Rigol DHO804 Test and Compare Thread

[Martin72]

You could say that, Thank you Lecroy 

[zrq]

I did some characterization of the input voltage noise of my DHO914S (250 M BW unlocked) at the full sampling rate (1.25 Gsps). Input shorted and scope is warmed up for ~1 hour.

[DaneLaw]

DHO800 it's OK as functionality, but the effective screen size is very small. The all-time active menus takes a lot of space. 10 inch is much better for this interface.

Also, the USB-C power supply connector it's not on my taste.

Yep. the DHOxxx vertical-screen aspect is undermined quite a bit by menus & info boxes..

From users-screenshots, it looks to be up around 35%?  That's a lot of your precious" vertical screen when you're dealing with a 7" that is in a 16/9 ratio that is already vertically cramped if you can't remove some of these top & bottom boxes.

[Fungus]

DHO800 it's OK as functionality, but the effective screen size is very small. The all-time active menus takes a lot of space.

It's easy to imagine that but I bet you won't even think about it after you use one for a few weeks.

You really have to see one in person to appreciate the tiny size.

From users-screenshots, it looks to be up around 35%?

Ditto.

That's a lot of your precious" vertical screen when you're dealing with a 7" that is in a 16/9 ratio that is already vertically cramped if you can't remove some of these top & bottom boxes.

But this 'scope does a lot of things horizontally.

[Martin72]

The DS1000Z wastes more space in the display, so in general you can either get by with the 7" or not.

t's easy to imagine that but I bet you won't even think about it after you use one for a few weeks.

Exactly that.
I've often said elsewhere that it makes a difference whether you try something out yourself or just read about it, look at pictures and watch videos...

[Mechatrommer]

screen is small if you want read pdf with it, but its not a pdf reader. once you try to debug a real circuit, even 4" screen is better than none at all.most reviews are imho only aeshetic or try to compare it with 27" screen entertainment machine.

[NE666]

See my post in the suitable thread, this is a sale of the old designations, I don't think it means anything more.

Plausible but I'd be more secure in that belief if it were not for the announcement of the 1000U model.

Might it not be the case that lower than expected sales revenue from the 1000 series has forced Rigol to look at its BOM cost, being just a DAC short of the considerably more expensive 4000, the result being the cost-reduced 1000U which will ultimately replace it in the product line?

Just a theory but the product line is starting to look very crowded already without yet another low-end 12-bit.  FWIW the signal generator range seems to be suffering the same, with the 800/900 Pro announcement.

[ebastler]

800/900 Pro? Would you have a link?

[bulba99]

800/900 Pro? Would you have a link?

https://www.rigol.com/products/products/waveform-generators

[ebastler]

Ah, thank you. I had misunderstood and thought you were talking about the internal signal generators in the scope, and an upcoming change in their voltage or frequency range.

[Martin72]

I have just had another go at decoding, this time feeding in the signal(SPI) from the competitor's demoboard.
After a few attempts, I managed to get a super-stable signal.
First with 3 channels, so CS included.
I used the "Pulse" trigger.
Then I looked to see if I could do the same with 2 channels and timeout.
Yes, but a few letters were missing, the solution was that the default timeout is 1µs, 8µs was then enough.
Finally I tried it with the SPI trigger.
This also enabled me to create a rockstable trigger with a timeout of 8µs.
Interesting:
In the SPI trigger menu you can only select MISO, but I had previously deactivated MISO in the decoder menu because it is not available on the demo board (only MOSI).
Conclusion:
The decoder signals on the siglentboard are also "bitchy"(like on the batronix board), but with the right settings the DHO achieves super stable decoding - very good.

[ebastler]

Hi @Martin72, I came across a thread in the German mikrocontroller.net forum a while ago which discusses I²C decoding on the MSO5000. It is claimed there that the MSO5000 can only decode reliably when it does a surprisingly high amount of oversampling: Sampling at 50x the I²C bit rate is supposedly not enough for reliable decoding, 100x works.

That observation seems very surprising to me, and I am not sure it is correct. The modest DS1054Z -- while being very limited by the fact that it only decodes from screen memory -- can at least do that nicely as soon as it can resolve the bits in the I²C signal. Could you try with the DHO800 which degree of oversampling it needs, by either limiting the memory size or zooming out to a very slow time base? Thanks!

[Martin72]

Can do it tomorrow with the batronix demoboard (I²C does not work on the siglent demoboard).

[tautech]

Can do it tomorrow with the batronix demoboard (I²C does not work on the my siglent demoboard).

FTFY 

[Martin72]

Hehehe....

[Martin72]

I tested it with 20kbit data rate.
20KSa/s is too low, nothing is decoded.
It has to be 50Ksa/s to display anything meaningful.
However, you can't always play with the manual memory, everything under 1Mpt is dropped from 200ms/s.
Since the batronix board offers different data rates, I will probably test another, higher speed.

[Fungus]

I tested it with 20kbit data rate.
20KSa/s is too low, nothing is decoded.

Well, obviously...

20kbit data rate means the clock signal is changing 40k times per second.

How will you capture that with 20kSa/s?

It has to be 50Ksa/s to display anything meaningful.

Working at 50kSa/s is quite impressive. It's only 20% above the minimum requirement.

(and the "minimum" still means you have to get lucky with the sample alignment)

[ebastler]

It has to be 50Ksa/s to display anything meaningful.

Working at 50kSa/s is quite impressive. It's only 20% above the minimum requirement.
(and the "minimum" still means you have to get lucky with the sample alignment)

Agreed, that's a pretty convincing implementation. 
Thank you for testing, Martin!

[Martin72]

How will you capture that with 20kSa/s?

It was only for demonstration...
See the previous question from ebastler.

[Martin72]

Now the data rate has been increased from 20kbits to 200kbits.
It needs 500KSa/s to decode this properly, very good.
I noticed this briefly when I was playing around earlier(with the lower datarate), but didn't go into it.
Now I noticed it again:
2.5MSa/s flawless decoding
1.25MSa/s NO decoding
500KSa/s flawless decoding again.
Interesting....

[ebastler]

Now the data rate has been increased from 20kbits to 200kbits.
[...]
2.5MSa/s flawless decoding
1.25MSa/s NO decoding
500KSa/s flawless decoding again.
Interesting....

I'd say that is another entry for the bug thread. 

Some of the addresses are still decoded correctly at 1.25 MSa/s (but most of them are not). But not a single letter? What does it look like if you zoom in, so that individual characters can be displayed on the decoder trace?

[Martin72]

Nothing gets better, I think because of the scarce 100Kpts.
But:
As usual, 1.25MSa/s, 5ms/div. nothing is displayed correctly.
Then press stop and increase to 10ms/div - now it is displayed correctly.
It gets even better, back to 5ms nothing displayed, then to 2ms...it is displayed correctly.

[ebastler]

[Martin72]

An old friend has found his way here.

[ebastler]

An old friend has found his way here.

Looks a bit yellowish-stained in comparison... And I guess it will look old in many other ways too.