Author Topic: Out of curiosity, are there DSOs with alternate trigger?  (Read 8529 times)

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Offline JPortici

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Out of curiosity, are there DSOs with alternate trigger?
« on: December 23, 2016, 10:20:45 am »
From time to time i have *unusual* tasks, at least unsual for a dso.
i have a device which has a square wave as an input and it produces a square wave of a different frequency, depending on a parameter... for example 1 KHz in, param=100 -> 900 Hz out
I'd like to see them both clearly, this would be an easy task for almost any CRO: alternate trigger. but none of the DSO i have at work or at home seem to be able to do it.. and none that i can think of, so the question: which DSO have alternate trigger? I remember an old topic that mentioned some but i can't find it
 

Offline EEVblog

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Re: Out of curiosity, are there DSOs with alternate trigger?
« Reply #1 on: December 23, 2016, 10:36:43 am »
I think the original Rigol DS1054 had it, as does one of the Hamegs or something?
 

Online Daruosha

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Re: Out of curiosity, are there DSOs with alternate trigger?
« Reply #2 on: December 23, 2016, 10:44:45 am »
Dave ment DS1052E,
Crappy owon SDS series have alternate trigger as well.
 

Offline rf-loop

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Re: Out of curiosity, are there DSOs with alternate trigger?
« Reply #3 on: December 23, 2016, 10:45:31 am »
Siglent SDS1000CML

It have rare Dual  Timebase Alternate trigger mode with  full independent trigger system for both channels. 

Rigol DS1000E do NOT have. It have only Single timebase ALT.
« Last Edit: December 23, 2016, 10:51:08 am by rf-loop »
If practice and theory is not equal it tells that used application of theory  is wrong or the theory itself is wrong.
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Online Alex Nikitin

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Re: Out of curiosity, are there DSOs with alternate trigger?
« Reply #4 on: December 23, 2016, 01:49:04 pm »
I've checked two scopes here in the lab - both Agilent DCO1014A and Tektronix MDO3104 have it.

Cheers

Alex
 

Offline nctnico

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Re: Out of curiosity, are there DSOs with alternate trigger?
« Reply #5 on: December 23, 2016, 02:13:54 pm »
GW Instek 2000E series for sure (I've used it) and probably others models as well. But you have to realize that with alternate triggering you are looking at traces without any relation because they are not sampled at the same time. If a rare anomaly causes a problem you will see it in only one trace.
« Last Edit: December 23, 2016, 02:32:54 pm by nctnico »
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Offline TheoB

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Re: Out of curiosity, are there DSOs with alternate trigger?
« Reply #6 on: December 23, 2016, 02:34:30 pm »
Ah, I didn't miss it yet but this is the second thing I 'assumed' would be present on the DS1054Z. The first one being variable time base.
I guess the workaround is to trigger on one signal, save it to a reference and then trigger to the other signal. That's what my old CRT scope could not do. Of course not exactly the same, but for a one time view of two asynchronous signals, this might work.
 

Offline JPortici

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Re: Out of curiosity, are there DSOs with alternate trigger?
« Reply #7 on: December 23, 2016, 05:44:44 pm »
GW Instek 2000E series for sure (I've used it) and probably others models as well. But you have to realize that with alternate triggering you are looking at traces without any relation because they are not sampled at the same time. If a rare anomaly causes a problem you will see it in only one trace.

of course! it's alternate trigger. I remember you already mentioned the 2000E would be able to but when i checked the manual i couldn't find anything in the trigger section

@TheoB yours was the topic i referred to before :D
 

Offline MrWolf

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Re: Out of curiosity, are there DSOs with alternate trigger?
« Reply #8 on: December 24, 2016, 01:16:47 pm »
Hm, did you not have something to do with Picos? No problem there...
Alternate trigger from PWM and resulting sine to keep it nice and aligned.
Of course it could be done with just PWM window triggering in this specific case, but will do as quick example.






 

Offline nctnico

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Re: Out of curiosity, are there DSOs with alternate trigger?
« Reply #9 on: December 24, 2016, 01:29:23 pm »
The PWM and sine are related. Alternate triggering is used to show two unrelated signals.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline MrWolf

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Re: Out of curiosity, are there DSOs with alternate trigger?
« Reply #10 on: December 24, 2016, 01:53:33 pm »
The PWM and sine are related. Alternate triggering is used to show two unrelated signals.

Here 2 triggers are used:
1) rising level for PWM to keep edge at exactly 0s
2) max level for sine to keep sine "hump" at approx 0s, sine is too unstable to do precise triggering, especially at zero crossing.
So signals ale related, but pretty vaguely.
Stable triggering cannot be done using either one of the specific triggers individually.

But yolo, if you still do not understand point of example its just fine by me :)
« Last Edit: December 24, 2016, 01:55:49 pm by MrWolf »
 

Offline JPortici

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Re: Out of curiosity, are there DSOs with alternate trigger?
« Reply #11 on: December 24, 2016, 03:28:38 pm »
as i'm using a pico2000 on the workbench i have to ask: how did you set up the trigger, exactly?
i want to see two stable square waves, each at an arbitrary frequency.
 

Offline MrWolf

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Re: Out of curiosity, are there DSOs with alternate trigger?
« Reply #12 on: December 24, 2016, 03:52:51 pm »
Well nobody said you cant use digital logic triggers on analog signals ;)

 

Offline MrWolf

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Re: Out of curiosity, are there DSOs with alternate trigger?
« Reply #13 on: December 24, 2016, 11:56:28 pm »
Since it interesting to max out hardware at hand did additional test:

f1 = 3.3VDC 48kHz square CH1
f2 = 2Vpp 51Hz sine CH2
f1 mod f2 <> 0

3 orders different frequency triggering no prob with CH1.Rising(1.65V) AND CH2.Rising(0V).
2% hystersis did give most stable result.

 

Offline Howardlong

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Re: Out of curiosity, are there DSOs with alternate trigger?
« Reply #14 on: December 25, 2016, 01:13:51 am »
The Owon HDS3102m-n does alternate trigger mode.

I am not convinced that there is some confusion in some of the above posts between alternate triggering, where the traces operate in Alt mode, with a different trigger on each trace (so you can see two uncorrelated signals), and a logic or delayed trigger.

For example, I don't know how you'd set up an MDO3000 to do Alt triggering, and the Pico examples look like logic triggers, which aren't the same as alt triggering.
 

Offline MrWolf

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Re: Out of curiosity, are there DSOs with alternate trigger?
« Reply #15 on: December 25, 2016, 10:06:06 am »
Hm, if there is some feature on some scope where you can have two not-time correlated traces (dual trace on CRO?) with full reso each and full hardware triggering on each then Pico does not do that. However this sort of loses point of showing the traces on same scope, no? I have just hooked two Picos to same PC for that and opened 2 instances of software on same screen.
But where there is some correlation point in time* it just comes down to scope memory amount (in Pico case). My old box has only 48kS so this sets maximum diff of frequencies to about 3 orders of magnitude. 2408B has 128MB would be interesting what that could do...
Anyway I did provide examples becasue OPs case seems trivial to solve with alternate logic triggers which work just as well on any analog signal.
Edit: *actually if you do logic OR or whatever they do not have to be correlated at all.
« Last Edit: December 25, 2016, 10:19:44 am by MrWolf »
 

Offline Howardlong

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Re: Out of curiosity, are there DSOs with alternate trigger?
« Reply #16 on: December 25, 2016, 10:20:09 am »
It is a rare scenario. But it's also the reason why we all need 20 oscilloscopes.
 
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Offline MrWolf

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Re: Out of curiosity, are there DSOs with alternate trigger?
« Reply #17 on: December 25, 2016, 10:27:01 am »
It is a rare scenario. But it's also the reason why we all need 20 oscilloscopes.

Think having ridiculous amount of mem on DSO would work around that in most cases. Gotta try it sometime. Torture testing is fun.

Anyway, specifically for OP who has Pico on desk logic indeed seems to solve it. With triggering on each channel with normal triggers other channel is "running around". Looking for some correlation freezes them real well, 48kHz + 52kHz:



« Last Edit: December 25, 2016, 10:50:14 am by MrWolf »
 

Offline rf-loop

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Re: Out of curiosity, are there DSOs with alternate trigger?
« Reply #18 on: December 25, 2016, 10:48:36 am »
Hm, if there is some feature on some scope where you can have two not-time correlated traces (dual trace on CRO?) with full reso each and full hardware triggering on each then Pico does not do that.
As told previously.
Old Siglent SDS1000CML have.

It have ALT mode where both traces have fully separate independent triggers. And even more. Both traces have independent time base. It is Dual Timebase ALT mode.  Many scopes have ALT mode with separate trigger but not with independent time base. 
Pity they have not implemented this for full digital triggering system models.


Most analog scopes have ALT mode but still only one beam. One beam is altered between channels and triggered separaately.  Disadvantage is that other trace need wait other trace trigged and sweeped.

And same in most digital scopes  what have ALT. One trace trigged and acquire and one trace wait. They can not simultaneously but independently capture with independent time bases and independent triggering. For this we need two scopes and watch two separate displays what is not always fun.

There is also true dual beam analog scopes.  These have one crt but fully two separate electron gun (two independent beam inside one tube with also separate independent deflection. (One example is Tektronix 7844 - I have one this beauty)
Where is this kind of DSO? Who knows if there is.

« Last Edit: December 25, 2016, 10:53:15 am by rf-loop »
If practice and theory is not equal it tells that used application of theory  is wrong or the theory itself is wrong.
It is much easier to think an apple fall to the ground than to think that the earth and the apple will begin to move toward each other and collide.
 

Offline nctnico

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Re: Out of curiosity, are there DSOs with alternate trigger?
« Reply #19 on: December 25, 2016, 11:46:18 am »
Hm, if there is some feature on some scope where you can have two not-time correlated traces (dual trace on CRO?) with full reso each and full hardware triggering on each then Pico does not do that.
As told previously.
Old Siglent SDS1000CML have.

It have ALT mode where both traces have fully separate independent triggers. And even more. Both traces have independent time base. It is Dual Timebase ALT mode.  Many scopes have ALT mode with separate trigger but not with independent time base. 
Pity they have not implemented this for full digital triggering system models.

And same in most digital scopes  what have ALT. One trace trigged and acquire and one trace wait. They can not simultaneously but independently capture with independent time bases and independent triggering.
Not entirely true. Zoom mode allows to see  signals at different time bases.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline MrWolf

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Re: Out of curiosity, are there DSOs with alternate trigger?
« Reply #20 on: December 25, 2016, 01:00:11 pm »
It is a rare scenario. But it's also the reason why we all need 20 oscilloscopes.

Think I f****d it all up, again!  |O OP probably just wanted excuse for a new toy from a boss :( Just like Church of Z sectants want to hear "Z is dope" couple times per day instead of performance tests  :-[
 

Online David Hess

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Re: Out of curiosity, are there DSOs with alternate trigger?
« Reply #21 on: December 25, 2016, 01:19:45 pm »
I am not convinced that there is some confusion in some of the above posts between alternate triggering, where the traces operate in Alt mode, with a different trigger on each trace (so you can see two uncorrelated signals), and a logic or delayed trigger.

For example, I don't know how you'd set up an MDO3000 to do Alt triggering, and the Pico examples look like logic triggers, which aren't the same as alt triggering.

When I was evaluating the Tektronix MSO5000 series, the sale engineer and I could not figure out how to do alternate triggering or timebases.  All of my analog oscilloscopes and most of my DSOs support alternate triggering and of course my 4-bay 7000 mainframes can operate as two independent oscilloscopes with the same display.

It is a rare scenario. But it's also the reason why we all need 20 oscilloscopes.

That was basically my solution.  If I need alternate triggering and digital storage, then I use two of the same or different DSOs.
 

Offline StillTrying

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Re: Out of curiosity, are there DSOs with alternate trigger?
« Reply #22 on: December 25, 2016, 10:08:15 pm »
"Old Siglent SDS1000CML have."

Alternate triggering/dual timebase is still there in the CML+.

It only works on RT sampling and only on the short 40k memory, but as it can use a different sampling rate for each traces' timebase I don't think there's any limit to the difference between the two timebase speeds.
« Last Edit: December 25, 2016, 10:11:43 pm by StillTrying »
CML+  That took much longer than I thought it would.
 

Offline mk_

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Re: Out of curiosity, are there DSOs with alternate trigger?
« Reply #23 on: December 25, 2016, 10:34:15 pm »
I've checked two scopes here in the lab - both Agilent DCO1014A and Tektronix MDO3104 have it.

Cheers

Alex

can you show or explain how you did it on the MDO3104? I needed it some weeks ago and didn`t find a way to trigger on signal at Ch1 and an more or less independent signal on Ch3 (which is no problem on my analog Iwatsu)

Michael
 

Offline JPortici

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Re: Out of curiosity, are there DSOs with alternate trigger?
« Reply #24 on: December 26, 2016, 08:05:43 am »
It is a rare scenario. But it's also the reason why we all need 20 oscilloscopes.

Think I f****d it all up, again!  |O OP probably just wanted excuse for a new toy from a boss :( Just like Church of Z sectants want to hear "Z is dope" couple times per day instead of performance tests  :-[

ahaha no, i already have the amount of scopes i need, if anything i'm looking for excuses for other kind of equipment but not scopes.
i admit i never even bothered to check out the logic trigger on the pico, after i found out it wasn't referring to serial triggering (which i was hoping to)
but yours looks like a good trick. will try wednesday at the workbench
 


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