How Thick is Your Baselne on Your Digital Oscilloscope?

[rf-loop]

From that document: Each scope was terminated into 50-?

So no open input

Yes, as also I have told: 1Mohm and 50ohm inputs.

I have tested only some hundreds of oscilloscopes but I have sometimes find that in some cases 50ohm terminator rise visible noise level. Specially if something is wrong in front end design or if there is example internal some special "common mode" noise. In these some cases 50ohm termonator may rise noise. There is road for internal noise current what produce voltage mainly over this 1 Mohm. I have seen this.
It can very fast check if terminator add noise or reduce noise. Also sometimes can use 1Mohm termination.
Agilent: "Plus, we used a 1-M? input termination rather than the original 50-? termination"

But this all is not so relevant here. Only what I hope see is some well known good oscilloscope as some kind of reference for this kind of noise images.

[Orange]

The Hameg 3522 is 'only' 100 MHz BW at the 1 and 2 mV... non the less, the signal looks really clean even for a 100MHz BW.

Tim, did you use average 

Sorry to be mean Tim, to be honest my Rigol has more noise in the 1mV range.

The Rigol DS2072 with BW hack does 250MHz at 1mv 

- Orange

[PA4TIM]

RF-loop:
I think you do not understand what they write.  They do not use the 50 Ohm open input, They terminate the the inputs with 50 Ohm.

I do not care how many hunderd scopes you have tested. Quantity is not the same as quality. Just make the pictures you want if you do so much testing that must be no problem I gues   

Orange: I did not use avarage.  The Hamegs have one of the lowest noise floors. They also have a real 1 mV range, most scopes only have a software <5mV range. They measure in the 5mV position but the software zooms in to 1mV

[rf-loop]

RF-loop:
I think you do not understand what they write.  They do not use the 50 Ohm open input, They terminate the the inputs with 50 Ohm.

I do not care how many hunderd scopes you have tested. Quantity is not the same as quality. Just make the pictures you want if you do so much testing that must be no problem I gues   

Orange: I did not use avarage.  The Hamegs have one of the lowest noise floors. They also have a real 1 mV range, most scopes only have a software <5mV range. They measure in the 5mV position but the software zooms in to 1mV

Of course I know what they did.  But you do not now perhaps understand what I mean.

But, why it is so difficult to show this test result. If Hameg is (and it is) good, why we can not use its test result as some kind of reference.
Of course we all want look nice clean sinewaves but...  I wonder why it is so difficult to show this tests result what even do not need any external equipment. But, also I wonder butterflies.

[Orange]

Orange: I did not use avarage.  The Hamegs have one of the lowest noise floors. They also have a real 1 mV range, most scopes only have a software <5mV range. They measure in the 5mV position but the software zooms in to 1mV

The 1mV and 500uV range on the Rigol is also a 'real' full ADC range, no up-scaling used on this model. In fact I have not seen this anymore since decades. The last scope if seen that used up-scaling on low ranges was a Tek 468, one of the first digital scopes I used.... (1983 i think....)

- Orange

[PA4TIM]

[qoute]But, why it is so difficult to show this test result. If Hameg is (and it is) good, why we can not use its test result as some kind of reference.[/qoute]
I have good (medical) reasons, that is all I want to say about it.

[Paul Price]

Galaxyrise,


Thanks, I think the memory depth is not adj able  on the DS4024 with most time base settings and if I could adj. it, it would take  convenience out the back door.
 I don't want to press and twiddle and fudge around if I get an urge to quickly measure some DC voltages.

[tinhead]

Why ? That is a rather useless test, If I have much RFI here then it will show more noise as in a surroundig where no other gear is powered on.

right, such test (assuming no signal connected to DSO, no external termination nor bnc shielding = open inputs ) is only
usefull when comparing DSOs at same day/location/temp. and even operator. Therefore a compare like "my DSO is having this,
so better than TEK but not such good as Agilent" is complettly useless, unless someone have of of these models from
Agilent app note and have exact same readings on such DSO - then, and only then, a compare to XYZ models make sense.

Btw, your proposal to test with signal is exact that bad as with no signal, as there is no situation (except channel grounded)
with no signal. And when using "defined" signal source you have still lot of differences due location/temp./operator etc.
and of course model.

So whatever you choose it's ok, as long you test more than one DSOs at time and compare results, a single measur of
something done somewhere by somebody at some time is useless, it is like "my dick is longer" (and everybody on earth
know that i have the longest  ).

RF-loop: I think you do not understand what they write.  They do not use the 50 Ohm open input,
 They terminate the the inputs with 50 Ohm.

from the Agilent document :
"Each scope was terminated into 50-? and was set up to acquire waveforms with no input signal connected,
using each scope’s maximum specified sample rate"

hmm, terminated into can be as well "internal 50R termination enabled", but anyway, as said above this didn't really
matter as we can't compare other DSOs to their in Agilent app note.

"using each scope maximum sample rate" is as well trap, however Agilent did it properly and (at least for peak-to-peak measurments)
did it 10 times and used avg vales. But still, this is 2.5 to 10GS/s span and 8 to 32Mpoint of data, you can see here everything
but not what really the noise is (the DSO with 10GS/s and 32M will pickup more peak-to-peak events than a 8M/ 2.5GS/s DSO).
It is as ell important, when comparing this way, to check what is the memory depth at specific timebase when specific sample
rate enabled.

Orange: I did not use avarage.  The Hamegs have one of the lowest noise floors.

oh well, Hameg is at least using this as sales argumentation. I give you example of cheap chinese DSO (Tekway/Hantek)
set to not filter anything up to 500MHz (yes, the firmware can be forced to not use any filter), with 250MHz bw at 2mV/DIV.
The signal didn't look bad (except the interleave distortion), not that far from what on Hameg.



But there is small extra difference, you would have to zoom to see it, Hameg is using the same amount on vertical DIV
as this chinese DSO, the resulting line looks thiner because Hameg is drawing half of the dots bit darker.
I like it, it looks "analog" to me.

Agilent/Rigol is using completly different way to draw waveform, their signal can be compared to Hameg
with persistency full on. But here again chinese DSO example, the baseline (not open input but external terminated with 50R)
looks thin. With infinite persistency it looks however thick, with bit of persistency (0.2s) it looks still thicker as without any persistance, and that is what you can see on Rigol/Agilent (intensity grading / shading combination looks similar to other
DSOs with persistency on).

So it's not (only-if any and not only marketing thing) lowest noise floor, but as well question how the UI designer decided
to draw waveform. Therefore it is better to compare Vrms of noise than line thickness.

TO: The whole question "How Thick is Your Baseline on Your Digital Oscilloscope?" with combnation of "i wish to use it as DMM"
is anyway crazy, who is using DSO as DMM? How can i casre about line thickness when the DSO inaccuracy is by 2-3% of full scale?

[robrenz]

Yeah its only 1MHz bandwidth but its pretty 7A22 diff. amplifier both inputs grounded in a 7603 at 10µV/div.

[Paul Price]

Some people here are saying the problem is me, not the scope...I disagree!

O: The whole question "How Thick is Your Baseline on Your Digital Oscilloscope?" with combnation of "i wish to use it as DMM"
is anyway crazy, who is using DSO as DMM? How can i casre about line thickness when the DSO inaccuracy is by 2-3% of full scale?
---------------------------or the quoted reply below:-------------------------------------------------------------------
"Once you set up a measurement you can test many values and it will just show you the value.  On most scopes it takes about four button presses to set up a simple DC measurement.  This seems like a really weird thing to bitch about when you are willing to go fiddling with different BW limits, acquisition modes, and averaging to get your clean baseline."


=========================================================================================
I say again, for the nth time:

What I often like or really need to do to analyze or troubleshoot a circuit is get a very quick overview of a circuit's operation, often DC voiltage at different critical points. This is especially important in repairing equipment and with breadboarding complicated new designs.

 I don't need DVM accuracy so much as instant feedback, I need an oscilloscope with a 10x shielded probe to get a readout of DC levels to get an idea every expected voltage is showing the circuit is working as expected, and a quick idea if there is any signal or noise present that is unexpected, showing if everything is working as expected or is it that I have some defect in my wiring or some IC's operation. This is a very valuable, time-saving, efficient test strategy for me.

[Paul Price]

Thanks again to UUp for clearly showing the problem, especially when trying to measure mV DC signals. What good is 10mV/div sensitivity if it is swamped out by noise.


Pa4tim:

I would very much appreciate to see a flat line display of the Hameg. It looks too good to be true. Is there any chance of anyone making a short video showing use of the this Hameg low-noise scope measuring a few DC voltages around a simple circuit..without any special effects settings...just using this scope without averaging or hi-res mode?

***************************************************************************************************
O: The whole question "How Thick is Your Baseline on Your Digital Oscilloscope?" with combnation of "i wish to use it as DMM" is anyway crazy, who is using DSO as DMM? How can i casre about line thickness when the DSO inaccuracy is by 2-3% of full scale?
---------------------------or the quoted reply below:-------------------------------------------------------------------
"Once you set up a measurement you can test many values and it will just show you the value.  On most scopes it takes about four button presses to set up a simple DC measurement.  This seems like a really weird thing to bitch about when you are willing to go fiddling with different BW limits, acquisition modes, and averaging to get your clean baseline."


===============Or this from the most quiet Hameg reply =============================================
What you want is something like comparing cars idling while waiting for a trafficlight.
=========================================================================================
I say again, for the nth time: To work on a circuit I want to, as quickly as possible, jump around different test points and see what is going on. 

What I often like or really need to do to analyze or troubleshoot a circuit is get a very quick overview of a circuit's operation, often DC voiltage at different critical points. This is especially important in repairing equipment and with breadboarding complicated new designs.

 I don't need DVM accuracy so much as instant feedback, I need an oscilloscope with a 10x shielded probe to get a readout of DC levels to get an idea every expected voltage is showing the circuit is working as expected.

I want a quick  view to get an idea if there is any signal or noise present that is unexpected, showing if everything is working as expected or is it that I have some defect in my wiring or some IC's operation. This is a very valuable, time-saving, efficient test strategy for me.

[Paul Price]

I wonder how much this costs.

[Carrington]

It is very nice of someone do tests and show images about:

Scope (DS2000: 70, 100 or 200MHz model) settings 1 or 2 channel in use.
Full BW
No average, no any kind of filtering, no high res mode.
Horizontal speed 1ms/div
Acquire (sampling) mode peak (or how it is named in Rigol) and normal 8 bit mode (no high res)
(or if not peac acquire mode, with 14M memory selected and then scope stopped and zoomed out so that more data is displayed)
Inputs open. (or external 50 ohm terminators on channels BNC. specially if envinroment is noisy)

(Just all settings so that pure maximum level of front end peak-peak noise is visible on the screen.)
Probe factor 1x

Vertical:
500uV/div
1mV/div
2mV/div
5mV/div
10mV/div

Please could someone attach these images. Thanks. 

[SLJ]

Don't really care much about the baseline display for my use.  I bought it for the waveform measurements at a glance.  If I want to see a good waveform displayed I'll use my analog scope.

What I would like to see is an option to choose to display maybe three or four measurements on the display at once in a large font like DC Volts, AC Volts, and Frequency at the same time along with a tiny waveform.  More like a souped up DMM.   Right now I have to sort through a table of around 16 measurements, most of which I don't care about.

[Carrington]

It is very nice of someone do tests and show images about:

Scope (DS2000: 70, 100 or 200MHz model) settings 1 or 2 channel in use.
Full BW
No average, no any kind of filtering, no high res mode.
Horizontal speed 1ms/div
Acquire (sampling) mode peak (or how it is named in Rigol) and normal 8 bit mode (no high res)
(or if not peac acquire mode, with 14M memory selected and then scope stopped and zoomed out so that more data is displayed)
Inputs open. (or external 50 ohm terminators on channels BNC. specially if envinroment is noisy)

(Just all settings so that pure maximum level of front end peak-peak noise is visible on the screen.)
Probe factor 1x

Vertical:
500uV/div
1mV/div
2mV/div
5mV/div
10mV/div

Please could someone attach these images. Thanks. 

This is the closest thing to this that I found in the eevblog. Please could someone attach more images.
rf-loop: What are you trying to prove?

[grenert]

To the OP:
Clearly this is important to you, and it sounds like money is not a primary limitation here.  Why not just demo a few of the instruments that seem most promising and see for yourself?   

[Carrington]

To the OP:
Clearly this is important to you, and it sounds like money is not a primary limitation here.  Why not just demo a few of the instruments that seem most promising and see for yourself?   

What or who is OP?

[dfmischler]

What or who is OP?

Original Poster.  In this case Paul Price.

[Carrington]

What or who is OP?

Original Poster.  In this case Paul Price.

OK thanks 

[rf-loop]

rf-loop: What are you trying to prove?

Prove something?

No need prove anything.

But many times we have seen measured risetimes, bandwidths, etc.

Just for data. Of course I'm also interest about oscilloscopes, new and old, noise levels, as much as BW, risetimes, accuracy, sampling speeds, how they use memory, etc. All things. Noise is just one.
Also, we have seen  many many times when entry level and also experienced users are wondering digital scopes noise and if it is normal or not and if it is problem.

If we can here really see reality of digital scopes normal things, and if also possible, measured or tested with some kind of comparable methods, it is just informative and may lead to better understanding.

I do not wonder at all these Rigol images. They are just normal.
But it is also nice if can see some low noise oscilloscope for some kind of reference.
Just for better knowledge.

Also we have seen lot of normal condition other oscilloscopes noise levels here and also oscilloscopes what have some real problem.

Also, it is good for information.

This is not some kind of agenda for proofing something.

Knowledge is also good for beginners so they do not be so much disappointes if they have wrong dream before buy entry level new oscilloscope. It is just good to know what is normal and what is problem.

Also some peoples have experience with analog scopes, then buy first digital oscilloscope and first day they are amazing why my digital scope trace is so noisy. This same noise is also in analog scopes (nearly). Just it can not see becouse phosphor do its work for hide it. 

This is one very common question: Why my digital scope is so noisy.

[Carrington]

Yep rfloop. Where does this noise come? What to do to mitigate it?
And of course would be very interesting a comparison between oscilloscopes, under conditions as similar as possible.


Between SDS7102V and DS2072. Which of the two you think is less noisy?

[rf-loop]

Between SDS7102V and DS2072. Which of the two you think is less noisy?

I do not have enough comparable data for this but my suspect is that DS2102 have some amount less noise. But not very big difference. (of course I talk Owon what do not have this special noise issue)
 

[Carrington]

Between SDS7102V and DS2072. Which of the two you think is less noisy?

I do not have enough comparable data for this but my suspect is that DS2102 have some amount less noise. But not very big difference. (of course I talk Owon what do not have this special noise issue)
 

I hope someone adds more images to compare.

[Galaxyrise]

Ok, then dots, least 5s persistence.

Sorry for the delay.  When I set up the suggested test, I got a result that I'd never seen before and I wanted to spend some more time playing with it.  It seems I've finally found a case where Anti-Alias actually removes waveform aliasing!  But without it, the display is really quite ugly.  I used infinite persistence so it would use the two-tone persistence, and then waited 5-10s before pausing the scope and taking the screenshot.  The persistence really makes the traces look heavy; it's probably not fair to compare these to any non-persistence captures.

The trace gets to its thinnest at 20mV and then stays there as the V/div goes up.  It's intriguing 10ms and 5ms have the same apparent noise. The only way to get a truly thin trace is with high res. I still feel like I must have messed something up; anyone else see that strange aliasing on theirs?  Until this test, I'd only run into images that look like the DS2000 images previously posted in this thread.

[Carrington]

Thank you very much "Galaxyrise". That is just ok. 
These signals do not have anything wrong.


I know, it sounds absurd, but please: Can you do the same test but now connecting both terminals of the probe together (ie live/central and ground wire) to the ground lug of the Probe Comp. terminals.

I want to compare the result with a similar test on the SDS7102V.
Thanks.