Rigol DHO804 Test and Compare Thread

[ebastler]

Inexpensive does not mean cheap nonfunctional shit. DHO800 is limited enough in capabilities that it's price is very good only if it works flawlessly.

Please don't blow this out of proportion. Yes, I want to learn about bugs and limitations of the DHO series, so I can make an informed purchasing decision -- which might be a decision for a more expensive scope, if the limitations are too severe. But so far I have not seen anything that would make the scope "nonfunctional" for me. (And yes, that's subjective and depends on one's use cases and expectrations.) Swear words don't help either if we want a productive discussion here.

On SDS2000X HD I can have 80V offset on 200mV/div range. And it shows full 140µV on input in that case... yes 140 microvolts. That is worst case scenario. On average it is 20-30µV.

Has anyone tried whether setting an offset (rather than a bias) causes the same voltage output on the DHO? I am still unsure whether they are different hardware settings, or just two different ways to set and display the same physical adjustment in the front end.

[Fungus]

e.g. by a pinch/zoom finger gesture. Not sure whether that is actually supported, though; I don't see it mentioned in the manual.

Yes, it is.

[2N3055]

Has anyone tried whether setting an offset (rather than a bias) causes the same voltage output on the DHO? I am still unsure whether they are different hardware settings, or just two different ways to set and display the same physical adjustment in the front end.

Thomas did and it is the same. Those are just two names for null offset and trace offset. So you can compensate to DC offset in run time and leave it there and separately adjust vertical offset with a knob. It is actually nice idea.. Picoscope has something like this (they have it automated though but same concept of being able to null out any offsets in runtime)

[2N3055]

e.g. by a pinch/zoom finger gesture. Not sure whether that is actually supported, though; I don't see it mentioned in the manual.

Yes, it is.

That is good news.  Can you please show how it looks ? Does it show smaller selection square in upper window similar to what I have shown?

[Fungus]

Has anyone tried whether setting an offset (rather than a bias) causes the same voltage output on the DHO? I am still unsure whether they are different hardware settings, or just two different ways to set and display the same physical adjustment in the front end.

The voltage changes if you use the vertical position knob to move the trace up and down.

That's how I got a voltage on my Micsig, it doesn't have a box to type in a number.

[iMo]

..Inexpensive does not mean cheap nonfunctional shit. DHO800 is limited enough in capabilities that it's price is very good only if it works flawlessly..

Yep, as of today the box is overpriced actually.
Making it really useful 2ch o'scope (for example like 802/812/822 such it fits the LCD size, sampling rate/BW with 2channels) with a well polished fw/UI should have placed it somewhere around $199/$249/$299 excl. VAT and postage, IMHO.

[Fungus]

e.g. by a pinch/zoom finger gesture. Not sure whether that is actually supported, though; I don't see it mentioned in the manual.

Yes, it is.

That is good news.  Can you please show how it looks ? Does it show smaller selection square in upper window similar to what I have shown?

Pinch-zoom works. Not selection window.

[2N3055]

e.g. by a pinch/zoom finger gesture. Not sure whether that is actually supported, though; I don't see it mentioned in the manual.

Yes, it is.

That is good news.  Can you please show how it looks ? Does it show smaller selection square in upper window similar to what I have shown?

Pinch-zoom works. Not selection window.

So it does not have full vertical and horizontal zoom in zoom window ? I'm confused now...

[Martin72]

I'm confused now...

I dissolve...

There is no vertical zoom option.
You can move the signal up and down, that's it.
If you change the vertical sensitivity, either by turning the corresponding button or by fingertouch, you change both, channel and zoom.
With my siglent, the basic vertical setting of the channel is retained when you increase the vertical resolution of the zoom signal.
You can also easily recognize it by the vertical labeling axes on the left, for both scopes.
On the rigol, both axes are labeled the same.
However, rigol has not claimed to be able to do both, so it is rather semi-tragic.

[Circlotron]

If you have a trace with some high level pulses and some low level detail between the pulses, can you wind up the vertical sensitivity very much to see the low level stuff without the X amplifier overloading and rendering the trace unusable?

[ebastler]

What if you connect a 32" 4K touch panel to this scope?

You will get a 1920*1080 picture with properly upscaled fonts, but no additional detail in the trace data. The graphical elements (settings bars at top & bottom, window frames etc.) will take up the same percentage of the screen real estate as on a small screen.

Hence, this is good for easier viewing and touch operation, but will not really fit more detail onto the screen.

EDIT: Heck, second time today that I respond to a post, and by the time I hit "send" the original post is gone. What gives?

[Fungus]

If you have a trace with some high level pulses and some low level detail between the pulses, can you wind up the vertical sensitivity very much to see the low level stuff without the X amplifier overloading and rendering the trace unusable?

Not as much as with a $2000 'scope.

OTOH you have 12 bits so you can get the whole wave on screen. press STOP, then magnify it and shift it around in software.

(and obviously a $3000, 12bit 'scope will do it even better)

[Martin72]

By the way, in my room where the three scopes are, the rigol is not the loudest one...

[2N3055]

If you have a trace with some high level pulses and some low level detail between the pulses, can you wind up the vertical sensitivity very much to see the low level stuff without the X amplifier overloading and rendering the trace unusable?

Not as much as with a $2000 'scope.

OTOH you have 12 bits so you can get the whole wave on screen. press STOP, then magnify it and shift it around in software.

(and obviously a $3000, 12bit 'scope will do it even better)

Good advice. There are some limitations doing that as reported but that will avoid overdrive.

[EEVblog]

A couple years ago when I was looking for an entry level scope, the DS1054Z and SDS1104X-E are the two that most reviews pointed to as very good bang for buck (with the GDS-1054B being thrown into the mix sometimes) - especially if hacking for extra bandwidth/features is acceptable.  I'd think that the DHO804 deserves to be in that list.  After a couple rounds of firmware fixes, it might even be considered the "go to" entry level scope.  At the very least it should drive down the prices of the other entry level scopes (the DS1054Z has already been dropped to $315).
If I were scopeless, I'd almost certainly choose the DH0804 over the DS1054Z or the SDS1104X-E - even with all the unknowns about it that are still floating around out there.

Is anyone actually having any showstopper problems in everyday use using the 1.00 firmware?

[mawyatt]

No showstoppers yet.

We've been using the DH0814 (V 1.00) for some typical simple measurements for a few days, and outside display dimness/reflectivity no serious complaints. The display issue is resolved by dimming lab lights, positioning one's self up close in front of the screen, thus reducing reflections from behind, and up close we can see the small screen and details fine (our eyes aren't good).

However, our client requested this evaluation, and has a different use environment, with bright shop, bright objects, and viewed/operated from a long-arms distance will decide if the DGHO814 DHO814 is acceptable. Electrically we've found it acceptable  with our limited evaluation.

Best, 

[Martin72]

Is anyone actually having any showstopper problems in everyday use using the 1.00 firmware?

Basic tasks are no problem.
And reduced to that, I would also currently recommend the DHO over other competitors in the absolute cheap segment.
I would not even cite the 12 bit resolution as a purchase argument.

[Fungus]

Is anyone actually having any showstopper problems in everyday use using the 1.00 firmware?

Not me.

The only thing that really affects me is the serial decoding threshold voltage not taking into account the probe setting but it has a very easy workaround (set probes to 1x)

I haven't had any crashes or restarts yet.

[Fungus]

I would not even cite the 12 bit resolution as a purchase argument.

Nor me. I only care that it has enough.

I'm much more into the form factor and the user interface.

[TurboTom]

I will return it. I ordered it expecting a functional Bode Plot implementation , and the recent findings by @Howardlong regarding sample rate vs. digital channels and the limits using the digital channels as protocol decoder inputs make me believe that it's more like an unfinished toy. The DHO804 is probably an okay product at the price point, but the DHO914S is not!

Hence my disappointment with the scope and the decision to wait for a better choice (regardless of the brand). I've definitely got enough other scopes to keep me "in business" so no problem with waiting. The DHO800/900 series is definitely good to stir up the market. Maybe in two or three years, there will be an instrument available that checks all boxes at a reasonable price.

[mawyatt]

Apparently the 900 series Bode function is a bad joke!! Rigol has had plenty of time to get this right as Siglent set the bar long ago for lower mid-level DSOs. Siglent learned from tier 1 folks like R&S, KS, LeCroy & Tek, and implemented a nice Bode function, albeit slow, but quite functional.....and they are "listening" to users an apparently will introduce a new version addressing some of the limitations (hints by some folks with early versions)!!

The 814 we have has an FFT implementation that's not applicable for professional use, nothing close to Siglent's. Suspect the 900 series has the same FFT as the 814 we have, if so then wouldn't bank on Rigol getting this right anytime soon, same as Bode Function.

The 814 is a really good basic DSO implementation, superb hardware & build, attractive form factor, good UI, nice HW features, and very good value IMO as a basic DSO. Most folks reporting haven't discovered any serious issues with the 800 series.

However, the 900 series seems riddled with issues, mostly related to the "expansion" from the 800 series, and not hardware related. This is likely the target for the upcoming Siglent SDS1000X HD, as Rigol hit a home run with the 800 series, but fouled out with the 900 series.

Without a custom ADC chip set, Siglent can't compete with the 800 series, so wisely focused on the higher price 900 series & market segment, and with the apparent issues with the 900, seems Rigol has left the door open.

Not surprised that some of the 900s are being returned, with what's been shown, we would have also done so. With the upcoming SDS1000X HD, expected polished performance like intro of the SDS2000X+, suspect the market for the 900 series will quickly shift away, especially if Siglent prices the HD within reasonable range of the 900 series.

We would have our own DHO814 if not for the upcoming SDS1000X HD, but may still get one since it's just a darn good little DSO in a small, stylish well build package, that's very reasonable and performs quite well as a basic DSO.

As mentioned we consider the DHO800 as the equivalent of a handheld DMM, and the larger more capable MSOs as Benchtop DMMs, gotta find an excuse, need, plan, requirement to have both 

Best,

[ebastler]

Apparently the 900 series Bode function is a bad joke!! [...]
The 814 we have has an FFT implementation that's not applicable for professional use, nothing close to Siglent's. [...]

Compared to your earlier, objective comments, I am surprised by your change to a "no facts, all opinion" approach. Could you explain a bit more? The Bode plot functionality obviously has a severe bug (causing the "wiggly" charts) which needs to be fixed. Where else does it fall short, to the extent of being a joke?

Likewise, what is missing in the FFT functionality besides the somewhat awkward, indirect control of span and resolution? It certainly outperforms Siglent's offering in this price range regarding speed (massively) and dynamic range (mildly), from what I have seen in Dave's review video. I don't think I have seen an in-depth review of the FFT on the forum, and would appreciate if someone could share their observations.

the 900 series [...] is likely the target for the upcoming Siglent SDS1000X HD, as Rigol hit a home run with the 800 series, but fouled out with the 900 series. Without a custom ADC chip set, Siglent can't compete with the 800 series, so wisely focused on the higher price 900 series & market segment, and with the apparent issues with the 900, seems Rigol has left the door open.

You wish -- and I wish, actually. As mentioned before, I have decided to wait for the SDS1000X HD before making the decision to potentially buy a DHO. But I don't have my hopes up. My guess is that the SDS1000X HD will be closer to 3x than 2x the price of the DHO 914, in which case it would be difficult for me to justify the extra cost for a hobby tool.

Rigol has left the door open, but I don't think Siglent plans to walk through it any time soon; they are taking a different route. There's just not enough margin for them in the entry-level scope class. And they can't price the 1000X HD too low, since that would cannibalize their 2000X HD sales too much.

[TimFox]

I started a different thread about the "wiggly" Bode Plots on the 914S  https://www.eevblog.com/forum/testgear/rigol-dho914s-bode-plot/  but I haven't had any problems with the FFT function.

[mawyatt]

Apparently the 900 series Bode function is a bad joke!! [...]
The 814 we have has an FFT implementation that's not applicable for professional use, nothing close to Siglent's. [...]

Compared to your earlier, objective comments, I am surprised by your change to a "no facts, all opinion" approach. Could you explain a bit more? The Bode plot functionality obviously has a severe bug (causing the "wiggly" charts) which needs to be fixed. Where else does it fall short, to the extent of being a joke?

Likewise, what is missing in the FFT functionality besides the somewhat awkward, indirect control of span and resolution? It certainly outperforms Siglent's offering in this price range regarding speed (massively) and dynamic range (mildly), from what I have seen in Dave's review video. I don't think I have seen an in-depth review of the FFT on the forum, and would appreciate if someone could share their observations.

As noted Apparently, which is why we used this as we don't have the 900 series, and generally don't provide direct statements wrt things we don't have "hands on" experience with. However, from what's been shown by folks that are knowledgable the Bode Function apparently is a bad joke!! Apparantly, one knowledgable individual has decided to return the DHO914 based on "hands on" experience related somewhat to the Bode Function experience. Just spend some time reviewing with an unbiased educated assessment of what's been reported wrt the Bode Function as implemented on the 900 series, you'll soon find all your answers!!!

We do have the DHO814 and can say the FFT implementation is not quite there for our professional use, the SDS2000X+ implementation is useful and we have both DSOs with "hands on". The 814 FFT implementation is Ok to play with, but lacks many of the necessary control & display features for our pro use. Couple examples, FFT averaging doesn't seem to work correctly, no FFT cursors which can be directly configured with peaks amplitude thresholds and directly displayed as table of amplitude and frequency, both of these are show stoppers for our pro use which directly relates to SA use (the SDS2000X+ has both features that work well). The 814 FFT speed is impressive tho, and with some work could be honed into a useful feature for our use.

Maybe we missed something, please enlighten if so!!

So as we've stated the 814 is quite an impressive little DSO for GP use, apparently the 900 series has missed the mark.

Anyway, YMMV as always

Best,

[2N3055]

Likewise, what is missing in the FFT functionality besides the somewhat awkward, indirect control of span and resolution? It certainly outperforms Siglent's offering in this price range regarding speed (massively) and dynamic range (mildly), from what I have seen in Dave's review video. I don't think I have seen an in-depth review of the FFT on the forum, and would appreciate if someone could share their observations.

Serious FFT review presumes knowledge, equipment and time. All at the same time.

One thing standing in a way is exactly FFT implementation. In order to make controlled experiment, you need control.
And control is what is missing. FFT automagically sets critical parameters as you change timebase and poke on the screen..

For instance, to compare noise levels, you need to compare two scopes at same bin width (number of bins) and sample rate...
Since you cannot force FFT to use exact numbers, you cannot compare...

It is good enough to see something is there and you can certainly twidle knobs until you generally see range you want and see vertical peaks where you visually adjust how thick you want them. And FFT has very decent refresh rate...
You can then use it to detect some peaks an you can also have relative comparisons.

But exact measurements and absolute comparison to other scopes.? Not so easy...

Problem with implementation is that is made like some kind of spectrum analyser app for a phone..
It wiggles, you get some idea, you can even relatively measure which car is louder, and general feeling of acoustic spectra...
But B&K audio analyser it ain't.

Funny thing is that if they implemented all the manual control, this auto mode would still be useful for quick and dirty "sniff around".