallyStable on March 10, 2018, 04:40:27 am

I'm not sure if relevant for your analyzer, but may be glitch detection. Some analyzers have circuitry to detect glitches that are smaller than the instrument's sample period. 

Title: Re: What are the dark rectangles on the logic analyzer waveform?
Post by: Paul Rose on March 10, 2018, 05:29:50 am

Yes.

https://reference.digilentinc.com/reference/software/waveforms/waveforms-3/reference-manual
 (https://reference.digilentinc.com/reference/software/waveforms/waveforms-3/reference-manual)
The online Waveforms manual section 4 ( Main Plot ) point  12:

Quote

Noise band indicating glitch or higher frequency components than the sampling frequency. See Real
channels options.

On figure 4.1, the corresponding label 12 shows a dark background for a portion of the plot

Title: Re: What are the dark rectangles on the logic analyzer waveform?
Post by: herbkanis on March 10, 2018, 05:32:57 am

Both answers are correct. I did a search for "Wavegen" and "Glitch" on marginallystable's suggestion and found the reference that Paul gave.
Thanks to you both!
Cheers