Uni-T UTD2102CM waveform capture rate - Page 1
Forum section: electronics / testgear

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: May 29, 2013, 10:01:41 am
content: I managed to get my hands on a UTD-2102CM from my Uni-T supplier but for various reasons I only had a few hours to play with it before I had to return it (but not because the supplier didn't let me keep it for longer). Lacking proper equipment (and knowledge) to perform any real test, basically for the most part I just literally "get my hands on it"Anyway, I just wanted to quickly show this video where you can see that it is capable of showing some very steady and smooth waveforms at the 50ns time base. The waveform updates are also smooth at the 5ns and 2ns time bases but I don't have a proper function generator to generate a meaningful waveform at those frequencies so they are not shown. At ALL other time bases, there's a lot of flickering on the screen.This scope does support triggering off both the rising and falling edges, so I tried following fellow forum membermarmad's techniqueto find out the waveform capture rate but with only an el cheapo Chinese function generator board (which is really unstable at low frequencies below a hundred Hz or so) to work with I failed to get any reliable result. The only somewhat repeatable results I got were around 9Hz at the 5ms time base and 14Hz at the 2ms time base.So here's the short video clip:

author: marmad
author_rank: Super Contributor
timestamp: May 29, 2013, 03:00:44 pm
content: Quote from: iloveelectronics on May 29, 2013, 10:01:41 amFranky:Thanks for this attempt, but looking through the UTD2000M manual, it says the following about rising/falling Edge triggering: "Set to trigger at the rising and falling edge of signal once each."This sounds as if it's doing 'alternating' Edge triggering - and not 'either' (every) Edge triggering - so my method wouldn't work. So it wasn't a problem with your FG.

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: May 29, 2013, 03:09:57 pm
content: Quote from: marmad on May 29, 2013, 03:00:44 pmYou are probably right.Looking at the short video clip do you agree the waveform update rate is significantly higher at the 50ns time base than the other ones?

author: Hydrawerk
author_rank: Super Contributor
timestamp: May 29, 2013, 03:18:20 pm
content: The scope looks nice. Is it better than Rigol DS1000?

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: May 29, 2013, 03:27:16 pm
content: Quote from: Hydrawerk on May 29, 2013, 03:18:20 pmI've never owned or used a Rigol DS1000 so I can't really compare. I would definitely say it's better than the Owan SDS7102 though. Screen looks more crisp (though smaller than Owon's). And I like the Uni-T's user interface more, just more intuitive to use. The Uni-T only allows up to 4 measurements to be displayed at any one time though (unless you press "measure"->"all").

author: tinhead
author_rank: Super Contributor
timestamp: May 29, 2013, 04:09:52 pm
content: Quote from: iloveelectronics on May 29, 2013, 03:27:16 pm... and didn't allow to hide menu, right? That's maybe not really best, but well, better than bugs (as sawn on Hantek in previous fw versions) while switching menu off.Btw, can you check what about the 16mpoint? Can this data be exported to flash drive? Is it sample buffer or recorder buffer (or both, like it can be on Hantek)?.

author: marmad
author_rank: Super Contributor
timestamp: May 29, 2013, 04:12:44 pm
content: Quote from: tinhead on May 29, 2013, 04:09:52 pmQuote from: iloveelectronics on May 29, 2013, 10:01:41 am

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: May 29, 2013, 04:32:49 pm
content: The menu can be turned off, but when you do that the space on the right will be taken by the 4 measurements so they won't cover the waveform. The actual waveform display area only measures about 5.5" diagonally.Unfortunately I didn't have time to test the storage features.Quote from: tinhead on May 29, 2013, 04:09:52 pm

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: May 30, 2013, 01:02:36 am
content: Oh, speaking of memory depth I forgot to mention that the UTD2102CM can only do either “general” or “deep”, which means it's either 6k pts or 16M, nothing in between.

author: Nermash
author_rank: Frequent Contributor
timestamp: May 30, 2013, 07:01:35 am
content: I wish you tried feeding it in with some live composite video signal. That could have given us some ballpark estimate on the update rate...

author: marmad
author_rank: Super Contributor
timestamp: May 30, 2013, 09:53:10 am
content: Quote from: Nermash on May 30, 2013, 07:01:35 amWhy would that give a ballpark estimate?

author: Nermash
author_rank: Frequent Contributor
timestamp: May 30, 2013, 11:16:26 am
content: By ballpark I mean subjective evaluation only:) Not scientific or empirical, but it would be clear immediately are we talking really fast update rate on a complex signal like Rigol DS2000 or simillar, or more like Owon and other budget scopes.Since claim for this model is 150k updates, I think that it would be quick and dirty method to verify if this claim has any validity.

author: marmad
author_rank: Super Contributor
timestamp: May 30, 2013, 11:28:44 am
content: Quote from: Nermash on May 30, 2013, 11:16:26 amBut how could you tell immediately? The DSO doesn't do any intensity grading so it doesn't bring any extra information to the screen that way. I think a more quick and dirty approach would be to send it a signal with a repetitive glitch, and try to roughly observe how often it's flashing on the screen.

author: Nermash
author_rank: Frequent Contributor
timestamp: May 30, 2013, 11:48:12 am
content: Well, I think that I could spot that high update rate on changing video signal, even without intensity grading. But also I might be wrong, I haven't tried it before.Since Franky didn't have a lot of time to play with it, this was my idea of the quickest and easiest check.I agree that glitch spotting would give us more empirical data, but that setup also requires more time and resources.

author: hgg
author_rank: Frequent Contributor
timestamp: May 31, 2013, 01:25:39 pm
content: Below is a follow up from Russ:-------------------------------------------Well, using the method below...I took my rigol dg1022 and tested the UTD2102CMThe fastest I could get this to trigger and see what the tests were is this:(Attached 1st Photo)That's 239khz on the counter and I was seeing this trigger Anomaly. From what I can tell that's a lot faster than what the guy has shown in the video on the same time base.??What do you get from this test with the Information provided?Helpful?This being the first time trying this test... I can't tell if that's good or bad.Thoughts?I can't get it to work on any faster sec/div... I don't know if the window is to small for me to see it or what.Here is the rest I could get. ( if you need higher res photos let me know. Im using my phone...(Rest of the attached photos)

author: marmad
author_rank: Super Contributor
timestamp: May 31, 2013, 01:47:22 pm
content: Quote from: hgg on May 31, 2013, 01:25:39 pmWhat method?My method? As stated above, my method won't work on this Uni-T (or any DSOs that don't have 'either' Edge triggering). Any 'perceived' results would be erroneous.

author: hgg
author_rank: Frequent Contributor
timestamp: May 31, 2013, 01:56:51 pm
content: Yes, I think so.

author: hgg
author_rank: Frequent Contributor
timestamp: May 31, 2013, 06:58:16 pm
content: He just told me that the Uni-T actually has 'either' edge triggering.Russ:Quote

author: hgg
author_rank: Frequent Contributor
timestamp: May 31, 2013, 07:37:42 pm
content: from Russ:Quote

author: marmad
author_rank: Super Contributor
timestamp: June 01, 2013, 12:13:30 pm
content: Quote from: hgg on May 31, 2013, 06:58:16 pmUni-T manual states:"Set to trigger at the rising and falling edge of signal once each."As mentioned above, that sounds like ALTERNATE Edge Triggering - not EITHER. There are two types that manufacturers use - with, it appears, 'alternate' Edge being found on most low cost DSOs.You can test if your DSO supports real 'either' Edge very quickly by setting it to 5ms/div, then sending it a sine wave between 1 - 12Hz (step 1Hz). If none of those 12 frequencies produces a stable, non-moving waveform (with just a single edge showing), then your DSO is skipping potential triggers and doing 'alternate' Edge .

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: June 01, 2013, 12:28:10 pm
content: Quote from: marmad on June 01, 2013, 12:13:30 pmIn that case the Uni-T does have either edge triggering. I am pretty certain I saw pretty stable one edge waveform down in that frequency range (though my FG is pretty unstable at those frequencies) for both the 5ms and 2ms settings.

author: hgg
author_rank: Frequent Contributor
timestamp: June 03, 2013, 07:56:06 am
content: Hi,Russ was kind enough to upload a YouTube video showing the basic functions of the UNI-T scopeand trying to apply Marmad's method for the wfrm/s rate.Russ thank you for your time and effort.The screen is excellent, the scope seems pretty responsive and the menu is very easy to look at and use.

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: June 03, 2013, 09:31:36 am
content: Thank you hgg and Russ! We finally have more information about this scope on the internetI'm still watching the video but I kind of feel silly that I missed the "Fast ACQ" option while I had the scope to play around with! That seems to be the key feature to the Uni-T claimed 150k wfms/s rate.I do agree that the menu system is quite well organised and intuitive to use. If intensity grading is not an important factor in your application this is actually not a bad scope in the sub $500 price range.

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: June 03, 2013, 10:35:26 am
content: Just finished watching the video. So there does seem to be something going on at the 50ns (and 5ns and 2ns) time bases as I stated in my opening post, even though I never had the Fast ACQ turned on. Perhaps that's why Uni-T is stating their waveform capture rate as ">150k" instead of just "150k"?

author: Wytnucls
author_rank: Super Contributor
timestamp: June 03, 2013, 12:57:39 pm
content: Franki, I think this Uni-T oscilloscope may have intensity grading.The operator's booklet is ambiguous on the subject, but it mentions a display feature not readily available on cheaper scopes.The best way to find out, it seems, would be to display a sine wave with, say 100% amplitude modulation in high acquisition rate mode, while the waveform light intensity is turned down. Hopefully, the analogue scope effect should become apparent, where the nodes are brighter than the rest of the display.

author: hgg
author_rank: Frequent Contributor
timestamp: June 03, 2013, 01:00:09 pm
content: Franki you are welcome. Indeed, there is some information now on the mysterious UNI-T!It looks like that it has the "either" edge trigger and that its fast.Marmad what's your opinion?I think I've rushed to buy the Siglent scope...If it also has some kind of intensity grading, I am selling the Siglent!...

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: June 03, 2013, 01:06:52 pm
content: Quote from: Wytnucls on June 03, 2013, 12:57:39 pmWell, from the couple of hours I had playing with it I didn't think it had intensity grading. Granted I didn't have the equipment to generate any AM waveform to test so I might be wrong.

author: Hydrawerk
author_rank: Super Contributor
timestamp: June 03, 2013, 02:35:29 pm
content: What the hell is that?They were somehow inspired by Agilent, but...Anyway, thank you for the video.

author: hgg
author_rank: Frequent Contributor
timestamp: June 03, 2013, 02:45:21 pm
content: It looks like that they all take measurements from the screen and if the screen is of variablesize the algorithms will have to take into account scaling factors that might slow down the scope.Just a guess.... or they are just lazy...

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: June 03, 2013, 02:46:44 pm
content: Quote from: Hydrawerk on June 03, 2013, 02:35:29 pmThat's normally where your 4 measurement values would show when there's no menu selected. But yes, it's a bit of a waste of space sometimes.

author: Hydrawerk
author_rank: Super Contributor
timestamp: June 03, 2013, 02:51:13 pm
content: Only three languages? Well, it's like this scope is meant for China market only, or what. I would expect at least German and French.

author: hgg
author_rank: Frequent Contributor
timestamp: June 03, 2013, 02:53:24 pm
content: Version with 5 languages:http://dx.com/p/uni-t-utd2102cm-digital-7-tft-lcd-1gs-s-2-channel-storage-oscilloscope-grey-214113

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: June 03, 2013, 02:57:04 pm
content: The red/dark grey version of this scope is from earlier production. As hgg has linked in the above post, the white/light grey version is the latest.

author: marmad
author_rank: Super Contributor
timestamp: June 03, 2013, 03:27:46 pm
content: Quote from: hgg on June 03, 2013, 01:00:09 pmIMO, he jumps too quickly to higher frequencies at the smaller time base settings - which means that his results are likely wrong at many of those settings - because you always get flickering at higher multiples of the real dead time BW. It's absolutely critical that you go through ALL lower frequencies slowly at first to do this method accurately.And why do I think he jumped to higher frequencies too quickly? Look at this chart comparing the Rigol DS2000 (a DSO that the Uni-T is advertised as being faster than) to the Uni-T. In the chart are the Rigol's rates (using 14kPts of sample memory) against the Uni-T (using less than one-half the sample memory of 6kPts). At every time base setting up to 10us, the Rigol is clearly faster than the Uni-T - then starting at 5us, he starts raising his sweeping frequencies much faster, based on the previous readings. When you get to faster time bases, the wfrm/s rate doesn't necessarily double like it does at slower time bases - it goes up much more slowly, if at all - because the 'free' time the DSO has to process the waveforms gets smaller and smaller .Quote from: Wytnucls on June 03, 2013, 12:57:39 pmI haven't seen the SLIGHTEST indication in ANY video of this DSO that suggests intensity grading.Edit:Just saw this - so am editing the info above:Quote from: iloveelectronics on May 30, 2013, 01:02:36 am

author: hgg
author_rank: Frequent Contributor
timestamp: June 03, 2013, 05:52:47 pm
content: Maybe you need to feed an amplitude modulated signal in order to better see if it has any kind ofintensity grading. Take for example the recent review from Dave of the GW Instek that hasintensity grading but its so badly implemented that he was not sure in the beginning if it wasworking at all...Inconclusive results for the lower time bases of the Uni-T. Anyway, won't you agree that even if itsnot faster than the Rigol 2000, it looks that it has a very fast sampling rate especially if you considerits price range? The Rigol its clearly a better scope, but if price was an important factor then theUNI-T looks like a very good candidate. I am saying that because I think that with a few more eurosI would have bought a much better scope than the Siglent.

author: Hydrawerk
author_rank: Super Contributor
timestamp: June 03, 2013, 07:55:31 pm
content: Well, remember that UTD2102CM is only a 2×500MSa/s scope

author: marmad
author_rank: Super Contributor
timestamp: June 03, 2013, 10:02:12 pm
content: Quote from: hgg on June 03, 2013, 05:52:47 pmWell, the Instek has 16 levels of grading - it's not great, but it's at least noticeable. But any rapidly changing signal should reveal grading - it doesn't have to be modulated - see the attached image of a 75MHz sine wave using 14MPts sample length and a slow time base setting. You could also just use white/gaussian noise signal and you should see grading if the DSO does it (image #2).QuoteYes, it definitely looks like it has a very good update rate for it's price class - no doubt about that. But I would like to know exactly what Fast Acquire Mode (which he used) means. You never get anything for free - it's always a trade-off between sample length, sample rate, number of waveforms, etc. So what does the DSO change when it goes from Normal Acquire Mode to Fast Acquire? These things are important to know so that you can accurately determine the full benefit/drawback of the implementation.For example, we now know that the GW-Instek only does 80k wfrm/s with a 1k sample size while sampling at 200MSa/s (10 times less BW than normal) - not such an impressive figure given the limitations. Both the Agilent and the Rigol are more powerful when you factor in the sampling speed and size.

author: tinhead
author_rank: Super Contributor
timestamp: June 03, 2013, 11:07:40 pm
content: Instek is like the first TDS3000 series, the DPO is not really "that good from feature set and depth point of view",but it is there (sidenote: TDS7xxD series from 1998 i think was much better, but of course expensive, TDS3000 wascheaper but less DPO/DPX functionality inside). On Instek, these 16 color grading is very similar to what Tektronix didwith first TDS3000 models.UNI-T is like Tektronix InstaVu "DPOs" on e.g. TDS7xxA series, "grading" (acutally the DPO Z buffer) only 1bit deepdepth (so in principle it is DPO persistency - what's that? Simply, a persistency build based on not processed sample data,typical persistency is based on postprocessed display data). Unfortunately i don't see any persistency colors in the publishedvideo, so "gray scale" DPO persistency only. I bet measurments are not based on the DPO buffer but on single waveform,so exact as InstaVu did. So yeah, it is DPO-like thing gear, with probably good wfms/s results, but with TEK technologyfrom 1996. Sure, this is not bad at all, you have to start somewhere, and UNI-T is not having a "technology partner" like Rigol.As a UNI-T "hater" i'm happy to see that they managed to develop something working (more or less, guys ... add please16 color grading and your product will be 100% like TEK InstaVu).Quote from: marmad on June 03, 2013, 10:02:12 pmno Z-buffer modulation, no color persistency, no gray scale (intensity grading), no measurments on DPO buffer - that's it.On the other side DPO-like buffer (probably 1-8k or so),DPO based persistency and high wfms/s - exact like InstaVu - is a bigstep forward (now ineed onlywish to see a teardown to see if they finally got that unshilded PSU in 5CM distance from FPGA/ADCs is crap - like in the other UNI-Z models).

author: marmad
author_rank: Super Contributor
timestamp: June 03, 2013, 11:27:17 pm
content: Quote from: tinhead on June 03, 2013, 11:07:40 pmIt's a pity none of these newer, less-expensive, DPO incarnations (Agilent, Rigol, etc) allow exporting of the 3D data for post-processing (like the post-1998 xxD Teks). That seems like a really interesting feature.

author: hgg
author_rank: Frequent Contributor
timestamp: June 05, 2013, 02:56:21 pm
content: Hi,Here are two more very interesting videos from Russ that show especially what theFast Acquire option can do:What do you think?

author: Hydrawerk
author_rank: Super Contributor
timestamp: June 05, 2013, 03:16:02 pm
content: Well, at first sight this scope looks better than Rigol DS1000 series...

author: hgg
author_rank: Frequent Contributor
timestamp: June 05, 2013, 06:07:37 pm
content: That's for sure...

author: hgg
author_rank: Frequent Contributor
timestamp: June 06, 2013, 10:17:20 am
content: Hi,Marmad did you see the two latest videos from Russ?What do you think?Thanks.