Rigol 1054z and 1074z timing problems at 500ms timescale and 24M memory depth - Page 1
Forum section: electronics / testgear

author: Sredni
author_rank: Frequent Contributor
timestamp: August 21, 2020, 11:00:32 pm
content: Is this a known bug?https://electronics.stackexchange.com/questions/517690/rigol-ds1074-oscilloscope-shows-very-wrong-timingBasically, acquisition at 500ms timescale with memory depth set to 24M gives timing results consistently 4% off.I wanted to post it in the rigol megathread, but I can't find it. EDIT: I finally found the Rigol megathread and posted there as well to alert all posters there of the issue.

author: Howardlong
author_rank: Super Contributor
timestamp: August 22, 2020, 09:28:42 pm
content: Quote from: Sredni on August 21, 2020, 11:00:32 pmI don't know if it's a known bug, but it seems to be that capturing at 4.00MSa/s ain't right (500ms/div, single channel, 24MSa). On mine, a 1Hz square wave calculates as 961mHz, and you can see it's not right. Recaptured at 200ms/div and 1s/div looks fine.

author: tautech
author_rank: Super Contributor
timestamp: August 22, 2020, 09:47:30 pm
content: Quote from: Howardlong on August 22, 2020, 09:28:42 pmWelcome to the world of DSO memory/sampling rate management.Looks as it should do to me......apart from the counter.

author: Sredni
author_rank: Frequent Contributor
timestamp: August 22, 2020, 10:22:59 pm
content: After posting here, I did some other test using the 1kHz test signal and the 4% error is there and is reproducible. Just acquire it with 24M with a 500ms timebase and the period will be 1.040 ms instead of 1.000 ms.And if the acquisition is done with a 5s timebase, the period will come out as 800us, a 20% error.(images at the updated link above)

author: Howardlong
author_rank: Super Contributor
timestamp: August 23, 2020, 06:59:39 am
content: Quote from: tautech on August 22, 2020, 09:47:30 pmIt's not aligned with the graticule.

author: tautech
author_rank: Super Contributor
timestamp: August 23, 2020, 09:18:41 am
content: Quote from: Howardlong on August 23, 2020, 06:59:39 amOh that bit, yes maybe a bug or the unit is in need of Self Cal.

author: Sredni
author_rank: Frequent Contributor
timestamp: August 23, 2020, 03:43:46 pm
content: Oh, for being a bug, it is a bug.I wonder if it has been already fixed or if it is present even in the latest firmware. My firmware version is kinda old: 00.04.04.01.01 and I did not upgrade anymore since I had read about an error in one of the subsequent versions of the firmware.The 800 us period of the 1kHz test signal is... unsettling.

author: Fungus
author_rank: Super Contributor
timestamp: August 23, 2020, 08:43:34 pm
content: Quote from: Sredni on August 23, 2020, 03:43:46 pmFWIW it happens on mine, too.Quote from: Sredni on August 23, 2020, 03:43:46 pmMe? I wouldn't be too unsettled by something that took five years for anybody to even notice it.

author: Sredni
author_rank: Frequent Contributor
timestamp: August 23, 2020, 11:44:17 pm
content: Quote from: Fungus on August 23, 2020, 08:43:34 pmWell, the point in my opinion is that this is a behaviour nobody would expect even in an entry level scope. It has gone unnoticed because people did not question the timing of well behaved signals at certain sample rates and memory depths only.This is an embarassing bug because it seems to be caused by flawed implementation of a mathematical routine.If it does that at 24M of memory and 4 MS/s when the time base is a 0.5 and 5 seconds, maybe it will happen with other combinations of memory depth, sampling rate and timebase. A 20% error in timing when you have no idea when it could happen, makes this scope more similar to a reverse slot machine. If you get the wrong combination, you hit the jackasspot.Luckily nobody would use an entry level hobbyist scope for anything serious but I wonder if this bug happens in the next level line up, such as the DS2000 series.If the firmware are based on the same mathematical algorithms, it might as well be the case...

author: rf-loop
author_rank: Super Contributor
timestamp: August 24, 2020, 03:34:06 am
content: Quote from: Sredni on August 23, 2020, 11:44:17 pmIt is intersting speculation if think...Someone have this in place where all instruments need have calibration certification.Now it they send also this to cal lab who check instruments and write certificates. Who believe this Rigol get pass in tests and after then it have certificate and cert. sticker somewhere in front panel etc. All happy use it and measured results are now made with nist traceable cal. instrument.Who have enough loose money for test. Send it with company other instruments to get new cal cert and without any notice about possible err.My forecast is, in return shipment there is one Rigol what have certificate.How about Rigol own factory calibration where they proof that it meets its specifications and even list about test instruments used for check/factory calibration and nice story how they are traceable to standards. This case show that whole process is just bullshit. They have not made any kind of full calibration check as it need do. If they have done it, it is not now here. How factory own calibration check can not detect this error what is not small. 4% abs acc. in vertical... blah...not big alarm if happen.But this error is in horizontal time axis! This is controlled by scope TCXO or what ever timebase what have some specifications in ppm units. This make big difference.Perhaps if take this 24M data out and analyze it carefully and calculate some things with some experimental tests may tell is it partially math problem in scaling to display or is it also in measurement small intermediate buffer or is it in whole true capture memory.In capture memory there is not floating "math" if they have done it right. There must be only decimation.I do not know what is real ADC samplerate in Rigol ADC in every cases.Is it possible to check if this failure also exist with same other settings but also then with 1, 2 and 3 or 4 channels in use simultaneously. Yes it drops true ADC samplerate and of course divide also memory.If ONE Ch is in use and very slow time scale... like example 500ms/div do they take all 4 ADC interleaved samples and decimate it or do they take just only one ADC and decimate it to get decimated 4MSa/s.Speculation. If they use full 4 ADC interleaved stream when one Channel open. it is 1GSa/s. For 4MSa/s it need decimate by 250. (drop out 249 and keep one and forward it to capture memory)If they use only one ADC (no interleaving) there is 250Msa/s true ADC speed (well enough also for this timescale). For 4MSa/s they need decimate by 62.5 what is impossible except is do not use constant decimation but 62 and 63 sequentially what is ... not so nice.If it is just pure decimation error it can perhaps detect when look saved acquisition memory with computer and using some external test signals.But, how factory have tested it so that they can write proof that it meet its specifications. Of course it need check with every single time scale. This is how we have done it in tens of years when there was only analog scopes and still it need do so today and for every timescale just for detect some programming errors in production. After it is checked then do not need every time check every time scale. Program do not drift. In analog scopes even this need check in every calibration procedure, as can see example in Tektronix old full service and calibration manuals.Is it possible that this have happen accidentally in some FW update or have this error been always after product start what is then even really more severe because then it tell they have never true checked it for proof specifications.They think, as many chinese companies, that customers are good for do beta tests or even more early tests.One bad is that some cases in some poor company perhaps same peoples do final tests before launching phase who are designing HW and who are programmers. This is real class A mistake.There need be separate test team who are far away from designers in test phase and more error they find more money they get, minor errors bit less and finding fatal class major error give pocket full of bank notes. This works. Why chinese and indian etc some companies jumps over this like lazy fox.Some say that this is not serious because it is only hobby scope. ReallyWho think hobbyists are some group what can eat what ever shit and crap fnirsijokes.This instrument have specifications. Who can think specifications can be like joke stories or other trumpths.This scope you can find in many places in real work and not only as hobbyist hobby corner decoration.No, this is real and serious error what responsible company need urgently repair and also better if set public Notice about this error so that users can avoid this error trap. I remember well HP and Tektronix Notification and Errata letters before arpanet and now internet.

author: Fungus
author_rank: Super Contributor
timestamp: August 24, 2020, 06:14:06 am
content: Quote from: rf-loop on August 24, 2020, 03:34:06 amI agree that this should be fixed. I don't agree that the sky is falling.(and you'd know why if you actually tried to reproduce it instead of just spouting...)

author: Adrian_Arg.
author_rank: Frequent Contributor
timestamp: August 24, 2020, 03:26:59 pm
content: I agree, Rigol should solve the failure as soon as possible, I don't think it is that difficult.

author: SERJSOCHI
author_rank: Contributor
timestamp: August 26, 2020, 11:17:14 am
content: Same problem.

author: Adrian_Arg.
author_rank: Frequent Contributor
timestamp: August 26, 2020, 12:11:06 pm
content: I sent an email to rigol with an explanation of the problem and a screenshot. for now acknowledgment of receipt.To: Info-IntlSubject: BUG rigol dsz1000zPosted on: 8/25/2020 12:06 PMwas read on 8/25/2020 10:16 PM.

author: Sredni
author_rank: Frequent Contributor
timestamp: August 26, 2020, 09:00:48 pm
content: LOL, the OP on EESE (OMG! WTF am I doing with all this acronyms?) has received a reply from Rigol, saying to upgrade to the version of firmware he already has, and that is affected by the bug.(This information is in the comments, and the question has been closed as off-topic - in fact it's not a question about how to find the resistance for a LED...)Perhaps somebody should write a bug report in Chinese?

author: Howardlong
author_rank: Super Contributor
timestamp: August 26, 2020, 09:29:03 pm
content: Quote from: Sredni on August 26, 2020, 09:00:48 pmThe value of the websites like that is so degraded by activity such as marking things as "off topic" to close them.The other useless trick they use, presumably to fraudulently improve their click rate, is to mark completely unsolved questions as solved. Toms Hardware is probably the worst for falsely claiming unsolved questions as solved.Of course, there's no reasonable way open to contest these arbitrary and disingenuous decisions.

author: Elmue
author_rank: Newbie
timestamp: August 27, 2020, 05:19:55 pm
content: HelloI'am the "OP" how published the bug at StackExchange.My thread has been reopened. So I could post an answer now:https://electronics.stackexchange.com/a/518731/101597

author: BlackDogWhite
author_rank: Newbie
timestamp: August 27, 2020, 11:06:34 pm
content: Just accept that I'm an idiot.How do I select some different Sa rate? The menu item always seems disabled.

author: Kean
author_rank: Unknown
timestamp: August 28, 2020, 12:26:20 am
content: Quote from: BlackDogWhite on August 27, 2020, 11:06:34 pmYou need to change the memory depth which then changes sample rate based on timebase. Or at least that is what I did.You also must be in run mode to change it, and only have channel 1 enable.I tested it on my MSO1104Z and got the same results. I added a reply with my findings on Stack Exchange.

author: Adrian_Arg.
author_rank: Frequent Contributor
timestamp: August 28, 2020, 12:42:25 am
content: We have to flood Rigol with emails with complaints, to see if we can get them to fix the failure.in spanishnosotros tenemos que inundar de mails con reclamos a Rigol, para ver si conseguimos que arreglen el fallo.

author: Fungus
author_rank: Super Contributor
timestamp: August 28, 2020, 05:31:31 am
content: Quote from: BlackDogWhite on August 27, 2020, 11:06:34 pmYou can only change it when the 'scope is running, not when it's paused.

author: Adrian_Arg.
author_rank: Frequent Contributor
timestamp: August 30, 2020, 10:02:11 pm
content: It would be good to know how many users of the rigol ds1000z have made the claim to rigolSeria bueno saber cuantos usuarios del rigol ds1000z han hecho el reclamo a rigol

author: Joe M
author_rank: Contributor
timestamp: August 31, 2020, 11:47:02 pm
content: I wonder if this sort of thing happens with the other Chinese brands like GW Instek, Siglent, Owon or Hantek.Shame on you RigolIf many of you complain there's a chance that Rigol will listen and correct the issue. Dave should make a video of this, I bet Rigol will come running after that.I own a Rigol Spectrum Analyzer and an arbitrary waveform generator, haven't had any problems yet, that I know of..

author: Adrian_Arg.
author_rank: Frequent Contributor
timestamp: November 24, 2020, 04:39:11 pm
content: After several months, the people of rigol consulted me what version of firmware I had installed and a screenshot, since the last firmware revision corrected that error, because it did not correct it, it remains the same !!!!

author: Sredni
author_rank: Frequent Contributor
timestamp: November 25, 2020, 10:39:11 pm
content: I mean, don't they have at least one scope to test it themselves???All they had to do is plug the probe on the calibration output and turn two knobs.Shameful.

author: Adrian_Arg.
author_rank: Frequent Contributor
timestamp: November 25, 2020, 11:53:17 pm
content: Is it too complex to solve that problem? or is it that they no longer care?

author: spacehen
author_rank: Contributor
timestamp: June 06, 2023, 12:40:15 pm
content: Quote from: Adrian_Arg. on November 25, 2020, 11:53:17 pmI don't think they care. I bought a Rigol scope this year and have the latest firmware but can still reproduce this issue.I was deciding on either a siglent or rigol scope and decided to go with rigol. I think I am now regretting that decisionI'm sure the siglent also has bugs but this is.... just shockingI don't even think hantek or yeapook scopes have this issue.