Author Topic: Help: My New Rigol DS1054Z Shows a Weird Double Trace  (Read 4754 times)

0 Members and 1 Guest are viewing this topic.

Offline Porcine Porcupine

  • Contributor
  • Posts: 35
  • Country: us
Help: My New Rigol DS1054Z Shows a Weird Double Trace
« on: November 30, 2017, 09:51:12 am »
I just bought a Rigol DS1054Z and received it today.

I've been playing with it a couple hours and can't figure out why it displays double traces. See the attached screenshots to see what I mean.

It just looks like noise when the display type is set to vector, but it becomes two separate traces when set to dots. It doesn't matter what the signal source is, and it also does it if the probe is grounded. The behavior is identical on all four channels.

I Googled the problem and found a Reddit thread posted by someone with the exact same problem. They returned their unit and received a replacement with the same problem.

https://www.reddit.com/r/AskElectronics/comments/5mi24b/recently_purchased_a_rigol_ds1054z_oscilliscope_i/

Mine has firmware version 00.04.04.SP3 (which I think is the latest) and board version 0.1.4.

I did a factory reset by pressing the fifth soft button to the left of the screen while booting, but that didn't make a difference. Doing the self calibration didn't help either. I have made no attempt to hack or upgrade the unit.

The Reddit poster seems to think it is a firmware bug that causes the peak detect and normal acquisition modes to render simultaneously when in normal acquisition mode. And just like the Reddit poster, I also get a single trace only in high resolution acquisition mode.

Does anyone know what's wrong with my oscilloscope and how to fix it?
 

Online Fungus

  • Super Contributor
  • ***
  • Posts: 8671
  • Country: 00
Re: Help: My New Rigol DS1054Z Shows a Weird Double Trace
« Reply #1 on: November 30, 2017, 11:04:09 am »
The Reddit poster seems to think it is a firmware bug that causes the peak detect and normal acquisition modes to render simultaneously when in normal acquisition mode. And just like the Reddit poster, I also get a single trace only in high resolution acquisition mode.

Nope. If that was true then everybody else would be seeing it,

Does anyone know what's wrong with my oscilloscope and how to fix it?

If you did a factory reset then I doubt it's the settings.

What's your probe set to? 1x or 10x? How are you probing? Do you press the hook on until it clicks into place?

What's your grounding like? Does your mains socket have a ground wire?
 

Offline rhb

  • Super Contributor
  • ***
  • Posts: 1747
  • Country: us
Re: Help: My New Rigol DS1054Z Shows a Weird Double Trace
« Reply #2 on: November 30, 2017, 11:05:55 am »
Connect the probe to the calibrator output.  That should be a known good signal.
 

Offline SkyMaster

  • Regular Contributor
  • *
  • Posts: 246
  • Country: ca
Re: Help: My New Rigol DS1054Z Shows a Weird Double Trace
« Reply #3 on: November 30, 2017, 11:10:06 am »
Hi Porcine Porcupine,

Do you have this problem only on channel 1, or on all of them?

Are you using a probe? Did you try the other probes?

 :)
 

Offline StillTrying

  • Super Contributor
  • ***
  • Posts: 1443
  • Country: gb
  • 100% Brand New and High Quality, in theory.
Re: Help: My New Rigol DS1054Z Shows a Weird Double Trace
« Reply #4 on: November 30, 2017, 11:27:43 am »
It certainly looks like peak detect, is the 2nd sine image triggering on the wrong edge?

Offline Porcine Porcupine

  • Contributor
  • Posts: 35
  • Country: us
Re: Help: My New Rigol DS1054Z Shows a Weird Double Trace
« Reply #5 on: November 30, 2017, 12:16:37 pm »
If you did a factory reset then I doubt it's the settings.

What's your probe set to? 1x or 10x? How are you probing? Do you press the hook on until it clicks into place?

What's your grounding like? Does your mains socket have a ground wire?

I've tried a couple of the Rigol probes that came with the unit and another probe I already had. I've tried them on 1x and 10x. I pulled the hook off one of the Rigol probes and put it back. I connected the probe to the calibration output on the oscilloscope with and without the probe's ground clip connected to the ground tab under the signal output. I also connected a function generator to the oscilloscope through a BNC cable. The double trace was always there.

Grounding should be good. The house I'm in was built about 30 years ago in compliance with the codes of the time. All the wall sockets have dedicated ground conductors. The ground and neutral wires are bonded only in the main breaker panel as they should be per the NEC, and the ground is connected to a copper ground rod driven into the ground near the main panel.

I verified continuity between the oscilloscope's ground and the power cord's ground prong. I tried plugging the oscilloscope into a surge protector that provides filtering and directly into several wall sockets on different circuits, but the double trace persisted.

Connect the probe to the calibrator output.  That should be a known good signal.

The screenshot I posted of the square wave is the oscilloscope's calibration output. The sine wave in the other screenshot is from a function generator connected through a BNC cable.

Hi Porcine Porcupine,

Do you have this problem only on channel 1, or on all of them?

Are you using a probe? Did you try the other probes?

 :)

The same double trace is displayed on all four channels.

I've tried two of the supplied probes and a third one I already had. I also tried connecting the oscilloscope with a BNC cable to a function generator. The double trace is always there.

It certainly looks like peak detect, is the 2nd sine image triggering on the wrong edge?

I'm not sure about the triggering. The sine wave looked a bit jittery like maybe it wasn't properly triggering consistently, but I attributed that to the cheap function generator (Sinometer VC2002) I was using.
 

Offline alsetalokin4017

  • Super Contributor
  • ***
  • Posts: 1798
  • Country: us
Re: Help: My New Rigol DS1054Z Shows a Weird Double Trace
« Reply #6 on: November 30, 2017, 12:36:39 pm »
Well, isn't that strange. I can reproduce the issue exactly as described here and in the reddit thread.

Even to the point of seeing the double trace when using the probe > FG but not when using a direct BNC patch cable connection from FG to scope.

However I can also state that I have never seen any problem like this when actually using the scope with realistic settings to display actual signals from a DUT.

My scope is running 00.04.04.03.02 ( aka 00.04.04.SP3)  Board ver. 0.1.1

Some example scopeshots from my actual usage of the scope: no such problem is evident.




... So I'm going to fall back on the old joke:

"Doctor, it only hurts when I do this!"
"Well, so don't do that!"

(Or the ultimate Rigol comeback: It's only a 400 dollar scope, what did you expect?)     |O
« Last Edit: November 30, 2017, 12:44:31 pm by alsetalokin4017 »
The easiest person to fool is yourself. -- Richard Feynman
 

Offline StillTrying

  • Super Contributor
  • ***
  • Posts: 1443
  • Country: gb
  • 100% Brand New and High Quality, in theory.
Re: Help: My New Rigol DS1054Z Shows a Weird Double Trace
« Reply #7 on: November 30, 2017, 12:45:15 pm »
It certainly looks like peak detect, is the 2nd sine image triggering on the wrong edge?
I'm not sure about the triggering. The sine wave looked a bit jittery like maybe it wasn't properly triggering consistently, but I attributed that to the cheap function generator (Sinometer VC2002) I was using.

I don't think there's any excuse for the wrong edge to be at the trigger position.

Try to produce a 1 or 2 Vpp mains waveform by touching the probe tip to see if it's mains related.

http://www.eevblog.com/forum/testgear/new-rigol-ds1054z-oscilloscope/msg1178338/#msg1178338
http://www.eevblog.com/forum/testgear/new-rigol-ds1054z-oscilloscope/msg1178420/#msg1178420

Offline Porcine Porcupine

  • Contributor
  • Posts: 35
  • Country: us
Re: Help: My New Rigol DS1054Z Shows a Weird Double Trace
« Reply #8 on: November 30, 2017, 01:02:43 pm »
Nope. If that was true then everybody else would be seeing it,

I agree, but I wonder if maybe the firmware could be corrupt or something. I'm tempted to try reloading the firmware, but I'm not sure if it will allow that if it already has the latest version.

Well, isn't that strange. I can reproduce the issue exactly as described here and in the reddit thread.

Even to the point of seeing the double trace when using the probe > FG but not when using a direct BNC patch cable connection from FG to scope.

However I can also state that I have never seen any problem like this when actually using the scope with realistic settings to display actual signals from a DUT.

My scope is running 00.04.04.03.02 ( aka 00.04.04.SP3)  Board ver. 0.1.1

Some example scopeshots from my actual usage of the scope: no such problem is evident.



That's interesting.

All I had to do was connect the probe to the calibration output and hit the auto button to notice it. At first I thought it was a noisy calibration signal, but then I changed the display type to dots and saw the double trace. I found the Reddit thread immediately when I Googled it.

I've hardly used an oscilloscope in the last 10 years, much less a modern digital one. I wasn't sure at first if it was just something stupid I was doing, but this seems to have others confused as well.
 

Offline alsetalokin4017

  • Super Contributor
  • ***
  • Posts: 1798
  • Country: us
Re: Help: My New Rigol DS1054Z Shows a Weird Double Trace
« Reply #9 on: November 30, 2017, 01:10:07 pm »
I'd recommend just filing it as a bug report with Rigol, and then ignore it and use the scope normally. As I've shown it doesn't seem to affect (my) normal use of the scope.

YMMV of course. Do you often find the need to use Dots display mode and very sensitive V/div settings? 

(As I have found when discussing this particular model scope, we will get answers and speculation from people who don't actually have this model scope, or who seldom use many of its features even if they do have it. If the problem can be resolved or worked around by using Peak Detect acquisition mode, that's good, right?)
The easiest person to fool is yourself. -- Richard Feynman
 

Offline alsetalokin4017

  • Super Contributor
  • ***
  • Posts: 1798
  • Country: us
Re: Help: My New Rigol DS1054Z Shows a Weird Double Trace
« Reply #10 on: November 30, 2017, 01:18:06 pm »
Except I do _not_ see the double trace when making the direct connection from FG to scope using a BNC patch cord. If I probe the FG output directly using the scope probe I do see the double trace, also when I use the probe on the end of the BNC cable from the FG.
The easiest person to fool is yourself. -- Richard Feynman
 

Offline tablatronix

  • Regular Contributor
  • *
  • Posts: 194
  • Country: us
Re: Help: My New Rigol DS1054Z Shows a Weird Double Trace
« Reply #11 on: November 30, 2017, 01:36:47 pm »
I was trying to post but this dumb forum keeps just going to a blank add new topic when i post.

Forum has issues with ios 11 it now saves images as heifnor jpeg both which are not allowed to upload.

Mine did this, it was fun.
« Last Edit: November 30, 2017, 01:58:06 pm by tablatronix »
 

Offline jjoonathan

  • Regular Contributor
  • *
  • Posts: 204
  • Country: us
Re: Help: My New Rigol DS1054Z Shows a Weird Double Trace
« Reply #12 on: November 30, 2017, 01:51:49 pm »
Have you checked continuity on the ground lead of the scope probe? EDIT: nevermind, you've tested multiple probes and a BNC to a FG.

If you capture a single trace and zoom in using dots mode, do you see a regular pattern (e.g. every 4th dot is high)?

If you use auto triggering with source = ac and zoom out to 10ms/div or in to the fastest timebase, do you see a regular pattern?
« Last Edit: November 30, 2017, 01:53:43 pm by jjoonathan »
 

Offline Porcine Porcupine

  • Contributor
  • Posts: 35
  • Country: us
Re: Help: My New Rigol DS1054Z Shows a Weird Double Trace
« Reply #13 on: November 30, 2017, 02:21:20 pm »

I don't think there's any excuse for the wrong edge to be at the trigger position.

Try to produce a 1 or 2 Vpp mains waveform by touching the probe tip to see if it's mains related.

http://www.eevblog.com/forum/testgear/new-rigol-ds1054z-oscilloscope/msg1178338/#msg1178338
http://www.eevblog.com/forum/testgear/new-rigol-ds1054z-oscilloscope/msg1178420/#msg1178420

I noticed with that signal it will swap edges as I adjust the triggering above and below zero. I think it might just be triggering on some noise or something.

I attached some screenshots I took while touching the probe tip with my finger. I can't really tell if the double trace is there or not because the high frequency noise on the waveform might be hiding it.

 

Offline Porcine Porcupine

  • Contributor
  • Posts: 35
  • Country: us
Re: Help: My New Rigol DS1054Z Shows a Weird Double Trace
« Reply #14 on: November 30, 2017, 02:36:30 pm »
I'd recommend just filing it as a bug report with Rigol, and then ignore it and use the scope normally. As I've shown it doesn't seem to affect (my) normal use of the scope.

YMMV of course. Do you often find the need to use Dots display mode and very sensitive V/div settings? 

(As I have found when discussing this particular model scope, we will get answers and speculation from people who don't actually have this model scope, or who seldom use many of its features even if they do have it. If the problem can be resolved or worked around by using Peak Detect acquisition mode, that's good, right?)

I doubt I'll often use the dots display. I only switched to dots to try to see what was going on here.

As long as this isn't a physical defect with my oscilloscope, it isn't a big deal for me. It mostly concerns me because I would like to quickly (i.e. before I get around to doing anything that might void the warranty :)) resolve it with either Rigol or the vendor if this is a warranty issue.
 

Offline Porcine Porcupine

  • Contributor
  • Posts: 35
  • Country: us
Re: Help: My New Rigol DS1054Z Shows a Weird Double Trace
« Reply #15 on: November 30, 2017, 02:40:00 pm »
Except I do _not_ see the double trace when making the direct connection from FG to scope using a BNC patch cord. If I probe the FG output directly using the scope probe I do see the double trace, also when I use the probe on the end of the BNC cable from the FG.

Maybe it is somehow caused by noise that's being picked up, and your BNC cable is shielded better than mine.
 

Offline K5HJ

  • Regular Contributor
  • *
  • Posts: 59
Re: Help: My New Rigol DS1054Z Shows a Weird Double Trace
« Reply #16 on: November 30, 2017, 03:20:53 pm »
The top of the trace is off of the screen.  Looks like the ADC is in severe clipping.
 

Offline Porcine Porcupine

  • Contributor
  • Posts: 35
  • Country: us
Re: Help: My New Rigol DS1054Z Shows a Weird Double Trace
« Reply #17 on: November 30, 2017, 03:59:28 pm »
Have you checked continuity on the ground lead of the scope probe? EDIT: nevermind, you've tested multiple probes and a BNC to a FG.

If you capture a single trace and zoom in using dots mode, do you see a regular pattern (e.g. every 4th dot is high)?

If you use auto triggering with source = ac and zoom out to 10ms/div or in to the fastest timebase, do you see a regular pattern?

If I zoom in on a captured trace (screenshots 1-5), it becomes clear that what looked like two lines is actually two groups of three lines. Maybe it's just noise and looks this way because of quantization, but that doesn't explain why everyone doesn't see this on their DS1054Z.

The 6th screenshot is 10 ms/div. Screenshots 7-9 show zooming in on a captured trace at 10 ms/div. The double traces go away at 200 µs and faster. Screenshots 10-13 are with it running, but the double trace doesn't go away until 20 µs or faster.
 

Offline Porcine Porcupine

  • Contributor
  • Posts: 35
  • Country: us
Re: Help: My New Rigol DS1054Z Shows a Weird Double Trace
« Reply #18 on: November 30, 2017, 04:11:03 pm »
The top of the trace is off of the screen.  Looks like the ADC is in severe clipping.

It's off the screen because I adjusted the vertical position and scale. You can still see the double traces in the attached screenshot showing the full vertical extent of the waveform.
 

Offline technogeeky

  • Frequent Contributor
  • **
  • Posts: 532
  • Country: us
  • Older New "New Player" Player Playa'
Re: Help: My New Rigol DS1054Z Shows a Weird Double Trace
« Reply #19 on: November 30, 2017, 04:15:14 pm »
The top of the trace is off of the screen.  Looks like the ADC is in severe clipping.

It's off the screen because I adjusted the vertical position and scale. You can still see the double traces in the attached screenshot showing the full vertical extent of the waveform.

Yeah. There's something wrong with that scope. I would request a replacement.
 

Offline Porcine Porcupine

  • Contributor
  • Posts: 35
  • Country: us
Re: Help: My New Rigol DS1054Z Shows a Weird Double Trace
« Reply #20 on: November 30, 2017, 04:36:23 pm »
Yeah. There's something wrong with that scope. I would request a replacement.

I'm afraid that's what I'm going to have to do. I'm a little reluctant because the Reddit poster who had the same problem received a replacement that had the same problem. I've sent the Reddit person a message to ask how he finally solved the problem if he ever did.

I'm also tempted to take the scope to a different location and try it to completely rule out local interference.
 

Online JPortici

  • Super Contributor
  • ***
  • Posts: 2292
  • Country: it
Re: Help: My New Rigol DS1054Z Shows a Weird Double Trace
« Reply #21 on: November 30, 2017, 05:17:11 pm »
single shot. are the multiple traces still in the display?

and do an FFT of the signal, make it use you can see the frequencies up to...
what are the AM and FM frequency bands in your area?
 

Online Fungus

  • Super Contributor
  • ***
  • Posts: 8671
  • Country: 00
Re: Help: My New Rigol DS1054Z Shows a Weird Double Trace
« Reply #22 on: November 30, 2017, 11:48:23 pm »
Well, isn't that strange. I can reproduce the issue exactly as described here and in the reddit thread.

Me too!

However I can also state that I have never seen any problem like this when actually using the scope with realistic settings to display actual signals from a DUT.

Nor me. I've had my DS1054Z for three years and never seen it.

I doubt I'll often use the dots display. I only switched to dots to try to see what was going on here.

Yep. I don't think I've ever used dots in all the time I've owned mine, so.  :-// No big deal.

And all the Rigol haters would have posted endlessly if they'd seen it so I'm guessing none of them has ever seen it before either.

The top of the trace is off of the screen.  Looks like the ADC is in severe clipping.

Yes, you have to zoom in vertically and squish the signal against the top of the screen to see the separation properly. Normally it just looks like a thick line.

Yeah. There's something wrong with that scope. I would request a replacement.
I'm afraid that's what I'm going to have to do. I'm a little reluctant because the Reddit poster who had the same problem received a replacement that had the same problem.

Seems like everybody else has it, too so you won't gain anything. Take comfort from the fact that nobody here even knew about it. Whatever the cause of the problem it has zero impact in real life.
« Last Edit: November 30, 2017, 11:57:47 pm by Fungus »
 

Online Fungus

  • Super Contributor
  • ***
  • Posts: 8671
  • Country: 00
Re: Help: My New Rigol DS1054Z Shows a Weird Double Trace
« Reply #23 on: December 01, 2017, 12:16:08 am »
It seems to be something to do with aliasing in 'dots' display mode. You can see it best in zoom mode (push horizontal timebase knob):

When you're zoomed out you see two lines.


When you zoom in a bit you see a single thick line but with most dots concentrated in two bands at top/bottom (is this where the two 'lines' come from?)



Zoom a bit more, looks like noise but if you squint your eyes you can still see the 'lines' at top and bottom:


On maximum zoom you see a sine wave:


(Radio interference? It changes if I put my hand around the probe...)

It might be that what we're seeing is a combination of quantization artifacts (concentrating the dots of the sine wave at top/bottom) plus display aliasing when you zoom out (ie. it can't average every single point in the pixel).

So the question is: What do other 'scopes do?  :popcorn:
« Last Edit: December 01, 2017, 12:51:03 am by Fungus »
 

Online Fungus

  • Super Contributor
  • ***
  • Posts: 8671
  • Country: 00
Re: Help: My New Rigol DS1054Z Shows a Weird Double Trace
« Reply #24 on: December 01, 2017, 12:54:20 am »
Just for reference, this is dots vs. lines display:

Dots:


Lines:

« Last Edit: December 01, 2017, 12:57:16 am by Fungus »
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf