Rigol HDO1000 and HDO4000 12bit oscilloscopes launched in China

[Martin72]

Hello,

Martin72: "Got bandwithlimiter on 20Mhz AND 200Mhz, should activate the 200 for this."

Yes.

Martin72: "No problem, but didn´t Dave used 1M ?"

Dave post the 50 Ohm Data with 1 MSa and 250 MSa but the 1 MOhm only with 1 MSa. I hope he will post the 1 MOhm files with 250 MSa too.

Martin72: "Open input is clear, but what´s the other, switched to GND ?"

Sorry my mistake, somehow I implicitly assumed that the input is already terminated by the 50 ohms. At 50 ohms, of course, also open.

Best regards
egonotto

Actually I save the second file - with 200Mpts it last a while...
I´ve choose "matlab" format.

[Martin72]

Gentlemen, are you sure to want 200Mpts ?
One file is 2.2Gb 

what is the practical benefit?

Maybe you remember the cardgame "Quartett" from your childhood?   

[nctnico]

Like rf_loop, sample stuffing is the first I have heard of such a term.

There is no shame in that. It is part of digital signal processing theory (more precisely on the subject of upsampling a signal in order to increase the samplerate).

[Martin72]

Link to the 1Mpts files, zipped:

https://drive.google.com/file/d/1KhZinD7F7LsLM8fBEr32mpLP14MEC_ea/view?usp=sharing

200Mpts....Must see how, maybe for an hour 4 files up, then the next 4...

[maxwell3e10]

Here is a comparison with the RTB2000 and the 1 MSa/1 MOhm data.
But what do the graphics actually show, what is the practical benefit?
Peter

Thanks, it's great to see them plotted together! I would say the main point to take from these plots is that for 1V scale, 20 MHz bandwidth, HDO is doing better than RTB because of higher ADC resolution.

But I personally don't agree with the set of parameter choices proposed here earlier for recording such data:
a) For 1 M Sample files the sample rate is low (50 MS/sec), so full bandwidth data are meaningless because of aliasing. Even 20 MHz data can have some aliasing depending on how steep the filter is.
b) Open input data to me are not that interesting or useful. It's sensitive to interference and only practically relevant example is when using 10X probe for weak signals, which is a bad combination.

When we did this exercise a few years ago (https://www.eevblog.com/forum/testgear/oscilloscope-input-noise-comparison/) I suggested always taking data with 50 Ohm terminator on input and comparing 50 Ohm and 1 MOhm scope settings. This shows if the amplifier paths are different and is relevant when recording most relatively-low output impedance signals.

Also I suggested always using maximum scope sampling rate. Perhaps there is a middle ground where the files are ~10-30 Mbyte and still manageable but don't go to low frequency. For investigating low-frequency 1/f noise one could take data at 100 MS/sec with 20 MHz bandwidth filter.

 

[Kleinstein]

There is some sense in also doing a test with reduced sampling rate, especially for scopes with limited memory. The way how the reduced sampling rate is realized may vary: they could have some kind of digital filtering befrore downsampling (so aliasing may not be an issue) or they may just skip samples for more noise and aliasing.

The 1 V/div range seems to use a divider of some 1:100 before the amplifier. This is often done with an additional resistor to get the same output impedance and this resistor does contribute to the noise. So the 1V/div range may not be the bet range to really judge about the ADC. Some of the ranges may well be limited by the amplifier (or divider) and not the ADC. This is not just the 1 mV/div and lower, were this is expected, but also other high ranges with a divider. For most test a shorter data section (e.g. 1/10 the points) should be sufficient - the low frequency noise is usually not that important.

[maxwell3e10]

There is some sense in also doing a test with reduced sampling rate, especially for scopes with limited memory. The way how the reduced sampling rate is realized may vary: they could have some kind of digital filtering befrore downsampling (so aliasing may not be an issue) or they may just skip samples for more noise and aliasing.

By definition a scope is supposed to have full bandwidth unless a low-pass filter is specifically selected or Eres is used. Aliasing is a useful feature that allows one to detect, for example, high-frequency oscillations where one might not expect them.

But I have been wondering why more scopes don't have an adjustable low-pass filter. Since many scopes now have software bandwidth limit and upgrade path, it seems one could turn it into an adjustable low-pass filter without much additional overhead.

[Hydron]

But I have been wondering why more scopes don't have an adjustable low-pass filter. Since many scopes now have software bandwidth limit and upgrade path, it seems one could turn it into an adjustable low-pass filter without much additional overhead.

+1
This is one of the feature requests I put in on the RTB2k thread - even would be very useful to have a _discrete_ extra step or two of low-pass filter available to reduce noise etc when you need >20MHz but less than the scope's maximum. They already have it built in for the SW upgradeable bandwidth options, so all it would need is a few bits flipped in the software and some extra menu entries.

[nctnico]

But I have been wondering why more scopes don't have an adjustable low-pass filter. Since many scopes now have software bandwidth limit and upgrade path, it seems one could turn it into an adjustable low-pass filter without much additional overhead.

+1
This is one of the feature requests I put in on the RTB2k thread - even would be very useful to have a _discrete_ extra step or two of low-pass filter available to reduce noise etc when you need >20MHz but less than the scope's maximum. They already have it built in for the SW upgradeable bandwidth options, so all it would need is a few bits flipped in the software and some extra menu entries.

IIRC the chips used to switch between bandwidth aren't continuously variable. From what I've seen you can select a few bandwidths and that's it.

[Hydron]

I sniffed the bus going to the VGA/BW filter chip in my RTB2k and if I recall correctly it was in the highest bandwidth mode, i.e. higher than the scope was capable of (I think even when the 20MHz filter was enabled). The steps available didn't really match the BW options either, so it seemed like it was done in SW rather than on the front end.

In any case even the limited options available in the front end ICs used would be better than nothing!

[egonotto]

Gentlemen, are you sure to want 200Mpts ?
One file is 2.2Gb 

what is the practical benefit?

Maybe you remember the cardgame "Quartett" from your childhood?   

Hello,

please yes. With the maximum sampling rate, the devices can not dizzy. In addition, I plan to try out different smoothing methods with the data.

Best regards
egonotto

[Martin72]

OK,

upload it in a couple of hours, say early afternoon..

[David Hess]

But I have been wondering why more scopes don't have an adjustable low-pass filter. Since many scopes now have software bandwidth limit and upgrade path, it seems one could turn it into an adjustable low-pass filter without much additional overhead.

+1
This is one of the feature requests I put in on the RTB2k thread - even would be very useful to have a _discrete_ extra step or two of low-pass filter available to reduce noise etc when you need >20MHz but less than the scope's maximum. They already have it built in for the SW upgradeable bandwidth options, so all it would need is a few bits flipped in the software and some extra menu entries.

Higher end DSOs often do have more than the standard 20 MHz bandwidth limit.  Even some old analog oscilloscopes have more than one.

[mawyatt]

Like rf_loop, sample stuffing is the first I have heard of such a term.

We called it Zero Filling back in 80!! Used in all sorts of DSP back then.

Best,

[coppice]

Like rf_loop, sample stuffing is the first I have heard of such a term.

We called it Zero Filling back in 80!! Used in all sorts of DSP back then.

Best,

Its used in just as much DSP today. People use various terms for it, but filling and stuffing are probably the commonest. Stuffing tends to be a more generic term for that kind of infill - e.g. bit stuffing in plesiochronous comms protocols.

[Fungus]

This is one of the feature requests I put in on the RTB2k thread - even would be very useful to have a _discrete_ extra step or two of low-pass filter available to reduce noise etc when you need >20MHz but less than the scope's maximum. They already have it built in for the SW upgradeable bandwidth options, so all it would need is a few bits flipped in the software and some extra menu entries.

Most DSOs have a "hi-res" mode for that... 

[maxwell3e10]

Here is a comparison of the noise for Martin72's SDS2000X HD and Rigol HDO4000. I would say each scope camp will have something good to point to and something to criticize.

[Fungus]

Here is a comparison of the noise for Martin72's SDS2000X HD and Rigol HDO4000. I would say each scope camp will have something good to point to and something to criticize.

Rigol wins!

Can't wait to see the results for the sub-$1000 model. 

[maxwell3e10]

For comparison I also added the data I had for Lecroy HDO4032 scope ( https://www.eevblog.com/forum/testgear/oscilloscope-input-noise-comparison/msg1966586/#msg1966586)

I don't have 1V/div data for HD Lecroy, would someone be able to contribute?

[rf-loop]

Like rf_loop, sample stuffing is the first I have heard of such a term.

We called it Zero Filling back in 80!! Used in all sorts of DSP back then.

Best,

Yess! 

I don't know why one have to use all kinds of slang when there are available also "right" terms.

I too have been scammed by selling a chicken stuffed with small stones. 

[egonotto]

Hello,

maxwell3e10 wrote: "For comparison I also added the data I had for Lecroy HDO4032 scope"

It would be interesting to see the Lecroy HDO4032 with 1V/div, because here Lecroy HDO4032 should be very good.

Best regards
egonotto

[EEVblog]

I want to get a SDS2104x+, then I see these rigol 12bit models and the sds HD 12bit scopes. But they would cost over 2x as much, at least the Siglent would.
I'd love if the rigol are closer to 2k, than 3-5k

The HDO1000 series will start at $699, still 12bit, but doesn't have the 100uV-500uV software expanded ranges.

Different class of instrument Dave, you are comparing apples and oranges.
SDS2000X Plus is a 500 MHz design vs 200 MHz, it also has 2x 2GSa/s, 200 Mpts x2 mem depth, inbuilt AWG, MSO, 10x probe sense.....need I go on ? 

Yes, but MathWizard seems excited by the 12bit architecture, but it put off by the price. The HDO1000 series is going to get you 12bit capability from $699.
As always YMMV.

[Martin72]

Rigol wins!

 

Anyway...

I don't have 1V/div data for HD Lecroy, would someone be able to contribute?

Tomorrow at work, from a Lecroy HDO6034A ?
Btw, file format matters ? Bin. file, Mat.file.....

[BmaxTom]

Why is there such a big difference between the two diagrams on the Rigol HD4000? I think the curve of the Rigol is very smooth in the second diagram.

[BmaxTom]

Ok, I just noticed it myself.