Digital Phosphor Oscilloscope - DPO Explained?

[Time]

So I was curious as to what the difference between a DPO and a DSO are.

When would you want to use a DPO over a DSO?  Does a DPO only offer superior waveform update rates over a conventional DSO?  What makes a DPO different from a DSO?  Is the difference in sampling rate?

How do the Tektronix DPOs match up against these new generation Agilent scopes that dave recently reviewed?

[alm]

DPO (and competing technologies from Agilent and Lecroy) is about getting the performance of a DSO (a DPO is still a digital sampling oscilloscope, fancy marketing names notwithstanding) closer to analog scopes. An early DSO (or the current bottom end) had a low refresh rate, and only displays one acquisition at a time (unless you enable persistence, which is useless for anything but simple, constant signals). Many of them have/had a refresh rate in the order of 10Hz. An analog scope can easily exceed thousands of updates per second an fast sweep speeds. The idea of DPO was to increase the refresh rate and use a variable persistence display with intensity grading based on frequency (basically a 2D histogram with color for frequency), just like a real phosphor does.