Author Topic: New Rigol DS1054Z oscilloscope  (Read 1469412 times)

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Offline David Hess

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Re: New Rigol DS1054Z oscilloscope
« Reply #4050 on: February 18, 2018, 06:53:47 pm »
Anyway, I was using my DS1054Z to look at a 0 to 40V 1kHz square wave I was making in a driver output stage. I increased the gain to look at the shape and noise on the low level of the square wave and found that I could only zoom in about 1 or two clicks from 10V/box before the input stage seemed to behave very very badly on saturation.

I want to look at the signal with much better resolution than 2 or 5 V/box.  Is it possible I'm doing something stupid?  I don't see what. This is very very disappointing behavior and is making me wonder if I should have just spent a bit more...
Any thoughts?
Doug

Most oscilloscopes have unspecified and poor overload recovery whether analog or digital.  Some are truly terrible in this regard.  Still, recovery from a 1 kHz overload should be plenty fast for the measurement you were attempting unless you were looking at the area immediately after the overload.

 

Offline DougM

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Re: New Rigol DS1054Z oscilloscope
« Reply #4051 on: February 18, 2018, 07:48:38 pm »
Yeah, maybe my expectations are unreasonable, but (perhaps naively) I didn't think this seemed a terribly challenging scenario.

Here are the screenshots at 10v/box 5v, and 2v.  I really want a much closer look at this waveform under a bunch of different load conditions. I'm not sure I can with this 'scope, unless there's something I'm missing or unaware of.
cheers,
Doug
 

Offline David Hess

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Re: New Rigol DS1054Z oscilloscope
« Reply #4052 on: February 19, 2018, 01:06:57 am »
All I can say is wow, that is terrible overload recovery.  CCD based digital storage oscilloscopes like my Tektronix 2440 have bad overload recovery but what you are showing there is much worse.
 

Offline alsetalokin4017

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Re: New Rigol DS1054Z oscilloscope
« Reply #4053 on: February 19, 2018, 03:49:56 am »
Yeah, maybe my expectations are unreasonable, but (perhaps naively) I didn't think this seemed a terribly challenging scenario.

Here are the screenshots at 10v/box 5v, and 2v.  I really want a much closer look at this waveform under a bunch of different load conditions. I'm not sure I can with this 'scope, unless there's something I'm missing or unaware of.
cheers,
Doug

I just have to ask... you are using your probe at 10x, and channel setting to match, right?
The easiest person to fool is yourself. -- Richard Feynman
 

Offline DougM

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Re: New Rigol DS1054Z oscilloscope
« Reply #4054 on: February 19, 2018, 05:24:22 am »
Yeah, maybe my expectations are unreasonable, but (perhaps naively) I didn't think this seemed a terribly challenging scenario.

Here are the screenshots at 10v/box 5v, and 2v.  I really want a much closer look at this waveform under a bunch of different load conditions. I'm not sure I can with this 'scope, unless there's something I'm missing or unaware of.
cheers,
Doug

I just have to ask... you are using your probe at 10x, and channel setting to match, right?

Indeed I am. I'm using the Rigol probes that came with the 'scope at 10x. 

Unless I can find some way to change this behavior, I'll likely have to get another scope. This kind of signal is not unusual for some of the stuff I'll be working on for a while.
Like I say, I'm quite surprised by this behavior. I've used many scopes over the years (decades!), though I'll readily admit I don't have much experience with low cost digital scopes. If it had even occurred to me that this sort of thing might be a problem I would have asked about it, specifically, on the forum.

cheers,
Doug
 

Offline Fungus

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Re: New Rigol DS1054Z oscilloscope
« Reply #4055 on: February 19, 2018, 07:11:10 am »
Anyway, I was using my DS1054Z to look at a 0 to 40V 1kHz square wave I was making in a driver output stage. I increased the gain to look at the shape and noise on the low level of the square wave and found that I could only zoom in about 1 or two clicks from 10V/box before the input stage seemed to behave very very badly on saturation.

I think what you're describing is called "overload recovery", it's a general problem with all opamps (not just the ones in the DS1054Z).

To see that signal you'll need to:
a) Buy a very expensive oscilloscope
or
b) Add some external components to isolate it
 

Offline Gandalf_Sr

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Re: New Rigol DS1054Z oscilloscope
« Reply #4056 on: February 19, 2018, 10:00:57 am »
"Not all accessories may be included" according to Tequipment. If that should mean missing probes, it would not be quite such a nice deal. But you could probably still get four replacement probes at less than the price difference.
Yeah, you're right that it is a refurb unit but it better have the probes or I'll return it.  One reviewer said it came with the wrong power cord - I don't care about that - but the other 2 reviewers said they were open-box units with all the accessories.
I'd like to make the world a better place but they won't give me the source code
 

Offline David Hess

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Re: New Rigol DS1054Z oscilloscope
« Reply #4057 on: February 19, 2018, 12:10:18 pm »
I think what you're describing is called "overload recovery", it's a general problem with all opamps (not just the ones in the DS1054Z).

Operational amplifiers started being used in oscilloscope front ends to control drift of the input source follower starting in the early 1980s and those oscilloscopes did not have this problem.  Unless this particular Rigol is broken, what is going on is due to a design flaw.

Poor overload recovery is 10s to 100s of nanoseconds.  What is shown here is literally 1000s of times worse.
 

Offline Fungus

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Re: New Rigol DS1054Z oscilloscope
« Reply #4058 on: February 19, 2018, 12:34:58 pm »
I think what you're describing is called "overload recovery", it's a general problem with all opamps (not just the ones in the DS1054Z).

Operational amplifiers started being used in oscilloscope front ends to control drift of the input source follower starting in the early 1980s and those oscilloscopes did not have this problem.  Unless this particular Rigol is broken, what is going on is due to a design flaw.

Really? Most manufacturers have discussion of this on their web sites, eg.:

https://www.tek.com/document/competitive/overdrive-recovery

https://www.keysight.com/upload/cmc_upload/All/ADMF2008_SwitchingModePowerMeasureUsingScopes.pdf

 

Offline David Hess

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Re: New Rigol DS1054Z oscilloscope
« Reply #4059 on: February 19, 2018, 02:24:27 pm »
I think what you're describing is called "overload recovery", it's a general problem with all opamps (not just the ones in the DS1054Z).

Operational amplifiers started being used in oscilloscope front ends to control drift of the input source follower starting in the early 1980s and those oscilloscopes did not have this problem.  Unless this particular Rigol is broken, what is going on is due to a design flaw.

Really? Most manufacturers have discussion of this on their web sites, eg.:

Old oscilloscopes did not have the magnitude of the problem displayed by this Rigol.  Other modern DSOs do not have the magnitude of the problem displayed by this Rigol.  100s of microseconds of overload recovery (1) time for an overload of only 9 divisions?  Really?  I have to overload my 2232 by 72 divisions to approach the same effect which is two more increases in vertical sensitivity and the 2232 has what I consider terrible overload recovery.  The Rigol overloaded immediately.

In the past they made special vertical amplifiers which could recover from any overload within a bounded time so for instance a 10 volt overload at 1mV/div or 10,000 divisions (!) required a recovery of 1 to 100 microseconds depending on the accuracy required.  (2) But even normal oscilloscopes did much better than the example here.

Quote
https://www.tek.com/document/competitive/overdrive-recovery

"404 not found" "Page not found"

Which is typical of Tektronix's broken web site.

Quote
https://www.keysight.com/upload/cmc_upload/All/ADMF2008_SwitchingModePowerMeasureUsingScopes.pdf

"Some oscilloscopes are known to have better overdrive recovery than other oscilloscopes."

This is true.

"However, all oscilloscopes are vulnerable to an overdrive state, so it is best to avoid this condition if possible."

This is completely false.  For instance sampling oscilloscopes are completely immune to overload short of damage making them uniquely useful for measurements where this is important.

The Rigol and any other modern DSO should be able to make this measurement despite overload.  The overload recovery demands in this case are not in any way extreme.

(1) It really should be called "overdrive" recovery.  Overload implies destructive levels.

(2) At this level of overload, thermal effects come into play so the amplifiers recover within a microsecond but it takes 100 microseconds for the thermal effects to dissipate.  These thermal effects are the same ones which limit settling time in precision operational amplifiers.
 

Offline DougM

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Re: New Rigol DS1054Z oscilloscope
« Reply #4060 on: February 19, 2018, 03:13:48 pm »
I think what you're describing is called "overload recovery", it's a general problem with all opamps (not just the ones in the DS1054Z).

Operational amplifiers started being used in oscilloscope front ends to control drift of the input source follower starting in the early 1980s and those oscilloscopes did not have this problem.  Unless this particular Rigol is broken, what is going on is due to a design flaw.

Really? Most manufacturers have discussion of this on their web sites, eg.:

https://www.tek.com/document/competitive/overdrive-recovery

https://www.keysight.com/upload/cmc_upload/All/ADMF2008_SwitchingModePowerMeasureUsingScopes.pdf


Can someone else with this 'scope please see if they can replicate this problem?  I don't have any reason to think mine is defective, but I'm quite disappointed by this performance...   (0V to 40V 1kHz square wave, and look at it at 2V/div)

cheers
Doug
 

Offline Fungus

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Re: New Rigol DS1054Z oscilloscope
« Reply #4061 on: February 19, 2018, 03:33:58 pm »
Can someone else with this 'scope please see if they can replicate this problem?  I don't have any reason to think mine is defective, but

There's been other threads on it, eg.:

https://www.eevblog.com/forum/testgear/rigol-ds1054z-vertical-distortion-problem/

I'm quite disappointed by this performance...   (0V to 40V 1kHz square wave, and look at it at 2V/div)
It's not something that's usually listed in datasheets.

Solutions: You could rectify your signal or clamp it with a zener diode to reduce the peak to peak voltage. It'll only cost $1 or so.
« Last Edit: February 19, 2018, 03:38:02 pm by Fungus »
 

Offline DougM

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Re: New Rigol DS1054Z oscilloscope
« Reply #4062 on: February 19, 2018, 04:44:45 pm »
Can someone else with this 'scope please see if they can replicate this problem?  I don't have any reason to think mine is defective, but

There's been other threads on it, eg.:

https://www.eevblog.com/forum/testgear/rigol-ds1054z-vertical-distortion-problem/

I'm quite disappointed by this performance...   (0V to 40V 1kHz square wave, and look at it at 2V/div)
It's not something that's usually listed in datasheets.

Solutions: You could rectify your signal or clamp it with a zener diode to reduce the peak to peak voltage. It'll only cost $1 or so.


Yeah, Indeed I could work around pre-conditioning the signal in a number of ways, but anything that would give the flexibility of a well-behaved 'scope would be a project that I just don't have time for right now.
It's my fault, I suppose. 8 bit and modest speed is fine for this type of use, I just didn't do enough research to realize that the input stages weren't capable of placing that 8-bits of dynamic range at the interesting part of the signal...

Doug
 

Online nctnico

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Re: New Rigol DS1054Z oscilloscope
« Reply #4063 on: February 19, 2018, 06:46:17 pm »
It's not something that's usually listed in datasheets.
Yes it is. It is called offset range. But ofcourse the scope should be able to deal with it properly.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline Fungus

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Re: New Rigol DS1054Z oscilloscope
« Reply #4064 on: February 19, 2018, 07:17:47 pm »
According to the manual the DS1054Z offset range is better with the probe on 1x setting. You could fiddle around with that.

It brings its own set of problems though, you might want to enable the 20MHz bandwidth limiter.

 

Offline DougM

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Re: New Rigol DS1054Z oscilloscope
« Reply #4065 on: February 19, 2018, 08:17:00 pm »
According to the manual the DS1054Z offset range is better with the probe on 1x setting. You could fiddle around with that.

It brings its own set of problems though, you might want to enable the 20MHz bandwidth limiter.

 
Yes, you're right. It doesn't even seem to specify the offset range at 10x.  1x looks more promising. I will try that and report back.
 

Offline David Hess

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Re: New Rigol DS1054Z oscilloscope
« Reply #4066 on: February 19, 2018, 08:21:19 pm »
It's not something that's usually listed in datasheets.

Yes it is. It is called offset range. But of course the scope should be able to deal with it properly.

Offset range and the offset function have nothing to do with overdrive recovery.
 

Online nctnico

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Re: New Rigol DS1054Z oscilloscope
« Reply #4067 on: February 19, 2018, 08:29:55 pm »
It's not something that's usually listed in datasheets.

Yes it is. It is called offset range. But of course the scope should be able to deal with it properly.

Offset range and the offset function have nothing to do with overdrive recovery.
That depends entirely on how the offset circuit has been designed. If it is designed to look at a signal with a large DC offset and not at a detail of a large signal (what DougM wants) then it will fail.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline DougM

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Re: New Rigol DS1054Z oscilloscope
« Reply #4068 on: February 20, 2018, 03:52:34 am »
According to the manual the DS1054Z offset range is better with the probe on 1x setting. You could fiddle around with that.

It brings its own set of problems though, you might want to enable the 20MHz bandwidth limiter.

 
Yes, you're right. It doesn't even seem to specify the offset range at 10x.  1x looks more promising. I will try that and report back.

Well, that was interesting. Looking at exactly the same signal with the probe and channel both set to 1x, I could get on to the 500mV/div range with ok performance.

That is literally an order of magnitude better!  In this particular case, the circuit is ok with a 1x probe, so it is the way to go for now. I am still surprised ((and disappointed) by the behavior on 10x, but this is really helpful.

cheers
Doug

 
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Offline 2N3055

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Re: New Rigol DS1054Z oscilloscope
« Reply #4069 on: February 20, 2018, 09:04:54 am »
There is no difference in specs in 1x or 10X.. it is simply x10.

Difference is because DS1000Z has an attenuator relay before first stage that switches at 500mV/div (1x). If you are at less than that, you are connected to first stage without attenuation. So your full dynamic range of input signal multiplied by first stage amplification must be less than +/- 5V used to power input amplifier..
If you are at more than 500uv/div (1x), first stage gets attenuated input and can stand it a bit better.

If you are at 10x,  switching happens at 5V/div. It so happens that it is not so good for this kind of measurement.

Offset range and the offset function have nothing to do with overdrive recovery.
Exactly..Overdrive is related to dynamic headroom of signal path.. Full P-P signal amplitude  that the signal path will let pass through it without clipping, and if it does clip, how it will recover.. Offset is to compensate for constant DC component, or just position traces on screen. Adding DC offset to clipping signal will only complicate things, making overdrive more severe and asymmetric...

Regards,

Sinisa
 

Online Adrian_Arg.

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Re: New Rigol DS1054Z oscilloscope
« Reply #4070 on: April 05, 2018, 09:03:45 pm »
Can I do something wrong with the rigol ds1054z, because the RMS varies if the vertical scale varies? so be direct to the source of power as in an arduino circuit ::)
 

Offline Fungus

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Re: New Rigol DS1054Z oscilloscope
« Reply #4071 on: April 05, 2018, 09:23:16 pm »
The calculation is done with the data shown on screen so you have to maximize the signal to get a decent result.

ie. Vertical scale of one division on screen won't be very good.
 

Online Adrian_Arg.

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Re: New Rigol DS1054Z oscilloscope
« Reply #4072 on: April 05, 2018, 11:12:43 pm »
continue with the silly questions, I have a bad habit I think, crocodile clamp the floor leaving it precionando the signal hook of the probe being connected, it hurts the oscilloscope something, because that way when I press the auto button does not trigger me the channel that in that amount I'm not using.
 

Online Adrian_Arg.

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Re: New Rigol DS1054Z oscilloscope
« Reply #4073 on: April 06, 2018, 01:29:05 pm »
I was referring to this connection, it harms the oscilloscope.
 

Online ebastler

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Re: New Rigol DS1054Z oscilloscope
« Reply #4074 on: April 06, 2018, 01:37:21 pm »
I was referring to this connection, it harms the oscilloscope.

Thanks for thwe clarification. I had indeed not quite understood your prior post.

But how would this connection "harm your oscilloscope"? It is a reasonable way to ground the input. (Not perfect, due to the little inductive loop.) Personally I don't do this -- I just disable the channel on the scope if I don't want to use it, or set the input mode to ground. But I don't see why it should be bad.

I understand your prior post to say that the scope no longer triggers on that channel (or that the "Auto setup" button does not work on it?). But isn't that what you woukd expect, with no input signal due to the grounded input?
 


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