Step response test to shed more light on response vs amplitude differences. Source is negative going square with 30ps rise, amplitude can be varied. For starters would be nice to center amplitude around zero with DC offset but some scopes do not have it. Can be still emulated by various methods and test software & features at once.
ADALM2000:
±50 mV: RT=~10ns BW=~35MHz (RT calculation broken)
±1 V: RT=11.2ns BW=31.3MHz
As can see response is indeed consistent. But many problems some little some bigger. Maybe have not discovered all the right ways to use software but still...
- seemingly no DC offset emulation, but can do with math channel
- to create reference must first save to CSV and then reload
- did not found averaging option
- no oversampling/ETS
- full +-1 sample jitter around trigger point (+-10ns @ 100MHz)
- zoom is very nasty to use with mouse, seems touch oriented, in general I do not like all those soft and fuzzy zooms, need numerical input for precise x10 or whatever
- many little weirdness, software needs polishing for UX
- no Sinc interpolation (min timebase whopping 100ns/div)
AD2:
±50 mV: RT=8.8ns BW=39.7MHz
±1 V: RT=9.9ns BW=35.4MHz
Big difference in response indeed. GUI is again good for the task, can even create function that calculates bandwidth from RT on the fly. There is oversampling that will give 1.6GHz effective rate but from past experience I know that it can have problems related to underlying RTS trigger jitter. No issues this time however.
PS2205:
+-100mV: RT=18.8ns BW=18.6MHz
+-2V: RT=19.7ns BW=17.8MHz
Response performance worse than with sine test, maybe due to using only small portion of ADC range (no DC offset). Software setup quite easy. 4GHz ETS (equivalent time sampling) gives extremely solid relative timing accuracy for this class of scope.
Winners: AD2/PS2205 because each one has strong points. ADALM2000 clearly inferior in everything but consistent response with differing amplitudes - software clearly needs more work.