after a couple of years of searching and waiting, I recently acquired a DSOX3054A which was dead due to a NAND corruption which I fixed here
https://www.eevblog.com/forum/testgear/agilent-dsox3054a-not-booting-possible-nand-corruption-help!/This is only my second Agilent scope ever after my old 54845A which I sold quite a while ago.
Unfortunately Keysight scopes do not have separate vertical DC offset and vertical position. They (and many other non-Tek scopes) only have vertical position which also involves a DC offset but is very different in that it moves your ground level up/down. Still I cannot understand why Keysight/Agilent don't implement that feature in their high end expensive scopes. It is understandable to not have that in a cheap scope but 3000 or even 2000 X series are not cheap.
My Tektronix scopes (TDS3000, DPO7000, MSO3000) all have separate DC offset and vertical position and I know MDO3000 and 4000 also do
even my old analog Iwatsu 7840 A.K.A Lecroy LH314 does have this. But not on my digital Lecroys and the Keysight.
Alan Wolke (w2aew) has an excellent video about this on youtube.
Suppose I want to look at a small AC ripple/noise on top of a "'slowly varying'" DC and I do want to keep an eye on the DC level variations as well as the AC signal. For example imagine a not so good regulated supply under a heavy load which is turned on and off. I want to see the changes in the DC level due to the load being off/on as well as to see the ripple. Or you can imagine many other scenarios. e.g. keeping an eye on the temperature variations of a small AC signal riding on a DC voltage....
AC coupling does not cut it (cut off freq is usually at 3Hz or higher which is still too fast to catch slow variations) I tried to use MATH (like Ax+B) to emulate that but it does not work because you have to have the waveform in the screen in first place but for that the V/div is too high and the ripple is invisible so the MATH trick doesn't work.
Other trick is to use two channels, one to show the DC level and one to see the ripple in AC coupled, but again if the (slow) variations of the DC level are small you face the same problem
Question: other than adding en external DC offset to the input signal, is there any other way to work around this?
On my Tektronix scopes I can do this very easily by setting the proper DC offset and then a high gain and still I can use the vertical position too, no need to AC couple.. so I can optimally use the whole ADC dynamic range.
perhaps a good topic for Dave to make a video about