Siglent SDS800X HD 12 bit DSO's

[Martin72]

Good Point ! 

[maxmatteo]

interesting, thanks!

best find so far is the already mentioned:

Noiseblocker BlackSilent Fan XR2
- Volume: 15 dB (A)
- Speed: 2,200 rpm
- Airflow: 24 m³ / h

might give this a try. noise is killing me slowly

[Martin72]

You should know which one is the original fan.

[tautech]

Removing fins on fan opening might increase EMC emissions... I said might.. I didn't try.

Did this to my SDS1104X-E to see if noise might be slightly reduced.....any improvement wasn't noticeable yet was never quantified by measurement.

[tmeub]

unfortunately the fan noise is quite loud :/

has anyone already tested similiar fan noise mods like with the SDS1204X ?

replacing with noctua fan? lowering voltage with diodes or 7809 regulator?

thanks for any insights

The fan was bothering me a lot also, so I did some tests and measurements.

I tested the stock fan, which is D-Fan DFM6025S, and a Noctua A6x25-FLX at various voltages.

I put temperature sensors on heatsinks of the FPGA and one of the ADCs, and also monitored air in and out temperatures. The sensor arrangement is shown in the attached pictures.

The scope settings were; all 4 channels active, inputs disconnected, vertical (each) at max sensitivity, Timebase delay 10.0ms 1.00us/div 5.000kpts 500MSa/s, simple measurements on.

Here is a table of measurements at reasonably stabilized conditions. Absolute accuracy does not matter here much, as this is just a comparative test of 2 fans, where sensor arrangement did not change between the tests. Anyway, the temperature sensors used were DS18B20, they should have ±0.5C accuracy.

T_in is the intake temperature in C, and the other temperatures are in relation to that.

D-Fan DFM6025S (stock)
U_fan   T_in    dT_air  dT_ADC  dT_FPGA
12.5    24.0    14.3    31.1    35.9    stock voltage
 9.0    25.1    16.4    37.3    43.6
 8.0    24.6    17.9    41.5    47.3
 7.0    24.8    18.7    44.7    50.3

Noctua A6x25-FLX
U_fan   T_in    dT_air  dT_ADC  dT_FPGA
11.0    24.1    15.3    33.6    35.6
 9.0    24.9    16.3    38.0    41.2
 8.0    25.1    17.1    42.0    44.5
 7.0    24.8    16.7    43.6    46.3   
 6.0    26.5    16.0    45.8    48.3

From these measurements it looks like the Noctua is about as effective as the stock fan even at a reduced voltage, 11V.
However the noise level is still a bit too much for for me. Personally I find the Noctua at 7V to be quiet (but not silent) and at 8V still acceptable.

I did not measure actual noise levels, but at the same voltage the Noctua was always quieter. Especially the type of noise from it was just airflow noise, where the stock fan has audible motor noise which I find annoying. I could hear that down to 8V.

From a quick look the air intake path looks non-optimal. It seems like the inner metal case was designed so that it guarantees decent air flow over the ADC heatsinks, but the outer plastic case is from some older design and there is unnecessary air flow turns and restrictions. Maybe one could improve this by cutting holes in the outer case in proper locations. This might improve airflow so that the fan sees less pressure differential and same cooling performance could be achieved with a lower fan speed. However, I would analyze this more carefully before starting to cut the case.

For my scope I'll probably just put in an analog fan control circuit that will use the FPGA heatsink temperature to adjust fan speed.

[tmeub]

I did also some tests with the rear part of the plastic case removed.

Noctua A6x25-FLX. Rear plastic cover removed.
U_fan   T_in    dT_air  dT_ADC  dT_FPGA
 7.0    26.2    10.2    33.5    34.4
 6.0    24.6    11.2    37.6    39.2
 5.0    24.9    11.5    42.0    43.7


Looks like when the rear casing is removed and fan is the Noctua running at 7V the cooling performance is close to the original setup.

[EvgenyG]

I was wondering if you could measure noise level with stock fan and aftermarket one. I don't want to go the path of lowering the voltage, but a quieter drop in replacement would be awesome.

[hp lee]

I found this tiny wifi bridge. Directly plugged into USB. No glue needed.

[markus_jlrb]

Sorry If this is not the right place to report my issue, but I found the inconsistency in measure mode
between the Peak-to-Peak and Amplitude value, see attached screen shot.

Perhaps already reported as I could not imagine that the other members missed this mentioned behavior.

My understanding is that Amplitude value  should by half of PP value when you monitors a symmetric signal.

Could you please confirm my observation or point me the way I'm thinking wrong.

Thanks in advance
Markus


 

[SHF]

does anyone have access to a circuit diagram of the SDS800X ??

[tautech]

does anyone have access to a circuit diagram of the SDS800X ??

For exactly what requirement ?

[SHF]

does anyone have access to a circuit diagram of the SDS800X ??

For exactly what requirement ?

25-MHz Time base circuit and environment would like to construct mod. for external ref

[tautech]

does anyone have access to a circuit diagram of the SDS800X ??

For exactly what requirement ?

25-MHz Time base circuit and environment would like to construct mod. for external ref

Would a simpler mod be to upgrade the reference crystal to like what's in SDS2000X Plus to provide ±1ppm timebase accuracy ?

[Performa01]

My understanding is that Amplitude value  should by half of PP value when you monitors a symmetric signal.

I cannot believe that the documentation is so misleading in that regard.

Maybe you're confusing a peak (Vp) measurement (which doesn't exist in most DSOs) with the Amplitude measurement, which is only applicable for square(ish) waveforms such as pulses; for noise-free sine waves it will yield very similar results to the Vpp measurement.

[ebastler]

I cannot believe that the documentation is so misleading in that regard.

The SDS800X HD manual is crystal clear in that respect. It's just that Siglent uses the term "amplitude" in a way that conflicts with what we all learned in school, so it invites misunderstandings. Users will assume they know what "amplitude" means and won't even think of looking it up in the manual.

[SHF]

does anyone have access to a circuit diagram of the SDS800X ??

For exactly what requirement ?

25-MHz Time base circuit and environment would like to construct mod. for external ref

Would a simpler mod be to upgrade the reference crystal to like what's in SDS2000X Plus to provide ±1ppm timebase accuracy ?

yes that would be possible, but it is too simple  I would like to have it more precise

[Performa01]

The SDS800X HD manual is crystal clear in that respect. It's just that Siglent uses the term "amplitude" in a way that conflicts with what we all learned in school, so it invites misunderstandings. Users will assume they know what "amplitude" means and won't even think of looking it up in the manual.

Granted, but one should also have learnt that in particular industries certain standards apply, which haven't much to do with lessons at school. An RF-technician or telecommunication engineer will already have a very different understanding of "amplitude". In fact, I've never seen the peak voltage (Vp) referred to as "amplitude" anywhere in the industry.

Don't make it look as if Siglent uses some exclusive non-industry standard definition of the automatic "Amplitude" measurement. We already had a similar discussion once:

https://www.eevblog.com/forum/testgear/siglent-sds2000x-plus-coming/msg3592210/#msg3592210

[ebastler]

It's complicated... For sine waves I would assume that most electrical engineers still adhere to the "schoolbook" definition of amplitude as the peak voltage. What about a superposition of a few sine waves? What about a superposition that happens to be a Fourier series that converges to a square wave? Confusing; I am not sure at what point the different definition often applied for square waves has crept in...

I didn't mean to imply that Siglent is the odd one out in the industry. But it's not a clearcut case the other way round either. See Keysight's definition below, from https://www.keysight.com/used/us/en/knowledge/guides/how-to-measure-amplitude-engineers-guide

[IC_Toaster]

Sorry If this is not the right place to report my issue, but I found the inconsistency in measure mode
between the Peak-to-Peak and Amplitude value, see attached screen shot.

Perhaps already reported as I could not imagine that the other members missed this mentioned behavior.

My understanding is that Amplitude value  should by half of PP value when you monitors a symmetric signal.

Could you please confirm my observation or point me the way I'm thinking wrong.

Thanks in advance
Markus

You are not thinking wrong, for me and the teachers I had, amplitude is the maximum value of a periodical signal.

[IC_Toaster]

The SDS800X HD manual is crystal clear in that respect. It's just that Siglent uses the term "amplitude" in a way that conflicts with what we all learned in school, so it invites misunderstandings. Users will assume they know what "amplitude" means and won't even think of looking it up in the manual.

Granted, but one should also have learnt that in particular industries certain standards apply, which haven't much to do with lessons at school. An RF-technician or telecommunication engineer will already have a very different understanding of "amplitude". In fact, I've never seen the peak voltage (Vp) referred to as "amplitude" anywhere in the industry.

Don't make it look as if Siglent uses some exclusive non-industry standard definition of the automatic "Amplitude" measurement. We already had a similar discussion once:

https://www.eevblog.com/forum/testgear/siglent-sds2000x-plus-coming/msg3592210/#msg3592210

The sinusoidal wave equation is: V(t)= A·sin(w·t)    Where 'A' is the signal amplitude
That seen from physics, mathematics and telecommunication fields, at least in Spain. I'd say that is Germany, at least in telecommunications (Nachrichtentechnik), is the same.
In the same way, Vp for a pure sinusoidal is the amplitude and Vp-p is the double of Vp because it is a symmetrical signal.

[2N3055]

Every 6 months or so we have this same argument.
Scope is simply an instrument. It is not a physics exam.

Use of word "Amplitude" for a P-P value between Top and Bottom plateau of square-wave signal (without overshoots but a steady state plateau) precedes time Siglent was founded.

Blame Keysight for it's use.

Definition of measurement on instrument is defined in instrument documentation.
When choosing names for certain measurements we always have a trade-off of choosing single word short name (so it fits in limited space),  previous industry practice and some kind of mathematical/ physical/ electrotechnical nomenclature correctness.

Amplitude (in English) is defined by Encyclopedia Britannica as "maximum excursion from steady state". So not as P-P but as a peak of absolute value of signal. Oxford does the same. Wikipedia uses amplitude as more general term.

So it is not so clear to be pedantic about it.
And as I said, many years ago, Keysight started using it on oscilloscope in a sense Siglent is using. And all the rest of them.
So it is a sort of "de facto" standard.

This measurement exists specifically for squarewave signals, like digital signals.

And on real life sinewave signals it might not be exactly the same as P-P because it measures different thing.
P-P will find absolute minimum and absolute maximum in a whole capture. There will be some noise riding on a signal.
Amplitude OTOH uses histograms to establish top and bottom of the signal. So actual top does not have single sample that is highest value (like in P-P measurement) but it will be small group on top of the signal from histogram. So basically it will take value not from the topmost part of the signal but from middle of the trace somewhere around the top.
It is not supposed to be used like that, but for square wave signals to extract plateau level.

[Martin72]

The manual describes the vertical measurements quite accurately.

[markus_jlrb]

Thanks o all for explanation the terms of Amp. and PP.
I'm clear aware what Amp. is, but was softly asking if the
Siglent terminology is clear to all or  if it is just a GUI bug.

Up to now my thinking concerning the terminus Amp.
was zero level to the maximum of the signal as already
mentioned by IC_Toaster via the formula "V(t)= A·sin(w·t)".

That's what my generation learned during university time.

It's not an big effort to use Siglent interpretation of this term
but I was only keen to clarify if this was a GUI problem or
a general issue of term definition.

Thanks for clarification and explanation effort.

In the lab while working it's not an issue, but could lead to
misinterpretations while using screen shots in the documentation
of measurements and pass them to others.

Bye
Markus

   
 

[Aldo22]

DSO2000 has nice pictograms that show you what the measurement is doing.
I find this really useful, especially with the somewhat unclear abbreviations (FRR etc.).

[newbrain]

DSO2000 has nice pictograms that show you what the measurement is doing.

As does the SDS800X HD: