Choosing between entry-level 12-bit DSOs

[tggzzz]

While not useful for your immediate task Bide plots are useful for filters, stop/pass band etc.

Or you can inject white noise and look at the FFT. Much simpler.

Yet another oscilloscope thread derailed by the eternal "FFT" discussion, even though it's stated as NOT a requirement.

That technique works, within the confines of some significant limitations.

[Martin72]

Why,   that's enough....

[nctnico]

Oh, I forgot to address one other point - a couple of times posters have mentioned that an 8-bit scope might be more than enough for my needs. Yes, very likely so - I'm open to suggestions!

There is literally no point in buying a new 8-bit 'scope now.

From Rigol or Siglent you mean. But there are many very valid choices beyond those brands!

[ebastler]

There is literally no point in buying a new 8-bit 'scope now.

From Rigol or Siglent you mean. But there are many very valid choices beyond those brands!

At times, this forum feels like a well-rehearsed play.
"Your cue, mate!"

[DaneLaw]

Oh, I forgot to address one other point - a couple of times posters have mentioned that an 8-bit scope might be more than enough for my needs. Yes, very likely so - I'm open to suggestions!

There is literally no point in buying a new 8-bit 'scope now.

They're not cheaper, and they all feel like antiques compared to this new generation.

8 bit or 12 bit.. mehh.. ofcourse if its the same device 8 or 12-bit? it goes without saying that more bits are preferred.
But many other factors that are more critical in my book on a modern scope, beside bw/sr.
One criteria that I value highly, are a generally fast waveform update rate, and a decent amount of memory for all channels.
Also been quite fund of variable filters.

[Martin72]

What a surprise.

[nctnico]

Oh, I forgot to address one other point - a couple of times posters have mentioned that an 8-bit scope might be more than enough for my needs. Yes, very likely so - I'm open to suggestions!

There is literally no point in buying a new 8-bit 'scope now.

They're not cheaper, and they all feel like antiques compared to this new generation.

8 bit or 12 bit.. mehh.. ofcourse if its the same device 8 or 12-bit? it goes without saying that more bits are preferred.
But many other factors that are more critical in my book on a modern scope, beside bw/sr.
One criteria that I value highly, are a generally fast waveform update rate, and a decent amount of memory for all channels.
Also been quite fund of variable filters.

Yup. I'm using adjustable filtering as much or maybe even more compared to FFT. Ideal to bring out signals buried in other signals (including turning PWM back into an analog signal).

[Martin72]

This can also be achieved with an appropriate RC combi.

[DaneLaw]

What a surprise.

Who are you addressing?

[nctnico]

This can also be achieved with an appropriate RC combi.

Nope. Digital filters in a DSO like the ones from GW Instek and MicSig (to stay within the same budget range) are much steeper compared to a single RC stage. And you can adjust the frequencies on the fly to really optimise wanted versus unwanted signal. Besides that, an RC filter will deteriorate your signal by loading the circuit and form an extra RC combination with the input capacitance of the scope (or probe). And there is the chance of picking up extra noise.

[Fungus]

The thing is... OP might get the idea from that the Rigol doesn't have an FFT, or it's somehow broken, which it isn't. It has a very good FFT and very simple to use.

Since you specifically brought that up: I'm afraid Rigol's FFT is broken in a few respects.

At least one of the window functions (Flattop, the important one if you want true peak heights) is wrong, resulting in nasty artefacts in the spectrum.

Only one is weird at the edges, whether it's the most important is arguable.

It can be fixed by replacing a file.

https://www.eevblog.com/forum/testgear/hacking-the-hdo1khdo4k-rigol-12-bit-scope/msg5202903/#msg5202903

[awakephd]

Nope. Digital filters in a DSO like the ones from GW Instek and MicSig (to stay within the same budget range) are much steeper compared to a single RC stage.

Thanks for making me aware of these other brands. I had not seen / read anything on either brand until now.

Can you point me to specific units and pricing? In my searching thus far, I have not been successful in finding something from either brand that is in the same ball park for price. The 4-channel units I can find for either one seem to be more in the $600 and up range, rather than the $400 range of the Siglent and Rigol.

[tautech]

I did a little reading on Bode plots just a bit ago - I now see where they could be very useful in some circumstances. Am I correct in thinking that the "magic" of the DSO Bode plot is that it gives you the whole plot across the frequency range automatically? As opposed to measuring amplitude and phase shift at, say, a dozen discrete points along the frequency range, and creating a rough graph? (I may have just revealed how little I understood of what I read ... !)

Essentially yes.

While everyone refers to Bode plot also consider it more correctly as Frequency Response Analysis. (FRA)
Implications can be fast or slow in that each each measurement point is measured several times and averaged before that single frequency is plotted.
While we might do a wide sweep initially it is more normal to control the range of the frequencies of interest and we have full control to do this within the menu.

Deep investigations of its capabilities with the previous X-E DSO's are here:
https://www.eevblog.com/forum/testgear/siglent-sds1x04x-e-bodeplot-ii-(sfra)-features-and-testing-(coming)/

An example testing a passive bandpass filter:
https://www.eevblog.com/forum/testgear/siglent-sds1204x-e-released-for-domestic-markets-in-china/msg1435854/#msg1435854

Later in Reply 550 we examine both stages of the same filter.

[Mechatrommer]

and then here is Bode Plot with DHO804 testing simple RC filter...
https://www.eevblog.com/forum/testgear/rigol-dho804-bode-plot/msg5378222/#msg5378222

when the project finalized, next thing i'm thinking is to revisit my long time dormant Goltek Bode Plotter to work with my new MSO 12bit toy...
https://www.eevblog.com/forum/beginners/goltek-bode-plotter-pc-sw-(for-ds1000ed-andor-hantek-dds3x25)/

some of the applications:
https://www.eevblog.com/forum/projects/easy-impedance-(lcr)-measurement-method
https://www.eevblog.com/forum/projects/frequency-response-analzer-proposal-using-a-agilent-20003000-series-scope

ymmv.

[KungFuJosh]

and then here is Bode Plot with DHO804 testing simple RC filter...

Is removing the back panel required for Bode plot performance? 😉😉

[Mechatrommer]

Is removing the back panel required for Bode plot performance? 😉😉

no. in experimental/prototyping/hack stage, yes have you seen DHO804 probing its own internals using LA probe?

[Fungus]

Nope. Digital filters in a DSO like the ones from GW Instek and MicSig (to stay within the same budget range) are much steeper compared to a single RC stage.

Thanks for making me aware of these other brands. I had not seen / read anything on either brand until now.

I own a Micsig.

It has a very good UI and can do a few things the Rigol DHO804 can't but if I have to choose only one it's an easy choice. I'm keeping the Rigol.

[Mechatrommer]

The 12 bits and low noise is just icing on the cake.

comparison PC FFT plot real life of same 20MHz signal 8 bit data vs 12 bit data... probably there will be slightly lower noise and artefacts?... but nil input shows about the same noise floor... some mystery.. 

[pdenisowski]

I was with you up to "ENOB" - I confess that I don't have a clue what that is, nor what its significance is.

[pdenisowski]

Fact that people write more on EEVBLOG about bugs of Rigol (or Siglent) than R&S is first and foremost because of price there is factor 1000x more Rigols and Siglent being bought by EEVBLOG community.

Very true.

And R&S RTB2000 has 17 pages of revision history where full 3 A4 pages are enumerated bugs fixed.
Same with RTM3000.

Also very true, although with two notes:  (1) the RTB2000 was released almost 7 years ago (2017) and (2) most of the bugs are pretty minor / rare / obscure

https://scdn.rohde-schwarz.com/ur/pws/dl_downloads/dl_firmware/pdf_3/RTB2000_Release_Notes_v02.400.pdf

[whodiini]

So I got the SDS804x based on this forum.  I am glad I discovered this forum, since I was not aware of these 12 bit (8 ENOB) scopes. I am blown away at the advances in prosumer level scopes.  The last scope I owned was the Tektronix 535, which I got cheaply many years ago and used it for a while.  Got rid of it because it was too heavy and it used about a KW of power. I recall using the first set of digital scopes by HP - cost over $10k and this Siglent outperforms it for a few hundred. I am teaching myself about power supplies and noise, and got this to get a FFT noise spectrum. Works OK, but I need to get a better 1x probe than what came with the unit.  So far what no one has mentioned in terms of usability is that the Siglent doesnt have wifi. I found a workaround so that the time stamp isnt 1969 all the time. Otherwise its great.

[KungFuJosh]

So far what no one has mentioned in terms of usability is that the Siglent doesnt have wifi. I found a workaround so that the time stamp isnt 1969 all the time. Otherwise its great.

That, and workarounds, have been mentioned in the main thread for the scope. You can use a mini wifi router in bridge mode to give it wifi.

[tautech]

Works OK, but I need to get a better 1x probe than what came with the unit. 

Why, is it faulty ?

[Harrow]

Hey there awakephd,

My guess is that there are at least a thousand blog lurkers who have been waiting for this thread. I've been asking myself the same question and have been deliberating for weeks. In the end, I figure if the decision is that hard to make, then the choice probably doesn't really matter, so I let a few superficial things guide me instead. Here's my list of reasons for choosing the Rigol DHO804:

- I don't like black front panels.
- The base model DHO804 comes with 150 MHz probes (with extended 1:1 bandwidth), compared to the 70 MHz probes that come with the SDS804.
- I like the idea of being able to run the scope on a battery and potentially float it at high voltage. (Yes, I know the safety implications....I used to design EHV substation earthing and 500 kV live line working procedures. I also ride motorbikes, windsurf in an area frequented by great whites, swim in an ocean pool that has blue-ringed octopuses, have funnel-web spiders enter my house regularly, and encounter eastern brown snakes from time to time, so having informed access to LV and MV in a controlled environment is low on my risk register.)

Ultimately, the price and availability of the DHO804 are better for me in AUS, so I've ordered it with the view that it is the simplest and cheapest way for me to meet my immediate needs and that in a couple of years, I'm likely to buy something a little more serious when I know just what features and specs I really need. Bode plots are of interest to me, but I'm used to doing them manually and it's an extra cost that I'll save and put toward my 'professional' purchase in a year or two if needed.

If you are still undecided, may I suggest a tried and tested method that works well for me in these situations....assign each option to heads or tails and then toss a coin. After you do, you can often find that you are either happy or not with the result, revealing your subconscious preference in the matter.

Good luck with your decision!!

[Fungus]

the choice probably doesn't really matter, so I let a few superficial things guide me instead.