Author Topic: New Rigol DS1054Z oscilloscope  (Read 1459997 times)

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Online Fungus

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Re: New Rigol DS1054Z oscilloscope
« Reply #4200 on: September 07, 2018, 02:20:57 pm »
Yes, but but it's not a legal requirement and we know that in this particular case one isn't.

Good business to consumer relationship is about trust and following best practices, not legal requirements...

I'd say that this:


Is a more true representation of the original signal than this:

 

Offline technogeeky

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Re: New Rigol DS1054Z oscilloscope
« Reply #4201 on: September 07, 2018, 04:03:08 pm »
* 20 MHz sine wave (I can't generate a 70MHz sine wave easily)

If you look my tests it is pretty adequate at that frequency, circus starts at about 50MHz when number of samples per wfm feature gets low and rig(x)/x kicks in heavily. So if analog-related tasks lie below 50MHz no prob.

I can only generate psuedo square waves above 50 MHz. I'll consider re-running the test later.
 

Online Fungus

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Re: New Rigol DS1054Z oscilloscope
« Reply #4202 on: September 07, 2018, 04:21:03 pm »
If you look my tests it is pretty adequate at that frequency, circus starts at about 50MHz when number of samples per wfm feature gets low and rig(x)/x kicks in heavily. So if analog-related tasks lie below 50MHz no prob.

This is complete rubbish. The only "problem" is that the dots don't conform to your (unfounded) expectations in dot mode with sin(x)/x turned off, they match the original waveform instead.

ie. The problem is in your head, not in the 'scope.

Your "50MHz" figure is also pulled out of your butt because you're ignoring that fact that you're not running at full sample rate, ie. that "analog-related tasks" can run at 100MHz with 10 samples per wfm on this 'scope.
 

Offline MrW0lf

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Re: New Rigol DS1054Z oscilloscope
« Reply #4203 on: September 07, 2018, 07:38:28 pm »
This is complete rubbish. The only "problem" is that the dots don't conform to your (unfounded) expectations in dot mode with sin(x)/x turned off, they match the original waveform instead.

ie. The problem is in your head, not in the 'scope.

Your "50MHz" figure is also pulled out of your butt because you're ignoring that fact that you're not running at full sample rate, ie. that "analog-related tasks" can run at 100MHz with 10 samples per wfm on this 'scope.

You seem upset, might it be poorly masked frustration due to low performance hardware at hand? About my expectations, I expect any properly engineered 100MHz scope to perform approx like this (just measured my main scope with same config as old test):

Scope set to 5ns/div.

3.500Vpp sine @100MHz reported by gen:

20GSa/s ETS - linear: 2.747Vpp
1GSa/s RTS - Sinc: 2.639Vpp; linear: 2.592Vpp
500MSa/s RTS - Sinc: 2.703Vpp; linear: 2.576Vpp
250MSa/s RTS - Sinc: 2.675Vpp; linear: 2.677Vpp

350mVpp sine @100MHz reported by gen:

20GSa/s ETS - linear: 284mVpp
1GSa/s RTS - Sinc: 273mVpp; linear: 268Vpp
500MSa/s RTS - Sinc: 280mVpp; linear: 266mVpp
250MSa/s RTS - Sinc: 277mVpp; linear: 277mVpp

Thats 0.5dB between two most apart readings or +-0.25dB like some would like to say.  As for amplitudes, what on earth they have to do with sampling rate? I can only see that drop is about 2dB @100MHz irrelevant of vertical range... :-// Will check some other scope also later.

Edit: Done. Analog Discovery 2. Since it has only 100MSa/s max tested at 10Mhz:

Scope set to dynamic ns/div, memory set to 32 samples.

350mVpp sine @10MHz reported by gen:

100MSa/s RTS, 16x oversampling: Sinc: 342mVpp; linear: 341mVpp
100MSa/s RTS: Sinc: 336mVpp; linear: 336mVpp
50MSa/s RTS: Sinc: 321mVpp; linear: 321mVpp
25MSa/s RTS: Sinc: 321mVpp; linear: 321mVpp

3.500Vpp sine @10MHz reported by gen:

100MSa/s RTS, 16x oversampling: Sinc: 3.385Vpp; linear: 3.386Vpp
...did not bother further, again 0.5dB max diff, scopes based on well established engineering practices are complete yawn to test  :=\
« Last Edit: September 07, 2018, 08:24:21 pm by MrW0lf »
 

Offline David Hess

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Re: New Rigol DS1054Z oscilloscope
« Reply #4204 on: September 07, 2018, 09:04:58 pm »
What about testing a 100MHz DS1104Z against another 100MHz DS1104Z ? Shouldn't it be considered also in these "scientific" analyses?

I would be nice to test lots of them but not very practical.  Few people with the needed test equipment have access to more than one or two and true 100MHz DS1104Zs are understandably rare.

Wasn't hard. First was a charged capacitor and fast switch. I do not recall what I was doing on the second, but probably something similar with different triggering. What should I be looking for?

Overload in this case depends on volts/second so if it is occurring, it also amplitude dependent.  Higher sensitivities are less likely to display it because the volts/second of the edge is lower to stay within the display.

So doing that test at 5 volts/division like you did should show it but there is also the complication that the high impedance divider before the high impedance buffer is being used.  That divider may be limiting input bandwidth preventing the problem.  The example I showed is at 400 millivolts/division which I assume is actually 200 or 500 millivolts per division as far as the various attenuators.  Worst case will be the lowest sensitivity where the high input impedance divider is not used.  The table of bandwidth measurements not long ago indicated that the high impedance divider had a major effect on input bandwidth.

I do not see any slew rate related overload in your examples.

Hmm.. I had made an assumption there myself, that of the different bandwidth models actually having different (analog) bandwidth and/or rise times (in the front end path). Which, afaik, requires, for example (might have more to it), hardware low pass filter being enabled/disabled/adjusted in the hardware (via software control on the basis of the model), thus my idea of "hardware used differently". (Put in other words: both models having the filters there = "same hardware"; one disabling a piece of it = "used differently".)

Dave's reverse engineered schematic shows two digital control signals which switch a pair of analog bandwidth filters (they switch some shunt capacitors and it is a common arrangement in oscilloscopes for this function) to provide 20, 50, 70, and 100 MHz bandwidths.  These numbers can be calculated from the component values shown in his schematic.  The thing he has labeled as "bandwidth" is something else which is not entirely clear.

Look for cause why scope which clearly does not have actual 200MHz analog frontend reports such rise time ;) 0.35/1.65ns=0.212GHz
Plotting amplitude response graph to sinusoidal signal sweep might give some clues.

The other post I mentioned reported the results of such a test and the bandwidth varied significantly with vertical sensitivity which is unusual; usually oscilloscopes are designed to have constant bandwidth.  Sometimes bandwidth decreases at the highest vertical sensitivity settings because gain stages are switched instead of attenuation stages but it still remains constant with different signal amplitudes.  It used to be a marketable feature if bandwidth was constant but buyers usually assume this is the case when it may not be.

What was not tested is if the bandwidth varied with amplitude indicating non-linearity and a full power bandwidth limit.

The single input divider relay of the DS1000Z switches between 330 and 335mV/div and this makes a big difference: at 335mV selection, the input amplifier "sees" much less signal and the VGA integrated in the A/D converter is adjusted at high gain. I kept that as a reference trace while I changed input sensitivity to 330mV, resulting in the input amp being driven with a much larger signal. The trace shapes and rise times differ by more than 1ns, but both appear to be well within the 100MHz range.

The shape is interesting in your second example.  The first shows a Gaussian response but the second shows a first order response.

So the response was Gaussian with the high impedance attenuator and high ADC gain but first order without the high impedance attenuator and low ADC gain.

Your first example seems to show a 5 nanosecond ledge immediately after the edge and it looks like it is in the reference recording of the same signal.  I wonder if that is something or not.  It is too bad that Leo Bodnar's pulser cannot generate a higher output amplitude.

We know the design is the same or at least I assume it is.  We do not know if Rigol grades or selects them.

Lots of people have tried to find a difference over the years, all have failed.

Most users lack either the equipment or experience to find this sort of difference.

Quote
(And there's absolutely no reason to think they're using borderline components that might go one way or the other during manufacturing).

Do you mean other than using 2N3904s in 100MHz transconductance amplifiers?  That by itself is suspicious.

Rigol did not include those emitter equalization stages with variable tail current without reason.  The variable tail current is suspicious as hell because a low tail current would lead to exactly this sort of problem.

Rigol also did not include collector series loads for thermal balancing but with that weird cascode arrangement, maybe they were not needed.  Nobody has tested for thermal balance but it is an even more obscure issue and I doubt anybody is using a Rigol oscilloscope where it would matter.  Thermal balance affects settling time in the 10s to 1000s of microseconds and is the major limitation for settling time in precision amplifiers.

Quote
A hacked 100MHz DS1054Z should be compared to a 100MHz DS1104Z.

It's been done several times over the years and no difference found.

If they are identical which I regard as a likely because for reasons of economy (I doubt Rigol is testing these oscilloscopes and only using the best ones for the higher bandwidth model), then that makes the DS1104Z just as flawed.  I only suggested that they are grading them to give them the benefit of my doubt.

An oscilloscope is primarily a visualization tool, with some capability to make low precision measurements.

I at least expect the visualization of the same edge at different vertical sensitivity settings to be consistent.  Changes in pulse shape with amplitude and position are actually a very good test for overload.

If the transition time measurements are changing over the range reported for the same edge, then that is even worse.

The individual man hours spent discussing this subject are worth more (in cash) than the money needed to buy a better scope!!

That is what I did by not buying a Rigol.  Back when I evaluated them just before the DS1000Z series became available, I concluded they were best to avoid and various reports on the DS1000Z series have convinced me that I made the right decision.

But my curiosity in oscilloscope design and performance is enough that I want to know what is going on.  The lack of documentation makes for a challenging puzzle.

I am not totally sure what the complaint is in this post, but I noticed that it was disclaimed as an old test. I think the complaint is the amplitude change when sin(x)/x is off on dots mode. So I made some animations of a current oscilloscope with the 2nd to latest firmware.

Amplitude should not be changing at different time/division settings, sample rates, or interpolation settings whether aliasing is present or not unless insufficient sample points are captured which is not the case here.  Somewhere the vertical histogram of the signal is being corrupted although Rigol may not be using it for measurements which does not improve the situation.

I am not really surprised by this behavior in a DSO which makes measurements on the display record instead of the processing record.  It is a major design compromise more suitable for a toy.
 
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Online Fungus

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Re: New Rigol DS1054Z oscilloscope
« Reply #4205 on: September 07, 2018, 10:57:55 pm »
Scope set to 5ns/div.

3.500Vpp sine @100MHz reported by gen:

20GSa/s ETS - linear: 2.747Vpp
1GSa/s RTS - Sinc: 2.639Vpp; linear: 2.592Vpp
500MSa/s RTS - Sinc: 2.703Vpp; linear: 2.576Vpp
250MSa/s RTS - Sinc: 2.675Vpp; linear: 2.677Vpp

Your own numbers show the importance of not turning off the sinc filter. You get significant errors without it - even on your high-bandwidth, 20GSa/s oscilloscope!

This video explains very clearly what the sinc function does and why a "join the dots" approach gives wrong answers. It should help clear up any confusion.  :-+



I am not totally sure what the complaint is in this post, but I noticed that it was disclaimed as an old test. I think the complaint is the amplitude change when sin(x)/x is off on dots mode. So I made some animations of a current oscilloscope with the 2nd to latest firmware.

Somebody else needs to watch that video. The importance of not turning off the sinc filter really can't be understated - you're not recreating the original signal without it. Any "measurements" you make while it's disabled are automatically suspect.

« Last Edit: September 07, 2018, 11:36:18 pm by Fungus »
 
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Offline technogeeky

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Re: New Rigol DS1054Z oscilloscope
« Reply #4206 on: September 07, 2018, 11:59:54 pm »

I am not totally sure what the complaint is in this post, but I noticed that it was disclaimed as an old test. I think the complaint is the amplitude change when sin(x)/x is off on dots mode. So I made some animations of a current oscilloscope with the 2nd to latest firmware.

Somebody else needs to watch that video. The importance of not turning off the sinc filter really can't be understated - you're not recreating the original signal without it. Any "measurements" you make while it's disabled are automatically suspect.

I appreciate the video link, which I will watch. But I don't necessarily need to be told what to do. I only wanted to contribute some new screen captures and only did so because the ones presented were listed as old (perhaps raising doubt if there are differences anymore) and tried to replicate the measurement. I had to guess as to what the point of the two screen shots was, and so I did.

 

Online Fungus

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Re: New Rigol DS1054Z oscilloscope
« Reply #4207 on: September 08, 2018, 12:08:44 am »

I am not totally sure what the complaint is in this post, but I noticed that it was disclaimed as an old test. I think the complaint is the amplitude change when sin(x)/x is off on dots mode. So I made some animations of a current oscilloscope with the 2nd to latest firmware.

Somebody else needs to watch that video. The importance of not turning off the sinc filter really can't be understated - you're not recreating the original signal without it. Any "measurements" you make while it's disabled are automatically suspect.

I appreciate the video link, which I will watch. But I don't necessarily need to be told what to do.

Sorry for not being clear: I didn't mean you need to watch it (although it's a good idea if you haven't seen it yet), I meant whoever posted that there's a difference in readings with sinc on/off. This difference won't surprise anybody who understands signal theory.

That video makes it very clear what the sinc function ("reconstruction filter") is, and why it's necessary.
« Last Edit: September 08, 2018, 12:11:06 am by Fungus »
 
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Offline alsetalokin4017

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Re: New Rigol DS1054Z oscilloscope
« Reply #4208 on: September 08, 2018, 12:51:43 am »
Quote from: David Hess
Most users lack either the equipment or experience to find this sort of difference.

Well, that tells you something about the scope, doesn't it? I mean...if you had a machinist or perhaps a team of surveyors check all the "right angles" in your home, I'll wager that they might find a few that aren't "exactly" 90.00 degrees. Most homeowners lack the equipment or experience to find this sort of difference. Yet... your house doesn't fall down.   >:D

This scope fills a niche that needed filling, as evidenced by its current competition. It sits right on the edge of hobby-semipro usage cases. As such, it isn't likely to be exposed to situations where "this sort of difference" really matters very much. It's "good enough" for the tasks at hand, most of the time, and after all the bugs are ironed out.


I am ecstatic that I can actually do something like this for under 400 dollars. I don't think the scope is lying to me in any significant manner:
The easiest person to fool is yourself. -- Richard Feynman
 
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Offline technogeeky

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Re: New Rigol DS1054Z oscilloscope
« Reply #4209 on: September 08, 2018, 01:00:58 am »

I am not totally sure what the complaint is in this post, but I noticed that it was disclaimed as an old test. I think the complaint is the amplitude change when sin(x)/x is off on dots mode. So I made some animations of a current oscilloscope with the 2nd to latest firmware.

Somebody else needs to watch that video. The importance of not turning off the sinc filter really can't be understated - you're not recreating the original signal without it. Any "measurements" you make while it's disabled are automatically suspect.

I appreciate the video link, which I will watch. But I don't necessarily need to be told what to do.

Sorry for not being clear: I didn't mean you need to watch it (although it's a good idea if you haven't seen it yet), I meant whoever posted that there's a difference in readings with sinc on/off. This difference won't surprise anybody who understands signal theory.

That video makes it very clear what the sinc function ("reconstruction filter") is, and why it's necessary.

That is an extremely good video. I really appreciate the link! I don't think he actually mentions 'sinc function' explicitly, either.
 

Offline bitseeker

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Re: New Rigol DS1054Z oscilloscope
« Reply #4210 on: September 08, 2018, 01:37:05 am »
There's a written version of the material as well. https://wiki.xiph.org/Videos/Digital_Show_and_Tell
I TEA.
 

Offline MrW0lf

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Re: New Rigol DS1054Z oscilloscope
« Reply #4211 on: September 08, 2018, 07:05:08 am »
The importance of not turning off the sinc filter really can't be understated - you're not recreating the original signal without it. Any "measurements" you make while it's disabled are automatically suspect.

Actually if you want to do any sort of postprocessing either in scope or in MatLab etc it is absolutely critical to have raw data, otherwise you are properly locked out of various wonders of DSP magic.
Think of it like a family car with stability control that cannot be turned off. All it ever does is bluntly understeer. But take out a little fuse and fun begins ;)
 

Online Fungus

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Re: New Rigol DS1054Z oscilloscope
« Reply #4212 on: September 08, 2018, 07:31:06 am »
That is an extremely good video. I really appreciate the link! I don't think he actually mentions 'sinc function' explicitly, either.

sinc is the mathematically correct function to use for reconstruction:

https://en.wikipedia.org/wiki/Whittaker%E2%80%93Shannon_interpolation_formula

The important thing to understand is that a reconstruction filter is necessary and that "joining the dots" is wrong.

Many modern oscilloscopes don't let you turn off the sinc function at all, eg. this $12,000 keysight. Guess what? There's still people looking for the 'off' button even here on EEVBLOG (where you'd think they'd know better).  :-//

 

Online Fungus

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Re: New Rigol DS1054Z oscilloscope
« Reply #4213 on: September 08, 2018, 07:42:03 am »
Actually if you want to do any sort of postprocessing either in scope or in MatLab etc it is absolutely critical to have raw data, otherwise you are properly locked out of various wonders of DSP magic.

You can turn off 'sinc' in the menu, right?

Ergo: The raw data must exist in memory somewhere.

(and the Rigol 'dump' function will give it to you)

 

Offline metrologist

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Re: New Rigol DS1054Z oscilloscope
« Reply #4214 on: September 08, 2018, 12:20:44 pm »
How is that done, Fungus? If that is true, then I am happier than I was after reading David Hess's post (and thanks for the reply, David). I need to think about it some, but wanted to see if there was a difference in the csv output with sinc vs raw sample points.

I had a full pulse (rise and falling edges) centered on screen, but the csv does not look like a full pulse. I see all 15 points both on screen and in the csv, but they are not at all the same points. I used memory instead of screen and was expecting more data than screen data, and why is there only ch1? I had ch3 active and ch4 was also on. I repeated with the source set to screen and I got all 1200 points. That seems backwards, but even if it is what does my first plot mean? What am I doing wrong? Further, my sweep time is 5ns/div*12 and 250MSa/s, so that is 15 points, so where does 1200 come from (100 pixels per division, but only 15 points?)?
« Last Edit: September 08, 2018, 12:46:17 pm by metrologist »
 

Online Fungus

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Re: New Rigol DS1054Z oscilloscope
« Reply #4215 on: September 08, 2018, 03:00:54 pm »
How is that done, Fungus? I had a full pulse (rise and falling edges) centered on screen, but the csv does not look like a full pulse. I see all 15 points both on screen and in the csv, but they are not at all the same points. I used memory instead of screen and was expecting more data than screen data, and why is there only ch1?

Without knowing anything at all about your methods? I have no idea.  :-//


You want the original sample data? I've never programmed it myself so don't quote me on this, but... a quick browse of the manual makes me think you might want to download data in "RAW" mode instead of "NORMAL" mode.

There's various things you have to do before you can do this, eg. stop the oscilloscope from sampling any new data. My interpretation of the manual is that if you don't get it right you'll get downsampled sin(x)/x data instead.

(it's the same "read" command for both types of data).

Here's the manual entry:


where does 1200 come from (100 pixels per division, but only 15 points?)?

I can answer that one: There's 600 horizontal pixels on screen. The FPGA filters blocks of 1200 datapoints from the sample memory into a in main memory buffer for the display (some memory which is accessible from the main CPU).

I assume they're averaged 2:1 when they're drawn on screen.

Why 2:1 ratio? Only Rigol knows for sure but my guess is that having twice the number of samples to work with makes the on-screen measurements a bit more accurate.

Anyway, anything that comes in blocks of 1200 points has almost certainly had sin(x)/x applied to it. Take that into account.
« Last Edit: September 08, 2018, 03:24:22 pm by Fungus »
 

Offline MrW0lf

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Re: New Rigol DS1054Z oscilloscope
« Reply #4216 on: September 08, 2018, 06:42:42 pm »
Actually 1200 points are probably related to peak detection feature:

https://www.eevblog.com/forum/testgear/rigol-ds1000z-series-(ds1054z-ds1074z-ds1104z-and-s-models)-bugswish-list/msg1094167/#msg1094167

Quote
But it cannot return a 1200 point peak detected record in 1200 8-bit words; it would take 2400 words.  I assume the FPGA always returns a 1200 word record but in peak detect mode, the record is composed to 600 pairs and in normal mode, it is 1200 separate points.  At least that is how other DSOs handle it.  By returning a record which is twice as long as necessary in normal mode, peak detection mode does not visibly halve the horizontal resolution.

Effective resolution for measurements on screen is 300 points, experimentally proven:

https://www.eevblog.com/forum/testgear/testing-dso-auto-measurements-accuracy-across-timebases/msg1091323/#msg1091323

Measurements accuracy seem to correlate with this formula:
Secondary (screen/buffer) sampling rate = 1 / (Timebase / 25)
(usually one would estimate accuracy from actual sampling rate)


 

Online Fungus

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Re: New Rigol DS1054Z oscilloscope
« Reply #4217 on: September 08, 2018, 07:28:12 pm »
Actually 1200 points are probably related to peak detection feature:

ie.

a) There's 600 pixels on screen.
b) Somebody at Rigol decided 600 wasn't really enough for numerical accuracy.
c) 1200 is the next logical size to use.
d) Profit!

Effective resolution for measurements on screen is 300 points, experimentally proven:

Yet again you just dump a huge list of numbers on the world with no explanation and expect people to believe a conclusion based on that.

We've already seen that some of your basic assumptions can be wrong, eg. "dots mode doesn't use sinc".
 

Offline MrW0lf

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Re: New Rigol DS1054Z oscilloscope
« Reply #4218 on: September 08, 2018, 08:05:07 pm »
Yet again you just dump a huge list of numbers on the world with no explanation and expect people to believe a conclusion based on that.

At 1GSa/s, 1us/div timebase scope reports <=10ns rising edge as 60ns.

Proposed formula:
1 / (0.000001 / 25) = 25000000 Sa/s => 25MSa/s => 40ns interval between "screen samples".

Check:
12us* / 300 = 40ns
*screen width in time

So 300 points is even sort of generous. If divide by actual minimal interval eg 60ns get 200 points...

We've already seen that some of your basic assumptions can be wrong, eg. "dots mode doesn't use sinc".

Where I talk about dots? In general, manual says that Sinc is "optional" and in the menu there is clear option Sinc=OFF. So it is fair assumption that it should be OFF, not replaced by god knows what. Some say that Sinc=OFF is some filter instead (due to massive amplitude drop). But some say Sinc is not Sin(x)/x but Rig(x)/x. So we do not really know maybe "normalized" amplitude at high frequency is rigged from much lower physical response in the front end?
« Last Edit: September 08, 2018, 08:16:16 pm by MrW0lf »
 

Offline metrologist

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Re: New Rigol DS1054Z oscilloscope
« Reply #4219 on: September 08, 2018, 08:30:51 pm »
My second plot represents what I see on the screen, with 5ns/div sweep and 250MSa/s, that is only 15 points possible. How does Rigol get more? BTW, I remember reading about the 1200 points, but how when sampling is so slow that you can only get 15 points? I can understand duplicating points to get 1200, but that is not so. I was using single trigger.

Also, what is the first plot? It looks like nothing based on the signal. Is that feature broken (save memory to csv)? Why do I not have 15 points that look like what's on screen, like I would expect? Wouldn't you expect that? Why not?

So, no scpi means no raw data or sample point data ever?
« Last Edit: September 08, 2018, 08:37:51 pm by metrologist »
 

Online Fungus

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Re: New Rigol DS1054Z oscilloscope
« Reply #4220 on: September 08, 2018, 08:42:39 pm »
My second plot represents what I see on the screen, with 5ns/div sweep and 250MSa/s, that is only 15 points possible. How does Rigol get more?

By using a reconstruction filter.

Why do I not have 15 points that look like what's on screen

Maybe because on screen there's a reconstruction filter in effect? It's not like you mention your settings or anything like that.
« Last Edit: September 08, 2018, 08:45:53 pm by Fungus »
 

Offline metrologist

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Re: New Rigol DS1054Z oscilloscope
« Reply #4221 on: September 08, 2018, 08:52:55 pm »
From default, all 4 channels on 5ns/div sweep. Input a 10 MHz pulse period, probably 40ns pulse width, to any channel and set the verticals and single triggering. It's a pulse like my second plot.

The only difference between my plots what the data came 1: from save memory csv data and 2: save screen csv data - to a USB.

1: why is there only 15 points? I expect that anyway, but why do those 15 points not reflect the actual waveform?
2: this is what I expected in the above.

I really do not think it matters what is set up, just that save screen vs memory to csv is totally different. I think it's a new bug.

This is not a difference like sinc vs no sync, it's like a difference of wave being offset and truncated 180 degrees.
 

Offline metrologist

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Re: New Rigol DS1054Z oscilloscope
« Reply #4222 on: September 08, 2018, 09:06:21 pm »
You see this trace, and I will save it as CSV screen data. What I should get? Here is also what I get, in second plot above. I get all 4 channels and 1200 points.

When I change only the data source to memory, I get 15 points, ONLY channel 1 (when ch3 is active), and nothing like the actual scope image.

WTF?



 

Online Fungus

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Re: New Rigol DS1054Z oscilloscope
« Reply #4223 on: September 08, 2018, 09:07:22 pm »
In general, manual says that Sinc is "optional" and in the menu there is clear option Sinc=OFF. So it is fair assumption that it should be OFF, not replaced by god knows what.

Says who?

Maybe it works like that $12,000 keysight 'scope I mentioned earlier:

https://www.eevblog.com/forum/testgear/dsox3000t-can-i-turn-off-sinc-interpolation/msg1266347/#msg1266347

(are you going to say that $12,000 Keysights are "wrong", too?)

We do not really know

That's the only sensible thing you've said in this whole thread.

We do know that we get good results from a DS1104Z if we stop dicking around in dots mode at maximum settings with no sin(x)/x and a head full of unfounded assumptions.

And that's all that really matters.
 

Offline metrologist

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Re: New Rigol DS1054Z oscilloscope
« Reply #4224 on: September 08, 2018, 09:15:31 pm »
looks like a bug. I shut off other 3 channels and saved memory (now 60pts), and the wave represents.
« Last Edit: September 08, 2018, 09:23:17 pm by metrologist »
 
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