Why does the waveform appear to be thicker on a DPO than on my Digital Storage Oscilloscope?

The DPO4000 series oscilloscopes are showing far more information about the signal than the typical DSO used to show.  The DPO4000 Series uses a fit-to-screen model where the entire waveform, regardless of selected record length, is compressed to fit in a 1000 pixel wide display.  So when the customer has 10M points turned on, each pixel column represents 10M/1000 = 10,000 points.  Unless the signal maintains the exact same amplitude over 10,000 consecutive samples, the trace will be thicker than one digitizing level.  With a DPO, every screen update may represents hundreds or thousands of acquisitions.  Again, unless the signal is precisely repetitive, the waveform will appear thicker than on a DSO because we are showing so much more true signal activity.

 

Customers who have objections to thick traces can take the following actions to minimize this.  In the Acquire menu, turn the record length down to 1000 points, and turn down the intensity. This will be familiar to previous analog scope users because the intensity knob also affected trace width on the screen.