If you have Channel 1, you can set trigger on edge, and signal is shown on current time scale.
But then for Channel 2, the signal is shown in same time scale, and not triggered to any edge?
Do some scopes have triggering on each signal individually?
But how are the signals then displayed? In separate windows and time scales?
What are the use cases? Isnt there always 1 common reference?
Would like to hear about the different use cases/advantages/disadvantages.
If you feel you might need this dual-timebase capability, take a look at something like the Rigol DS1052E, which supports it. Along with another feature missing from the current gen of cheap scopes...
I believe the reason Alt-Trigger is not present in the current line of less-expensive DPOs (Agilent X-Series, Rigol UltraVision, etc) is because it would be difficult to support intensity-grading of two distinct time bases at a reasonable speed.
In some situations, you can at least achieve a stable display of two non-time-correlated waveforms by using one of the dual source triggers of the Rigol - such as the Delay or Duration Trigger - which allows you to trigger after edges (or other conditions) from each channel with an adjustable </>/<>/= time between them.
I believe the reason Alt-Trigger is not present in the current line of less-expensive DPOs (Agilent X-Series, Rigol UltraVision, etc) is because it would be difficult to support intensity-grading of two distinct time bases at a reasonable speed.
Would it?
I can obtain something less unstable wih the Rigol scope by playing with advanced trigger modes (delay in particular), and by setting the maximum memory size (28Ms).
Furthermore, I noticed that if I change the Volt/div setting, the minimum voltage level at which trigger occurs is changing. For exemple with the 3.3V signal:
- 500mV/div gives 0.2mV for triggering
-1V/div gives 0.680V
- 2V/div gives 1.65V
- 5V/div never triggers
I have not found it on any of the lower end scopes and that is keeping me from buying any of them (as long as I still have access to the better ones).
The other problem is in normal mode, edge triggering and DC trigger coupling, if I change the volts/div setting of the triggered signal, the level at which the signal is stable varies.
Since the trigger sensitivity is expressed in division, does the trigger consider what is displayed instead of the true value of the signal?
Does any of the Rigol scopes out there have support for dual time bases?
Does any of the Rigol scopes out there have support for dual time bases?Yes, the DS1052E has Alternate mode via menu Trigger -> Mode -> Alternate.
Yes, agree - I could have been preciser.
I reacted on the same posters original question on the possibility to have two time-unrelated channels stable on screen.
In "Vert" mode, the Tek perfectly stabilize the two traces (in this mode, it triggers on the first raising edge among the two channels)
Do some scopes have triggering on each signal individually?
Yes. Dual time-bases have been around a long time. They can be correlated (simply time-delayed, or offset), or independent (alternating).
I believe the reason Alt-Trigger is not present in the current line of less-expensive DPOs (Agilent X-Series, Rigol UltraVision, etc) is because it would be difficult to support intensity-grading of two distinct time bases at a reasonable speed.
Would it?
Well, I'm not sure, but it would require two distinct intensity buffers - plus the very nature of DPOs is fast waveform updates, so the sampling is highly optimized. It's been awhile since I've had a scope with alt-trigger, but I seem to remember that you can really fool around with both trigger offsets and delays - so that the whole display updating can get a bit slow and choppy. Anyway, it's just a theory - otherwise it seems strange it wouldn't be implemented, since it's simple to do.
Non-DPO oscilloscopes also lack it so I suspect it is because there are other ways to achieve almost the same thing and a lack of demand for dual timebases. There would be some duplication in things like the decimation and reconstruction stage but for performance reasons, that duplication may already exist. Alternate triggering should be easy but they lack that as well with the mentioned older Rigol being a notable exception.
Non-DPO oscilloscopes also lack it so I suspect it is because there are other ways to achieve almost the same thing and a lack of demand for dual timebases. There would be some duplication in things like the decimation and reconstruction stage but for performance reasons, that duplication may already exist. Alternate triggering should be easy but they lack that as well with the mentioned older Rigol being a notable exception.
Virtually every older generation, low-cost DSO (Rigol, Owon, Hantek, Siglent, etc) has Alternate trigger - and virtually every newer generation, low-cost DPO (Agilent, Rigol, Siglent, etc) does not. Most people that use oscilloscopes are familiar with the feature and find it handy from time to time - so I doubt it was just a simultaneous decision by every manufacturer to drop the feature at the same time. I think it's implementation on the newer DPOs is made difficult/time-consuming by either the DPO architecture or digital triggering.
Which is not (the same as) dual time bases.. I assume he wants each channel to have its own time base - I suppose in addition to alternate trigger. This would be a very confusing configuration, I have no clue as to its usefulness.
I am fairly certain no Rigol scope has this feature.
...I have not found it on any of the lower end scopes and that is keeping me from buying any of them (as long as I still have access to the better ones).
The DS2000 has at least four 2-channel triggers that can use both channels to validate the trigger.