Looking forward to seeing the whole series.
Add Keyboard, mouse, touch screen
Add Keyboard, mouse, touch screen
include noise floor comparison if you can
The SDS already has two USB connectors but for whatever reason, mine fails to work well with a hub.
The rear USB-B is for USB device communication only.The SDS already has two USB connectors but for whatever reason, mine fails to work well with a hub.
Interesting. Have you tried all three USB ports?
The rear USB-B is for USB device communication only.The SDS already has two USB connectors but for whatever reason, mine fails to work well with a hub.
Interesting. Have you tried all three USB ports?
Could be just RBBVNL9's hub, IDK. :-// We need some more feedback if other SDS2kX+ owners are having problems with hubs.
One thing that bugged me was the statement that the SDS2000X had probe sense for 1x/10x. What about 20X and 100X ? So I checked, and it doesn't do those. :(What is the pin to BNC outer resistance ? This 100x probe measures 6.2k and autosenses just fine.
What is the pin to BNC outer resistance ? This 100x probe measures 6.2k and autosenses just fine.
Don't have a SDS2kX+ unboxed so checked on my SDS5kX demo.
Seems entirely the wrong probe to use with a SDS2kX+.What is the pin to BNC outer resistance ? This 100x probe measures 6.2k and autosenses just fine.
Don't have a SDS2kX+ unboxed so checked on my SDS5kX demo.
I have a Tek P6156 with switchable 1x/10x/20x/100x.
Seems entirely the wrong probe to use with a SDS2kX+.
https://w140.com/tekwiki/wiki/P6156
It is designed for use with wide band oscilloscope amplifiers with 50 Ω inputs
A post or 2 back you answered your own question:Seems entirely the wrong probe to use with a SDS2kX+.
https://w140.com/tekwiki/wiki/P6156
It is designed for use with wide band oscilloscope amplifiers with 50 Ω inputs
The SDS2xxxX+ isn't all that? What part is it not? At 500MHz the P6156 10x will have a higher impedance than any 10M 10x probe like the SP3050A. Of course it is resistive, not reactive, but that's another matter.
In any case, that shouldn't affect the operation of the readout pin, which is what I was testing. And my other probe that I tried is for a standard 1M input.
Earlier I posted this ~6.2k sense pin resistance for 100x probe for SDS5kX and in previous checks with SDS2kX+ also sensed fine with the same 100x stock probes we have.What is the pin to BNC outer resistance ? This 100x probe measures 6.2k and autosenses just fine.
Don't have a SDS2kX+ unboxed so checked on my SDS5kX demo.
I have a Tek P6156 with switchable 1x/10x/20x/100x. The resistances for each are open, ~10k, ~1.5k and ~5k. These all indicate correctly on my Tek scopes except for 20x, which was only supported on the 11000-series sampling scopes. I also have a Probemaster 100X w/ readout and it measures 6.9k. Again, both Tek scopes recognize it as 100x. The SDS2000X+ switches to 10X if any probe I have with a readout pin is attached, and I checked all 4 channels. From what I've read the nominal values are 10x--11k, 100x--6k, 1000x--??. My 2465B actually recognizes the 20x one as 1000x, so I assume that the 1.5k is in the ballpark for that. The 2221A probably doesn't know about 1000x probes.
Hi,Yes.....
loads of effort :-+
Regarding the UI Layout... I don´t share Your opinion about a unlogic Layout of the SDS -where I truely miss that You don´t show examples, but just talk talk talk. :=\
For example Meas and Cursor buttons are close to the universal rotary knob .... just where they should be.
The same applies to the Setup Run/Stop, Default buttons which I would expect in proximity of the trigger settings ... just where they are.
Others mentioned already the quite sensible logic behind the illumination of the channel buttons.
The only buttons which may seem be a bit off at first glance are the Navigate row-of-4. But then ... where better to put them?
I find the R&S layout not at all more intuitive ... let alone the Keysight, where you can´t even see the buttons due to the stupid black casing colour. :palm:
In the end its probabely just a matter of personal history and preference which UI one prefers.
I have lots of good experiences with Siglent -no lost foot at all on any of the 6 devices I work with and no terribly loud fan on either) and rather negative experiences with R&S (RTH handheld Osci) their service and their ridicolous accessories prices.
And I´m certainly p***** off by Keysights new ´we-sell-you-but-don´t-wanna-serve-after´ policy.
So I´m a bit biased in the opposite direction from Yours.
In the comparison table I miss the EasyWave software listed under the section Windows Apps.
Apart from that ... keep up the evaluation work :-+ :clap:
regards
Calvin
The R&S RTM3004 has several, easely accessible presets for the probe attenuation factor; I assume the RTB2004 is the same.
Could it be that the white balance in your camera is a little on the warm side?
I suggest you get a 10k pot out and find the 100x sense pin thresholds for your 2kX+ as it appears they don't match Tek but is that any surprise ?
Since forever there has been no hard and fast standard for sense pin resistances.
FYI this is how the same probe autosenses in 50 Ohm mode.
Not at all. The information on that page is simply wrong. The Tektronix P6156 is a general purpose Low-Z (passive) probe which is supported on many Tektronixs DSOs including the TDS500/600/700 series. I have a couple of these as well but it sucks to have the autosense pin isolated because non-Tektronix scopes interpret the resistance wrong.Seems entirely the wrong probe to use with a SDS2kX+.What is the pin to BNC outer resistance ? This 100x probe measures 6.2k and autosenses just fine.
Don't have a SDS2kX+ unboxed so checked on my SDS5kX demo.
I have a Tek P6156 with switchable 1x/10x/20x/100x.
https://w140.com/tekwiki/wiki/P6156
It is designed for use with wide band oscilloscope amplifiers with 50 Ω inputs
Not recognizing why Siglent have laid out the channel button indicators how they have seems like the user has recently migrated to a DSO after years of experience with only CRO's.
Concerning having (button) LEDs on for all active channels (vs. selected channels): I realize from the comments this is a bit of a user preference aspect and also may depend on the devices you come from, respectively the other devices you use.
2N3055 makes an important point that we should not forget about people with visual impairment. They may indeed prefer to have button lights illuminating on selected channels only. I must note, however, that the RTB and DSOX both can show the text “Channel 3” written on the screen when channel 3 is edited, and both also show it with trace markers (left of the trace). The RTB furthermore shows it with a highlight at the bottom of the screen. So, there are multiple clues for the (colour) visually impaired onj these devices.QuoteNot recognizing why Siglent have laid out the channel button indicators how they have seems like the user has recently migrated to a DSO after years of experience with only CRO's.
I don’t think that is a fair point, tautech: having lights on the front panel illuminated for all active channels does not seem to be uncommon for modern DSOs at all. Unless I am mistaken, this is the implementation on various models of Teledyne LeCroy (WavePro HD, WaveRunner 8000HD, HDO6000B, WaveSurfer 4000HD), Tektronix models (3 series, 4 series, 5 series), R&S (RTM3000, RTA4000, RTE1000, RTO2000 and RTP RTP), and Keysight (2000X, 3000X, 4000X), to name a few. Most of these examples have shared vertical controls.
Looking at various manufacturers, I even asked myself whether any brand other than Siglent on recent models made the choice to illuminate the buttons for selected channels only. But I am sure others can fill in the gap and show who did, and who did not.
In any case, it’s a matter of user preference; will change this in the document.
At some point in time, I will try to improve the video (colour) but now I will first give priority to the videos themselves ;-)
Concerning the probe sensing… It’s an area where the SDS certainly has a plus over the RTB and DSOX (as I mention in the video).Correct, I now have an SDS2104X+ out and these have a 100x probe detection bug whereas SDS5000X detect 100x probes correctly.
In my video and document, I just relied on the User Manual of the SDS, and an old 10x Tek P6105A 10x probe I happened to have in the lab (and which is correctly identified as a 10x probe by the SDS).
I now tried a couple of resistor values. As far as I can see, the SDS interprets any resistance between 0Ω and 56kΩ as “10x”, and resistance between 82k to infinity as “1x”. So, it seems that there is no recognition for other attenuation values, as it is.
Correct, I now have an SDS2104X+ out and these have a 100x probe detection bug whereas SDS5000X detect 100x probes correctly.
Will report it with a high priority fix request.
I can confirm that the Siglent is a bit of a power hog, 50-60W running and 4.2W when off. A hard power off switch would be good.Yes, that is also what I measure. Some 4 watt is quite a bit (and from this standby, the device does not boot any faster than with a cold start). The RTB consumes 0.5 watts on standby.
The Rigol MSO5000 is hardly missed in there.
i think there is a mistake in the document regarding the vertical scale / sensitivity for the Siglent. At least my Siglent has a range from 500µV/div to 10V/div and it is the 100MHz version as received from the dealer without any hacks. So the full range is not only available if the 500MHz option is enabled.
This is also a major drawback of the R&S in my opinion. If you work with european mains voltage you need additional x100 probes because with x10 probes the RTB can "only" show 500Vpp. This might not be a big deal for most people i guess. But another drawback in that case is the more or less unusable FFT if you want to check harmonics of 50Hz mains voltage. At least until the last update. Might have changed now but i can't ckeck since i don't have the RTB anymore.
Indeed, the Siglent goes to 10V/div (thus 100V/div with a x10 probe) and the RTB only to 5V/div (thus 50V/div with a 10x probe). However, tho things to take into account:
1. The RTB has 12 vertical divisions (compared to 10 on the SDS), so can show 12 * 50 = 600V with 10x probes
The RTB has 10 divisions while Siglent has 8 as far as i know.
QuoteThe Rigol MSO5000 is hardly missed in there.
The honest answer is: I don’t own an MSO5000. If I had one, I would certainly be happy to include it. But I want to base my comparison on first-hand observations... If someone owns both the SDS2k+ and MSO5000, do compare, and be my guest to use the structure of the document (https://github.com/RudisElectronicsLab/RTB_SDS_DSOX_review) prepared for this comparison.
(And there are a couple of other scopes I’d love to lay my hand on, too ;-)
About including the Keysight DSOX: I thought it would be worth including this one because Keysight, with this oscilloscope, competes squarely with the R&S RTB oscilloscope in the educational market. While the DSOX1204G was only introduced in March 2019, it has a design/UI concept without a touch screen, and I thought it would be interesting to see how that compares. Is the touch screen design/UI concept overvalued, do other things matter more? Or is it really a no-go to buy a non-touchscreen device today? (Note that also the current Keysight InfiniiVision 2000 X-Series has no touch screen…)
I also recall EVVBlog’s Dave even recently writing that the DSOX is his go-to scope in the lab. Made me curious too, what qualities make him turn to this instrument, while he (arguable) has choices in his lab?
Finally, I found that the DSOX has some nice tricks up its sleeves too that the other scopes I reviewed could learn from. Some examples: (1) when a channel is set to AC coupling, it disables the DC mode of the DVM. The RTB, for instance, does not do this and hence present wrong measurement results. (2) It can do XY imaging with blanking coming in on a “Z” channel. (3) It can link the trigger system to modulation of the internal AWG, thus exploiting the fact the AWG is built into the same device. (4) When in web access mode, the device itself (!) delivers an extensive HTML guide of SCPI commands to the connected computer. Do such points alone make it a more attractive scope than others? I don’t think so. But we do learn from it.
With the RTB2004 you can activate the Z channel with SCPI commands.
It would be great if there were timestamps on the video.
Keysight OTOH is much simpler platform and has much less features, releases were mostly bug fixes and paid features unlocks
@ Pope:QuoteIt would be great if there were timestamps on the video.
Done.
@2N3055:QuoteKeysight OTOH is much simpler platform and has much less features, releases were mostly bug fixes and paid features unlocks
I was surprised myself to see how many actual new features were added by Keysight via firmware updates. Examples (just looking since at FW2.x versions, after Keysight moved to Linux OS):
- Measurement statistics (FW2.12)
- USB Keyboard entry for labels, annotations, file names, etc. (FW2.10)
- Table (lister) of serial decode messages (FW2.10)
- DEMO function with training signals etc. (FW2.10)
- LXI compliance and VXI-11 protocol support (FW2.10)
- Save and upload waveforms and other files via web interface (FW2.10)
- SCPI Device Control online manual via web interface (FW2.10)
- USB or LAN attached printer support (FW2.10)
Granted, some of these just brought the instrument in line with what was already there in competing scopes, but still, it's nice to see that functionalities are added, even as of recently (September 2021).
Performance improvements include:
- Increased waveform update rate (FW2.10)
- Increased number of memory segments (FW2.10)
- Additional memory depth (FW2.10) (even if it's still not impressive compared to competitors...)
I have played around with the RTB2004 XYZ mode for some time,
That's the link to youtube studio and not the video for viewing ;)
QuoteThat's the link to youtube studio and not the video for viewing ;)
Eh, yes. :-[
Video is here (really):
https://youtu.be/T_A3TPn-2IU
An error with the 10Bit mode. SDS2000X+ is limited to 100MHz in 10Bit mode. Not 10MHz or 20Mhz.
v40 - Page 8 - Acquisition system & memory
- Segmented memory depth
RTB2000 - 160Msample
should be: 320 Msample (e.g. 1 Channel, Record Length 10 MSa, No. of Segments 32)
I have a request: when you're showing the UI of any given scope, can you show the screen itself, as opposed to the remote UI for it? I ask because the real responsiveness (good or bad) of the scope's UI isn't going to come through in the remote UI. This is especially true of the Keysight, where the remote UI looks very slow, but the in-person experience is very fast
On top of that a UI may be fast but you'll also need to look at efficiency. Needing to go through several layers of menus versus having all settings in 1 screen to setup decoding for example.
In 40:43 on the right side is a USB scope. It looks like some 3000 or 5000 series from Picotech.
Sorry but I am curious what it is exact?
https://youtu.be/TAoB5614hs4
I'm not sure why--perhaps YouTube hosting this far away from me--but I see low video quality (resolution), buffering and skipping. I'll try downloading it and see what I get.
Hi Cesare, thanks for the comments, and information on the specific file that the scope is looking for when that error pops up. My current thinking is that the BIN file might you identified is not, as you suggest, an executable file that needs to be launched, but instead a waveform data file (Siglent can save waveforms as Binary (BIN) as well as CSV and matlab). I tried to save a BIN file with that specific name from the device interface itself but I don't seem to be able to get to that specific folder the scope is looking into. Perhaps a TELNET session allows us to move a file there. Something we should dig deeper into!
I think they mean the frequency is max 10 MHz and 250 Ms/s.
So i ran:
# cp /usr/bin/siglent/config/arb/18_sinc_ram.bin /usr/bin/siglent/usr/AWG_channel_wave.bin
And then selecting stored/channel pops me up with a sinc waveform.
It is possible to transfer a waveform from one of the vertical channels to the Arbitrary Waveform Generator.
This is done from the vertical channel menu dialog box.
One of the menu items is " Apply To ".
Selecting " Apply To ", brings up a list of options, one of these is ARB.
This copies the current channel waveform to the Arbitrary Waveform Generator.
You can then go to the Arbitrary Waveform Generator and select "Stored" and then " Channel' to output the waveform.
This is mentioned in the User Manual in section 12.2, Channel Setup, but the way it is explained is somewhat confusing.
Dear Egonotto,QuoteI think they mean the frequency is max 10 MHz and 250 Ms/s.
Yes, that does make sense. The sample rate indeed needs to be more way than the 10 MSa/s R&S mention in the specifications in order to output the waveform you show (and assuming it would be the same on the RTB as the RTA). I agree with you it is likely the same 250 MSa/s as used for the regular waveform generation. Will update my overview document. Thanks for checking!
Can anyone enlighten me? Why does the RTB have periodic interruptions? And, more importantly, why is the SDS so slow to re-trigger ?!?Double check the memory depth you have set, it often has a large effect on the update rate. Not sure if the SDS 2000X will approach "perfection", older models were similar to what you see:
Do I overlook relevant device settings?
Double check the memory depth you have set, it often has a large effect on the update rate.I tried each memory depth setting available in the SDS (see my post) but none of made a difference in seeing this pattern. But will do some more attempts later. (This setting did make a difference for the RTB though.)
If you look very carefully over a long period even on the Keysight there will be some gaps in the triggers (or use a pulse width trigger to catch it!).That might be the case. But as can be seen from the PicoScope screen print, the Keysight DSOX’s average of 333.3 trigger out pulses per second was very stable; over 109 observations (of each ~150 pulses) there is an extremely low standard deviation. So, if it misses triggers, it’s not many. Indeed, a pulse width trigger (or mask test) could reveal this.
Edit, found some measured values for the 2000X:Like in the post of Martin72 you refer to, I am indeed finding similar, very low waveform update rates on the SDS (orders of magnitude lower than advertised). That is the reason why I started to do these trigger experiments…
This has been asked before, here is Rich's answer:Thanks for forwarding Rich’s answer. Before posting, I did a search on the forum but it’s not always easy to find what you are looking for, even if it’s there :-| But anyway, questions answered!
RTB and SDS take time to execute the samples. Meanwhile they do not sample.Yes, seems so. Perhaps the reason the DSOX is doing so well here is that it dedicated these tasks to different hardware resources so it can keep on triggering even when it’s buffering and plotting on the screen.
RTA behave little wilder.Can you perhaps elaborate on what you mean here?
RTB and SDS take time to execute the samples. Meanwhile they do not sample.Yes, seems so. Perhaps the reason the DSOX is doing so well here is that it dedicated these tasks to different hardware resources so it can keep on triggering even when it’s buffering and plotting on the screen.
Bottom line: While it’s now clear to me what the RTB is doing, the bigger concern here is the SDS. After a trigger, it misses something like 10 possible triggers before its ‘arming’ again. For a trigger signal as slow as 1 kHz, this is quite strange. Perhaps, like Martin72 suggests, there might be a serious bug here that is still waiting to be fixed?I do not think it is a bug, but just the way they work. As you say above these different scopes have different hardware separation of the work, DSOX puts most things in ASIC/FPGA which makes it fast but less flexible (examples: cannot reduce memory depth, or turn off interpolation, even though that would make it faster). Probably Siglent do much more of the display drawing in CPU/software for more flexibility/cheaper product (example benefit: colourised intensity view).
I do not think it is a bug, but just the way they work.
Bottom line: While it’s now clear to me what the RTB is doing, the bigger concern here is the SDS. After a trigger, it misses something like 10 possible triggers before its ‘arming’ again. For a trigger signal as slow as 1 kHz, this is quite strange. Perhaps, like Martin72 suggests, there might be a serious bug here that is still waiting to be fixed?
I have not seen published/advertised waveform rates for different timebases, do you have a link/copy? Only value in the advertising/marketing is the peak:I do not think it is a bug, but just the way they work.Well, even if these devices do work differently, Siglent does publish a waveform update rate. And if the actual update rate is orders of magnitude lower than what is published (see the posts of Martin72 and Performa01 referred to above, which are indeed in line with my own measurements, see my video Episode 7 at 47:27) then I think it is correct to speak of a bug...
Waveform capture rate up to 140,000 wfm/s (normal mode), and 500,000 wfm/s (sequence mode)We usually only see these figures across many acquisition window sizes in "competitive comparisons" or user generated figures (such as on this forum).
QuoteI do not think it is a bug, but just the way they work.
And if the actual update rate is orders of magnitude lower than what is published <clip> then I think it is correct to speak of a bug...
Waveform capture rates up to 120,000 wfm/s (normal mode) and 500,000 wfm/s (sequence mode)
Waveform capture rate (Max.)
Normal mode：120,000 wfm/s;
Sequence mode：500,000 wfm/s
Waveform capture rate
Normal mode: 120,000 wfm/s max.
Sequence mode: 500,000 wfm/s max.
Key Features
New generation of high speed display technology
› Waveform capture rate up to 120,000 wfm/s
(normal mode), and 500,000 wfm/s (sequence
mode)
Waveform Capture Rate (Max.) 120,000 wfm/s (normal mode), 500,000 wfm/s (sequence mode)
Waveform Capture Rate Up to 120,000 wfm/s (normal mode), 500,000 wfm/s (sequence mode)
do you have Slow or Fast mode set there? You need to be in the dot mode also..First I think dot mode is not a normal situation to use a scope when wanting to look at waveforms! Its these sorts of "games" that can make comparisons silly, always best to try and find a common setting that all products can meet (and mention that they can do better in their special/preferred setting).
A small suggestion, if I may. To avoid confusion, may I suggest a wording specificum: a time that scope needs to be ready for a new trigger event can be called retrigger time. We can also use a term rearm time or even a blind time to signify time that scope is "blind" to new events while trigger engine is being rearmed for another go. I say that because saying that "scope is missing triggers" can be misconstrued as scope being ready for trigger but it didn't recognize it properly.
Difference is that first one is operating specification of the scope and the other one (missed triggers) is defect, a bug.
what is the right lecroy scope to compare to the RTB. for example if it includes that specific feature at a low enough price point to be an alternative option to the RTB 2004
What is wrong now. Is it difficult to uderstand "up to" or "max"Peak value does not predict others! yes. A previously popular scope claimed best waveform rate but in real world performed badly:
If this is difficult I think it is education problem or lack of enough knowledge and experience. I can predict this kind of problems may lead to severe problems when need read what ever instruments or electronics, mechatronics, etc data sheets. Is it correct to say... bug in understanding data sheets. :) :)
Only LeCroy had rights to market SDS3000X (WS3000Z) DSO's to western markets and SDS3000 (WS3000) models before them as their development was a joint venture.what is the right lecroy scope to compare to the RTB. for example if it includes that specific feature at a low enough price point to be an alternative option to the RTB 2004
ah, i remember now Martin72 had one...
https://www.eevblog.com/forum/testgear/siglent-sds2000x-plus-coming/msg4054573/#msg4054573 (https://www.eevblog.com/forum/testgear/siglent-sds2000x-plus-coming/msg4054573/#msg4054573)
it was the WS3024Z
what is the right lecroy scope to compare to the RTB. for example if it includes that specific feature at a low enough price point to be an alternative option to the RTB 2004
ah, i remember now Martin72 had one...
https://www.eevblog.com/forum/testgear/siglent-sds2000x-plus-coming/msg4054573/#msg4054573 (https://www.eevblog.com/forum/testgear/siglent-sds2000x-plus-coming/msg4054573/#msg4054573)
it was the WS3024Z
And now at work too !what is the right lecroy scope to compare to the RTB. for example if it includes that specific feature at a low enough price point to be an alternative option to the RTB 2004
ah, i remember now Martin72 had one...
https://www.eevblog.com/forum/testgear/siglent-sds2000x-plus-coming/msg4054573/#msg4054573 (https://www.eevblog.com/forum/testgear/siglent-sds2000x-plus-coming/msg4054573/#msg4054573)
it was the WS3024Z
AFAIK Martin has WS3024 and WS3024Z at work. At home he has SDS2104X+..
so if this part of the series is all about detecting unusual events or glitches then...I know I called for input on this topic, but I should also mention that my comparison is certainly not aiming to focus on this aspect only, it’s one among many aspects I’m liking into.
Preparing for a new video on observing infrequent events and mask tests, and seeing huge differences there, so I thought I should first dig a bit more into actual triggering behaviour.
I see something I am not sure I understand well.
In short:
- I feed all oscilloscopes with a 1kHz square wave on channel 1.
- I set the horizontal time base such that I see two periods on the screen (200uS/DIV on the SDS and DSOX, and 170uS/DIV on the RTB as it has 12 instead of 10 horizontal divisions). Attaching a pic.
- I activate the trigger out on each device and look at these on a fourth oscilloscope (a PicoScope 3405D). Channels are 1: RTB, 2: SDS, 3: DSOX and 4: input square to scopes.
All scopes are set to regular trigger settings (trigger on positive edge, level halfway square, no holdoff, DC coupling, no noise reject or filter). Record length / memory depth is chosen for best results, if there is any difference. Segmented acquisition off. Auto trigger or normal trigger makes no difference on any of the devices. Lastly, on the RTB I set the trigger out a pulse to 1mS to make it well visible (using SCPI command TRIGger:OUT:PLENgth 1E-3).
Ideally, I would expect to see a trigger every one out of three periods (where the positive edges of the two other periods are shown on the screen), so a constant 333.3 pulses per second on the trigger out bus. After all, 1kHz is such a slow signal and any eventual blank time these scopes need to write to memory etc. should be neglectable.
The results are in the attached screen print.
- The Keysight DSOX behaves exactly as expected, triggering every third period.
- The Rohde & Schwarz RTB mostly every third period but there are some (predictable) interruptions. Is the scope doing something else every once in a while ?!?
- The Siglent SDS triggers much, much less. Only 30 pulses per second instead of the expected 333.
Can anyone enlighten me? Why does the RTB have periodic interruptions? And, more importantly, why is the SDS so slow to re-trigger ?!?
Do I overlook relevant device settings?
Thanks for your insights!
First I think dot mode is not a normal situation to use a scope when wanting to look at waveforms! Its these sorts of "games" that can make comparisons silly, always best to try and find a common setting that all products can meet (and mention that they can do better in their special/preferred setting).
A problem with blind time as a measure is that it is not a constant/deterministic value in most (all?) scopes when in realtime mode, it may be accurate for sequence/segmented modes where nothing is drawn to the screen.
ah ok. but then does that lecroy 3000 series actually have the feature in question? if it is actually a rebranded siglent and not a true windows based lecroy scope?
the feature seems to be able to detect any arbitrary random glitches or anomalies. such as the failed or unclean logic transitions etc
Thanks all for digging so deep into this. And thanks to 2N3055 for suggesting clear terminology. I noted that sometimes specifications sheets are also not super clear on this. The SDS2000X+ spec sheets talk both of “waveform capture rate” and “waveform update rate”. They seem to mean the same thing with these two terms, but I’m not 100% sure and find it confusing. .....
Please can you clarify every oscilloscope sampling speed and current acquisition true memory length used in this image.
Could you check something on Siglent? If you go into Acquistion menu, do you have Slow or Fast mode set there? You need to be in the dot mode also..
In reponse to 2N3055 and rf-loop:QuotePlease can you clarify every oscilloscope sampling speed and current acquisition true memory length used in this image.QuoteCould you check something on Siglent? If you go into Acquistion menu, do you have Slow or Fast mode set there? You need to be in the dot mode also..
Below are the settings that were used for the measurement reported earlier (in the PicoScope screen print):
RTB:
- Record length: 10 kSa. Note: at 200kSa I start to see a slight reduction in trigger events per second. At 10Msa there are roughly half the number of trigger events per second.
- Sample rate is 4.81 MSa/s (this number changes when other record lengths are selected)
- Trigger output pulse set to 1ms using TRIGger:OUT:PLENgth 1E-3
SDS
- Record length (parameter “MAX record length”) setting is 20k. Interestingly, any other setting (200k, 2M, 20M, 200M) does not make any difference for this measurement
- Sample rate is 10.0 MSa/s (this number changes when other record lengths are selected)
- “Acqu Mode” set to “Fast”. Interestingly, changing it to “Slow” does not make any difference for this measurement
- “Seq. Acq. Switch” set to off. When it is turned on, I see sets of n acquisitions (where n is the number set by the “Seq Segment” parameter” with almost 100mS in between, so a considerable drop in the number of trigger events per second.
- Display Type = Vectors. But setting it to dots makes no difference whatsoever.
DSOX
- Sample rate is 500MSa/s. ASAIK this rate is simply a function of the chosen timebase setting, there is no other way to choose this.
- Segmented memory is off (but when turned on, that has no impact on the number of trigger out pulses)
SDS
- “Seq. Acq. Switch” set to off. When it is turned on, I see sets of n acquisitions (where n is the number set by the “Seq Segment” parameter” with almost 100mS in between, so a considerable drop in the number of trigger events per second.
They also mention casually memory sizes, but 3000T has only 500k of sample memory when doing 4ch+ digital normal mode (4 buffer-2 per ch-1 with digital -0.5 Mpts for ping pong buffers. 1Mpts for Single mode). Scope with 100Mpts will be 100x slower everything else being equal. Scope with 500MPts will have soo much more work to do.You can keep pulling up the same "small memory" argument, except it is common for memory to change in different acquisition settings across most scopes. Those characteristics are not avoided in the Keysight data sheets or left as only up-to/maximum/peak values, and made very clear in the manuals (contrasting to these other examples discussed here where it is not clear at all what is expected).
I think the explanation is good, with the sequence mode in run mode:SDS
- “Seq. Acq. Switch” set to off. When it is turned on, I see sets of n acquisitions (where n is the number set by the “Seq Segment” parameter” with almost 100mS in between, so a considerable drop in the number of trigger events per second.
This is really weird. Even If I test with this same signal with SDS1104X-E and 200us/div and Sequence. I take oneshot sequence with 50MSa/s 140k length and when I look segments time stamps they have all 3ms (3000us) delta time. So 333.33 segments in second.
Then I change it to 14k memory so 5MSa/s and look 1900 segment single sequence. Every single segment in sequence time stamp delta time is 3ms. So 333.33... segment/s
Then with 1GSa/s 2.8M current mem lenght (one segment length)... still all 19 segments delta time is 3ms.... 333.33... segment/s
(or mS as you said, aka milli Siemens what is conductance SI derived unit)
They also mention casually memory sizes, but 3000T has only 500k of sample memory when doing 4ch+ digital normal mode (4 buffer-2 per ch-1 with digital -0.5 Mpts for ping pong buffers. 1Mpts for Single mode). Scope with 100Mpts will be 100x slower everything else being equal. Scope with 500MPts will have soo much more work to do.You can keep pulling up the same "small memory" argument, except it is common for memory to change in different acquisition settings across most scopes. Those characteristics are not avoided in the Keysight data sheets or left as only up-to/maximum/peak values, and made very clear in the manuals (contrasting to these other examples discussed here where it is not clear at all what is expected).
But you make the false claim that there is a comparison with memory depth, the waveform capture measurements that competitors use keep the memory depth very short to inflate their numbers. Look at how much slower the competitors are despite choosing less memory! (when at same memory they are far behind). Scopes are not some computer system where the parts are put together in imbalanced ways by the end user, they are a finished product from the manufacturer who has decided on the system performance. Keysight make a real time scope with 100Mpts of memory, the EXR or MXR series, without a significant drop in waveform rate (keeping the system balanced).
Where you keep falling over is trying to make out like all scopes work/function the same. The Keysight megazoom method has been to decouple display and waveform memory, they are two different paths that dont interact. Acquisition data is piped to the display plotter/memory (through decimation etc) separately to the waveform memory. As you say before, to make things fast they chose to put most of the emphasis/features on the decimated view (positive example: fast eye diagrams). Most other scopes draw the waveforms from the acquisition memory, and take measurements from the original data (Lecroy being the extreme example of that, positive example: higher resolution measurements). Completely different with advantages and disadvantages, for comparisons they are best listed as characteristics rather than put as a good/bad binary check box against specific/your preference.
I think the explanation is good, with the sequence mode in run mode:SDS
- “Seq. Acq. Switch” set to off. When it is turned on, I see sets of n acquisitions (where n is the number set by the “Seq Segment” parameter” with almost 100mS in between, so a considerable drop in the number of trigger events per second.
This is really weird. Even If I test with this same signal with SDS1104X-E and 200us/div and Sequence. I take oneshot sequence with 50MSa/s 140k length and when I look segments time stamps they have all 3ms (3000us) delta time. So 333.33 segments in second.
Then I change it to 14k memory so 5MSa/s and look 1900 segment single sequence. Every single segment in sequence time stamp delta time is 3ms. So 333.33... segment/s
Then with 1GSa/s 2.8M current mem lenght (one segment length)... still all 19 segments delta time is 3ms.... 333.33... segment/s
[n sequences without gaps] 100ms processing interval [n sequences without gaps] 100ms processing interval... etc
Interesting it was not in a circular mode (does not support it?) where the sequences capture around forever until stop is pressed.
Honestly, I miss MSO5000 from Rigol in this. It would have been good to add it to what so far I see as very good and impartial research by Rudy. There have been quite a few discussions where there are no good info on real performance form real life MSO5000 users. I know there are quite a few of them out there, but maybe one or two contribute quality info.
Right there, the opening statement. You keep bringing it back to memory depth.I'm not sure what I wrote was false.They also mention casually memory sizes, but 3000T has only 500k of sample memory when doing 4ch+ digital normal mode (4 buffer-2 per ch-1 with digital -0.5 Mpts for ping pong buffers. 1Mpts for Single mode). Scope with 100Mpts will be 100x slower everything else being equal. Scope with 500MPts will have soo much more work to do.You can keep pulling up the same "small memory" argument, except it is common for memory to change in different acquisition settings across most scopes. Those characteristics are not avoided in the Keysight data sheets or left as only up-to/maximum/peak values, and made very clear in the manuals (contrasting to these other examples discussed here where it is not clear at all what is expected).
But you make the false claim that there is a comparison with memory depth, the waveform capture measurements that competitors use keep the memory depth very short to inflate their numbers. Look at how much slower the competitors are despite choosing less memory! (when at same memory they are far behind). Scopes are not some computer system where the parts are put together in imbalanced ways by the end user, they are a finished product from the manufacturer who has decided on the system performance. Keysight make a real time scope with 100Mpts of memory, the EXR or MXR series, without a significant drop in waveform rate (keeping the system balanced).
Where you keep falling over is trying to make out like all scopes work/function the same. The Keysight megazoom method has been to decouple display and waveform memory, they are two different paths that dont interact. Acquisition data is piped to the display plotter/memory (through decimation etc) separately to the waveform memory. As you say before, to make things fast they chose to put most of the emphasis/features on the decimated view (positive example: fast eye diagrams). Most other scopes draw the waveforms from the acquisition memory, and take measurements from the original data (Lecroy being the extreme example of that, positive example: higher resolution measurements). Completely different with advantages and disadvantages, for comparisons they are best listed as characteristics rather than put as a good/bad binary check box against specific/your preference.
Fact is that real time processing of 250 Mpts is harder than 4 MPts.
I think the explanation is good, with the sequence mode in run mode:SDS
- “Seq. Acq. Switch” set to off. When it is turned on, I see sets of n acquisitions (where n is the number set by the “Seq Segment” parameter” with almost 100mS in between, so a considerable drop in the number of trigger events per second.
This is really weird. Even If I test with this same signal with SDS1104X-E and 200us/div and Sequence. I take oneshot sequence with 50MSa/s 140k length and when I look segments time stamps they have all 3ms (3000us) delta time. So 333.33 segments in second.
Then I change it to 14k memory so 5MSa/s and look 1900 segment single sequence. Every single segment in sequence time stamp delta time is 3ms. So 333.33... segment/s
Then with 1GSa/s 2.8M current mem lenght (one segment length)... still all 19 segments delta time is 3ms.... 333.33... segment/s
[n sequences without gaps] 100ms processing interval [n sequences without gaps] 100ms processing interval... etc
Interesting it was not in a circular mode (does not support it?) where the sequences capture around forever until stop is pressed.
AFAIK the history buffer should work thay way (although likely not with fast sequence mode).I think the explanation is good, with the sequence mode in run mode:SDS
- “Seq. Acq. Switch” set to off. When it is turned on, I see sets of n acquisitions (where n is the number set by the “Seq Segment” parameter” with almost 100mS in between, so a considerable drop in the number of trigger events per second.
This is really weird. Even If I test with this same signal with SDS1104X-E and 200us/div and Sequence. I take oneshot sequence with 50MSa/s 140k length and when I look segments time stamps they have all 3ms (3000us) delta time. So 333.33 segments in second.
Then I change it to 14k memory so 5MSa/s and look 1900 segment single sequence. Every single segment in sequence time stamp delta time is 3ms. So 333.33... segment/s
Then with 1GSa/s 2.8M current mem lenght (one segment length)... still all 19 segments delta time is 3ms.... 333.33... segment/s
[n sequences without gaps] 100ms processing interval [n sequences without gaps] 100ms processing interval... etc
Interesting it was not in a circular mode (does not support it?) where the sequences capture around forever until stop is pressed.
It was nice you rise this circular mode up.
Siglent do not have it (least yet afaik)
It was nice you rise this circular mode up.I am not fully familiar with all these models, thanks for confirming how the Siglent handles it: burst - display - burst - display - etc
Siglent do not have it (least yet afaik)
Looking at the manual, and getting the confirmation from rf-loop, the Siglent does not have any continuous mode. While the Keysight does not have any mode where it will do displays along the way. Quite different, orthogonal, and singular/forceful/narrow minded in their approaches!AFAIK the history buffer should work thay way (although likely not with fast sequence mode).I think the explanation is good, with the sequence mode in run mode:SDS
- “Seq. Acq. Switch” set to off. When it is turned on, I see sets of n acquisitions (where n is the number set by the “Seq Segment” parameter” with almost 100mS in between, so a considerable drop in the number of trigger events per second.
This is really weird. Even If I test with this same signal with SDS1104X-E and 200us/div and Sequence. I take oneshot sequence with 50MSa/s 140k length and when I look segments time stamps they have all 3ms (3000us) delta time. So 333.33 segments in second.
Then I change it to 14k memory so 5MSa/s and look 1900 segment single sequence. Every single segment in sequence time stamp delta time is 3ms. So 333.33... segment/s
Then with 1GSa/s 2.8M current mem lenght (one segment length)... still all 19 segments delta time is 3ms.... 333.33... segment/s
[n sequences without gaps] 100ms processing interval [n sequences without gaps] 100ms processing interval... etc
Interesting it was not in a circular mode (does not support it?) where the sequences capture around forever until stop is pressed.
AFAIK the history buffer should work thay way (although likely not with fast sequence mode).I think the explanation is good, with the sequence mode in run mode:SDS
- “Seq. Acq. Switch” set to off. When it is turned on, I see sets of n acquisitions (where n is the number set by the “Seq Segment” parameter” with almost 100mS in between, so a considerable drop in the number of trigger events per second.
This is really weird. Even If I test with this same signal with SDS1104X-E and 200us/div and Sequence. I take oneshot sequence with 50MSa/s 140k length and when I look segments time stamps they have all 3ms (3000us) delta time. So 333.33 segments in second.
Then I change it to 14k memory so 5MSa/s and look 1900 segment single sequence. Every single segment in sequence time stamp delta time is 3ms. So 333.33... segment/s
Then with 1GSa/s 2.8M current mem lenght (one segment length)... still all 19 segments delta time is 3ms.... 333.33... segment/s
[n sequences without gaps] 100ms processing interval [n sequences without gaps] 100ms processing interval... etc
Interesting it was not in a circular mode (does not support it?) where the sequences capture around forever until stop is pressed.
It was nice you rise this circular mode up.
Siglent do not have it (least yet afaik)
SDS
- Record length (parameter “MAX record length”) setting is 20k. Interestingly, any other setting (200k, 2M, 20M, 200M) does not make any difference for this measurement
- Sample rate is 10.0 MSa/s (this number changes when other record lengths are selected)
- “Acqu Mode” set to “Fast”. Interestingly, changing it to “Slow” does not make any difference for this measurement
- “Seq. Acq. Switch” set to off. When it is turned on, I see sets of n acquisitions (where n is the number set by the “Seq Segment” parameter” with almost100mS100ms in between, so a considerable drop in the number of trigger events per second.
- Display Type = Vectors. But setting it to dots makes no difference whatsoever.
- Only Channel 1 activated.
| Points | Samples/sec | Frequency (avg) |
| ------ | -------------- | ------------------ |
| 20k | 10M | 333 |
| 200k | 100M | 300 |
| 2M | 1G | 153 |
| 20M (actual: 4M) | 2G | 30 |
| 200M (actual: 4M) | 2G | 30 |
@ kcbrown,
Thanks a lot for replicating this, leading to what seems to be a quite important finding!
So it seems a change in memory depth setting (and hence sample rate) only takes effect if the user afterwards changes the timebase settings...
So, thanks again! Excellent work!
. rudi
That it fails to apply changes in max. record length without a detour (nice finding, @kcbrown!) might add to the problems, but it's certainly not the only one.
Performa01, thanks for the input.Sorry for the late reply...QuoteThat it fails to apply changes in max. record length without a detour (nice finding, @kcbrown!) might add to the problems, but it's certainly not the only one.
Can you explain exactly what you believe these other problems are with the SDS2000X+ in terms of its trigger engine?
Thanks!
Dear all,
A new episode is ready on the comparison series, now on Bode Analysis. On paper, the Siglent SDS2000X Plus has the best cards of our three instruments. Is this true?
(Spoiler: yes, but you need to be very patent, and the specs don’t tell you the full story…)
The updated comparison document is available here (https://github.com/RudisElectronicsLab/RTB_SDS_DSOX_review/blob/main/v67%20RTB%20SDS%20DSOX%20Functional%20Comparison.pdf).
The Bode Plot in the Siglent is slow, especially at low frequencies.
Like Performa said, it uses frequency selective algorithm,
That makes it have very good dynamic range and more robust if you are not working in a Faraday cage.Great, but I would have wished that the user could choose to have such strategies in place or not. In my test case (and I think in many user's test cases) a Faraday cage neither special strategies to deal with very low signals or wide dynamic range are needed. Unless such special situations apply, I would rather like the instrument to be more responsive.
Your complaint about not being able to set fine steps for the amplitude axis has aready been addressed in the SDS2000X HD and will be available in the next SDS2000X Plus firmware. We can now set the scale in 1 dB increments.Good to know. I don't own that HD scope, but once the firmware update for the SDS2000X Plus is out that fixes this and I have been able to test it, I'm happy to update my comparison document!
Your complaint about not being able to have a look at the time domain view has aready been addressed in the SDS2000X HD and will be available in the next SDS2000X Plus firmware.Same as above!
Thanks for the replies and compliments.QuoteThe Bode Plot in the Siglent is slow, especially at low frequencies.QuoteLike Performa said, it uses frequency selective algorithm,
I djust did some more tests and I can confirm the speed is frequency dependent indeed (and will update the future comparison document):
[attachimg=1]QuoteThat makes it have very good dynamic range and more robust if you are not working in a Faraday cage.Great, but I would have wished that the user could choose to have such strategies in place or not. In my test case (and I think in many user's test cases) a Faraday cage neither special strategies to deal with very low signals or wide dynamic range are needed. Unless such special situations apply, I would rather like the instrument to be more responsive.QuoteYour complaint about not being able to set fine steps for the amplitude axis has aready been addressed in the SDS2000X HD and will be available in the next SDS2000X Plus firmware. We can now set the scale in 1 dB increments.Good to know. I don't own that HD scope, but once the firmware update for the SDS2000X Plus is out that fixes this and I have been able to test it, I'm happy to update my comparison document!QuoteYour complaint about not being able to have a look at the time domain view has aready been addressed in the SDS2000X HD and will be available in the next SDS2000X Plus firmware.Same as above!
In your table there is no information if Siglent was tested using automatic level control (ALC), on or Off (In Siglent "language" it is: Channel Gain: Auto or Manual)
Just watched the new episode, I would like to know how they perform when encountering a phase shift beyond +-180°. The Keysight 1102g has this thing where it can't determine if the phase is + or - 180° so you see jumps like this when it crosses either point, could you test for this on the 1204g and the others? thank you!
...
Topic of next video is not yet decided but it might well be ... FFT
On request, I have decided to do the FFT episode as the next one in the series. It's quite an extensive topic to cover, resulting in a mammoth video… But I have provided extensive TOC (so you can jump to what you want to see), and I’m sure there are new insights things to be discovered by everyone, also the most seasoned users of these oscilloscopes!
Once again, the comparison document is updated (now 54 pages, 267 footnotes, quite some detail….).
Enjoy!
Rudi
Please don't take this as offense. The topic is quite complicated and it is very involved to create representative presentation.. It is obvious a lot of work is put in it. Minor errors are understandable..
First, there is no RBW in FFT, really
RBW is resolution bandwidth, not realtime bandwidth.
RTB doesn't have regular FFT implementation. What they have is kind of simplified version of spectrum mode from it's "bigger" brethren..
Fact that FFT in RTB2000 takes over control of the scope is annoying as hell to me, personally.
On SDG2000 (or 6000) you don't need to press amplitude for few seconds to get dBm. If you have it set for 50 Ohm, you simply start typing number 0 and press dBm like you did..
On SDS2000X+, sort peaks (frequency/amplitude) is applied to TABLE view. Peaks markers are always enumerated from left to right in increasing number order.
Noise floor comparisons are valid only if you have exactly same number of data points, time interval bins, averaging and same windowing. Otherwise they will differ..
For the FFT math, the correct term for the frequency spacing is "bin-width". For a 1 Mpts FFT at 1 GSa/s, if you have a mega (1048576) bins, each of them is 953,67 Hz wide.
The effective Resolution Bandwidth (RBW) is closely related to the bin-width, but not identical. There is a factor involved, depending on the window function in use.
In theory, that factor ranges from 0.89 (Rectangle) up to 2.94 (Flattop), yet when I last measured it, the Flattop window in some Siglent DSO required a factor of 3.8 to determine the true -3 dB bandwidth. Rectangle window is to be avoided except some very special applications like short transients, whereas Flattop is the most accurate window function that is universally used in spectrum analyzers.
On request, I have decided to do the FFT episode as the next one in the series.
1) You can change the horizontal scaling of the spectrum using the horizontal knob
2) Autoset sets both the channel parameters and the FFT parameters
I also see RBW shown on the screen of some other brands of scopes with FFT, such as the GW INSTEK MDO-2000E (screenshot here (https://www.gwinstek.com/en-global/2019_EDM/index/20190606)).Actually that is a spectrum analysis mode. Basically you can divide oscilloscopes in two categories:
For my RTB, I am doing the calculations as posted above by Performa01 and rf-loop, but I’m not getting what I would expect. Probably I’m doing something wrong; I'm sure someone can help me.
It is possible the FFT size varies on the RTB. In recent firmware R&S improved the performance when using low frequencies but I don't know whether 8kHz counts as 'low'. If you use a higher frequency (8MHz for example) I guess (!!!) variable FFT size won't be used. It is worth a try.
Never forget that there can be two different dample rates:
So it's essential to look at the FFT samplerate, like it's reported by the SDS in the FFT info block and not the sample rate in the timebase tab.
QuoteSo it's essential to look at the FFT samplerate, like it's reported by the SDS in the FFT info block and not the sample rate in the timebase tab.
Well, interesting enough, on my SDS2000X+ these values are (typically?) the same... When it reads "Sa=40.00MSa/s" in the FFT info block at the top of the screen, I also see "40.0MSa/s" in the grey "timebase" at the bottom. But the calculations I did of “Frequency interval (△f)” (a.k.a. FFT frequency spacing a.k.a. the "bin-width") were always spot on when I used this sample rate value.
The number of FFT samples is displayed in the Acquire/Acquisition Menu under Record Length.
... Maybe I should go even higher, to find out whether indeed FFT point size varies depending on settings...
I finally got around to watch the FFT-video. Nice work, this was quite informative!
Reply #23 in the following thread has a complete checklist for setting up the FFT for a Siglent SDS2000. Many of the hints there will apply to any FFT implementation.
Axis annotation will have a sensible resolution in the next firmware. Among other things, this means just one place after the comma for the y-axis (dB).
The icons in the file manager get an additional annotation in future firmware. So no more guesswork.
QuoteAxis annotation will have a sensible resolution in the next firmware. Among other things, this means just one place after the comma for the y-axis (dB).QuoteThe icons in the file manager get an additional annotation in future firmware. So no more guesswork.
Good to know that there are plans to improve this type of thing! The last two firmware updates seemed to address few things only, and I was unsure about the pipeline. In my comparison document, I provide quite a list of wishes for the SDS2000X+ firmware. Not everyone would find all of them equally important (or disagree with some) but I think there is plenty of room to make this instrument more attractive to current and future users.
Hopefully, both the X and Y value axis will get to see some changes in the next firmware, and not only for FFT but for regular modes too.)
I've attached a screenshot to illustrate the problem:
I quickly checked the ability of the SDS to perform two FFT analyses at the same time, and it looks great! I have the impression that the FFT menu settings are individual for each of these, but settings such as the time base are, of course, common. It never came to my mind to check such simultaneous use, and I don’t think the manual or any other material I have seen refers to it. I think many people are happy to learn about it ;-)Yes, there might not be too many use cases, but it shouldn't be too much of a surprise: we can have two math channels at the same time and FFT is a math function - so this is to be expected. The SDS6000A can even display four FFTs at the same time... ;)
Yes, there might not be too many use cases, but it shouldn't be too much of a surprise: we can have two math channels at the same time and FFT is a math function - so this is to be expected.
Since the RTB tries to emulate an SA, thus hiding the underlying math from the user, they might as well refer to frequency-bins instead of FFT-points.
Changing the RBW from 60 Hz to 350 Hz has no effect, except for the first two values for Value and Ratio.Code: [Select]Res Value; Res Ratio; Data Points; Data Header (4 Values); Acq Srate; Acq Points; Acq Points Arate
RBW 60 Hz:
6.003E+01; 3.13E+02; 65536; 0.000000E+00,1.024575E+06,65536,1; 2.05E+06; 131072; 2.0492E+06
RBW 350 Hz:
3.5019E+02; 5.36E+01; 65536; 0.000000E+00,1.024575E+06,65536,1; 2.05E+06; 131072; 2.0492E+06
Meanwhile I had a totally different question: where does the claim of 128 kpts FFT-length for the RTB come from? I could not find the slightest hint in the datasheet or user manual.
Here are the read-in FFT data as a comparison to the screenshots from the RTB2000.
>> This way, there will be no reduction in sample rate and no unexpected aliasing
For me, the ultimate test is to create a signal that results in a known aliasing tone. Then we can change (RBW) settings and confirm that FFT sample frequency remains constant. Will try when I’m back.
If for example you use that 2.05 MSa/s setup again, then you can feed a 900 kHz and 1.15 MHz into the RTB in sequence. In both case, you should see a spectral line at 900 kHz. Then try different RBWs and see if it always behaves the same. I'm pretty positive that it will...
This does not work like this. There are more FFT points than are displayed on the screen. You can zoom out in stop mode, and then the 900 kHz or 1.15 MHz signals appear.
I am just looking at these medium-range scopes for a specific feature: ability to do fast waveform averaging.
To test the speed of averaging I use a 1 Hz sine wave as an input, a short time base and minimum number of waveform points. One can use auto trigger or a 100 kHz or higher trigger source. Then switch acquisition to averaging mode and keep increasing the number of averages until the amplitude of the 1 Hz waveform oscillating on the screen reduces by 1/2 (the waveform appears as just a straight line going up and down).
Among the low-cost scopes I tested the winner appears to be Keysight EDUX1002 scope, which can do 128 averages before the amplitude of 1 Hz sinewave reduces to 1/2.
It would be great to test these scopes for this metric or any other than could be contender for fast real-time averaging.
>> The undocumented SCPI command can be used to read out the FFT window factor:
Very nice, thanks! Now we know the exact values the instruments uses and plug these into our calculations.
In my last video, the Rohde & Schwarz RTB2004 was still holding secrets in terms of how its FFT analysis actually work. In this video, I go into greater detail unravelling them.
Thanks to various people that contributed to this thread with useful suggestions and ideas!
https://youtu.be/D1dVqcjbWm4
May I revisit this older thread? I have just started to work my way through Rudi's very helpful series of videos -- mainly with an interest in the hands-on demonstration of the SDS2104X plus, which I'm seriously considering as my next scope.
One thing that struck me in episode #4 (Measurements) is that the SDS came out last, by an order of magnitude (!), regarding the speed of collecting measurement statistics. See the attached table and the video linked below. Given how the strength of quantitative measurements and analysis is always stressed when discussing the Siglent scopes (and their LeCroy role models), I had not expected this.
I did not find any comments on this in the present thread. Is the slow measurement update rate just a reality with the SDS2000X plus? Are there some memory or acquisition settings that should be changed to get much faster measurements? Has anything been improved in recent firmware updates?
Thanks for your comments!
https://www.youtube.com/watch?v=TAoB5614hs4&t=1270s (https://www.youtube.com/watch?v=TAoB5614hs4&t=1270s)
You should be able to count not 6, also not 12 but no less than 52 measurements at once.
You have already named it – this is a MSO with main focus on analytic capabilities. Of course there is a difference between analytic scopes, which require deep measurements, and standard scopes, which prioritize speed and try to measure (estimate would be more appropriate) on heavily decimated data. To understand this, here’s a simple example:
SDS2354X_Plus_Meas_Pulse_10Mpts
This screenshot shows just a pulse train. Pulse width is 10 µs, transition times are ~1 ns and repetition rate is 4 kHz. At a time base of 500 µs/div and 2 GSa/s, this results in a record length of 10 Mpts. The key parameters of the pulse train shall be measured: period, amplitude, rise and fall times and pulse width. Everything is measured reasonably correctly. Of course, at 2 GSa/s this scope isn’t fast enough to measure a 1 ns transition time precisely, yet it’s well within reasonable expectations. For more accurate measurements on such short time intervals, we’d have to zoom in up to the point, where sin(x)/x reconstruction calculates additional data points. We cannot use a much faster timebase right from the start, because at faster time bases we lose the measurements, one by one: At < 25 µs/div we could not measure the period anymore, at <1 µs/div we lose the pulse width measurement and can only measure a single transition, I.e. either the rising or the falling edge.
Now try the same exercise with the fast Keysight, which uses 64 kpts decimated data – good luck!
It is worth to take a closer look at this screenshot. We see advanced measurements in M1 mode, where statistics and Histicons (small histogram icons) are enabled. If we look at the “count” in the measurement statistics, it becomes obvious that only the vertical (amplitude) related measurements appear to be slow. For the time measurements, the scope analyzes the entire record, hence a single acquisition yields some 20 measurements of period, rise and fall times and pulse width. It just so happened that not a single time related measurement was shown in this comparison.
Apart from that the SDS2000X Plus firmware has seen a few optimizations since this comparison. My measurements yielded at least twice the speed as the numbers found in this review. If I make the conditions a bit more equal, then the vertical measurement rate reaches >16 measurements per second if I reduce the record length to 100 kpts, thus getting into the ballpark of the measurements on decimated data of the competing instruments.
Furthermore we have these M1 and M2 measurement modes (limited to max. 12 measurements) only in the “advanced measurements” mode. But there is also a “simple” mode, which allows a lot more than just 12 measurements in parallel:
SDS2354X_Plus_Meas_Simple
You should be able to count not 6, also not 12 but no less than 52 measurements at once. The glitch, that the measurement window closes as soon as we select an item (so that we cannot read the help text and have to re-open the window if we need to add more measurements) is long fixed either.
How to enable all the measurements at once in “simple” mode with SDS2354X Plus?
just a note, you cannot do this kind of math (you used on efficiency calculations) on either Keysight or RTB2000. Keysight has only simple math and RTB2000 has different math architecture without formula editor.Hi 2N3055,Code: [Select]just a note, you cannot do this kind of math (you used on efficiency calculations) on either Keysight or RTB2000. Keysight has only simple math and RTB2000 has different math architecture without formula editor.
It’s true that the Siglent has a formulae editor, which the RTB does not. Yet, the RTB has five math channels (compared to 2 in the Siglent). So, what you typically do, is to break down tasks. The formula you refer to can be broken down into several parts (see the attached screenshot), which have the end result.
I understand some will really prefer scopes with a math formula editor (I myself particularly like the one in the PicoScope). And there certainly are formulas that cannot be broken down into parts the RTB can handle. On the other hand, having five math channels, like the RTB, can be valuable in other situations. Moreover, if you use it to break down a formula, you can also monitor each element separately in a measurement function, which can be useful for tracking issues.
The Keysight DSOX1000 is much more basic when it comes to math: one channel only, and no formulae editor.
I have now updated the series of comparison videos with an episode on math channels. Enjoy!