Siglent SDS2000X Plus

[Martin72]

Hi,
Did anyone open his SDS2000x+ to enhance its perf by tweaking this or that ?

I know it's a pretty weird question...
but I just ask because I'm used to tweak some PCBs on my hifi gear (full digital, no analogue parts) and in that kind of stuff (digital is real-time flow of data, where PDN of the PCBs plays a key role, as well as precise & stable clocking), when you lower the noise of a SMPS, and change an quartz or a XO oscillator by a good TCXO or OXCO (& PS accordingly) => music is nicer.

It could be a little difficult to hear music with the siglent scope.
What I´ve done was to exchange the fan and indeed, it sounded nicer..

Based on that "experiences" (don't laugh please  ), I "think" that :
- the main PS into the SDS is a switching PS, thus ripple & noise and so on related to the SMPS
- on the PCB, that I didn't open yet, we can expect regulators (switchers) to get voltages x/y/z to this & that parts
- clock : 1 or several clocks ? I guess it's not a top-notch OCXO. Thus, we have a basic XO or a good TXCO (what kind of output ? no clue...) ?
well... a few basic tweaks that can enhance the hardware, and why not enhance the results.

Well...It´s an instrument made by people who are knowing how to made instruments.
Especially your point with the PS...You won´t get such a low noise the sds2k+ got when the PSUs are noisy.
And:
Did you notice that the sds2k+ got a 1ppm oscillator on board, which is somekind of unique in it´s priceclass and much above ?
My hint:
Never touch a running good working system..

[bdunham7]

Does anyone agree with that and has already done some experiments (successfull & non-lethal is preferred  ?

The key to audiophilia and related delusions is that the claims made typically are inherently non-falsifiable.  What changes do you expect to be able to claim after modifying your scope?

[points2]

hi Martin72,

Did you notice that the sds2k+ got a 1ppm oscillator on board, which is somekind of unique in it´s priceclass and much above ?

Honestly, I can't remember the characteristics of oscillator(s) inside the SDS...
please, could you confirm this "1ppm" ?
Sure ? You didn't mistype ppm instead of ppb ?

"1 ppb", fine => impossible, too pricey etc
but "1ppm"... come on ! I bought from digikey last month a tcxo @ +/-0.2ppm & an OCXO @ 20ppb (with pretty phase noise figures)
If we have a 1ppm oscillator inside the SDS => that's cool ! It means we have there a pretty big room for improvement !

Never touch a running good working system..

"don't do this don't do that".
please, we're here on a EE forum, it's the right place no ?
Of course, if I open the box, it doesn't mean that the SDS will die right away and I'll mess up in trying to close the box.
A DSO is a device like any others ;it's not a quantum computer as far as I guess 

@bdunham7 :
what can we expect from any modification on a scope ? I don't know.

Honestly, I find strange yours replies => straight saying => "don't open the box, it's perfect"
I find strange because I use my SDS with active probes to do measurements on small voltages at PCB level (3.3VDC at max), and at that level you find interesting stuff : PDN is far from perfect in most devices, and I guess on the SDS PCB too.

Just to understand your replies : what range of voltage to you measure with your SDS ? is it PCB level voltages (3.3VDCmax) ? or mainly high voltages >100V, where PDN at PCB level is of course not an issue ?
Rgds

[tautech]

hi Martin72,

Did you notice that the sds2k+ got a 1ppm oscillator on board, which is somekind of unique in it´s priceclass and much above ?

Honestly, I can't remember the characteristics of oscillator(s) inside the SDS...
please, could you confirm this "1ppm" ?
Sure ? You didn't mistype ppm instead of ppb ?

"1 ppb", fine => impossible, too pricey etc
but "1ppm"... come on ! I bought from digikey last month a tcxo @ +/-0.2ppm & an OCXO @ 20ppb (with pretty phase noise figures)
If we have a 1ppm oscillator inside the SDS => that's cool ! It means we have there a pretty big room for improvement !

FFS Please, please RTFM Datasheet.....it's all there in black and white:
Time base Accuracy ±1ppm initial; ±1ppm 1st year aging; ±3.5ppm 10-year aging

Siglent felt this was perfectly adequate for a DSO in this class and if you do your homework you should find it's better than most.
They had the dilemma, add a good spec oscillator and reuse the SDS2000X rear cover or add a run of the mill oscillator and a 10 MHz reference input plus rework the rear cover.
IMO they made a good and wise choice otherwise we might be paying a good bit more for these scopes.

[bdunham7]

@bdunham7 :
what can we expect from any modification on a scope ? I don't know.

Just to understand your replies : what range of voltage to you measure with your SDS

Well if you want to have the discussion, why not start with what improved result you'd hope to see?  As far as noise from the PSU, remember that it is fundamentally an 8-bit acquisition system with a certain amount of front end amplifier noise.  If noise from the PSU (the amount that gets into the signal) is well below that, improving the PSU will not do much.  The HD model with 12 bits and a much lower noise floor uses an SMSP as well AFAIK.

Same for  the timebase.  Yes, you could improve its accuracy and stability--but to what end?  It may not matter as much as you think for many things.

I use the scope for all sorts of measurements, including right down to the noise floor.  I wish it were even lower, but its pretty much best-in-class and then some, so I can't complain.  If you can improve it, show us the way!

[MathWizard]

Can u use a pencil/eraser-end on the touch screen of these ? That would be great, and I wouldn't even have to stretch as much to reach it, when I get 1.

 I've barely read anything about touch screens, but I know there's different types.

[thinkfat]

Stability and accuracy of oscillators are two different properties. The PPM figures in the datasheet are for accuracy, not stability.

It's a bit harder to judge the stability in terms of phase noise, but you can try with feeding a very, very stable signal and then setting up a CCJ measurement with histogram and trend graph and then exchange the main crystal with a "better" one and do the measurement again.

The problem is, as usual, that you need an input signal that is significantly more stable than the built-in timebase of the scope. Otherwise you'll not know what you're actually measuring.

[tautech]

Can u use a pencil/eraser-end on the touch screen of these ? That would be great, and I wouldn't even have to stretch as much to reach it, when I get 1.

I tried with an eraser on a pencil and an eraser by itself, result = no !
It may work with a proper stylus but I couldn't find one anywhere.

I've barely read anything about touch screens, but I know there's different types.

From the 2kX Plus webpage:
Capacitive touch screen supports multi-touch gestures

TBH get a cheap mouse, any mouse and it nearly negates any need at all to use the touch screen and although all the alphanumeric and numeric input boxes do pop up a virtual keypad when you tap them the mouse scroll wheel can also be used to change any numeric settings.

[Bad_Driver]

It's the first time that I hear that someone is keen to improve a scope instead of looking for a better fitting measurement solution.

I'm sure that at the end all the efforts to improve the SDS will not pay out .... but I'm not that audiophile guy 

I spend a lot time and money to improve the power supply and the XO of a cheap chinese arbitrary wave generator (FeelElec 6900).
There is a thread here where many people explain how they spend significant life time for improving a cheap 80€ plastic box.
At the end the improvement result was NOTHING. I removed all the expensive PSU and OCXO stuff and re-used the cheap (1,20 € @ Ali) original SPSU again and bought a Siglent SDG 2042X with
external 10 MHz clock input - feed from my GPS-controlled double oven Trimble OCXO. (would be a nice feature for the SDS as well but I'm happy that the SSA benefits from an external clock)

For me a designated 192 kHz/24 bit audio interface is enough "high end" to do measurements with my Revox B77 or my collection of "high end" tape decks from the 90s.  But this pure analog…

[H.O]

Can u use a pencil/eraser-end on the touch screen of these ?

Pencil eraser does not work. A stylus meant for capacitive touch screens does.

[Performa01]

For the ones who try to understand the consequences of certain settings in the FFT analysis – this is about the window functions.

Why are there so many different windows (only few of them available on the SDS oscilloscope)? What is the best window to use?

There are descriptions about the benefits and drawbacks of the various window functions, yet most folks don’t care and rather want a universal setting that works for them everytime. And fortunately there is one…

There are several features of a window function, and two of them are amplitude accuracy and resolution bandwidth. If we look at just these properties, then the rectangle window would have the narrowest resolution bandwidth but the worst amplitude error, whereas it’s just the opposite for the Flattop window.

So, whenever we need the best frequency resolution, we just sacrifice a bit accuracy and use the Rectangle window?

It’s not that simple. An FFT divides the entire analysis bandwidth into frequency bins. If, for instance, we have an FFT-length of 262144 points, then we get 131072 such frequency bins and at an effective sample rate of 400 MSa/s each of them will be 1526 Hz wide. In this case, 1526 Hz is the bin width and the bin spacing at the same time. The center of a bin will always be an integer multiple of the bin width.

Now FFT-windows behave differently, depending on the offset of the input signal frequency from the bin center. I did the test for the various window functions available on an SDS2000X Plus and used the before mentioned parameters:

FFT-sample rate = 400 MSa/s
FFT-Length = 262144 pts
Bin-width = 1526 Hz

The test will be for amplitude accuracy and the -40 dB bandwidth. Why -40 dB? Resolution bandwidth is normally defined at -3 dB.

Answer: because -3 dB might be most important for characterizing the passband of a wideband structure, but for a filter, where the selectivity is the main concern, the bandwidth at a useful attenuation is even more important, because this is what finally enables us to distinguish various spectral components. -60 dB might have been even more appropriate, but the FFT window functions cannot always provide such a stopband attenuation in certain cases.

A 0 dBm test signal of 9.999084 MHz has been used for the following test, this is precisely 6553 times the bin width, hence the exact center of a bin.

What do we get?

Window     Top Ampl. [dBm]  -40 dB BW [Hz]
Rectangle            0,058            1710
Blackman             0,038            6940
Hanning              0,038            4360
Hamming              0,066            4260
Flattop              0,027           12430

As we can see, the rectangle window is fantastic. It has a very low amplitude error of less than 0.1 dB and an ultra-narrow bandwidth of just 1710 Hz for -40 dB. Yes, the Flattop window seems to be tad more accurate, but look at the bandwidth – wide as a barn door! All the experts that tell us that the rectangle window should best be avoided must clearly be idiots.

The only problem is, that our signals will not always be an exact integer multiple of the bin-width.

In any practical application where the FFT of a general-purpose oscilloscope is to be used, we often cannot freely define the signal frequencies, hence thy will be more or less off center. Even if we can select a frequency, then most related signals like harmonics and intermodulation (mixer) products can have any frequency offset with regard to the bin spacing. Consequently, we need to take the worst case into consideration, that is a frequency offset of half the bin-width.

A 0 dBm test signal of 9.999847 MHz has been used for the following test, this is precisely 6553,5 times the bin width, hence the exact bin-border.

Window     Top Ampl. [dBm]  -40 dB BW [Hz]
Rectangle           -3,879           96300
Blackman            -1,028            8060
Hanning             -1,377           10070
Hamming             -1,689            6400
Flattop              0,027           12480

This looks very different, doesn’t it? All of a sudden, the rectangle window has the widest bandwidth by quite a margin together with a massive amplitude error. By contrast, the Flattop window hasn’t changed at all: the amplitude error is effectively zero as it was before and the also the -40 dB bandwidth remains unchanged.

So yes, the Rectangle window is the worst choice by far and should be avoided by all means.

What we can see from these measurements, Hanning, even though way better than Rectangle, is clearly not ideal either. Even though it can produce a substantial error of nearly 1.4 dB, its -40 dB bandwidth comes close to Flattop.

Hamming has half the bandwidth but nearly 1.7 dB maximum error.

Blackman has two third of the Flattop bandwidth and a still bearable 1 dB error, so it might be an alternative.

But if we are realistic, none of the other windows has a significantly narrower bandwidth as long as we cannot guarantee that all signal frequencies of interest are at an exact bin-center. As a consequence, Flattop is our best bet by quite some margin.


There are yet other aspects, like leakage and side lobes. Window functions can waste a significant amount of energy in side lobes. The Flattop window is very good in these regards and will also guarantee a usable -60 dB stopband regardless of the frequency offset.

Look at the attached screenshots. They show the filter shape and measurements of each window function for the best case (0.0 offset) as well the worst case (0.5 offset).

SDS2354X Plus_FFT_Rectangle_0.0
SDS2354X Plus_FFT_Rectangle_0.5

SDS2354X Plus_FFT_Blackman_0.0
SDS2354X Plus_FFT_Blackman_0.5

SDS2354X Plus_FFT_Hanning_0.0
SDS2354X Plus_FFT_Hanning_0.5

SDS2354X Plus_FFT_Hamming_0.0
SDS2354X Plus_FFT_Hamming_0.5

SDS2354X Plus_FFT_FlatTop_0.0
SDS2354X Plus_FFT_FlatTop_0.5

[gf]

It possibly helps to look at the DFT from the perspective of a filter bank.
See https://www.dsprelated.com/freebooks/sasp/DFT_Filter_Bank.html

...we will show how the DFT can be computed exactly from a bank of N FIR bandpass filters, where each bandpass filter is implemented as a demodulator followed by a lowpass filter.

The window function is the FIR kernel which forms the low-pass prototype for these bandpass filters.
In other words, the window function is eventually the spectrum analysis filter of a windowed DFT, analog to the RBW filter of a SA.

Attached is the frequency response of the bandpass filters that correspond to different window functions, normalized to the DFT bin width.
If the aim is to mimic a spectrum analyzer, then a filter (window function) with a high selectivity and high stop band attenuation is desired (e.g. Kaiser).
OTOH, for a good amplitude accuracy of single arbitrary CW frequencies, a filter with a wider passband is desired (-> Flattop).
Unfortunately both come at the cost of a wider main lobe - there is no free lunch. This can only be compensated by using a larger number of points. Good that modern scopes support a large number of points.

It also seems that many (most?) scopes don't support Kaiser windows, although a Kaiser window has the nice property that it approximates a Slepian window, which concentrate most energy in the main lobe (which leads to high selectivity).

Btw: There exist multiple (different) Flattop windows (I used the Matlab/Octave variant). And Kaiser windows can have different shapes too, depending on a paramter alpha or beta, which determines the slectivity and main lobe width.

[hhappy1]

I am considering purchasing this product.

It is better to have a pretty screen than a professional one as a hobby.
This is the screen where the probe tip is in contact with the ground.

It is a screen of dsox1102a. It is disappointing that the gradation seems to be only two to three stages.


I want to see the screen of sds2000x plus with reduced intensity.

[Performa01]

Attached is the frequency response of the bandpass filters that correspond to different window functions, normalized to the DFT bin width.

Well, that’s part of what I was referring to when I wrote

There are descriptions about the benefits and drawbacks of the various window functions

All these nice plots for the frequency response of various window functions are only valid when the frequency of a signal to be analyzed happens to be equal to the exact center of a bin. My screenshots show how different the filter shape can look when (as usual) the input frequency does not match this condition. 

The main point of my posting was to make folks aware that in a realistic scenario, where the input signal can have a random offset to the bin center frequency, the usable -40 dBc bandwidth might not differ that much. Regardless of the number of FFT-points, the -40 dBc bandwidth only varies by a factor of about two, so nothing much to be gained by selecting e.g. Hamming and accepting its drawbacks. About the only sensible alternative might be Blackman.

Look at the attached screenshots, which demonstrate a random use case by looking at the 50% AM-modulation by 400 Hz of a 29.6 MHz carrier (these tests have been done on an SDS2000X HD, but results should be the same). Even with 2 Mpts, the sidebands are difficult to separate. In this random scenario, the Signal frequency happens to be about 496605,6 times the bin-width of 59,6 Hz, so this is not even the worst case. So yes, in this border case Flattop doesn’t cut it anymore while other windows do, yet in my view, Blackman is the only viable alternative.

SDS2504X HD_FFT_Rectangle_29.6MHz_M50%_400Hz
SDS2504X HD_FFT_Blackman_29.6MHz_M50%_400Hz
SDS2504X HD_FFT_Hanning_29.6MHz_M50%_400Hz
SDS2504X HD_FFT_Hamming_29.6MHz_M50%_400Hz
SDS2504X HD_FFT_Flattop_29.6MHz_M50%_400Hz

It also seems that many (most?) scopes don't support Kaiser windows, although a Kaiser window has the nice property that it approximates a Slepian window, which concentrate most energy in the main lobe (which leads to high selectivity).

I’m not surprised. It does exist occasionally (e.g. R&S RTE), but why would you want the Kaiser Window in a DSO?

It really shouldn’t matter whether you have side lobes down at -90 dBc or “only” -70 dBc in a DSO that will have a true 12-bit acquisition system at best. Usually, it’s just 8 bits. It simply doesn’t matter for this application. What does matter is the flatness and accuracy of the passband though.

Even in spectrum analyzers, which use at least 16-bit IF processing nowadays, the flattop window is universally used – except some special applications, which might use Nuttall or CISPR (Gaussian) windows (together with the clear recommendation to stick with Flattop in all other cases).

Btw: There exist multiple (different) Flattop windows (I used the Matlab/Octave variant). And Kaiser windows can have different shapes too, depending on a paramter alpha or beta, which determines the slectivity and main lobe width.

Not only Flattop and Kaiser…

[tautech]

I am considering purchasing this product.

It is better to have a pretty screen than a professional one as a hobby.
This is the screen where the probe tip is in contact with the ground.

It is a screen of dsox1102a. It is disappointing that the gradation seems to be only two to three stages.


I want to see the screen of sds2000x plus with reduced intensity.

Here's a couple of screenshots of the Display menu and most of the adjustments available.
If you want to see something else in particular please ask.
BTW, open input.

[hhappy1]

Thank you.

I like the straight line, but I want to see the gradation of the waveform on the noise screen.
At around 30% intensity, it should be similar to the waveform in dsox1000x above.

[Performa01]

Thank you.

I like the straight line, but I want to see the gradation of the waveform on the noise screen.
At around 30% intensity, it should be similar to the waveform in dsox1000x above.

See attachment.

[Bad_Driver]

Big thanks to Performa01 for this FFT windowing explanation.

I have another - may be very dumb - question. As I mentioned before I do some noise measurements with PSUs and the help of my 40/60 dB Low Noise Amp.

Attached you see two screenshots of the noise floor of our beloved SDS.
BW=20 MHz, StdDeviation (to avoid DC contribution) for Channel1 und 3. One screenshot with internal 50 ohms termination, one with 1 Mohms.

If I calculate the thermal noise for 50 ohm and 1 Mohms, BW=20 MHz and room temp of 25 deg Celsius I get the following numbers:

50 ohms: Vrms = 4 uV; 1 Mohms: Vrms = 574 uV

The measurements of the scope show for 50 ohms 37...40 uV RMS (makes sense for me) but for 1 Mohms only 44 uV RMS! 

I'm pretty sure that physical laws always works but what is my point of misconception??? How can the 1 Mohms input noise be so low?
Thanks for any explanation!

[gf]

All these nice plots for the frequency response of various window functions are only valid when the frequency of a signal to be analyzed happens to be equal to the exact center of a bin. My screenshots show how different the filter shape can look when (as usual) the input frequency does not match this condition.

I disgree with the first sentence. The frequency responses of the window functions are continuous-frequency functions, and valid for any frequency.

But the frequency scale of the DFT spectrum is not continuous, but the spectrum is discretely sampled, at evenly spaced frequency intervals of fs/N.
The bandpass filter of each bin is centered at the bin frequency, and each bin integrates the (complex) amplitude of all frequencies passing through its filter, weighted by the frequency response.

The consequence is that frequencies falling between two adjacent bins simply happen to be attenuated by the filters of both adjacent neighbor bins (so that none of the neighbor bins sees the full amplitude), unless a filter with a passband with of >= 1 bin (and low passband ripple) is used. The frequency response at offset +/-0.5 bins from the center is an indicator for the maximum amplitude error to be expected for single-frequency CW signals.

The main point of my posting was to make folks aware that in a realistic scenario, where the input signal can have a random offset to the bin center frequency

Yes, good point, since many folks are likely not aware.
My aim is to explain some background why it happens - once it is understood, the effect becomes self-evident.

EDIT:

Btw, since you mentioned Gaussian:
One nice property of a Gaussian spectrum analysis filter is that quadratic interpolation of the log magnitude in the frequency domain is exact (i.e. in dB space).
I.e. you can draw a quadratic parabola through 3 adjacent frequency points around a peak, in order to find the location of the peak (both, frequency and amplitude).
Flattop has a good amplitude accuracy for a single-frequency CW signal, but the actual frequency between two bins cannot be determined easily from the discrete spectrum.

[Performa01]

All these nice plots for the frequency response of various window functions are only valid when the frequency of a signal to be analyzed happens to be equal to the exact center of a bin. My screenshots show how different the filter shape can look when (as usual) the input frequency does not match this condition.

I disgree with the first sentence. The frequency responses of the window functions are continuous-frequency functions, and valid for any frequency.

But the frequency scale of the DFT spectrum is not continuous, but the spectrum is discretely sampled, at evenly spaced frequency intervals of fs/N.
The bandpass filter of each bin is centered at the bin frequency, and each bin integrates the (complex) amplitude of all frequencies passing through its filter, weighted by the frequency response.

The consequence is that frequencies falling between two adjacent bins simply happen to be attenuated by the filters of both adjacent neighbor bins (so that none of the neighbor bins sees the full amplitude), unless a filter with a passband with of >= 1 bin (and low passband ripple) is used. The frequency response at offset +/-0.5 bins from the center is an indicator for the maximum amplitude error to be expected for single-frequency CW signals.

You are certainly right - but at the end of the day we want to know how well the function can separate closely spaced spectral lines.

Maybe I should better say that the selectivity and bandwidth can look very promising if checked with a single frequency at the exact bin-center, but the half-bin offset from that frequency will reveal the true limitiations of the windowing function in question with regard to amplitude arror and side lobe suppression. And this in turn reveals how bad the rectangle window (which in actual fact is just nothing) really is.

[Performa01]

If I calculate the thermal noise for 50 ohm and 1 Mohms, BW=20 MHz and room temp of 25 deg Celsius I get the following numbers:

50 ohms: Vrms = 4 uV; 1 Mohms: Vrms = 574 uV

The measurements of the scope show for 50 ohms 37...40 uV RMS (makes sense for me) but for 1 Mohms only 44 uV RMS! 

I'm pretty sure that physical laws always works but what is my point of misconception??? How can the 1 Mohms input noise be so low?
Thanks for any explanation!

Your calculation doesn't take into account that the typical DSO frontend looks very different to just a low noise amplifier whose input is terminated with either 50 ohms or 1 megohm.

The input specification already gives you the crucial hint: 1 MOhm // 17 pF. This means that the input impedance is already down below 10 kOhm at 1 MHz. But you are really measuring the full bandwidth - and with 20 MHz bandwidth limiter the input noise will slowly drop by 6 dB/octave above that.

So the contribution of the high input impedance is nearly negligible as long as you don't look at the noise spectrum specifically below e.g. 10 kHz (by means of an FFT), where you will easily find your calculated 574 µV and even up to 20 dB more, because of the very different design of a DSO frontend mentioned before...

Another hint: With High-Z input selected, you would expect that it makes a huge difference whether the inputs are terminated or left open - but it does not. Not even at low frequencies, where it does make a difference, but not nearly as much as one might expect.

[hhappy1]

Thank you.

I like the straight line, but I want to see the gradation of the waveform on the noise screen.
At around 30% intensity, it should be similar to the waveform in dsox1000x above.

See attachment.

Thank you sir.

[Bad_Driver]

Your calculation doesn't take into account that the typical DSO frontend looks very different to just a low noise amplifier whose input is terminated with either 50 ohms or 1 megohm.

The input specification already gives you the crucial hint: 1 MOhm // 17 pF. This means that the input impedance is already down below 10 kOhm at 1 MHz. But you are really measuring the full bandwidth - and with 20 MHz bandwidth limiter the input noise will slowly drop by 6 dB/octave above that.

So the contribution of the high input impedance is nearly negligible as long as you don't look at the noise spectrum specifically below e.g. 10 kHz (by means of an FFT), where you will easily find your calculated 574 µV and even up to 20 dB more, because of the very different design of a DSO frontend mentioned before...

Another hint: With High-Z input selected, you would expect that it makes a huge difference whether the inputs are terminated or left open - but it does not. Not even at low frequencies, where it does make a difference, but not nearly as much as one might expect.

Thanks for your explanation! With your hint I did a quick noise analysis in Multisim and got 15 uV RMS noise contribution of the 17 pF/1 Mohms input combination -
independed of any BW settings.
(Yes I'm pretty sure that some of you can do the math with paper and pencil but I'm to old for that  )

And that number makes more sense to me. 

[Martin72]

Hi,
Question in the round:
The 19" rack mount kit for the SDS2000X, would it also fit for the plus version?
Actual I´m planning a testsystem in a 19" rack and want to include a scope in it, ideally  the sds2k+.

[tautech]

Hi,
Question in the round:
The 19" rack mount kit for the SDS2000X, would it also fit for the plus version?
Actual I´m planning a testsystem in a 19" rack and want to include a scope in it, ideally  the sds2k+.

It does, see here from the X Plus Options page at Siglent HQ:
https://int.siglent.com/article/detail-709.html