Siglent SDS800X HD Review & Demonstration Thread

[2N3055]

Dropout mostly implies completely missing signal or signal that drops out below defined threshold...

No, this is defined as a Runt.

Different potato .. 

[2N3055]

Please suspend all talk about Wfm/s rates from that table based on early FW.
It will need to be re-tested again...
When currently tested FW is released...

[2N3055]

Please suspend all talk about Wfm/s rates from that table based on early FW.
It will need to be re-tested again...
When currently tested FW is released...

Is it a bug then?

Where did I said that.

I said that discussing a speed of FW that had changes in meantime is waste of time.
It is equally relevant like discussing how tall was I when I was 18 while buying a coat today.
Irrelevant.

It needs to remeasured and then yap away all you like...

[2N3055]

Please suspend all talk about Wfm/s rates from that table based on early FW.
It will need to be re-tested again...
When currently tested FW is released...

Is it a bug then?

Where did I said that.

I said that discussing a speed of FW that had changes in meantime is waste of time.
It is equally relevant like discussing how tall was I when I was 18 while buying a coat today.
Irrelevant.

It needs to remeasured and then yap away all you like...

It is a simple question, that could have been answered with a word, no longer than two letters. And you did not answer it at all.   

You are provocateur, deliberately making inflamed pompous discussions..... Clickbait type of conversation.
I do not intent to participate.

I have a bad news for you.
In a short time there will be new FW.

That you will have to test all over again. Every. Single. Detail.
All of the stuff you did and said will mostly matter no more.

Have fun.

[pdenisowski]

Dropout mostly implies completely missing signal or signal that drops out below defined threshold...

No, this is defined as a Runt.

I've usually seen "runt" defined as a signal whose amplitude crosses a lower threshold twice in a row without crossing an upper threshold.  That is, a runt trigger requires defining a lower and an upper threshold (and optionally some other things, depending on the scope).

Again, maybe another terminology mismatch between manufacturers

Edit: very sorry (@ebastler) if this is in the wrong thread - so many SDS800X threads.  I promise to be better if it is

[2N3055]

All you just could have done would be say "no", even if it wasnt true. Instead you are deceived by a wrong bias, still reading rudeness in almost every sentence i write. It seems that you did not really accepted my apology.

I'm not going to say "no" or "yes" just placate your ego's need to control my narative.
Even less I'm going to lie. Never, ever, even suggest that. Ever again.
I'm not going to lie even if I could materially gain from it.
It is called principles.

I answered "it doesn't matter, it is rendered irrelevant" because that is the answer.
Since modern digital scopes are based on FPGA cores, the Field Programmable Gate Arrays, it is possible for manufacturers to literally changed how hardware works. Significantly and fundamentally even.

To the point that it practically becomes a new revision of hardware, on logical level.

And since there was work done on hold-off in trigger, there were changes done on the very triggering.
Making previous measurement mere historic curiosity.

Until triggering is remeasured it is Tabula rasa to us. Complete mystery.
We.Simply.Don't.Know.
It might be slower than it was for all I know. Or faster. Or same. Or any other combination in-between.
If we knew exactly what was done, we could extrapolate educated guess.
But we don't know any details. So we don't know.

[Martin72]

Can we move further discussion to the general SDS800X HD thread please? Let's try to keep the S/N ratio high here. Thanks!

+1
(Please)

[Performa01]

Well, I don't want to unveil too many details about a still unreleased beta firmware, yet a decent hint shall be allowed...

You might have noticed that according to my review, the waveform update rate doesn't quite reach 120 kWfm/s, even though it is specified that way in the datasheet. People knowing me would not be surprised that this fact was in Siglents bug base the very next day.

This is just one of many bugs that have been addressed.

[eTobey]

I just had a occasion, where the measurement could not keep up with a trigger rate of less than 166 times per second. Of 10 possible measurements, only 3 were measured/counted.
https://www.eevblog.com/forum/testgear/sds800x-hd-bug-reports-firmware/msg5463370/#msg5463370

Is there any information about where the limit exactly lies?

It would be an idea to add this to the table in future measurement tests.

[eTobey]

SDS824X HD Trigger rate

What do the values in the third column mean? I just dont get it. Even after the next day. I only see a proportinal relation to the record length.


I have deleted my off-topic posts in here, and i suggest others to do the same.

[electronics hobbyist]

What do the values in the third column mean? I just dont get it. Even after the next day. I only see a proportinal relation to the record length.

What I see is the theoretical total number of points, which is the second column multiplied by the fourth column.
In fact, a frame of data is not just points on the screen, but also needs to search for trigger points, so the actual frame of data is more than the screen points.

I have deleted my off-topic posts in here, and i suggest others to do the same.

[Performa01]

Mask Test 2

Here’s another use case for the Mask Test: Power Line Monitoring. What I show is just a simulation, assuming a x100 Probe connected to an European 230V / 50 Hz power line.

In this case we need not draw the pass/fail-mask ourselves, but let it construct automatically from a reference waveform, i.e. a pure sine without distortions and interferences plus some tolerance.

Of course, I’ve exaggerated in this example and used very tight tolerances – I guess we would get lots of mask violations in a real world power grid. But then again, this is just a demo and tolerances can be tailored to the actual conditions and requirements.

We can configure the Mask Test in several ways; one of them would be to make a screenshot for every detected mask violation. We just need to plug in some USB-stick and configure the screenshot properly, e.g. PNG format into the SIGLENT folder on the flash drive.

After setting up the Mask Test, we can have the monitoring running as long as we desire – until the USB flash drive is full. With ~36 kB memory requirement per screenshot (for PNG) we can get lots of mask violations though – that is more than 110k screenshots per Gigabyte.

Here are a few example screenshots; the violations are marked in red:


SDS824X_HD_PNG_118


SDS824X_HD_PNG_119


SDS824X_HD_PNG_120

If we have set up date and time correctly, we can see the exact date/time of the occurrence in the bottom right corner in the screenshots.

Of course, for power supply monitoring tasks, we should operate the scope from an UPS to survive a power outage, but even without that all previous mask violations are still safely stored on the USB stick.

[markone]

I was playing with SDS814X FFT math (Hanning window) comparing results with my SSA3021X (Gaussian filter), in attachment some screens of 50MHz 0dBm CW sine wave (from SDG2042X) with different SPAN / RBW.

I would lik to know your opinion about SDS814x spectrum images @ 100Hz RBW, there is something wrong.

Am I doing something wrong or am I pushing the measure system over some limit ?

 

[markone]

I forgot to mention : trace average engaged with both instruments.

In attachment 2 additional spectrums of 50MHz carrier AM modulated with 1KHz sine wave, 100%.

[markone]

Same topic, comparison with DHO1000 that does not show unwanted spuries :

[Martin72]

Hi,
What is that source-signal in your last post?

[markone]

Hi,
What is that source-signal in your last post?

0 dBm 1 MHz carrier, AM modulated with sine wave 10Khz / 100%, sourced by SDG2042x, where SDS814x shows 2 additional lateral peaks that, of course, do not actually exist.

It's only one example among many others that I spotted today, as soon as you push down the RBW the spectrum becomes a spurious fest, not  present in DHO1000 FFT / SSA3021x spectrum sweep.

[Martin72]

0 dBm 1 MHz carrier, AM modulated with sine wave 10Khz / 100%, sourced by SDG2042x

In addition, you have changed the window to "Blackman" and manually reduced the sample rate to 10MSa/s,  to complete the settings...
Then I get the same result.
I don't know if these are the right settings.
In any case, anything below -72dBm can be doubted as to whether it actually exists.
Possibly these "artifacts" below this threshold are faded out in the DHO, unfortunately I don't have any more to investigate this.

[Martin72]

This is also nothing specific to the sds800.
I know we've had this topic before.
If I find it again, we should continue there.

[markone]

0 dBm 1 MHz carrier, AM modulated with sine wave 10Khz / 100%, sourced by SDG2042x

In addition, you have changed the window to "Blackman" and manually reduced the sample rate to 10MSa/s,  to complete the settings...
Then I get the same result.
I don't know if these are the right settings.
In any case, anything below -72dBm can be doubted as to whether it actually exists.
Possibly these "artifacts" below this threshold are faded out in the DHO, unfortunately I don't have any more to investigate this.

That's not the case, DHO noise floor is well below, simply they (spurious) are not there with the Rigol in this case as well as many others signal / settings combinations.

I played a lot (read some hours) with both DSOs and what you mention normally happens quite  beyond the rule 12 x 6 = 72dB dynamic range, in my humble opinion this is a fixable bug in FFT math.

I was exploring the possibility to make use of SDS814x in place of SSA at least in some user cases, where for instance it is much faster, but considering what I've seen I can't trust it (and this is a pity).

[2N3055]

0 dBm 1 MHz carrier, AM modulated with sine wave 10Khz / 100%, sourced by SDG2042x

In addition, you have changed the window to "Blackman" and manually reduced the sample rate to 10MSa/s,  to complete the settings...
Then I get the same result.
I don't know if these are the right settings.
In any case, anything below -72dBm can be doubted as to whether it actually exists.
Possibly these "artifacts" below this threshold are faded out in the DHO, unfortunately I don't have any more to investigate this.

That's not the case, DHO noise floor is well below, simply they (spurious) are not there with the Rigol in this case as well as many others signal / settings combinations.

I played a lot (read some hours) with both DSOs and what you mention normally happens quite  beyond the rule 12 x 6 = 72dB dynamic range, in my humble opinion this is a fixable bug in FFT math.

I was exploring the possibility to make use of SDS814x in place of SSA at least in some user cases, where for instance it is much faster, but considering what I've seen I can't trust it (and this is a pity).

Fact that those are 72dB below carrier means they are beyond ADC dynamic range. At 200 mV/div scope full scale is cca 8 dBm. So those spurs are -80dB below full scale.

Let's reverse the picture: if you create dual tone, let say 1MHz 0dBm combined with 1,1 MHz -80 dBm and feed that to Rigol what you will see?
Will you see -80dBm peak?
Following your logic, from your FFT plots this -80dBm should stick out nicely from noise floor.

[Performa01]

I was playing with SDS814X FFT math (Hanning window) comparing results with my SSA3021X (Gaussian filter), in attachment some screens of 50MHz 0dBm CW sine wave (from SDG2042X) with different SPAN / RBW.

I would lik to know your opinion about SDS814x spectrum images @ 100Hz RBW, there is something wrong.

Am I doing something wrong or am I pushing the measure system over some limit ?

The first thing I noted was the seemingly random usage of window functions. Hanning and Gaussian are not comparable and for a meaningful test we should stick with the Flattop window on both instruments.

Then I wonder how the signal can actually be 50 MHz / 0 dBm. If so, then the SSA shows a level error of -0.91 dB, which might be attributed to the Gaussian window. But even the rather unsuitable (for spectrum analysis) Hanning window cannot explain a +0.97 dB amplitude error on the SDS800X HD.

Let’s compare the first test with 30 kHz RBW now:


SDS824X HD_FFT_50MHz_0dBm_RBW28kHz

Now compare this with the SSA screenshot. The SDS level measurement isn’t too far off at -0.288 dBm, the filter shape factor is as expected for a spectrum analysis and the noise floor is <-90 dBm. At 51 MHz that is some 20 dB better than the SSA – and the difference would be even greater if we measure closer to the carrier.

Next is 1 kHz RBW:


SDS824X HD_FFT_50MHz_0dBm_RBW900Hz

Yes, we see some modulation sidebands below -72 dBm now, and again we cannot decide if they would be visible on the SSA as well, as the noise floor there completely masks everything that low. By contrast, the SDS800X HD shows a noise floor of -100 dBm.

But we can try the same scenario with a higher class DSO, like the SDS2000X HD:


SDS2504X HD_FFT_50MHz_0dBm_RBW700Hz

This proves that the signal source is clean and the spurious modulation happens within the SDS800X HD somehow.

Finally 100 Hz RBW. This just isn’t possible at 50 MHz – the SDS800X HD is a DSO, hence a baseband instrument and not a spectrum analyzer. The FFT would need to compute at least 4 Mpts to handle this.

Yet we can try to come as close as possible: using the full 2 Mpts at 250 MSa/s we can get about 440 Hz RBW with the Flattop window. In a pinch we could use the Blackman window, which has still acceptable amplitude accuracy and a great side-lobe suppression. This way we can get ~200 Hz RBW:


SDS824X HD_FFT_50MHz_0dBm_RBW200Hz

Yes, there are those spurious modulation sideband signals again, and these are not visible on an e.g. SDS2504X HD:

SDS2504X HD_FFT_50MHz_0dBm_RBW165Hz

So yes, the SDS800X HD has a problem there. Since the FFT should be the same across the platform, this is more likely to be a hardware issue.

In attachment 2 additional spectrums of 50MHz carrier AM modulated with 1KHz sine wave, 100%.

Once again, 1 kHz is a tough request. It is just about manageable:


SDS824X HD_FFT_50MHz_0dBm_RBW200Hz_Mod1kHz

Yet a closer look reveals a 10 kHz modulation frequency for the provided examples anyway, so here we go:


SDS824X HD_FFT_50MHz_0dBm_RBW200Hz_Mod10kHz

Yes, there are various spurious signals again. On the SDS2504X HD we get the third order intermodulation products only:


SDS2504X HD_FFT_50MHz_0dBm_RBW165Hz_Mod10kHz

These are not unexpected though. A wideband amplifier can only have so much linearity, and I’ve covered this topic in more detail here in this thread (reply #6, section “Distortion Measurements”):

https://www.eevblog.com/forum/testgear/sds800x-hd-review-demonstration-thread/msg5293759/#msg5293759

The main source of distortion in a modern DSO frontend would be the PGA, where third order intermodulation distortion is specified as -65 dBc (typically) at 250 MHz. Harmonic distortion is even worse at -50 dBc (typical) at 100 MHz. Both SDS meet the expectations at ~-67 dBc.

https://www.ti.com/product/LMH6518

BTW, in the SDS800X HD datasheet, the spurious-free dynamic range SFDR is specified as only ≥35 dBc.

Same topic, comparison with DHO1000 that does not show unwanted spuries :

Yes, that’s quite amazing. As stated above, such distortion figures cannot be expected with industry standard parts like the LMH6518.

[markone]

0 dBm 1 MHz carrier, AM modulated with sine wave 10Khz / 100%, sourced by SDG2042x

In addition, you have changed the window to "Blackman" and manually reduced the sample rate to 10MSa/s,  to complete the settings...
Then I get the same result.
I don't know if these are the right settings.
In any case, anything below -72dBm can be doubted as to whether it actually exists.
Possibly these "artifacts" below this threshold are faded out in the DHO, unfortunately I don't have any more to investigate this.

That's not the case, DHO noise floor is well below, simply they (spurious) are not there with the Rigol in this case as well as many others signal / settings combinations.

I played a lot (read some hours) with both DSOs and what you mention normally happens quite  beyond the rule 12 x 6 = 72dB dynamic range, in my humble opinion this is a fixable bug in FFT math.

I was exploring the possibility to make use of SDS814x in place of SSA at least in some user cases, where for instance it is much faster, but considering what I've seen I can't trust it (and this is a pity).

Fact that those are 72dB below carrier means they are beyond ADC dynamic range. At 200 mV/div scope full scale is cca 8 dBm. So those spurs are -80dB below full scale.

Let's reverse the picture: if you create dual tone, let say 1MHz 0dBm combined with 1,1 MHz -80 dBm and feed that to Rigol what you will see?
Will you see -80dBm peak?
Following your logic, from your FFT plots this -80dBm should stick out nicely from noise floor.

I agree with your math, 200mV/div corresponds to about 8.06dBm, so those 2 dreaded peaks are about  80dB below that, but in most cases dither effect of the noise brings to higher dynamic ranges so i'm quite sure that if I put in place the test that you are suggesting the Rigol will "stick out" an injected  frequency component @ -80dBm and even below, same should be valid for SDS814x.

Even my 8 bits Picoscope 3203D is making a better work with AM modulated carrier in respect to its vertical resolution :



Here lateral spurious are about 69dB below the carrier and 79dB below the full scale that is 10dBm  (+/- 1V).

I would dare to say that SDS814x, spurious wise, can (shall) do better in this regard thankfully to its 12bits ADC, as is doing the DHO1000) that as we all already know has quite poor math capabilities than SDS800x.

Right now I do not have a 50 ohm RF splitter to proceed with this  check, the internal SDG2042x wave combiner does not have such dinamyc range, but being quite curious about this matter I just put in the Amazon basket a cheap RF resistive divider  .

Instaed  I'm able to feed a single signal below the theoretical "resolution" of the DSO, I will try later and I will post results.

Anyway, your point does not explain i.e. this other case, clean 50MHz CW carrier, no modulation :





here spurious are well above the dinamyc range limits, so there is for sure something that lurks in the shadows ...

DHO1074, same signal :





What the hell is going on ?

[gf]

Why do you use a lower signal level with the DHO1074?

[newbrain]

Why do you use a lower signal level with the DHO1074?

It looks the same to me:
0 dBm ~= -13.5 dBV (for a 50  Z0}