I have an old Tek scope. A great 50MHz analog beast that was surely the envy of every engineer — well every engineer in 1976 anyway.
Of course, its a Tek so it is built like a tank and has the usual great features — for a 1976-vintage analog scope. One thing it has that is very cool is “delayed sweep.” The idea is that the scope will trigger as normal and then you can pick a fixed time delay and a different time base to actually drive the display. Huh? All that means is that while watching a regular wave form you can “zoom” in on a section of it. The delay tells you how far into the original screen to start, and the faster sweep gives you the zoom factor. The user interface for this is comical but effective. The scope has a special mode where the time delay and “zoomed” time base makes the trace very bright. So you twist the knobs until the part you want to zoom in on is bright and then you can zoom in.
The Rigol DS1102E (or is it a DS1052E? I forget) has the same capability, but being digital it is very simple and the user interface is much more effective. See the screen shot? The top trace shows a 32kHz PWM signal (about 4%) generated, of course, from a . The bottom trace is the “zoom in” — you can pick delayed sweep from the menus or if you are lazy just click the horizontal scale knob (did you know if you press and hold any button you’ll get help — unless you’ve uploaded unofficial firmware).
Once you turn on delayed sweep you get blue bars on the top that show you the part of the wave you are zooming. You can move the trace with the horizontal position knob and change the zoom level using the horizontal scale. Note that the main window (top trace) is at 10uS/division (you can read that near the bottom of the screen). But the zoomed in part is 500nS/division (right under the enlarged pulse).
When you have seen enough, just click the horizontal scale knob again and you are back to “undelayed trigger” or whatever you want to call it. This can be really handy when you are navigating a long buffer. The top view shows you where points of interest in the buffer are, but the bottom view shows you the detail you want.
What would all of this been worth in 1976? My Tek retailed for about US$2500 in its day. Amazing.