SDS800X HD Wanted Features

[eTobey]

Thank you for providing a complete gudance how to reproduce the issue. I've used 100 Hz to 1 MHz sweep and enabled advanced measurements on top of that, just to prove that the scope was running for at least 10 minutes with 3 ms trigger holdoff:

Please test again with other holdoff values and the exakt procedure as ebastler explained (with 3ms holdoff). This bug is like a mosquito: You only know if its has been killed, if you dont have any itchy place on your skin the next morning.
It was a fun one to figure out together with ebastler though ;-)

[eTobey]

I haven't figured out a good solution because don't know if the user wants to choose the cursor or select an area. If want to distinguish between single and double clicks, I don't know if it's technically feasible.

Do you want to keep the persistance until you clear it?

Its an easy job to implement this. Have done this myself in the past.

Yes, i want to keep the persistance.

[ebastler]

Please test again with other holdoff values and the exakt procedure as ebastler explained

Good point. Based on the work I have seen from Performa01 so far, I strongly assume that he started with the exact conditions I had described, confirmed that the bug did not occur, and then went on to a more "agressive" test scenario (and one that allowed to show extended stable operation from a single screenshot). Right?

Edit: I did not find that specific holdoff time to be critical. A minimum holdoff time is required to produce the freeze -- it varies with the chosen time base, and apparently must be a bit larger than the sweep time. Any holdoff times larger than that will produce the issue with the current firmware.

[tautech]

Thank you for providing a complete gudance how to reproduce the issue. I've used 100 Hz to 1 MHz sweep and enabled advanced measurements on top of that, just to prove that the scope was running for at least 10 minutes with 3 ms trigger holdoff:

Please test again with other holdoff values and the exakt procedure as ebastler explained (with 3ms holdoff). This bug is like a mosquito: You only know if its has been killed, if you dont have any itchy place on your skin the next morning.
It was a fun one to figure out together with ebastler though ;-)

Cough.

Are you testing 1.1.3.5 like we are ?

[eTobey]

Are you testing 1.1.3.5 like we are ?

How could i? But if i would, i would have really made sure that i "slept well, and would not have a itchy bite in the morning".

[ebastler]

Cough.

Are you testing 1.1.3.5 like we are ?

That is besides the point. If the required conditions to produce the bug are very specific under 1.1.3.3, obviously they need to be specifically observed when testing under 1.1.3.5. (And then varied from there.) Which I assume Performa01 has done, see my post above. Nevertheless eTobey's caveat is a very valid one.

[eTobey]

Edit: I did not find that specific holdoff time to be critical. A minimum holdoff time is required to produce the freeze -- it varies with the chosen time base, and apparently must be a bit larger than the sweep time. Any holdoff times larger than that will produce the issue with the current firmware.

I already posted a critical time quite a few posts ago. 

[tautech]

Are you testing 1.1.3.5 like we are ?

How could i? But if i would, i would have really made sure that i "slept well, and would not have a itchy bite in the morning".

Put some cream on the itch and be patient, there will be a new firmware for you to drive right into soon.

There are many changes, several more than have been reported here.

[newbrain]

Some days ago I posted a couple of screen captures to show that FFT decimation is just that, i.e. no filtering to prevent alias.

I used the output of my TinySA, since I had it handy, assumed the 2nd harmonic came from that, and had no way to verify.
This morning I used a self built AD9954 based DDS, at 400 MSa/s, with 9th order 35 MHz elliptic low pass, set to 10 MHz and about -3 dBm.

The output spectrum is quite good, here's a TinySA capture (it had been verified also with a R&S costing 3 × my car...unfortunately no longer available to me).


The FFT in the SDS804X (cough, 824) shows quite a pronounced number of harmonics, fiddling with channel 1 vertical setting it is possible to reduce them a bit, but never at the levels shown by the SAs.


More than a bug reporting, this is a question: is this level of harmonic distortion - which I assume coming from the front-end - normal for a scope of this class?
I can live with that, this is just to make sure my scope is OK. With the pitiful FFT of my previous DS1054Z, this kind of check was unthinkable...

EtA: and yes, I see the noise floor is much lower in the FFT. Harmonics are still higher though, and the capture is with the setting for vertical that gave the best results.

[2N3055]

Improvement suggestion:
Placing the zoom window with a double tap on the upper window does not work, if there is a cursor at the same spot.

Edit:
Improvement suggestion 2:
After having captured a few traces on persistance, moving the traces to measure with cursors is not possible, since all traces except one dissappear. 

Persistence is visual aid on display only. If you force display to redraw (by moving trace) persistence will disappear.

That is how it is implemented. That is same as on my Keysight.

What you can do is to use history mode, enable persistence, and let scope run through previous captures.
That way you can recreate persistence at will.
Or shall I say you will be able to do it when beta gets published.

But if you share what you wanted to measure specifically, maybe we can suggest other/better way to measure some parameter, instead of manual cursor measurements?
This is a little analytic scope that has many tricks up its sleeve...

[eTobey]

What you can do is to use history mode, enable persistence...

LoL this works in quite a funny way.

If i would have came upon this, i guess i would have called it a bug. 

I use persistance not only for visual aid, since you can really do measurements with it! You can measure min and max of a pulse and roughly the average of it.

[ebastler]

I use persistance not only for visual aid, since you can really do measurements with it! You can measure min and max of a pulse and roughly the average of it.

That may work, but 2N3055's point was that the scope has better ways to do it. If you set up a measurement for pulse height (or duration, depending on what you are after), in advanced measurement mode and with statistics enabled, you will get precise max, min and average values. Plus a histogram of the distribution if you care about that! 

Edit:
I also like to look at traces to get a first and direct idea of what's going on. And I think that interactive, visual use of any DSO is important and should be fast, lag-free, with pleasant-looking smooth waveforms etc. (And I have run into some arguments about this with experienced users who focus on the "analytical" capabilities... )  But when it comes to quantifying things, cursors are better than eye-balling, and automated measurements are better than cursors!

[electronics hobbyist]

I use persistance not only for visual aid, since you can really do measurements with it! You can measure min and max of a pulse and roughly the average of it.

That may work, but 2N3055's point was that the scope has better ways to do it. If you set up a measurement for pulse height (or duration, depending on what you are after), in advanced measurement mode and with statistics enabled, you will get precise max, min and average values. Plus a histogram of the distribution if you care about that! 

Yes, if better methods can be used to solve the problem, it can save a lot of time, as 2N3055 said, let the machine work for you.

[2N3055]

What you can do is to use history mode, enable persistence...

LoL this works in quite a funny way.

If i would have came upon this, i guess i would have called it a bug. 

I use persistance not only for visual aid, since you can really do measurements with it! You can measure min and max of a pulse and roughly the average of it.

For that you have full statistical package to do that in pro way.
You enable +Pulse Width and -Pulse width measurement.
Go into measurement, enable Advanced, Enable statistics. Go into statistics config, set Count Limit to Unlimited, AIM limit to MAX, and enable Histograms.

Then set timebase to more than one period of signal. Put 1000 pulses on the screen. Let scope run.
Go get a coffee. Few minutes later you have advanced stats on millions of pulses with Min, Max, Stdev, P-P, Mean and also a small histogram that shows distribution. Tap on histogram for large version.

Someone asked me once, what do I mean by saying a scope is analytical scope. Well, this, for instance.

Until this scope arrived to market there was no scope for less than 5000 € that could do this. Except from some Siglents of course..
Enjoy..

Once I learned to use measurements, I don't really use manual cursors that much.
What I do use is automated measurements and Gating. Gates are like cursors that allow you to instruct scope "Here you measure, right here!!"

[rf-loop]

Thanks to performa01 and electronics hobbyist for checking the trigger behaviour with both, the current and the upcoming firmware. This seems to confirm that, while the symptoms are different from the previously reported holdoff malfunction, the underlying cause is a common one and has now been fixed. Great!

Also I can confirm, fixed. (if 20 minute run with 10kHz-1MHz sweep (using ebastler's  setup) is enough)

[eTobey]

... the scope has better ways to do it.

It actually was not a simple pulse. i measured over 3 channels.

But when it comes to quantifying things, cursors are better than eye-balling, and automated measurements are better than cursors!

Here i must say: It depends. 

[eTobey]

Tap on histogram for large version.

Damn i never thought about that. I thought "neat but without scales kinda useless". Never thought about clicking that. But i gues its in the manual. But i do not go into that now. But you sure made me hungry ;-)

Gates are like cursors that allow you to instruct scope "Here you measure, right here!!"

Please dont overwhelm me. 

[eTobey]

Also I can confirm, fixed. (if 20 minute run with 10kHz-1MHz sweep (using ebastler's  setup) is enough)

This sweep goes over 100ms?

[2N3055]

Also I can confirm, fixed. (if 20 minute run with 10kHz-1MHz sweep (using ebastler's  setup) is enough)

This sweep goes over 100ms?

I also tried Ebastler setup, yes with 0.1s sweep time. It ran some 40 minutes..No problems.
Then I went to try other things...

[2N3055]

Tap on histogram for large version.

Damn i never thought about that. I thought "neat but without scales kinda useless". Never thought about clicking that. But i gues its in the manual. But i do not go into that now. But you sure made me hungry ;-)

Gates are like cursors that allow you to instruct scope "Here you measure, right here!!"

Please dont overwhelm me. 

And in measurements you also have CH Delay page... For inter-channel measurements.

[ebastler]

... the scope has better ways to do it.

It actually was not a simple pulse. i measured over 3 channels.

Depending on what exactly you need to measure, you may be able to define a Math function which provides the required combination of the raw traces, then take automated measurements on that. There are also quite a few functions which measure relative timing across two channels (CHDelay tab in the measurements dialog, section 18.3.4 in the manual).

Edit: Ah, 2N3055 beat me to it (as far as the second sentence is concerned) while I was trying stuff out on the scope. 

[Performa01]

Another example.

Input: 1 Vpp Square, 1 ns rise time, f = 10 kHz swept  to 1 MHz;

This time an advanced trigger, that actually triggers on something meaningful, i.e. the start of the sweep.

It is an interval trigger set for a period >=99.99 µs, so that it reliably catches the 10 kHz start frequency. The Input field in the menu shows this as 100 µs, but true 100 µs wouldn't work anymore, for obvious reasons. Also it wouldn't work this way with a straight sweep, because then the 10 kHz start frequency  isn't actually 10 kHz anymore because the sweep is so fast, that the first period would be quite a bit shorter than 100 µs. Therefore I've inserted a start hold time of 1 ms in the sweep. And just to verify that Holdoff does not introduce any ill effects, I've set it to 10 ms and let the scope run for some time:


SDS824X HD_Trigger_Interval_HO10ms

This is a nice example how we can easily do without mostly obsolete techniques and crouches  from last century, like cursor measurements as an eyeballing aid, ETS in a GP DSO to look at fast periodic signals with slow ADCs, long trigger delays and peak-detect to overcome short memories, alternate triggers (not to confuse with alternate edge triggering!) and the like. They were common and some even mandatory to get the job done. Trigger holdoff is almost in the same league - and this example (as almost any other) works perfectly fine (and even more robust) without.

EDIT: oh - and look at the measurements. What are they telling you?

[eTobey]

And in measurements you also have CH Delay page... For inter-channel measurements.

Lots to play with. But for now, i stay a cursor fanboy. I like to see what i actually measure. I guess you can measure things without the restriction of the timebase (zoomed to far out)? But that histogram is definately something that will come into play at certain situations.

[eTobey]

Depending on what exactly you need to measure, you may be able to define a Math function which provides the required combination of the raw traces, then take automated measurements on that.

That sounds very good. I guess i can use CHdelay on two math channels?

[ebastler]

Depending on what exactly you need to measure, you may be able to define a Math function which provides the required combination of the raw traces, then take automated measurements on that.

That sounds very good. I guess i can use CHdelay on two math channels?

Yes, that should work. Note that setting up a measurement in advanced mode is a bit finicky:

- Make sure that you have all required channels and math functions enabled.
- Click on a free '+' icon in the measurement area, or on an existing item
- In the dialog that opens, click on the desired category (tab). That will make sure that the right number of channel selectors is shown on the left.
- Select the channel(s).
- Only then click on the desired measurement icon. This implies an "OK" and will close the dialog.

Edit: That actually appears to be a little glitch in the UI. There are nice explanatory texts for each measurement item. But there is no way to see them without actually selecting that item (before you see its explanation) and auto-closing the dialog. Well, you can re-open the dialog afterwards, to see explained what you just did...