Author Topic: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems  (Read 388951 times)

0 Members and 1 Guest are viewing this topic.

Offline staze

  • Frequent Contributor
  • **
  • Posts: 798
  • Country: us
  • I _might_ have a problem...
    • Everybody Staze...
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #150 on: November 15, 2014, 08:09:57 am »
AC vs DC triggering... since this seems to largely be a square wave issue, could the trigger be triggering off harmonics (randomly), and that's the cause of the jitter?

I have seen this happen before with oscilloscope triggers but the harmonics are synchronous with the square wave so this would not by itself explain the jitter.  When it happens, the trigger occurs after or sometimes before the fundamental of the square wave but is relatively stable.  It usually indicates a problem with the trigger circuits.
This makes perfect sense. Thanks!
“Give a man an answer, he’ll keep his job for a day. Teach a man to Google, and he’ll be employed for a lifetime”
 

Offline staze

  • Frequent Contributor
  • **
  • Posts: 798
  • Country: us
  • I _might_ have a problem...
    • Everybody Staze...
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #151 on: November 15, 2014, 08:17:17 am »
Huge thanks for responding Rigol! Sounds like the 5us trigger bug probably got fixed in a firmware Dave isn't running (but who knows). Dave, can you show/post which firmware/hardware you're running on the 1000z and 2000 dso's? Or could be the calibration (which I've done since I've had the scope). I'm not seeing the 5ns jitter, but I certainly see the AC coupled triggering jitter. wow. But, can't say I have any use for it. =)
« Last Edit: November 15, 2014, 08:25:41 am by staze »
“Give a man an answer, he’ll keep his job for a day. Teach a man to Google, and he’ll be employed for a lifetime”
 

Offline miguelvp

  • Super Contributor
  • ***
  • Posts: 5549
  • Country: us
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #152 on: November 15, 2014, 08:31:07 am »
Huge thanks for responding Rigol! Sounds like the 5us trigger bug probably got fixed in a firmware Dave isn't running (but who knows). Dave, can you show/post which firmware/hardware you're running on the 1000z and 2000 dso's? Or could be the calibration (which I've done since I've had the scope). I'm not seeing the 5ns jitter, but I certainly see the AC coupled triggering jitter. wow. But, can't say I have any use for it. =)

Not fixed yet, Rigol used the Channel DC coupling for those tests as shown here (in red box), Dave had the Channel AC coupled for the 5 us bug.



Edit: just watched Dave's video again and he did indeed have the channel DC coupled, so maybe it's fixed after all.

Still. Thanks for the fast response about trying to solve this issue  :clap:  :clap:  :clap:
« Last Edit: November 15, 2014, 09:18:45 am by miguelvp »
 

Offline mikeselectricstuff

  • Super Contributor
  • ***
  • Posts: 12027
  • Country: gb
    • Mike's Electric Stuff
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #153 on: November 15, 2014, 08:39:58 am »

We tested 3 DS1000Z scopes here with different board revisions including the FW and HW used by Dave. Screenshots of the results in the attachment.
None of the scopes showed the problem at all.

What was the signal source?
 Did you try making small variations to the frequency?
Youtube channel:Taking wierd stuff apart. Very apart.
Mike's Electric Stuff: High voltage, vintage electronics etc.
Day Job: Mostly LEDs
 

Offline rf-loop

  • Super Contributor
  • ***
  • Posts: 3069
  • Country: cn
  • Starting with DLL21
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #154 on: November 15, 2014, 09:09:44 am »

AC trigger coupling

.
.
.

I can’t think of any use cases on this scope where you would want to AC couple the triggering of a DC coupled channel. It doesn’t work for me. If anyone is willing to share insight with us please follow this link to help us improve the interface.

http://beyondmeasure.rigoltech.com/acton/form/1579/0019:d-0001/1/index.htm

Here is a summary of the questions after the link in case you want a sneak peak:
•   How often do you use AC coupling on your scope?
•   When you use AC coupling on a channel, why do you do it?
•   When you trigger on a AC coupled signal how often do you want to view that signal DC coupled on the display? If you do, please explain the use case.
•   If you do this, how do you want the trigger level shown on the display since it is now decoupled from the signal visualization on the display?

Lastly, if anyone has questions or concerns they want to discuss with us, we are always here. Contact your local Rigol office or distribution partner. Our USA number is 877-4-RIGOL-1. Every DS1000Z bought in the USA is under our 3 year warranty program and Rigol quality is important to us all over the world.

Thanks,

Chris Armstrong
Director of Product Marketing & SW Applications
Rigol Technologies USA

Note: I do not have any Rigol scope today but this whole question about separately set trigger coupling AC when trigger source is signal channel where is also AC/DC coupling and specially when we talk scopes what have digital side trigger generation, is common, not brand related.


•   How often do you use AC coupling on your scope?

Very often.

•   When you use AC coupling on a channel, why do you do it?

For block DC / very low f AC from signal.  One simplest example is testing power supplies ripple.
But then also I use sometimes oscilloscope  input DC coupling but external very low freq corner DC block for analyze very low freq signals but blocking still DC from signal. (some example is also example some amplifier etc 1/f noise)

•   When you trigger on a AC coupled signal how often do you want to view that signal DC coupled on the display? If you do, please explain the use case.

If your guestion is: Signal input A and input coupling DC  and  Trigger coupling AC and trigger source from this same channel A.

Answer is: Never.  (exept in some very rare cases with some old analog scope for finding trigger stability)

Specially in cases that trigger is generated digitally from digitized signal somewhere after ADC.
And if I have understood right Rigol these models have digital trigger if source is input channel.

In this case also if signal input A and input coupling AC  and Trigger coupling AC and trigger source from this same channel A.

Answer is: Never.

I can not imagine any need in this case for set trigger coupling AC in this kind of oscilloscope where trigger is derived from digitized side of main channel.  This setting in this setup combination can remove from scope menu.

In old analog scopes where trigger is analog derived from input or ext trig and also both AC/DC couplings are in separate independent pathways my answer is different but not handle it here.


•   If you do this, how do you want the trigger level shown on the display since it is now decoupled from the signal visualization on the display?

If someone do this my opinion is that he do not really understand what he is doing  and what he want. Exept if want find feature (setup) what do not need occur at all. 



Then, but this is totally different case.
If talk about EXT trig channel, this is different case. (btw, how Rigol produce trig there. Analog comp. method? I have not seen ADC there.
So or so but there this EXT trig channel input coupling need of course have also AC.)

When signal source is main channel where is selectable input AC/DC coupling, and trig is produced from main channel digitized data, there is no need for separate trigger AC/DC coupling. Who can  logically explain what useful it may do and for what it is implemented.
« Last Edit: November 15, 2014, 09:36:25 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 TheBay

  • Supporter
  • ****
  • Posts: 745
  • Country: wales
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #155 on: November 15, 2014, 09:47:08 am »

AC trigger coupling

.
.
.

I can’t think of any use cases on this scope where you would want to AC couple the triggering of a DC coupled channel. It doesn’t work for me. If anyone is willing to share insight with us please follow this link to help us improve the interface.

http://beyondmeasure.rigoltech.com/acton/form/1579/0019:d-0001/1/index.htm

Here is a summary of the questions after the link in case you want a sneak peak:
•   How often do you use AC coupling on your scope?
•   When you use AC coupling on a channel, why do you do it?
•   When you trigger on a AC coupled signal how often do you want to view that signal DC coupled on the display? If you do, please explain the use case.
•   If you do this, how do you want the trigger level shown on the display since it is now decoupled from the signal visualization on the display?

Lastly, if anyone has questions or concerns they want to discuss with us, we are always here. Contact your local Rigol office or distribution partner. Our USA number is 877-4-RIGOL-1. Every DS1000Z bought in the USA is under our 3 year warranty program and Rigol quality is important to us all over the world.

Thanks,

Chris Armstrong
Director of Product Marketing & SW Applications
Rigol Technologies USA

Note: I do not have any Rigol scope today but this whole question about separately set trigger coupling AC when trigger source is signal channel where is also AC/DC coupling and specially when we talk scopes what have digital side trigger generation, is common, not brand related.


•   How often do you use AC coupling on your scope?

Very often.

•   When you use AC coupling on a channel, why do you do it?

For block DC / very low f AC from signal.  One simplest example is testing power supplies ripple.
But then also I use sometimes oscilloscope  input DC coupling but external very low freq corner DC block for analyze very low freq signals but blocking still DC from signal. (some example is also example some amplifier etc 1/f noise)

•   When you trigger on a AC coupled signal how often do you want to view that signal DC coupled on the display? If you do, please explain the use case.

If your guestion is: Signal input A and input coupling DC  and  Trigger coupling AC and trigger source from this same channel A.

Answer is: Never.  (exept in some very rare cases with some old analog scope for finding trigger stability)

Specially in cases that trigger is generated digitally from digitized signal somewhere after ADC.
And if I have understood right Rigol these models have digital trigger if source is input channel.

In this case also if signal input A and input coupling AC  and Trigger coupling AC and trigger source from this same channel A.

Answer is: Never.

I can not imagine any need in this case for set trigger coupling AC in this kind of oscilloscope where trigger is derived from digitized side of main channel.  This setting in this setup combination can remove from scope menu.

In old analog scopes where trigger is analog derived from input or ext trig and also both AC/DC couplings are in separate independent pathways my answer is different but not handle it here.


•   If you do this, how do you want the trigger level shown on the display since it is now decoupled from the signal visualization on the display?

If someone do this my opinion is that he do not really understand what he is doing  and what he want. Exept if want find feature (setup) what do not need occur at all. 



Then, but this is totally different case.
If talk about EXT trig channel, this is different case. (btw, how Rigol produce trig there. Analog comp. method? I have not seen ADC there.
So or so but there this EXT trig channel input coupling need of course have also AC.)

When signal source is main channel where is selectable input AC/DC coupling, and trig is produced from main channel digitized data, there is no need for separate trigger AC/DC coupling. Who can  logically explain what useful it may do and for what it is implemented.
Very valid points. I use AC coupling for smps and audio work. But am I reading this right and from my tests AC coupling is not affected, I certainly see no issues on my DS2702. It's just AC triggering. Which I have never used on any scope?
 

Offline TMM

  • Frequent Contributor
  • **
  • Posts: 436
  • Country: au
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #156 on: November 15, 2014, 10:17:37 am »
Changing the channel coupling does not fix the 5us issue. Channel coupling is completely independent of the jitter issues. Also, my DS1054Z has firmware 04.02.SP3 which is even newer than what RigolTechUSA is running and it still suffers from the 5us problem.

Channel coupling DC, trigger coupling DC = ok at 0us, jitter at 5us.
Channel coupling AC, trigger coupling DC = ok at 0us, jitter at 5us.
Channel coupling DC, trigger coupling AC = jitter at 0us, very bad jitter at 5us.
Channel coupling AC, trigger coupling AC = jitter at 0us, very bad jitter at 5us.
« Last Edit: November 15, 2014, 10:28:04 am by TMM »
 

Offline electr_peter

  • Supporter
  • ****
  • Posts: 935
  • Country: lt
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #157 on: November 15, 2014, 10:32:36 am »
Alan has made a video about trigger coupling on analog scopes (from 5:00)


Basically, AC trigger coupling allows to keep trigger level at the same spot when signal reference level is moved up and down. I do not see how this could be used on or apply to digital scope.

 :-+ for Rigol for looking at the issue.
« Last Edit: November 15, 2014, 10:34:53 am by electr_peter »
 

Offline EEVblog

  • Administrator
  • *****
  • Posts: 29891
  • Country: au
    • EEVblog
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #158 on: November 15, 2014, 10:34:29 am »
I am not at all convinced that Rigol testing 3 scope means the problem does not exist and/or has not been fixed. There are too many people have reported it, including the very last post with newer firmware than Rigol used.
So either Rigol lucked out with the 3 scope they are using (based on the reports, not all units are affected), or they have used an input signal which is not causing it. There are few reports that the signal rise time might be the issue.
 

Offline EEVblog

  • Administrator
  • *****
  • Posts: 29891
  • Country: au
    • EEVblog
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #159 on: November 15, 2014, 10:35:42 am »
I did not expect anyone to so badly confuse AC trigger coupling with AC input coupling. I'm pretty sure I showed I was suing the trigger menu more than once in the video, and mentioned it was trigger coupling.
 

Offline frogmaster

  • Contributor
  • Posts: 11
  • Country: de
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #160 on: November 15, 2014, 10:47:48 am »
There is no real inherent jitter in those captured signals, so I’d expect a FW solution if there is a verified problem on some units after a self-cal.

I performed a self-cal yesterday, makes no difference.
 

Offline TMM

  • Frequent Contributor
  • **
  • Posts: 436
  • Country: au
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #161 on: November 15, 2014, 10:51:51 am »
There is no real inherent jitter in those captured signals, so I’d expect a FW solution if there is a verified problem on some units after a self-cal.

I performed a self-cal yesterday, makes no difference.
Yep, me too. No difference.

I'm pretty convinced that it is an issue with frequency modulation of the system clock. That would go a long way to explain why no one can replicate the issue using scopes own function generator, yet there is an abundance of people who can with external generators.
 

Offline eV1Te

  • Regular Contributor
  • *
  • Posts: 181
  • Country: se
  • Your trusted friend in science!
    • richardandersson.net
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #162 on: November 15, 2014, 11:04:18 am »
I'm pretty convinced that it is an issue with frequency modulation of the system clock. That would go a long way to explain why no one can replicate the issue using scopes own function generator, yet there is an abundance of people who can with external generators.

That sounds like a logic conclusions.

However I can not reproduce the 5 us jitter with any settings (always using external signal generator, DS1074Z-S, 04.01.02). Apparently some scopes do not have the Jitter for real, and it is not only related to people using the internal signal gen.

Or is there a special settings that is needed in order to reproduce the jitter?

I still have the AC trigger jitter, that seems to be a separate issue.

Edit:
The built in signal generators outputs drifts over time with respect to each other, they seem to have different source clocks...  :wtf:
« Last Edit: November 15, 2014, 11:28:31 am by eV1Te »
 

Offline TMM

  • Frequent Contributor
  • **
  • Posts: 436
  • Country: au
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #163 on: November 15, 2014, 11:21:11 am »
What would be interesting would be if someone can check if there is measurable jitter at 5us on a signal generated by a DS1000Z-S with another scope that is not a 1000Z.
« Last Edit: November 15, 2014, 11:24:47 am by TMM »
 

Offline EEVblog

  • Administrator
  • *****
  • Posts: 29891
  • Country: au
    • EEVblog
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #164 on: November 15, 2014, 11:41:17 am »
I performed a self-cal yesterday, makes no difference.

I had also performed a self-cal some time before that (within 24 hours) as part of my review video.
 

Offline EEVblog

  • Administrator
  • *****
  • Posts: 29891
  • Country: au
    • EEVblog
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #165 on: November 15, 2014, 11:42:42 am »
Or is there a special settings that is needed in order to reproduce the jitter?

Some reports seem to indicate it is rise-time related. Mine was sub 20ns I think.
 

Offline tirulerbach

  • Contributor
  • Posts: 33
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #166 on: November 15, 2014, 11:53:42 am »
My DS2000A don't show the 5us-Jitter.

But for the AC-trigger issue I discovered it a few month ago, too. First I though that my test setup was buggy and I changed it. So I didn't bothered. Never noted the public.

But, important, there are some more bugs in the trigger system (at least DS2000A):

a.) Setting "Ext.-Trigger" with "AC-Coupling" don't work et all. The extern trigger is always DC coupled.

b.) Same with the LF- and HF-reject on extern triggering: Don't work.

c.) Using extern trigger in DC-mode cause some jitter too, but not as much as with AC-trigger on a channel.


So, maybe Rigol, if you touching the code for the AC-trigger anyway please take a look at the other issues as well. Seldom used feature, but annoying.
 

Offline TMM

  • Frequent Contributor
  • **
  • Posts: 436
  • Country: au
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #167 on: November 15, 2014, 12:03:21 pm »
Or is there a special settings that is needed in order to reproduce the jitter?

Some reports seem to indicate it is rise-time related. Mine was sub 20ns I think.
I haven't seen any solid proof that it's affected by rise time, i think people are getting confused at what they are observing.

Here is a 5MHz square wave generated by my DG4000, DC coupled everything:


Now here is 20MHz sine wave, without touching any of the settings on the scope


And here's a 5MHz sine wave, again without adjusting anything on the scope.


Obviously it looks less severe with a slower rise time because the trace isn't as fat but if you observe the amount of the x-axis that the trace covers at the zero crossing you find that the amount of jitter is exactly the same at around 8ns wide for all of the signals.

edit: now that i look back at rolycat's post (reply #17), his is really severe, over 20ns!
« Last Edit: November 15, 2014, 12:12:52 pm by TMM »
 

Offline rs20

  • Super Contributor
  • ***
  • Posts: 2172
  • Country: au
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #168 on: November 15, 2014, 12:14:48 pm »
I did not expect anyone to so badly confuse AC trigger coupling with AC input coupling. I'm pretty sure I showed I was using the trigger menu more than once in the video, and mentioned it was trigger coupling.

Yeah, I watched the video again and you did indeed use the "triggering" word in there quite a lot, so my earlier criticism was too harsh. I guess the issue is that people not watching with 110% attention will just hear "AC coupling", see the Coupling > AC/DC menu on the screen, and just sort of think "oh yeah, that AC coupling thing I'm familiar with". An explicit "this is NOT the thing you're thinking of" would have prevented some confusion (but again, I'm very much saying this with a huge benefit of hindsight and third-partyness.) Keep up the awesome work!

BTW, I've just got a video rendering now explaining the dual slope thing. In short, not a bug at all, just an interaction between the holdoff (in your case, the default ~100ns or so holdoff on the DS2202 vs the smaller default holdoff on the DS1000Z), and the period of the 20 MHz wave  :)
« Last Edit: November 15, 2014, 12:28:13 pm by rs20 »
 

Offline hans

  • Super Contributor
  • ***
  • Posts: 1040
  • Country: nl
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #169 on: November 15, 2014, 12:19:43 pm »
There is no real inherent jitter in those captured signals, so I’d expect a FW solution if there is a verified problem on some units after a self-cal.

I performed a self-cal yesterday, makes no difference.
Yep, me too. No difference.

I'm pretty convinced that it is an issue with frequency modulation of the system clock. That would go a long way to explain why no one can replicate the issue using scopes own function generator, yet there is an abundance of people who can with external generators.

I have got a DS1074Z-S and I have not seen any "5us jitter" issues with a internal signal generator or an external signal source (25MHz oscillator on a PCB). The scope is an "older" model from spring this year, and I the impression I get is that most if not all issues appear on much newer batches of scopes (especially surrounding the brand-new 1054Z).
The AC coupling triggering issue is there on my older model.

Also the signal generator in the -S models are on a separate module:
https://www.flickr.com/photos/jameslothian/sets/72157645222357567/

The bottom has a 10MHz crystal mounted, with various support circuits around it probably for driving the oscillator into the FPGA. The FPGA can have PLLs to multiple it to the 200MS/s clock rate required for updating the DAC's. It's a completely time base than the scope timebase.





If I AC trigger on a square wave from the internal signal generator the trigger phase is way off (the trigger center is lagging by tens of nano seconds) and lots of jitter. If I use a sine wave and move the trigger point near the peaks the hardware frequency counter stops counting, yet the scope triggers without any or much jitter. However the update rate is rather low, so I assume it's a very marginal trigger setting. There is a band where the hardware frequency is erroneous in frequency but the update frequency is sufficient (>8k wfms, which is probably it's maximum for the time base) and there is still very little jitter.
 

Offline rf-loop

  • Super Contributor
  • ***
  • Posts: 3069
  • Country: cn
  • Starting with DLL21
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #170 on: November 15, 2014, 12:39:14 pm »
I hope Rigol answer this question or someone who really know.

Attached is image.

Do Rigol (DS1000Z and/or DS2000) use conventional trigger principle (top in image) or true digital trigger system (bottom in image).

If trigger system is digital, then:  What is exactly trigger coupling AC doing there? How it is implemented in this case. (And for what purpose this setting is in this case)

Also overall good to read this whole appnote from R&S.

So, which one in principle?  And as told, I do not wait "maybe" answers and speculations.



« Last Edit: November 15, 2014, 12:44:04 pm 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 rs20

  • Super Contributor
  • ***
  • Posts: 2172
  • Country: au
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #171 on: November 15, 2014, 12:47:10 pm »
Do Rigol (DS1000Z and/or DS2000) use conventional trigger principle (top in image) or true digital trigger system (bottom in image).

If trigger system is digital, then:  What is exactly trigger coupling AC doing there? How it is implemented in this case. (And for what purpose this setting is in this case)

Rigol pretty clearly stated earlier in the thread that it's all going on in FPGAs, so the bottom image is more relevant. You can still offer (or, if you insist, "emulate") AC trigger coupling by highpass filtering the samples, and this is useful for exactly the same reasons outlined earlier in the thread (link). Whether it's done in the digital or analog domain is of little relevance to its usefulness (but fortunately, that fact that it's digital makes it more likely to be repairable).
 

Offline Supercharged

  • Regular Contributor
  • *
  • Posts: 61
  • Country: ch
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #172 on: November 15, 2014, 12:48:24 pm »
I can't reproduce either errors on my DS1074Z-S (Software version 00.02.03.SP5), by using the internal Function generator.

Hardware versions?

Alexander.

My Scope doesn't show the hardware version for some reason.
Science is about what is, engeneering is about what can be.
-Neil Armstrong
 

Offline Carrington

  • Super Contributor
  • ***
  • Posts: 1201
  • Country: es
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #173 on: November 15, 2014, 01:23:28 pm »
@ TMM: Thanks for checking that. Indeed, the jitter seems constant.

Anyone know what type of trigger is used in the DS4000 series (Digital or Conventional)?
My English can be pretty bad, so suggestions are welcome. ;)
Space Weather.
Lightning & Thunderstorms in Real Time.
 

Offline David Hess

  • Super Contributor
  • ***
  • Posts: 9907
  • Country: us
  • DavidH
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #174 on: November 15, 2014, 01:35:36 pm »
But, important, there are some more bugs in the trigger system (at least DS2000A):

a.) Setting "Ext.-Trigger" with "AC-Coupling" don't work et all. The extern trigger is always DC coupled.

b.) Same with the LF- and HF-reject on extern triggering: Don't work.

c.) Using extern trigger in DC-mode cause some jitter too, but not as much as with AC-trigger on a channel.

I have always wondered about the last thing in your list with the 2-channel DS2000A series.  If the external trigger input uses a comparator and reference to drive one of the FPGA logic inputs, then its timing resolution should be limited to that of the FPGA's internal clock unless they implemented some sort of time delay counter.  The same thing should happen if one of the digital MSO inputs is being used for external triggering.

The resulting trigger jitter would not be random though; it should show as discrete bands.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf