Rigol DHO804 Test and Compare Thread

[ebastler]

And does the DHO804 decode full memory or only the part of the signal shown on screen?

As mentioned earlier (referencing Fungus' findings), it seems to be "ful memory" when you are in Zoom mode, while it's only the part shown on the screen (but with the full resolution from memory!) in normal view.

So basically it decodes only what is on screen which is not full memory.

It decodes from memory over the time interval defined by the screen view. Makes sense?
Or, to say it another way: Only "the part" which is on the screen, but not only "the data" (or "the detail") visible on screen.

[Martin72]

I wonder whether (and very much hope that!) there is similar progress in the "measurements" department. Again, the DS1054Z does these from the screen data: As soon as the relevant details are no longer resolved on screen, measurements show wrong values or indicate that they are unable to measure anything ('*****'). Does the DHO800 handle this better?

Example, 10khz sine wave...

[ebastler]

Example, 10khz sine wave...

Progress never stops!     

[Martin72]

Just wondering: how is the 7" screen in terms of operator comfort?

Hard on the edge for people with thick sausage fingers...
The arrows in the top right corner are impossible to hit without a mouse or stylus.
But it has to be said that the UI fits together pretty well in terms of the touchscreen and how the individual menus are structured.
With a little practice, operation is much faster than with the SDS1104X-e or DS1054Z, for example.
But they should rework the window function, which is a good idea in itself, but somewhat sloppily implemented.
You cannot determine the size and the number of positions on the screen is also fixed (top/bottom/sideways).
Changing the position is like a little game of patience.

[rpro]

The arrows in the top right corner are impossible to hit without a mouse or stylus.

One can just swipe that ribbon left/right (with momentum), without tapping on the arrows...

(I've also noticed the utility menu opens up with a single tap on the LXI logo, bottom right. I also like navigating from within the timebase/acquire menu to the vertical/tab menus and from there to the trigger or measurement menus, etc. Lots of entry points to all menus...)   

[Fungus]

And does the DHO804 decode full memory or only the part of the signal shown on screen?

As mentioned earlier (referencing Fungus' findings), it seems to be "ful memory" when you are in Zoom mode, while it's only the part shown on the screen (but with the full resolution from memory!) in normal view.

So basically it decodes only what is on screen which is not full memory.

Read that again...

When you're in zoom mode it does full memory.

How can you determine for sure whether it is from the complete memory?
This is a fundamental question.

You can see it in this image (the line "B1" in the zoom area):

[nctnico]

Now try the same without needing the zoom window that A) takes a lot of space and B) has a better purpose than selecting which part of the acquisition you want to decode. The screen is already tiny, you'll want to waste as little as possible (keep in mind that in a real world use case you'll have meaningfull analog traces on screen as well). In addition, with a full memory decode as a table, you can keep track of where you are within a set of messages IF the contents remains the same regardless of any other setting. If the contents of the decode table changes by what is on the display, it is impossible to make a correlation between messages while inspecting the analog signals in detail using your oscilloscope as the message index changes.

[Fungus]

You also get a long event table, although it seems to be limited to 1000 entries.

Here's a decode of some data captured at 2s/div. It decodes correctly.


There's 1000 entries in the event table but when I exported a .csv I got more than 3000 lines.

[Fungus]

Now try the same without needing the zoom window that ...

We went through all this last week...

Start here: https://www.eevblog.com/forum/testgear/rigol-dho804-test-and-compare-thread/msg5152266/#msg5152266

A) takes a lot of space and B) has a better purpose than selecting which part of the acquisition you want to decode

Don't knock 'til you've tried it. The zoom window is a great way to navigate a lot of data when you have a touch screen.

[Martin72]

You can see it in this image (the line "B1" in the zoom area):

What I can see is that what is visible in the zoom is decoded.
Furthermore, the DHO804 behaves in the same way as the MSO5000, the SDS2000xplus and the SDS2000X HD.
This means that either all these models decode from the memory or not, hence my question as to how this can be determined.

[nctnico]

Now try the same without needing the zoom window that ...

We went through all this last week...

Start here: https://www.eevblog.com/forum/testgear/rigol-dho804-test-and-compare-thread/msg5152266/#msg5152266

So my assertion is correct: the DHO804 decodes only what is on screen (which is in line with previous / other Rigol scopes).

[Fungus]

So my assertion is correct: the DHO804 decodes only what is on screen (which is in line with previous / other Rigol scopes).

Nope.

The DS1054Z works with screen PIXELS (ie. 1200 data points). If you zoom out the decoding will break.

On these DHOs you can zoom out and you still get a decode. Here's almost 10Mpts of data "on screen" being decoded.

On screen you just see little vertical lines where the bytes are but the table has the decoded data.



Or flip it around and zoom out some more:


As noted earlier: The table shows max 1000 lines but if I export the decoded data as a .csv file I get much more.

[Fungus]

And, yes, if you scroll left/right the first few characters of those 1000 lines can be garbage:

[Fungus]

I also like navigating from within the timebase/acquire menu to the vertical/tab menus and from there to the trigger or measurement menus, etc. Lots of entry points to all menus...)   

Yes, there's lots of links to related functions in the UI. Many ways to get to other places:

eg.


(...and yes, you can touch the little switches in the diagram to flip them, you don't have to use (eg.) the AC/DC dropdown, just touch the switch where it says "AC")

[csuhi17]

Did those who replaced the original memory card experience an improvement in operation or boot time?
What card was it originally?

[ebastler]

Now try the same without needing the zoom window that ...

So my assertion is correct: the DHO804 decodes only what is on screen (which is in line with previous / other Rigol scopes).

Are you just not listening/reading, or are you actively trying to troll this thread?

We explain twice that the scope decodes the full buffer in Zoom mode (which takes a noticeable time), or decodes the time section visible on the screen, but with full resolution, in regular view (which is nice for interactive work). And then you come back with your passive-aggressive "now try the same again without needing zoom". 

Fungus explains it to you a third time -- and you come back with a summary that is still plain wrong, regarding both (!) modes. The DHO804 already goes beyond DS1000Z capabilities in regular view mode, because it accesses the deep memory to resolve and decode details not visible on-screen.

What's next? Are we going to get GW Instek recommendations from you?

[iMo]

How do you know the "measure" results (the sine wave in the replay #802) are made a) from all data in the memory, or, b) from the data visible on the screen only?

PS: in order to check that you would need a more complex modulated signal, like 100mV sine for say 300ms and then 1V sine for 300ms, etc. Moving with the zoom inside that signal will show how the measurement is made then..

[ebastler]

How do you know the "measure" results (the sine wave in the replay #802) are made a) from all data in the memory, or, b) from the data visible on the screen only?

What we know is that measurements are made on the data in deep memory (with full time resolution), rather than on the screen buffer data themselves (like the DS1000Z does). That's clear since the measurements can quantify details which are not resolved on screen.

I have not seen your (a) vs. (b) scenarios discussed for measurements. But I strongly assume it is (b), at least while not viewing in Zoom mode. Otherwise the measurements would be much slower than they are.

So it is "limited time span, but full time resolution". And you can easily define which time span you want covered by going to a slower time base, so you can control the tradeoff between statistical precision and measurement speed. I quite like that approach.

[Fungus]

The DHO804 already goes beyond DS1000Z capabilities in regular view mode, because it accesses the deep memory to resolve and decode details not visible on-screen.

...and that's without going into segmented mode decodes, etc. (which have all been discussed here)

Bottom line: The decoding on this is orders of magnitude better than the DS1054Z.

[Fungus]

This worked quite well, but it is a bit annoying that you can only get back to the decoder menu via the menu button at the bottom left - unless you have activated the table, from there you can go directly to the menu.
A bit confusing and illogical.

If you're going in/out of the decode dialog a lot then you can scroll a shortcut into view at top-right... 

[Martin72]

Aha..
It would be cleverer if it were right at the position, because you have the mode active.
But good to know.

[Martin72]

Topic decode from memory or not:
If it can only decode what is visible on the screen, then this(attached pic in run mode) shouldn't work at all...or should it?

[nctnico]

Now try the same without needing the zoom window that ...

So my assertion is correct: the DHO804 decodes only what is on screen (which is in line with previous / other Rigol scopes).

Are you just not listening/reading, or are you actively trying to troll this thread?

No. I just wanted to have something clarified beyond any doubt about decoding behaviour through a very simple question which actually was not answered before.

[nctnico]

Topic decode from memory or not:
If it can only decode what is visible on the screen, then this(attached pic in run mode) shouldn't work at all...or should it?

Try to figure how to drive the number of messages in that table display and you'll know it.

[Martin72]

Try to figure how to drive the number of messages in that table display and you'll know it.

Just tried it out, you can only change the number of decoded packages displayed via the time base.
If you set it to 50ms, you have 15 packages. 37 packages
If you set it to 10ms, you get 7.
If you now use the manual allocation of the memory and set it to e.g. 10Mpts, the number of packages displayed remains at 7, although the memory is now much more than in auto mode.