Author Topic: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems  (Read 399807 times)

0 Members and 1 Guest are viewing this topic.

Offline EEVblog

  • Administrator
  • *****
  • Posts: 30895
  • Country: au
    • EEVblog
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #350 on: November 20, 2014, 03:28:34 am »
And they still have the third bug  to address, I am dying to learn which one out of the 3 reported it is.

There is no third bug, that was an unverified throw-away PEBKAC on my part.
 

Offline David Hess

  • Super Contributor
  • ***
  • Posts: 10691
  • Country: us
  • DavidH
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #351 on: November 20, 2014, 03:34:01 am »
And they still have the third bug  to address, I am dying to learn which one out of the 3 reported it is.

There is no third bug, that was an unverified throw-away PEBKAC on my part.

Just to keep us on our toes.  Gotcha. ;)

 

Offline David Hess

  • Super Contributor
  • ***
  • Posts: 10691
  • Country: us
  • DavidH
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #352 on: November 20, 2014, 03:35:09 am »
2. Trigger jitter when using AC trigger coupling.

Not sure what the third bug is?
There is actualy 4th one. I've showed it in my video: on DS2000A with EXT source it works only with DC coupled trigger. Menu is the same (AC/DC/rejects), but it doesn't affect anything, EXT trigger always work with DC coupling.

I suspect this bug only exists in the documentation and user interface with external triggering only supporting DC coupling because of the hardware.
 

Offline (In)Sanity

  • Regular Contributor
  • *
  • Posts: 229
  • Country: us
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #353 on: November 20, 2014, 06:04:13 am »
The menu options to select AC coupling need to go away on the DS2000A when using the external trigger.  I've confirmed as well that it only supports DC coupling.  You can of course put a cap inline and now you have your AC coupling  :-\

Jeff
 

Offline wlanfox

  • Newbie
  • Posts: 4
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #354 on: November 20, 2014, 07:40:22 am »
Maybe another bug will come up... Nah!

And they still have the third bug  to address, I am dying to learn which one out of the 3 reported it is.

1. Trigger jitter when using 5us horizontal offset
2. Trigger jitter when using AC trigger coupling.

Not sure what the third bug is? The "dual slope triggering not working bug" is not a bug at all, just correct behaviour of trigger holdoff: link to earlier in this thread.

EDIT: MarkL, must have pressed "reply" at the same time! Great minds, right?  :)  :P

I believe that third one still a bug. Including pictures, input signal is a 1 kHz square wave 50% duty cycle, the hold off is set to 100ns and only by changing the time base (nothing else) some times it will triggers on both falling/rising, notice didn't change anything else other then time base.

Scope Details:
MSO2202A, SW ver 00.03.01, HW ver 2.2
« Last Edit: November 20, 2014, 07:52:39 am by wlanfox »
 

Offline rs20

  • Super Contributor
  • ***
  • Posts: 2182
  • Country: au
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #355 on: November 20, 2014, 08:06:15 am »
I believe that third one still a bug. Including pictures, input signal is a 1 kHz square wave 50% duty cycle, the hold off is set to 100ns and only by changing the time base (nothing else) some times it will triggers on both falling/rising, notice didn't change anything else other then time base.

Scope Details:
MSO2202A, SW ver 00.03.01, HW ver 2.2

This is very, very interesting. For context, having the effective holdoff "change" as the timebase is manipulated is standard fare for analog oscilloscopes (or at least, the one analog I've played with). The reason is that the holdoff period doesn't start until the horizontal sweep is completed; which means that the distance between triggers is timebase + holdoff. So a change in behaviour due only to a timebase change is completely expected...

Except, in the video in my earlier post, I demonstrated very explicitly that the Rigol DS2202 doesn't do this. The holdoff is measured from the trigger point, and the selected timebase has absolutely no bearing on the trigger behaviour -- down to the exact nanosecond value of holdoff that flips it between states. So it's extremely strange that your Rigol MSO2202A is behaving more like a Hitachi 20MHz Analog CRO than a Rigol DS2202.

To confirm exactly how it's behaving, could you please show the behaviour with the following 6 holdoff settings:

200us/div, holdoff = about 0.3ms (that's 300us, or 300k ns)
200us/div, holdoff = about 0.7ms
200us/div, holdoff = about 1ms
And the same three holdoffs, but with 500 us/div.

That way, we can see if it's just the timebase futzing with the holdoff settings, or something more broken.
« Last Edit: November 20, 2014, 08:25:21 am by rs20 »
 

Offline wlanfox

  • Newbie
  • Posts: 4
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #356 on: November 20, 2014, 08:25:53 am »
I believe that third one still a bug. Including pictures, input signal is a 1 kHz square wave 50% duty cycle, the hold off is set to 100ns and only by changing the time base (nothing else) some times it will triggers on both falling/rising, notice didn't change anything else other then time base.

Scope Details:
MSO2202A, SW ver 00.03.01, HW ver 2.2

This is very, very interesting. For context, having the effective holdoff "change" as the timebase is manipulated is standard fare for analog oscilloscopes (or at least, the one analog I've played with). The reason is that the holdoff period doesn't start until the horizontal sweep is completed; which means that the distance between triggers is timebase + holdoff. So a change in behaviour due only to a timebase change is completely expected...

Except, in the video that I linked in my earlier post, I demonstrated very explicitly that the Rigol DS2202 doesn't do this. The holdoff is measured from the trigger point, and the selected timebase has absolutely no bearing on the trigger behaviour -- down to the exact nanosecond value of holdoff that flips it between states. So it's extremely strange that your Rigol MSO2202A is behaviour more like a Hitachi 20MHz Analog CRO than a Rigol DS2202.

To confirm exactly how it's behaving, could you please show the behaviour with the follow 6 settings:

200us/div, holdoff = about 0.3ms (that's 300us, or 300k ns)
200us/div, holdoff = about 0.7ms
200us/div, holdoff = about 1ms
And the same, but with 500 us/div.

That way, we can see if it's just the timebase futzing with the holdoff settings, or something more broken.

FYI I quickly tried on my old DS1052E, and it trigger just fine on both edges at 300us holdoff (and it kept trigger on both all the way from 500ns to 300us), I had tried it before to compare.

here they are:

« Last Edit: November 20, 2014, 09:36:56 am by wlanfox »
 

Offline Fagear

  • Regular Contributor
  • *
  • Posts: 83
  • Country: ru
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #357 on: November 20, 2014, 09:18:01 am »
I suspect this bug only exists in the documentation and user interface with external triggering only supporting DC coupling because of the hardware.
But it is still a bug. ;)
And I mentioned it in the video: Rigol either have to remove coupling settings for EXT input (due to hardware) or fix all items in the menu.
I don't know which way they designed trigger circuit, but if it is "purely digital" (as it is for analog channels) maybe they can implement "AC coupling" on EXT input as well.
And it will be nice if they'll add multiplier setting for the EXT input (0.0001x...1000x) as it is in the channel menu (for correct trigger voltage display).
DS4000 does AC coupling for EXT input as well as voltage multiplier auto sensing.
« Last Edit: November 20, 2014, 09:20:49 am by Fagear »
 

Offline rs20

  • Super Contributor
  • ***
  • Posts: 2182
  • Country: au
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #358 on: November 20, 2014, 12:41:47 pm »
here they are:

Very interesting, thank you for doing that. Something whacky is going on there because regardless of how holdoff is implemented (with respect to when the holdoff countdown begins), adding one full waveform period (1ms in this 1kHz case) to the holdoff setting should produce identical results. So your "1ms" results should look identical to the 100ns (let's call it 0ms) results from your earlier post. But they're backwards, reversed. However, on the other hand, changing holdoff is changing the behaviour, so it's close to right. Sort of. I don't suppose 0.95ms or 1.05ms produce different results? We might just be sitting on a noisy edge case. (Sorry, in hindsight the holdoffs I chose were... poorly chosen.) No need to upload screenshots, just report whether there's a change in behavious when moving +/- 0.05ms from 1ms holdoff.

I wish I could be there to try putting in different frequencies, figuring out exactly which holdoff values cause the waveform to transitions from locked/unlocked, inferring what the true trigger-to-trigger holdoff values are... sounds like a fun debugging job!

I suspect this bug only exists in the documentation and user interface with external triggering only supporting DC coupling because of the hardware.
But it is still a bug. ;)
And I mentioned it in the video: Rigol either have to remove coupling settings for EXT input (due to hardware) or fix all items in the menu.
I don't know which way they designed trigger circuit, but if it is "purely digital" (as it is for analog channels) maybe they can implement "AC coupling" on EXT input as well.
And it will be nice if they'll add multiplier setting for the EXT input (0.0001x...1000x) as it is in the channel menu (for correct trigger voltage display).
DS4000 does AC coupling for EXT input as well as voltage multiplier auto sensing.

I'm fairly sure it's not implemented as the same way as the analog channels, at least on the DS2202, because the EXT input is not available for triggering modes other than "Edge". This indicates to me that there isn't a dedicated ADC on the EXT input. (Well, there is a 1-bit ADC, also known as a comparator :P ). The DS4000 is expensive so maybe they sprung for a real ADC, or maybe even real AC coupling (you know, with a capacitor!!!). What trigger modes (e.g. Pulse, Slope, RS232!?) are supported by EXT on the DS4000?
 

Online MarkL

  • Supporter
  • ****
  • Posts: 1598
  • Country: us
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #359 on: November 20, 2014, 01:55:56 pm »
Short and not explanatory, but:

Quote
1: We have reproduced the two issues in R&D side;
2: All issues can be fixed by firmware updating without deleting any feature;
3: The trail firmware form R&D will be released in early next week, that can be used for Dave or some urgent cases.

It would be greatly appreciated if they or you would post both the trial firmware and the previous full release version as open downloads instead of having to play the email game to get them.

When they announce availability of a fix, I think everyone who wants a copy should barrage their technical support system and open a case to request it.

Make them fix this ridiculous software distribution method.
 

Online dr.diesel

  • Super Contributor
  • ***
  • Posts: 2162
  • Country: us
  • Cramming the magic smoke back in...
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #360 on: November 20, 2014, 03:07:28 pm »
A cold beer says they will fix the 1000/2000 and ignore the 4000s.

Offline David Hess

  • Super Contributor
  • ***
  • Posts: 10691
  • Country: us
  • DavidH
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #361 on: November 20, 2014, 04:34:22 pm »
The menu options to select AC coupling need to go away on the DS2000A when using the external trigger.  I've confirmed as well that it only supports DC coupling.  You can of course put a cap inline and now you have your AC coupling  :-\

The thing I find amusing about this is that the oscilloscope I use most often has no AC trigger coupling selection for the internal trigger (it supports peak-to-peak triggering instead) but does have selectable AC coupling on the external trigger input.  The reason for this is that the internal trigger can make use of the AC coupling from the vertical input which has been suggested as a work-around for the Rigol oscilloscopes while the external trigger cannot and has to support AC coupling on its own which the Rigol DS2000A series apparently does not.  The Rigol DS1000Z series does not have a problem with this because it relies on its extra vertical inputs as external trigger inputs and they support AC coupling just fine.

There is a parallel here with some of the old portable 4 channel Tektronix oscilloscopes; their two extra channels are limited in only supporting DC coupling like the DS2000A.  Just like with the DS2000A external trigger input, their 3rd and 4th channel cannot remove large DC offsets to pass just the AC signal.  I like to think of them as oscilloscopes with an improved "trigger view" function and 2 external trigger inputs instead of as 4 channel oscilloscopes.  Their extra inputs are very handy for digital logic signals which is probably what Tektronix had in mind.

I don't know which way they designed trigger circuit, but if it is "purely digital" (as it is for analog channels) maybe they can implement "AC coupling" on EXT input as well.
And it will be nice if they'll add multiplier setting for the EXT input (0.0001x...1000x) as it is in the channel menu (for correct trigger voltage display).
DS4000 does AC coupling for EXT input as well as voltage multiplier auto sensing.

I'm fairly sure it's not implemented as the same way as the analog channels, at least on the DS2202, because the EXT input is not available for triggering modes other than "Edge". This indicates to me that there isn't a dedicated ADC on the EXT input. (Well, there is a 1-bit ADC, also known as a comparator :P ). The DS4000 is expensive so maybe they sprung for a real ADC, or maybe even real AC coupling (you know, with a capacitor!!!). What trigger modes (e.g. Pulse, Slope, RS232!?) are supported by EXT on the DS4000?

This is what I concluded about the DS2000A external trigger input as well.  If it was just another digitized input, then it would support all of the trigger modes that the vertical inputs support.  That the external trigger input only supports edge triggering points toward a more traditional analog trigger circuit using a comparator and in the case of the DS2000A, they apparently left out the AC coupling which a vertical input would include.

On the other hand if it was just another digitized input, then why go to the expense of including another digitizer and not have 3 or 4 channels like the DS1000Z series?  This also points toward the external trigger input using an analog trigger design.

What this does not explain however is how Rigol gets the same timing resolution on the DS2000A external trigger input as on the vertical inputs.  Either they had to implement a digital time delay counter in the FPGA logic which is certainly possible or they did something more clever.
 

Offline alank2

  • Super Contributor
  • ***
  • Posts: 2004
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #362 on: November 20, 2014, 05:01:55 pm »
A cold beer says they will fix the 1000/2000 and ignore the 4000s.

Is the 5uS a ds4k issue?  Or do you mean the ac trigger issue?  Or both?
 

Online dr.diesel

  • Super Contributor
  • ***
  • Posts: 2162
  • Country: us
  • Cramming the magic smoke back in...
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #363 on: November 20, 2014, 05:04:58 pm »
A cold beer says they will fix the 1000/2000 and ignore the 4000s.

Is the 5uS a ds4k issue?  Or do you mean the ac trigger issue?  Or both?

Only item I can reproduce is the delay jitter, but it doesn't alternate from bad to good every 5us, the greater the delay the more bad.

Offline marmad

  • Super Contributor
  • ***
  • Posts: 2979
  • Country: aq
    • DaysAlive
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #364 on: November 20, 2014, 06:22:19 pm »
Every other manufacturer (and even half of the cheap DIY china scopes) is capable of implementing AC coupled trigger/channel, so where is the problem for Rigol?
there must be something wrong with you:

1- in lot of countries one have to give lot of blowjobs to earn $400 (and cheap does not means bad or broken)
2- fully loaded DS2000A costs nearly $4000, and it does have same shit bug (that should be enought to care, right?)

Man, if I had a dollar for each time the Hantekway DSO crashed on me - or a feature didn't work as advertised - I would have had that $400 lickety-split. I have to say, considering the absolute mess of the FW in the Hantekway, I had to laugh when I read your post, Thomas  ;D

The fact of the matter is that EVERY low-cost Chinese DSO has problems - every single one. The new Siglent SDS2000 was released with 2 of the 4 main acquisition modes not functioning correctly (Peak Detect / High Res) - and that DSO can cost even more than your "fully loaded" figure from above. As a buyer, all you can do is hope that the company will eventually sort out all of the problems (and there are almost always a fair amount of them when new Chinese models are released), and often they will - over time.

And it's fine if you (and others here) claim to use AC-coupled triggering every day. I (and many many others) don't - so as far as bugs go, it's less important to me than, for example, the DSO crashing every hour or so - or the main acquisition modes not functioning correctly.
« Last Edit: November 21, 2014, 04:05:28 pm by marmad »
 

Offline alank2

  • Super Contributor
  • ***
  • Posts: 2004
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #365 on: November 20, 2014, 06:22:57 pm »
Only item I can reproduce is the delay jitter, but it doesn't alternate from bad to good every 5us, the greater the delay the more bad.

I think it might be something different than the 5us delay jitter issue.  It happens on mine if I push the trigger off the display a bit, with an occasional off screen trigger not always doing it.  I think it has to do with the intensity grading, but perhaps not.  It does not get better and worse though as far as I can tell, but perhaps I need to evaluate it wave by wave to see if the interval is different than 5us...
 

Offline David Hess

  • Super Contributor
  • ***
  • Posts: 10691
  • Country: us
  • DavidH
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #366 on: November 20, 2014, 06:45:26 pm »
Only item I can reproduce is the delay jitter, but it doesn't alternate from bad to good every 5us, the greater the delay the more bad.

I think it might be something different than the 5us delay jitter issue.  It happens on mine if I push the trigger off the display a bit, with an occasional off screen trigger not always doing it.  I think it has to do with the intensity grading, but perhaps not.  It does not get better and worse though as far as I can tell, but perhaps I need to evaluate it wave by wave to see if the interval is different than 5us...

The jitter is the sum of the jitter from the trigger and the long period jitter from the sampling clock.  It should get worse with longer delays but how much delay are we talking about here?  100s of microseconds?  Milliseconds?

My 2440 can only delay out to 500 microseconds at its highest sampling rate and at that point the added jitter is insignificant although barely measurable and no more than what would be expected from a crystal controlled timebase.  It has less than 200ps of trigger jitter and less than 400ps of total jitter at a delay of 500 microseconds.
 

Offline H.O

  • Frequent Contributor
  • **
  • Posts: 641
  • Country: se
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #367 on: November 20, 2014, 07:14:57 pm »
Quote
Only item I can reproduce is the delay jitter, but it doesn't alternate from bad to good every 5us, the greater the delay the more bad
Quote
The jitter is the sum of the jitter from the trigger and the long period jitter from the sampling clock.
As far as I can see neither the 5us delay issue nor the AC coupled trigger issue have been confirmed on the DS4k. I've tried three times during the week and I can't reproduce it. Yes dr.diesels video does show jitter as the delay gets larger but I'd certainly expect that, especially with a DDS generator (which I don't know if dr.diesel used or not but I am)

Anyway, here's another screenshot from my DS4 with a 10MHz square wave (from DG4162), 25us delay and AC coupled trigger.
 

Offline marmad

  • Super Contributor
  • ***
  • Posts: 2979
  • Country: aq
    • DaysAlive
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #368 on: November 20, 2014, 07:16:05 pm »
This is very, very interesting. For context, having the effective holdoff "change" as the timebase is manipulated is standard fare for analog oscilloscopes (or at least, the one analog I've played with).
No, it's really not that interesting if you understand how the DSO works - and it has nothing to do with holdoff per se (although changing the holdoff can affect it). The DS2000 does EITHER Edge triggering - as opposed to ALTERNATING Edge triggering (as many low cost DSOs use) - so having it lock onto a single edge is just simply hitting a multiple of the input frequency and blind time (i.e. waveform update rate) at any particular timebase. You can actually use this "feature" to measure waveform update rate in the absence of a Trigger Out, as I showed in a video I posted here.





To clarify: there is absolutely NO BUG involving the DS2000's Either Edge triggering - it works just fine.

...at least on the DS2202, because the EXT input is not available for triggering modes other than "Edge".
This is also wrong. It's available as a source to the "Pulse" trigger as well.
« Last Edit: November 20, 2014, 07:43:45 pm by marmad »
 

Offline jlmoon

  • Supporter
  • ****
  • Posts: 608
  • Country: us
  • If you fail the first time, keep trying!
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #369 on: November 20, 2014, 07:40:48 pm »
A cold beer says they will fix the 1000/2000 and ignore the 4000s.

Is the 5uS a ds4k issue?  Or do you mean the ac trigger issue?  Or both?

Only item I can reproduce is the delay jitter, but it doesn't alternate from bad to good every 5us, the greater the delay the more bad.

5us or 5ns?  I concur with this as well, I see the jitter at 0 - end of graticule on my 2000, not just every other 5ns interval as some are experiencing.
Recharged Volt-Nut
 

Online dr.diesel

  • Super Contributor
  • ***
  • Posts: 2162
  • Country: us
  • Cramming the magic smoke back in...
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #370 on: November 20, 2014, 07:46:17 pm »
Yes dr.diesels video does show jitter as the delay gets larger but I'd certainly expect that, especially with a DDS generator (which I don't know if dr.diesel used or not but I am)

My first video was done with a DG4000, and it was definitely worse than the others, the next two were done with a 16/20Mhz OCXO.

I no longer have anything better than the MSO4000 to test against, and to be completely honest, I rarely run/scroll that far back, on any of my scopes, perhaps I am just expecting too much.

Appreciate those that attempted to recreate.

Offline alank2

  • Super Contributor
  • ***
  • Posts: 2004
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #371 on: November 20, 2014, 09:01:53 pm »
H.O. can you post that same image at T=0?  Does it look better at T=0?
 

Offline i4004

  • Regular Contributor
  • *
  • Posts: 71
  • Country: hr
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #372 on: November 20, 2014, 09:10:09 pm »
I (and many many others) don't - so as far as bugs go, it's WAY less important to me than, for example, the DSO crashing every hour or so - or the main acquisition modes not functioning correctly.

and how much do you use scrolling thru the waveform?
 

Offline marmad

  • Super Contributor
  • ***
  • Posts: 2979
  • Country: aq
    • DaysAlive
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #373 on: November 20, 2014, 09:20:30 pm »
I (and many many others) don't - so as far as bugs go, it's WAY less important to me than, for example, the DSO crashing every hour or so - or the main acquisition modes not functioning correctly.

and how much do you use scrolling thru the waveform?

Do you mean while using Delayed Sweep or with Segments? I'm not sure I understand the question (in the context of the bugs we're discussing here), but I would say I use scrolling during about 50% of the DSO usage. Either I'm rarely using it (usually when I'm focused on using the fastest timebases) - or I'm using it a lot (long, slow captures, segments, or bus decoding).
 

Offline marmad

  • Super Contributor
  • ***
  • Posts: 2979
  • Country: aq
    • DaysAlive
Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #374 on: November 20, 2014, 09:26:16 pm »
BTW, as far as these bugs go - while they are certainly annoying and need to be fixed by Rigol - if I was a new owner of a DS1000Z series, I'd be more pissed about the fact that High Resolution mode doesn't work correctly (certainly not to 12 bits) than I would about these bugs.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf