Author Topic: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems  (Read 409970 times)

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Offline jkrichards

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Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #450 on: November 23, 2014, 03:49:37 am »
(...) Attached is a montage of 4 different screenshots. T=0, T=5us, T=15us and T=105us. Same 10MHz Square wave from DG4162, 50% dutycycle. Input DC coupled, trigger AC coupled. For reference, this is on a DS4k.

As you can see it does a look a bit better at T=0 and gets progressively worse as T increases (as expected). It's not much of a difference between T=0 and T=15 but it's clearly vissible at T=105us.

It looks more like intensity level feature related, because all images have actually basically the same trace width (5 pixels), but on the smaller T ones you have a stronger central trace line and that gets dimmer and dimmer with increasing T. I guess I would implement the core intensity level feature (phosphor "inertia") by setting the trace intensity to a function of its T ("older" traces get drawn dimmer)... maybe some confusion here.

What does this have to do with the topic here???  These off topic post make it really hard to follow the original intent.  over 2 pages of resolution jabbering and false promises to take it elsewhere.   |O  Mods.... Is there a way these OT post can be moved?

Seriously? They are discussing the jitter mentioned by Dave. Perhaps you need to relax and get to know the way this forum operates - some of the best stuff here happens perpendicular-to-topic.

How is this related to the jitter issue?  Sorry I thought this was part of the ongoing resolution discussion.
« Last Edit: November 23, 2014, 03:53:08 am by jkrichards »
 

Offline marmad

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Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #451 on: November 23, 2014, 03:53:06 am »
How is this related to the jitter issue?

The images are an attempt to duplicate the jitter issue on a DS4000 - another of the Rigol UltraVision DSOs which Dave doesn't own, but which I'm sure he would have tested if he had (as he did with the DS2000).
 

Offline jkrichards

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Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #452 on: November 23, 2014, 03:54:57 am »
How is this related to the jitter issue?

The images are an attempt to duplicate the jitter issue on a DS4000 - another of the Rigol UltraVision DSOs which Dave doesn't own, but which I'm sure he would have tested if he had (as he did with the DS2000).


Sorry, I thought this topic was the Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems discussion.  My bad... Ill move on.
« Last Edit: November 23, 2014, 03:59:57 am by jkrichards »
 

Offline TheBay

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Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #453 on: November 23, 2014, 03:53:52 pm »
(...) Attached is a montage of 4 different screenshots. T=0, T=5us, T=15us and T=105us. Same 10MHz Square wave from DG4162, 50% dutycycle. Input DC coupled, trigger AC coupled. For reference, this is on a DS4k.

As you can see it does a look a bit better at T=0 and gets progressively worse as T increases (as expected). It's not much of a difference between T=0 and T=15 but it's clearly vissible at T=105us.

It looks more like intensity level feature related, because all images have actually basically the same trace width (5 pixels), but on the smaller T ones you have a stronger central trace line and that gets dimmer and dimmer with increasing T. I guess I would implement the core intensity level feature (phosphor "inertia") by setting the trace intensity to a function of its T ("older" traces get drawn dimmer)... maybe some confusion here.

What does this have to do with the topic here???  These off topic post make it really hard to follow the original intent.  over 2 pages of resolution jabbering and false promises to take it elsewhere.   |O  Mods.... Is there a way these OT post can be moved?

Seriously? They are discussing the jitter mentioned by Dave. Perhaps you need to relax and get to know the way this forum operates - some of the best stuff here happens perpendicular-to-topic.

Well said  :-+
 

Offline Nonorthogonal

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Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #454 on: November 25, 2014, 12:47:59 pm »
Any update from Rigol on a fix? Some of us are approaching the 30 day return window.

If anyone out there has a bodge for the ADF4360-7 to fix the 100 KHz modulation... I'm prepared to void my warranty! ;D
 

Offline Bud

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Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #455 on: November 25, 2014, 03:42:23 pm »
I can build a small board with a good 1Ghz clock and mail to you. Let me check if i have any proto PCBs left, if not i will order. But lets see first what Rigol has to say this week as they promised.
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Offline MrElectro

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Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #456 on: November 25, 2014, 05:21:09 pm »
I can build a small board with a good 1Ghz clock and mail to you. Let me check if i have any proto PCBs left, if not i will order. But lets see first what Rigol has to say this week as they promised.

Would this board replace / bypass the ADF4360-7 ?
 

Offline Bud

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Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #457 on: November 25, 2014, 05:31:13 pm »
It would have its own 4360-7 IC. The one on the scope can technically be used and reprogrammed  but that would require doing some damage to the PCB traces to hijack the SPI bus. We can do a less intrusive by just unsoldering the existing two decoupling capacitors and injecting our own clock. That is what i am thinking.

Alternatively, we could remove the decoupling cap on the 25 Mhz reference line and connect an external signal gen and vary frequency a little and see if the PLL locks. If Nonorthogonal has a suitable signal gen he could try this now.

ADDED: And the indication of a lock condition would be the voltage on the 4360-7 CP pin going from sawtooth to a straight line at some level of DC. Once that is achieved, go and recheck if the 5us jitter gone.
« Last Edit: November 25, 2014, 06:19:27 pm by Bud »
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Offline MrElectro

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Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #458 on: November 25, 2014, 07:49:51 pm »
It would have its own 4360-7 IC. The one on the scope can technically be used and reprogrammed  but that would require doing some damage to the PCB traces to hijack the SPI bus. We can do a less intrusive by just unsoldering the existing two decoupling capacitors and injecting our own clock. That is what i am thinking.

Alternatively, we could remove the decoupling cap on the 25 Mhz reference line and connect an external signal gen and vary frequency a little and see if the PLL locks. If Nonorthogonal has a suitable signal gen he could try this now.

ADDED: And the indication of a lock condition would be the voltage on the 4360-7 CP pin going from sawtooth to a straight line at some level of DC. Once that is achieved, go and recheck if the 5us jitter gone.

Could the 4360-7 be reprogrammed with a firmware update?  If Rigol doesn't come through with a fix at least we have other options.
 

Offline Bud

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Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #459 on: November 25, 2014, 07:55:33 pm »
The IC gets initialized at power up, so should be reprogrammable via firmware updates from Rigol.
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Offline NiHaoMike

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Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #460 on: November 25, 2014, 08:08:46 pm »
Maybe use a spectrum analyzer to make sure it really is a noisy sampling clock and not a strange bug in the digital trigger?
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Offline XFDDesign

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Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #461 on: November 25, 2014, 08:48:06 pm »
Changing the component values of the loop-filter is more likely to be an easier and more effective solution -- if it's actually the PLL to begin with.

Maybe use a spectrum analyzer to make sure it really is a noisy sampling clock and not a strange bug in the digital trigger?

The SpecAn would be the best tool to look at the output of the VCO, if it didn't load down the system. As well, it would display any jitter as "phase noise." The thing is, looking at the Charge-pump/VTune pin is the easier and less invasive route. When you look at MikeL's picture (https://www.eevblog.com/forum/index.php?action=dlattach;topic=38902.0;attach=119488;image) you see a ramp-like behavior on a period of 10uS with a bunch of noise riding on it. The loop filter is likely running around 100kHz with a 10MHz PFD frequency. The integrating nature of the '4360's VCO is doubtful to be slow enough to "neglect" the noise on the CP and average it out. Redesign the loop-filter for something slower, and you will likely see the whole system clean up.
« Last Edit: November 25, 2014, 08:56:23 pm by XFDDesign »
 

Online MarkL

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Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #462 on: November 26, 2014, 03:34:17 pm »
It would have its own 4360-7 IC. The one on the scope can technically be used and reprogrammed  but that would require doing some damage to the PCB traces to hijack the SPI bus. We can do a less intrusive by just unsoldering the existing two decoupling capacitors and injecting our own clock. That is what i am thinking.

Alternatively, we could remove the decoupling cap on the 25 Mhz reference line and connect an external signal gen and vary frequency a little and see if the PLL locks. If Nonorthogonal has a suitable signal gen he could try this now.

ADDED: And the indication of a lock condition would be the voltage on the 4360-7 CP pin going from sawtooth to a straight line at some level of DC. Once that is achieved, go and recheck if the 5us jitter gone.

If the on-board 4360-7 is to be replaced with something else, it should be verified that Rigol is not programming any other frequency into it when other sweep speeds are selected.  Since the part is only spec'd for 350MHz to 1800MHz, the only other option would be 500MHz to fit nicely into the ADC and sweep selection.

I think it's highly unlikely they're changing the frequency anyway, but it's not beyond possibility.

For me, I'm going to wait to see what Rigol comes up with.  No word yet.
 

Offline Bud

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Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #463 on: November 26, 2014, 04:35:54 pm »
The purpose of the test is to see if this is indeed what is causing the 5uS screaming issue. Other modes can be checked too, including AC trigger coupling but that is secondary. Rigol will need to fix that one first and anyway.
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Offline Bud

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Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #464 on: November 26, 2014, 04:41:30 pm »
Maybe use a spectrum analyzer to make sure it really is a noisy sampling clock and not a strange bug in the digital trigger?

Good idea. Please see page 19 of this thread.
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Offline Bud

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Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #465 on: November 26, 2014, 04:58:33 pm »
MarkL,
Can you measure all or any of this:

25Mhz oscillator frequency
Loop filter component values
PLL programming data at power up

We could plug it in to the simulator and see if makes sense
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Online MarkL

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Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #466 on: November 26, 2014, 05:12:31 pm »
The purpose of the test is to see if this is indeed what is causing the 5uS screaming issue.
I guess I lost track that this was just for a test and not for a fix that was being proposed.  My bad.

MarkL,
Can you measure all or any of this:

25Mhz oscillator frequency
Loop filter component values
PLL programming data at power up

We could plug it in to the simulator and see if makes sense

I can but I'm out traveling for the holiday (US Thanksgiving) for the rest of the week.  I can do it when I get back early next week if Rigol still has no response.  It's going to take a little more disassembly since the loop filter components are on the underside.  I haven't gone that far yet.
 

Offline Bud

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Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #467 on: November 26, 2014, 06:45:48 pm »
Thanks MarkL. I can actually see in the board level photos the two loop filter resistors marked 55B and 93A, a search on smt resistor marking resulted in 3.65K and 909 Ohm. And two out of the three capacitors could probably be measured by simply measuring the capacitance from pins CP and Tune to ground. So just one unknown will be left if do not want to disassemble the scope.


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Offline jkrichards

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Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #468 on: November 26, 2014, 08:32:42 pm »
I received an email from Rigol this AM.  They are testing the beta firmware now and should release it soon.  They have been very responsive to these issues.  I take back my comment about not purchasing another Rigol product as it turns out they proved to have excellent customer service.  Remember this issue was discovered only a week or so ago and will most likely have it fixed this week.  :clap:
 

Offline Bud

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Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #469 on: November 26, 2014, 09:21:41 pm »
Didn't people say AC trigger coupling problem was reported 2 years ago?
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Offline dr.diesel

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Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #470 on: November 26, 2014, 09:30:05 pm »
have excellent customer service.

Only because it was reveled on one of Dave's videos.  The forum has many examples of Rigol completely ignoring issues and problems. 

I and many others have contacted Rigol with dozens of issues on the 4000 series and have been completely ignored for almost a full year now.

Offline pickle9000

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Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #471 on: November 26, 2014, 09:35:39 pm »
Customer service often require "a little push". Loss of sales will get the fastest action.
 

Offline jkrichards

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Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #472 on: November 26, 2014, 10:03:14 pm »
have excellent customer service.

Only because it was reveled on one of Dave's videos.  The forum has many examples of Rigol completely ignoring issues and problems. 

I and many others have contacted Rigol with dozens of issues on the 4000 series and have been completely ignored for almost a full year now.

I think he just revealed the AC triggering issue in the same video.  Maybe that will be fixed in the 4000 also.
 

Offline Hydrawerk

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Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #473 on: November 26, 2014, 10:35:17 pm »
It is funny that there are bugs in DS4000 series while this is an expensive scope with good hardware that is not intended for hobbyists.  :(
And it was released in January 2012 or so (?).
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Offline Bud

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Re: EEVblog #683 - Rigol DS1000Z & DS2000 Oscilloscope Jitter Problems
« Reply #474 on: November 26, 2014, 10:48:55 pm »
That is why i called them a mickey mouse company, i. e. not serious. I think i saw someone saying they worked for Agilent. Well may be, but i think it was Agilent who was in charge of the quality control part of the house.
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