Siglent SDG1032X Harmonic Distorsion - Page 1
Forum section: electronics / testgear

author: mio83
author_rank: Regular Contributor
timestamp: May 03, 2020, 08:07:37 am
content: Hello,I received yesterday a SDG1032X AWG and I am overall very happy about it.One thing though... I tried to verify the harmonics distortion with a spectrum analyzer:(see video at around 10:06https://youtu.be/QpZYlpBSQEc?t=606)I measured about -55dbc at 1Mhz, 5Mhz and 10Mhz.The datasheet claims a -60dbc Harmonic distortion.(see, e.g., page 7 athttps://www.batronix.com/files/Siglent/Funktionsgeneratoren/SDG1000X/SDG1000X_Datasheet_EN.pdf)Can somebody else replicate the measurements? Am I the only one with this "below specs" performance?Or perhaps I am doing something wrong in my measurement setup?thanks!EDIT: not included in the video linked above, but I get the primised -60dbc if I reduce the power from 0dbm to -10dbm.

author: Frex
author_rank: Regular Contributor
timestamp: May 03, 2020, 08:48:18 am
content: Hello,Maybe the THD come from spectrum analyzer itself.Try to use the internal attenuator of the analyzer to reduce the input level of mixer and look if THD is lowered.If THD value is not same, then it come from the analyzer.Regards.Frex

author: mio83
author_rank: Regular Contributor
timestamp: May 03, 2020, 09:36:26 am
content: Hi Frex,thanks a lot of your answer!The deafult attenuation setting of my SA (HP 8591E) is (as in the video) of 10db attenuation.Here are results with other attenuators (carrier 5Mhz at 0dbm) reading at 10Mhz:1) 10db attenuation: 10Mhz -55dbc, 15Mhz -68dbc2) 20db attenuation: 10Mhz -61dbc, 15Mhz -69dbc3) 30db attenuation: 10Mhz -63dbc, 15Mhz -69dbc4) 40db attenuation: 10Mhz -65dbc, 15Mhz -70dbc(I checked that varying the attenuation from 10db to 40db does not change the readings of the 5Mhz carrier which stays stable at 0dbm).So it looks like you are right and the true value is approx. -65dbc @10Mhz with a 0dmb carrier 5Mhz!Thanks I have learnt something!But I admit I don't quite understand what's going on.Why is the attenuation giving these different results on the harmonics but it is stable at the carrier?The attenuator should attenuate linearly all frequencies, right?Thanks!

author: 2N3055
author_rank: Super Contributor
timestamp: May 03, 2020, 10:21:04 am
content: Quote from: mio83 on May 03, 2020, 09:36:26 amHello!If you open datasheet for your spectrum analyser, you will see that it's own Second harmonic distortion, third order IMD and other spurious signals specifications are rated at -10, -20, -30 and even -40dBm signal levels. So, even if input can work with 0 dBm, it will start to distort there and create it's own distortion artefacts and spurs. So when measuring like this, you need to use attenuators (like you did) to bring signal into sweet spot of your SA, like Frex said. In datasheet you have levels defined per parameter and frequency range (it won't be the same for all frequencies)

author: mio83
author_rank: Regular Contributor
timestamp: May 03, 2020, 10:33:24 am
content: Thanks guys! Awesome informations!EDIT: Just to make 100% sure I now understand what is going on...I have checked the datasheet of my SA:https://www.testequipmenthq.com/datasheets/Keysight-8591E-Datasheet.pdfIt says:Second Harmonic Distortion, HP 8591E (5 MHz to 1.8 GHz): < –70 dBc for –45 dBm toneat input mixerThird-Order Intermodulation, HP 8591E (5 MHz to 1.8 GHz):< – 70 dBc for two –30 dBm tonesat input and > 50 kHz separationSo, it looks like generally my SA analyzer (HP 8591E), even with 40db attenuation (to bring the input to the sweet spot of -45dbm) cannot reliably measure Harmonic distorsions of less than -70dbc, because it does itself generate a ~-70dbc harmonics.Is this a correct interpretation?Thanks a lot again!

author: TurboTom
author_rank: Super Contributor
timestamp: May 03, 2020, 12:59:33 pm
content: @mio83: You may want to have a look atthat threadfor a comparison of a few AWGs (and also SGs) and some discussions regarding the effects of measurement setups.

author: mio83
author_rank: Regular Contributor
timestamp: May 03, 2020, 01:22:06 pm
content: @TurboTom,thanks I missed that post of yours! Very well made!Full of very useful informations both for using properly the SA and for comparingwith other SWG...Looks like the Siglent 1032X with its -65dbc harmonics at 0dbm@5Mhz is standing very well.

author: mio83
author_rank: Regular Contributor
timestamp: May 03, 2020, 08:26:16 pm
content: Update:just for the sake of completeness I added a new videos where I confirm that my Siglent SDG 1032X meets the specifications:Also, in my case the frequency counter works fine up to 250Mhz, while the specification is only 200Mhz.I am super happy with this unit so far!(disclaimer: this is my first AWG)

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: October 01, 2020, 08:29:23 am
content: @mio83Here's a couple of video clips which might ruin your day (or maybe only my day).The jpg is showing the AWGs' settings.The short 5 second clip shows the 10MHz sine wave output from the SDG1032X on CH2 with CH1 triggering the 'scope from CH2 of the FY6600 which is locked to my 10MHz GPSDO reference. CH3 shows the free running RFS and CH4 shows the FY6600's 10MHz Sinc pulse from its CH1 port.The SDG1032 is using its internal 50ppm smd XO (25MHz? as in the SDG1025 or is it a 10MHz XO chip?) which is the cause of the flicker noise like jitter (checking the reference output reveals the same jitter). The jitter disappears completely when using the external 10MHz GPSDO reference (but this reveals a +1.43mHz offset which equates to an error of one second per 45 years versus the one second error in1.8 million yearsof the FY6600).The SDG1032X is a brand new unit that arrived just three days ago. I've posted these movie clips into a couple of other SDG1032X related topic threads to get opinions/evidence as to whether this is just a rogue defect or a more general issue due to Siglent's use of cheap crappy 50ppm smd XO chips as per Feeltech's use of a 50ppm 50MHz one in their FY6600 and FY6800 models (the later FY6900 models use a 10MHz 20ppm smd XO chip).My hope is that someone will be curious enough to repeat my tests and risk having their day spoilt by the result. I'm curious to know whether, as in the case of my FY6600, this is an inescapable consequence of the use of a cheap smd XO chip or just my bad luck to get a faulty unit. I'd seen similar jitter before upgrading the crap XO chip used in the FY6600 to a 50MHz 0.1ppm TCXO when trying to match its output frequency to some DIP14 XOs in an exercise not unlike the game of "Chase Will o' the Whisp" trying to keep both waveform traces matched in frequency for more than 5 seconds at a time).After this first oscillator upgrade, this game seemed a little easier to play. Having subsequently upgraded to a CQE branded (as used in some Symmetricom kit) 10MHz OCXO with a 3N502 clock multiplier sat where the crappy XO chip used to reside to multiply this up to the 50MHz used by the FPGA, the only issue with matching the frequencies of DIP14 XOs is their temperature driven deviation which eventually settle down if sheltered from random breezes in my "Lab".This jitter effect is very disturbing since it makes a total mockery of Siglent's low jitter claims of 300ps (an RMS figure BTW rather than the less misleading Pk-Pk value of 900ns compared to the 200 to 250ns Pk-Pk jitter visible in 'scope traces of the FY6600's Sine and Sinc pulse wave forms).Quite frankly, as much as the SDG1032X (SDG1062X) is an improvement over not only the FY6600 but the SDG2000X series in the square wave performance department along with other desirable features absent from my much modified FY6600, I'm minded to return it as "Not fit for purpose" by way of this oscillator defect and put the cash back into my account.The longer 1 minute video clip is demonstrating yet another shortcoming of the SDG1032 over the FY6600 with regard to the stability of the Sinc pulse. In this case, I'm comparing a 6MHz pulse (maximum frequency limit) from the Siglent against a 12MHz pulse (not a maximum limit) from the Feeltech. I won't bother describing this clip (a picture is worth a thousand words and, in this case, this movie clip is worth some 1800 pictures).I'll post another video clip which may demonstrate the jitter issue a little more effectively - I've hit the 5000KB limit with these attachments, hence the next posting to show another 3.7MiB 20 seconds long clip. You'll have to download them and either remove the ,zip extension or else right click and select your favourite media player to open them in (EEVBlog won't allow you to attach video clip files, hence the .zip filename extension to bypass this file type filter).Regards, John

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: October 01, 2020, 08:35:28 am
content: As promised, here is that 20 seconds long video clip demonstrating the jitter on a 10MHz square wave output from my brand new SDG1032XJohn

author: mawyatt
author_rank: Super Contributor
timestamp: October 01, 2020, 07:07:57 pm
content: Did a quick test with the built-in AWG in the SDS2102X Plus, compared to the SDG2042X, both with 10MHz Square-wave at 2vpp into 50 ohms. Using the scope rise time mean and standard deviation as a reference. The scope AWG has a Mean rise time of 24.8ns and SD of 105ps, the 2042X AWG has a Mean rise time of 8.7ns and SD of 43ps.You can set 2042X to 9 digits, example 999.999999Hz, 999.999999KHz on the 2042X. You program the 2 channels slowly drift wrt each other by programming C1 as 1KHz and C2 as 999.999999Hz.BTW what format are the videos in, I can't view them on my Mac after renaming without the xx.zip extension?Best

author: DL2XY
author_rank: Regular Contributor
timestamp: October 01, 2020, 07:59:59 pm
content: @JohnThe jitter is not caused by the generator.You are triggering on a 10.000 000 Mhz sine (CH1) and comparing a 10.000 010square.So 10 times a second you got the same phase. Your scope seems to have a screen update rate of about 10/s, but this rate is not perfectly uniform.It´s simply a stroboscope effect.I have tried to reproduce it on SDG6052 and SDS2504. The update rate is at 31/s and interestingly without any jitter.Maybe some of your active measurement functions are introducing the jitter in update rate.

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: October 01, 2020, 11:06:44 pm
content: Quote from: mawyatt on October 01, 2020, 07:07:57 pmAs long as your second frequency source is completely independent from the AWG and is a reasonably stable and low jitter one, you only need to get the AWG and the second frequency reference matched to within +/- 0.5Hz in the range 1 to 10 MHz (the higher the frequency, the more obvious the jitter becomes but 10MHz is more than high enough in this case).The moment you have both sources locked to the same reference frequency, all bets are off. The prime example being looking only at the the AWG's output as a single 'scope trace, triggered by the same signal when looking for such low frequency jitter as this.Thank you for providing a hint at there being more digits available (11 in fact!) to set the frequency. I discovered that by entering the value, 99999999999 via the keypad (basically until it wouldn't accept any more digits) and pressing the uHz button, I could program a frequency of 99.9999999KHz which would be rounded up to 100.000000KHz as a consequence of the final two digits being overwritten in the display by the "KHz" characters.This is obviously a right royal pain of a software bug (a software writer's error due to an incomplete understanding of the GUI's requirement - aka, incompetence) requiring such a work around to enter the maximum number of digits that can be stuffed into the frequency variable. In all probability, it's likely only a matter of rewriting the GUI code to allow a full 14 digits' worth of resolution to be used to define the frequency input and thus match the humble FY6600's frequency resolution and fulfil the promise of the uHz frequency setting resolution implied in Siglent's datasheet specs.This might seem to be a 'nit picking' criticism on my part but, in an AWG blessed with an external 10MHz precision reference input socket, without this sort of resolution (uHz or, at the very least mHz) that improved stability and accuracy gained from the use of an external reference just goes completely to waste.Incidentally, the mysterious 1.43mHz offset I thought I'd discovered in the SDG1032 now appears to have vanished without trace. The only hypothesis for this that I can think of is that I must have been triggering the 'scope from the free running Rubidium Reference Standard when I originally made that observation (the RFS must have been adrift from my GPSDO reference by 1.43mHz at that time). It seems it might match the 1 second shift in 1.8 million years stability of the Feeltech. My apologies for making this error.The video format is H.264 (x264). If you have VLC media player installed, you should be able to open them in that without any problems.John

author: mawyatt
author_rank: Super Contributor
timestamp: October 01, 2020, 11:17:20 pm
content: Quote from: DL2XY on October 01, 2020, 07:59:59 pmCould you check the square wave rise time standard deviation on your SDG6052? Curious to how it compares to the SDG2042X mentioned above.Best,

author: mawyatt
author_rank: Super Contributor
timestamp: October 01, 2020, 11:49:18 pm
content: Quote from: Johnny B Good on October 01, 2020, 11:06:44 pmI second shift in 1.8 Million years is 1/(1.8M yrs *365 days/yr *24 hrs/day *60 minutes/hr *60 seconds/minute) or 1/56.7648 ^12 or 17.6166 ^-15. That's 18 parts per thousand trillionThanks for the video info, I don't have VLC installed on the Mac.Best

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: October 02, 2020, 12:26:58 am
content: Quote from: DL2XY on October 01, 2020, 07:59:59 pmWell, that strobing effect of the 'scope's screen refresh rate is an interesting hypothesis but I'm far from convinced that the observed effect has anything to do with such strobing effects Perhaps you can explain your testing methodology so we can discern where the disagreement between our test results has come from.When examining such low frequency jitter, we need to compare against another completely independent low jitter frequency reference that is stable enough to remain within one or two hertz for a matter of minutes at a time.I chose to trigger from the the Feeltech's 10MHz sine wave output since this was locked to the 10MHz lab reference with the RFS and the Sinc pulse output from the Feeltech thrown in for good measure displaying the 10MHz sine output from the Siglent on CH2 to display the low frequency jitter inherited from its internal 10MHz XO (switching to the external GPSDO reference completely eliminates this jitter).If I triggered from the Siglent's 10MHz output on CH2, the jitter effect would be transferred to the other three traces, leaving the Siglent's 10MHz, apparently jitter free. Call me a "Doubting Thomas" if you must, but I can't see how a screen refresh mechanism can account for any of this behaviour with even the cheapest and crappiest of DSOs.If you're just examining each signal in isolation (triggering the scope from the very signal you're examining), you simply won't be able to observe such low frequency jitter. You need a second low jitter signal to trigger from that can be matched to within +/- 1Hz of the suspect signal.If that is what you've done, that just means neither signal source is cursed by this effect and you can breathe a sigh of relief.John

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: October 02, 2020, 01:57:55 am
content: Quote from: mawyatt on October 01, 2020, 11:49:18 pmThat accuracy only relates to the error introduced by rounding errors in the DDS processing of a 250MHz clocked sample stream into a 10MHz sine wave output and assumes the 10MHz external reference used is drift free (i.e, that the GPS or its many successors should last that long.) IOW, the DDS errors in the Feeltech system won't be playing a significant part in the overall scheme of things any time soon.For that matter, it looks like the same can be said for the Siglent which has remained resolutely fixed to the same nanosecond marker for the past three or four hours.When I was trying to work out the frequency accuracy of the Feeltech's 10MHz sine wave output versus a newly installed injection locking module to allow a glitchless transfer between the on board OCXO and an external clock reference, it was to initially answer the question as to whether the 1uHz adjustments did anything or where simply just ornamental.In the end, I discovered I could have answered this question even before I'd upgraded the crappy smd XO. It was just a matter of setting both channels to a 10MHz sine wave and offsetting one by just 1uHz and waiting for the wave traces to drift by a nanosecond in just over 2 hours and 46 minutes, proving that the 1uHz tuning increment had been a "real feature" after all.Comparing both channels, fed from the same internal clock source, no matter how bad it is, neatly cancels all of the jitter between them. However, I had noticed a slight discrepancy between positive and negative 1uHz offsets which implied the existence of a small rounding error which led me to run a 24 hour test to discover, afaicr, a 1.5ns drift which led me to calculate that 1.8 million year figure (actually, 1.825 million years now that I've repeated the calculation).Since VLC is available for both MS Windows and Unix based OSes (Linux and Free BSD platforms) I imagine there'll be a version available for the Apple Mac platform. Still, I'm surprised that you don't already have a suitable media player installed or built into the OS. These Full HD movie clips are simply H.264 inside of Matroska container files if that's any help.John

author: mawyatt
author_rank: Super Contributor
timestamp: October 02, 2020, 02:09:51 am
content: Just ran a simple test with SDG 2042X AWG where C1 was 1MHz and C2 was different by 0.001Hz. I watched the phase slowly & smoothly change and timed the shift for a 40ns phase drift, it was 40 seconds or 1ns per second. At 1MHz it takes 1us (1000ns) to complete a cycle, so a shift of 40ns in 40 seconds is correct for a 0.001Hz difference (1000 seconds per cycle). Now I have more confidence in the AWG frequency settings.When I have the AWG from the SDS2102X Plus scope on C2 set to 1MHz and the SDG2042X AWG on C1 I need to adjust the frequency to about 999.999895KHz to get the phase drift to remain somewhat stable. I had calibrated the SDG2042X a few weeks ago and used the Reference of a SSA3021X Plus figuring it has the better accurate frequency oscillator. There is a type of very slow "random walk" of the phase drift between the two AWGs but no hint of any significant jitter, high or low frequency.Best,

author: DL2XY
author_rank: Regular Contributor
timestamp: October 02, 2020, 06:19:17 am
content: Quote from: mawyatt on October 01, 2020, 11:17:20 pmSDG6052 internal oscillatorCH1: 1MHz square standard.CH3: 1MHz square without output filter (modulation bug)

author: mawyatt
author_rank: Super Contributor
timestamp: October 02, 2020, 01:10:22 pm
content: Quote from: Johnny B Good on October 02, 2020, 01:57:55 amAt 10MHz you have a waveform period of 100ns, at 1uHz you have a period of 1000000 seconds. So the phase will shift for a full cycle at a rate of 100ns*1^6 or 0.1seconds. For a 1ns drift this will be 1ns*1^6 or 1ms. Please show how you arrived at 2 hrs and 46 minutes??QuoteI'm not following this, please show how you arrived at 1.825 Million years??Best,

author: mawyatt
author_rank: Super Contributor
timestamp: October 02, 2020, 01:16:57 pm
content: Quote from: DL2XY on October 02, 2020, 06:19:17 amThanks, that looks really good. Not sure what you mean about the output filter, does the Square Wave pass thru an output filter?Best,

author: TurboTom
author_rank: Super Contributor
timestamp: October 02, 2020, 02:54:14 pm
content: Every at least half-decent digital waveform generator has got a "reconstruction filter" which resembles a very steep low-pass (at least) several ten percents below nyquist frequency (half sampling frequency). Moreover, most modern AWGs don't produce square wave slopes by just outputting one sample low and the next one high or vice versa, even though this would provide the fastest slopes. But in this case, the slopes would always be synchronous with the sampling frequency, resulting in very bad phase jitter, depending on the quotient of sampling frequency and output frequency.Instead, the more recent AWGs purposely limit the rise times of the slopes and generate them by a number of samples, smoothed out by the reconstruction filter. By properly calculating the vlues of the "slope samples", the zero crossing time (or whatever voltage is half-way between max positive and max negative amplitude), can be tweaked to be within very few picoseconds where it's supposed to be as predefined by the selected frequency.Some generators change operational mode when for example sweeps, modulation or other other functions are activated, the SDG6000X apparently being among them. "standard" maximum rise time is 2ns which results in fairly clean slopes since the sample sequence (@ 2.4GSa/s) involves almost five samples, allowing the reconstruction filter to produce nice and smooth slopes. In case the additional function is activated, for whatever reason the slopes are directly generated or at least the number of samples considerably reduced, resulting in the reconstruction filter (remember , it's an R-L-C network of nineth order in case of the SDG6000X) to start to ring, causing the overshoot.So, yes, the square wave passes through a low pass filter which in some cases is beneficial and in others not so much so...

author: mawyatt
author_rank: Super Contributor
timestamp: October 02, 2020, 03:11:05 pm
content: I thought that the better AWG would have used a simpler reconstruction filter with a faster pulse response for the square wave, thus "bypassing" the complex reconstruction filter necessary for the other analogish waveforms where waveform purity is required.Makes sense that you can't produce a squarewave from the clock with finer resolution that the clock period (actually 1/2 period using both edges), thus must revert to interpolation for finer time resolution. Recall the "older method" was to use the full reconstruction filter and "zero cross" detect the post-filter waveform with an analog comparator to create the square wave, this worked well but had some additional jitter/noise introduced by the comparator.Thanks for the explanation.Best,

author: 2N3055
author_rank: Super Contributor
timestamp: October 02, 2020, 04:24:09 pm
content: Quote from: DL2XY on October 01, 2020, 07:59:59 pmI tried the same with my SDG6000X and got same result. It has no perceptible jitter. It smoothly travels over screen in accordance to frequency difference...Set to output 9.999994 MHz it measures like this:So I agree with stroboscopic effect conclusion..

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: October 02, 2020, 09:14:16 pm
content: Quote from: mawyatt on October 02, 2020, 01:10:22 pmIt can be a little hard to wrap your head around this calculation but once you have it fixed in your head that with a difference frequency of zero when both signals are equal and remain locked in phase as is the case with a DDS AWG, you're looking at a DC output (0Hz) until you offset one of those signals by 1uHz where, as you've already calculated, it will require a million seconds to go through one full cycle of phase drift over (in this case) the 100ns period of a 10MHz test frequency.It will take 1% of a million seconds to phase shift by 1ns which is 10,000 seconds or 166 minutes and 40 seconds (2 hours, 46 minutes and 40 seconds to be exact). An easier example for starters is to get your head around the fact that a 1000 seconds (16 minutes and 40 seconds on a stopwatch) per full cycle of drift against a 10MHz reference frequency represents a 1mHz offset which, btw, in this case equates to an error of 100ppt (1.0E-10). In this case, such a 1mHz offset represents a drift rate of 1ns every 10 seconds (another way to see that a drift rate of 1ns per 10000 seconds corresponds to a 1uHz offset)Once you have determined a 1.5ns drift per day figure by running a 24 hour test to measure this drift between the external GPS derived 10MHz reference and a precisely set 10MHz signal on one of the AWG's channels (just about doable in the presence of some 300ps Pk-Pk of jitter noise that you are no longer shielded from by the use of the other equally jittering channel as your reference to cancel out the jitter noise in a form of common mode rejection normally associated with unshielded balanced transmission lines), it then just boils down to a simple calculation to work out how long it will take to accumulate a whole second's worth of drift at a rate of 1.5ns per day.You can use a cheap 8 digit office calculator for this calculation if you break it down into digestible (for that cheap calculator) chunks. I started by calculating how many days it would take to accumulate an error of 1000ns (1us) which is simply 1000 divided by 1.5 giving me a manageable total of 666.66666 days. Dividing that result by 365.25 to express it in years is what gave me the 1.8252338 figure that I'd truncated to just 1.825 years permicrosecond'sworth of error. Once you have that figure, you have no further use of a calculator since it simply requires a million-fold increase to equate the 1us error to a one second error. Ergo, that 1.825 years becomes 1.825millionyears!Phew! Just reliving the calculations above had me going through bouts of confusion until I remembered that the question over how I'd arrived at a 2 hour 46 minutes and 40 seconds figure to equate a 1ns drift with a 1uHz offset and the one regarding my 1.825 million years estimate for one second's worth of error to accumulate were two entirely separate problems.The first being over how I'd formulated the calculations required and the second being the application of a test measurement taken from a 24 hour experiment to figure out the accuracy in the now popular format of so many millions of years required to accumulate a one second error. Hopefully, that's answered your questions.John

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: October 02, 2020, 10:30:31 pm
content: Quote from: 2N3055 on October 02, 2020, 04:24:09 pmTsh, tsk!You should know better than to jump to such a conclusion when the more likely (and desirable from your point of view) conclusion will be due to a total absence of this defect in either of your frequency generators which reminds me to check the one in my SDS2104/2504... I'm quite impressed! It's only 1.04Hz down on frequency!It drifts slowly up and down within just a tiny fraction of a cycle with no sign of the flicker noise like jitter of a Siglent product, namely my SDG1032X, whose prime purpose is to provide as low a phase noise as practicable (you'd think at least the equal of an FY6600 which has had an smd xo -ectomy in favour of, initially, a cheap 0.1ppm 50MHz TCXO upgrade).I guess it's just reflecting the remarkably accurate (for a DSO, that is!) reference oscillator which allows all 7 digits in its hardware frequency counter display to be used with some confidence that only an eighth digit might reveal its feet of clay.Anyhow, lets use that as the reference and reconnect the SDG1032... and, as expected, the SDG1032 is still jittering.My conclusion? You shouldn't need to ask but if you'd like to know my opinion of your tests, I'd have to say that neither of your oscillators is suffering from this SDG1032 defect - there's no need to assume any bogus hypothesising about DSO screen refresh strobing effects onone singularwave trace out of four, the other three of which all show no such jitter symptoms whatsoever.TBH, I'm rather surprised and just a little bit disappointed that you even lent any credence to this unproven "Stroboscopic effect" hypothesis.John

author: mawyatt
author_rank: Super Contributor
timestamp: October 02, 2020, 11:31:37 pm
content: Ok John, I think I understand where you are coming from regarding these time/phase/shift calculations. Need to see if I can, as you say "get my head" around this.Anyway, I don't see any of these "jitter" type effects on the SDS2102X Plus internal AWG, nor the SDG2042X AWG.Best,

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: October 03, 2020, 01:10:43 am
content: Quote from: mawyatt on October 02, 2020, 11:31:37 pmThanks for that. Assuming you were displaying both signals together, matched as closely in frequency to each other to reduce, if not eliminate, any drift and you weren't able to observe the jumpiness (jitter at low frequency flicker noise rate) that I'm still currently observing with my own SDG1032X, I think we can safely conclude that neither of your signal sources suffer from this defect.However, I've not heard from anyone who has run this test with an actual SDG1032 or SDG1062, which still leaves me in the dark as to whether this is just an unfortunate fault that happens to afflict the particular example that was shipped out to me or whether it's something peculiar to this particular model which, btw, was supplied with the latest software (Firmware, surely?) update (V1.01.01.33R1B6) with hardware version 02-01-00-24-00.I'd still like to hear from any SDG1032/SDG1062 owners who have tried this test which requires the use of another independent frequency generator to reveal this particularly nasty form of jitter that originates from the internal clock oscillator. Locking it to an external 10MHz reference (GPSDO or Rubidium oscillator or even just a well calibrated double ovened XO) completely eliminates this clock jitter. If you're in the habit of keeping it locked to an external 10MHz frequency standard, you'll have to switch it back to its internal clock in order to perform this particular test.John

author: mawyatt
author_rank: Super Contributor
timestamp: October 03, 2020, 02:40:26 am
content: Since this low frequency jitter is eliminated when locked to an external signal, I would suspect the SDG1032X crystal oscillator as the jitter source and likely just a bad (noisy) component rather than a bad design.Best,

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: October 03, 2020, 04:04:07 am
content: Quote from: mawyatt on October 03, 2020, 02:40:26 amYou're probably right with your suspicion. I believe this is a consequence of using a dirt cheap commodity smd XO chip by Siglent instead of a better quality TCXO more in keeping with a higher priced upmarket offering than those cheap Chinese toy AWGs offered by Feeltech and friends.In retrospect, the similar jitteryness I'd seen when testing against a bunch of salvaged DIP14 XOs before I'd upgraded the crappy 50ppm 50MHz smd XO chip used in the FY6600 which I'd assumed had originated in the DIP14 XOs, now looks to have been an issue with the FY6600's smd XO chip, hence my bemusement at Siglent for stooping so low as to use such a cheap junk smd XO in such a pricey product.Perhaps they used a cheap smd XO simply because most would be free of this issue and "Good Enough" in view of the option to use an external clock reference and any that weren't. were likely to go unnoticed for quite some time (a cursory examination with a DSO would simply fail to reveal this particularly nasty form of clock jitter).Anyway, it looks like I'll have to return this to Telonic Instruments Ltd as "Unfit for purpose" for a refund even though it looks like I'll have to stump up for the return carriage costs. I now have less than a week in which to take this action before I'm stuck with a function generator that doesn't compare against my much modded FY6600-60M quite as well as I'd hoped it would.TBH, I'm very disappointed with this particular Siglent product. Their DSOs are a much more refined offering. The SDS1202X-E I'd purchased almost two years ago for just a fiver more than the SDG1032X's asking price at that time was a much better value proposition that still leaves me impressed by its performance and quality.I had considered negotiating an exchange for the SDG2042X on a deliver and collect basis to save me the return shipping costs but since both share the same UI which, imo, needs some serious debugging to put right, will leave me with an even greater sense of dissatisfaction than I'm feeling right now, I think the best option is simply return it for a full refund and accept the cost of return postage. At least that way, I am free to reconsider all of my options which, despite my reservations, could even include an FY6900 from Feeltech.I've just started a search to confirm the existence of a 100MHz model which has just been interrupted by a PM from a fellow EEVBlog member asking me whether I'd still recommend any of the Feeltech AWGs. In view of my recent experience with what was supposed to be an upmarket AWG, I think I can safely recommend the FY6900 as a product that won't disappoint at its price point (it just requires some remedial work to remove Feeltech's gross act of grounding vandalism plus a small fan to make it usable and acceptably reliable).John

author: 2N3055
author_rank: Super Contributor
timestamp: October 03, 2020, 08:17:17 am
content: Quote from: Johnny B Good on October 02, 2020, 10:30:31 pmOK I'll byte...Let's run with your hypothesis.So what is your estimate for this jitter? P-P and RMS ?If you trigger on signal coming out of SDG1032X, delay from trigger 1ms, enable persistence, do you see smearing?The way it looks on your screen, you should.As for "stroboscopic" effect it might be unfortunate name. What you are doing is actually stroboscopy in a way, looking at the difference between signals.Problem is that many digital scopes don't acquire data in regular intervals. They are actually capturing bursts, than pause and display and on. There is lot of jitter in that process.It is not like with analog scopes where you have retrigger time and that's it, which guarantees uniform time between sweeps.It is quite easy to get exactly the effect you see because of that. A jitter in display. And it is related with frequency difference, so sometimes you see it or don't....And yes what I wrote is a hypothesis, not a proven fact. I don't have SDG1032X here to try, so I cannot claim anything.You should not hang on to every word. You seem to be very eloquent in expressing yourself, and a stickler for every word said.Don't do that. Many of us are not born English speakers, and nuances of languages are not something we do.. I know you just want to be very accurate, but it doesn't work that way...Best regards,Siniša

author: mawyatt
author_rank: Super Contributor
timestamp: October 03, 2020, 02:00:20 pm
content: Quote from: Johnny B Good on October 03, 2020, 04:04:07 amFrom what I've seen from the Siglent gear I have, and my unfortunate (long story) detailed venture into the innards of the SDS2102X Plus (also quick look into the SSA 3021X Plus), and the many teardowns of Siglent gear by Dave, I don't think they use cheap components, including these XO devices. The fact that they use the same components for many of these devices that can be software "upgraded" to higher performance levels basically means that the high performance components are utilized in the baseline products, the hardware is capable of the upper performance levels without change, so uses the higher performance components.I don't think jitter is a parameter that is verified and tested when the AWG was built, and thus likely to "slip" thru QA. I'd wager that the XO is your specific AWG is defective and noisy, which is easily verified if you got a replacement AWG and compared side by side before returning the defective one. If that was true then I would think you shouldn't have to pay for return postage, since you've verified you were originally shipped a defective AWG, worth a try with TelonicI personally have no serious complaints with the SDG2042X AWG, either performance or UI. I've even considered building a boost amplifier for it to get to 200Vpp levels and another for high current (+-3A).Good luck,Best,

author: 2N3055
author_rank: Super Contributor
timestamp: October 03, 2020, 03:40:25 pm
content: In attachment a short video that shows display jitter on a scope from a stable signal (SDG6000X) triggered from 10 MHz out from my Sighound SA (not very accurate, but jitter free, stable source).Scope is Micsig STO1104C.This same combination of sources creates perfectly smooth display on Keysight 3104T.... Also, changing settings of generator, creates nice display on Micsig too...That is why I said that itcan bescope capture/display interaction with signal frequencies artefacts..P.S. File is MP4, remove .ZIP extension from the end.

author: mawyatt
author_rank: Super Contributor
timestamp: October 03, 2020, 05:06:22 pm
content: That's a very interesting video!! Almost looks like the scope is having an issue triggering rather than jitter on the signal. You could reverse the roll of the signal and trigger source to see what happens.My thinking is if the edge jitter is due to the internal AWG clock, then having the trigger frequency and signal frequency equal shouldn't matter, as long as the are integer multiples, and neither which is the trigger and which is the input. The AWG signal used as a trigger at say 1MHz should show jitter relative to a stable reference like the 10MHz source used as an input, and vice versa. I just tried this with one AWG (scope) at 10MHz and the other at 1MHz which was adjusted (few mHz) to get the waveforms to remain somewhat stationary (slow random walk). Triggering off either makes no difference, and changing the frequency around makes no difference, and changing the waveform from Sine to Squarewave makes no difference. The scope waveforms show no hint of any kind of jitter.I wondered if the AWG in the scope might be different since the scope and AWG might share the same XO which may have some type of synch effect. So I used the best source I have available, the 10MHz Ref Output from my SSA3021X Plus. The results were the same, so hint of any jitter.Best,

author: 2N3055
author_rank: Super Contributor
timestamp: October 03, 2020, 05:56:39 pm
content: Mawyat,I'm not saying Johnny is wrong, or that his SDG1000X doesn't have jitter.But what I'm saying, is that if does have such a horrible jitter, it would be plainly visible just connecting output to a scope, and put some trigger delay. It should be plainly visible, and some persistence would show P-P jitter. No need to trigger from some other source and do phase drift comparison ...And as I shown in the video from Micsig, you can create all kind of funny things on scope display, just by hitting sweet spot with scope own triggering frequency/pattern and interaction with signals. I couldn't create similar thing with Keysight 3000T, because it's trigger pattern is more similar to analog scope and faster....All the best,Siniša

author: mawyatt
author_rank: Super Contributor
timestamp: October 03, 2020, 07:58:43 pm
content: I wasn't inferring that you or Johnny is wrong or right, just trying some simple experiments with what I have readily available and reporting what I've seen.Agree, the simplest test is just use the scope delay and persistence to see if you have any significant cycle to cycle, or over multiple cycle jitter from the AWG. This won't show low frequency jitter tho, unless you can create a very long delay.Best,

author: 2N3055
author_rank: Super Contributor
timestamp: October 03, 2020, 08:44:41 pm
content: Quote from: mawyatt on October 03, 2020, 07:58:43 pmHi,If you enable infinite persistence and wait long enough it will show all jitter components (unless jitter is some kind of deterministic modulation and you sample synchronous to modulation). Since your trigger is not related to jitter, it will, after some time, sample most of possible periods combination and it will show the smearing. You can delay for one signal period only, it wouldn't matter.Delaying helps to see it, if you have jitter that accumulates over time in one direction, so you can see added contraction of time intervals of signal period over, say, 100 periods. You would see that with deterministic, periodic jitter. Basically FM modulation. With stochastic jitter, if you delay enough, shifts left and right will average over time, so if you delay too much, you might see less, not more...What I'm saying, is that when you see something that looks odd, you need to verify it in several ways, to confirm it's really there or you might be measuring artefact of measurement itself. Good way to do it is to measure with several different instruments and methods. When they start to agree, you're on a good path...Regards,

author: TurboTom
author_rank: Super Contributor
timestamp: October 03, 2020, 09:21:25 pm
content: Get yourself an MDA (HP 53310A) and be happy!There's probably no better tool (toy??) for a (soon-to-be) time-nut. It won't take long until you need to own a GPSDO, Rb or even Cs time base...I can tell from my own experience. There's no way of getting out of this -- join TEA

author: mawyatt
author_rank: Super Contributor
timestamp: October 03, 2020, 10:54:03 pm
content: Quote from: 2N3055 on October 03, 2020, 08:44:41 pmI took a few measurements of the SDG2042X AWG at 10MHz with infinite persistence & a trigger delay of 1us (10 cycles, PNG76), 10us (100 cycles, PNG75) and 1ms (10,000 cycles, PNG74). All 3 look the same, no hint of any jitterAnother way to look for jitter is with a SA in the way of excessive Phase Noise, did so with 100Hz span and 1Hz resolution BW (PNG4). Then looked at the SDG2042X Reference Output (PNG5), then the SSA3021X Plus Reference Output (PNG6) for comparisons.Best

author: 2N3055
author_rank: Super Contributor
timestamp: October 03, 2020, 11:18:56 pm
content: Quote from: TurboTom on October 03, 2020, 09:21:25 pmI try to stay away as much as I can... Don't tempt me...

author: mawyatt
author_rank: Super Contributor
timestamp: October 03, 2020, 11:32:11 pm
content: Quote from: TurboTom on October 03, 2020, 09:21:25 pmDon't have that tool, but the SSA3021X Plus when fully "upgraded" has a Modulation Analyzer which has FM capabilityI've never used this but decided to give it a go using the SDG2042X AWG output at 10MHz, then the AWG 10MHz reference, then the SSA3021X Plus 10MHz reference. The AWG outputs showed a FM deviation of 0.06Hz with SNR of 14.5dB, while the AWG reference showed a deviation of 0.06Hz with SNR of 18dB and the SSA was 0.03Hz with SNR of 66dB. This agrees with the SA plots regarding the lower Phase Noise of the SSA reference which is to be expected, it's also measuring itself.Best,

author: TurboTom
author_rank: Super Contributor
timestamp: October 04, 2020, 12:01:28 am
content: This appears to be quite a nice measurement function of the SSA3000X-Plus. But measuring of the device's own reference won't tell you much about the quality of the reference itself (I assume that you've "only" used one SSA for the test...) but rather about the characteristics of the PLL circuitry inside the SSA that generates all the local frequencies required to analyze the input signal.You are right at the verge of "time nuttery", always in need of that slightly better reference to be able to characterize all the others...I know what I'm talking aboutCheers,Thomas

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: October 04, 2020, 12:18:25 am
content: Quote from: 2N3055 on October 03, 2020, 08:17:17 amOk, it'smyturn to "bite"The only way I can delay from the trigger point by 1ms is to use the zoom function and even this is insufficient to demonstrate this low frequency jitter. However, after a lot of knob twiddling, I managed to configure a timebase setting of 50ms/div (500ms per unzoomed scan) and build up a delay of 50ms from which point I could zoom down to a 10ns/div allowing me to examine a single cycle of the 10MHz square wave from the SDG1032 50ms after the trigger point. I used a 10 seconds persistence to reveal a level of jitter peaking at around 15 to 20ns pk-pk. This method of looking for such jitter is what I'd categorise as "Doing it the hard way."Obviously with a refresh rate of just 4 per second, I won't be seeing the full picture revealed by triggering from another 10MHz signal syntonised to the SDG1032's signal at the normal unzoomed 10ns/div timebase setting (aka, "Doing it the easy way").I've attached a couple of photos showing the above results. I wanted to use a long exposure time to help enhance the 10 seconds persistence effect (the traces are rather thin and dim) and it took me a while to figure out how to adjust ISO, aperture and shutter speed selections in the manual mode but, after turning off extraneous light sources (my desktop PC monitor for one), I landed up with a 4 second and an 8 second exposure shot (tripod mounted and two second shutter delay to remove camera shake from pressing the shutter button).The 8 second exposure is the "money shot" but leaves the timebase settings over exposed, hence the 4 second exposure (which in hindsight, should have been a 1 or 2 second exposure to best reveal the settings).Of course, when you're using such a low frequency timebase in fine detail like this (a 100ns segment some 50ms after the trigger event) the question about jitter in the 'scope's timebase does enter one's mind but since I already had two independent low jitter 10MHz reference sources (the RFS and the 10MHz Sine wave phase locked to a 10MHz GPSDO) connected to the 'scope, I was able to trigger from either of those in turn and check a 100ns segment 50ms after the trigger event to examine what jitter, if any, there was on these signals by way of comparison.I'm happy to report that whilst there was some tiny hint of jitter, it did seem to all originate with the timebase rather than from the signals themselves. IOW, the jitter seen on the SDG1032's 10MHz sine wave using this technique was essentially all AWG with virtually no contribution from the SDS2504X Plus timebase.TBH, I think I'm seeing the evil jitter effect exhibited by that class of XO known as a DDS XO where singular frequency quartz blanks, produced by the million to cut costs, drives a DDS synthesiser, laser programmed to select the output frequency requested by the final customer.Not every application requires a low jitter clock source, especially those applications in cheap digital toys where such jitter is absolutely demanded to provide a built in "spread spectrum" EMC mitigation function to reduce interference on spot frequencies below the thresholds used in EMC compliance labs.Curious about just what sort of jitter one might expect from a 'modern day' dds based smd xo, I did a bit of research and landed up looking at a Silicon Labs datasheet here:https://www.silabs.com/documents/public/data-sheets/si510-11.pdfAssuming Siglent would not be regarding the one dollar fifty cent cost per unit in thousand off quantities as excessive and be looking towards an even cheaper source (but, who knows what nasty cost cutting tricks their friggin' bean counters might be getting up to?), I could simply be looking at the effect of a faulty 'modern smd XO' rather than a systemic issue with the SDG1000X model range.BTW, I don't disagree with the point you made regarding the fact that oscilloscopes are simply another form of stroboscopy. What I was disagreeing with was the hypothesis that this effect, common to all four channels, should pick out just the one that happened to be displaying the AWG's output, regardless of which channel was used, leaving the other three to be displayed unmolested by any such a strobing effect.I know some DSOs (possibly even some specialised CROs) have the feature of displaying channels with independently triggered time bases but this model, afaiaa, offers no such feature (and IknowI certainly haven't accidentally selected such a timebase/triggering mode).Anyhow, since I'm running out of time to effect a return with full refund on the basis of it not being fit for purpose, that's all rather academic now. There's quite clearly an LF flicker frequency like jitter effect going on which is afflicting the generator's output waveforms since it can be detected using both the hard and the easy ways to lift this particular rock to reveal this otherwise hidden gremlin.It's time I composed an email of complaint, with video attachment (or a link to one of these EEVBlog postings into SDG1000X related topic threads (two others besides this one) if their email client rejects such or any attachments). Or, I might just start a new topic thread dedicated to this specific issue rather than direct them to here or any of the other two topic threads if their email client software does reject attachments.John

author: mawyatt
author_rank: Super Contributor
timestamp: October 04, 2020, 12:39:29 am
content: Quote from: TurboTom on October 04, 2020, 12:01:28 amI've already fallen to the Volt-Nut, having built some References based on the LM399 & LTZ1000 for use with my HP34401A, Agilent 34401A and recent Keysight 34465A. So suspect you are correct about the Time-Nut nowBest,

author: mawyatt
author_rank: Super Contributor
timestamp: October 04, 2020, 01:25:51 am
content: Quote from: Johnny B Good on October 04, 2020, 12:18:25 amAgree, that is a horrible result. Just did the same "Zoom" test at 50ms zoomed in to 10ns/div with every 10MHz source I have, and all are showing no signs of jitter, even the DSO AWG. Even used the waveform Combine Function in the SDG2042X to sum the 2Vpp 10MHz signal with a 50mv noise signal to try and duplicate your result. Surely this is a defective XO in your AWG.Best,

author: rf-loop
author_rank: Super Contributor
timestamp: October 04, 2020, 06:28:53 am
content: Quote from: Johnny B Good on October 04, 2020, 12:18:25 amFirst I do not understand why you do not take just screen dump png from scope. is it somehow difficult? Yes I have read your nonsense explain about reason. Screen dump show much more clearly all settings and it do not loose anything over example 10s persistence period. If not enough you can use longer persistence.Nut it is not now important itself at all. Important is jitter you analyzed somehow. If I do this test I use different methods and I am not now familiar with this scope you have used here. I do not exactly know example its external reference lock performance and I do not know your external reference signal quality at all. All have error, more or less. What you see is Sum of all errors.I am now very far from my homeland and from my workshop and I do not have my previous some test data here available at all.What I remember is that SDG1000X clock jitter is more than SDG2000X. Also there was some weird things if use external reference for SDG1000X. I remember one test when external reference of course null average freq error but rise phase noise, specially very near carrier phase noise and this time my ext ref was for this purpose in practice better than enough good HP high grade DOCXO.But now in your image, if I read it right. There is Trigger positio and then zoomed position is from around 45ms after trigger.There can see roughly 11ns peak jitter. (22 peak to peak)There can not well see, due to lack of data, its distribution. But most high (time) peaks are alone and least it can say distribution is not linear but also looks like not pure gaussian or just amount of data is not enough. Perhaps it can run example half hour or more with peersistence (because one shot takes more than 100ms so 10 sec you get least well under 100 acquisitions and this is really small amount. If you use other Sig model I perhaps know more exactly how many...)So, in this small tiny displayed test setup you get total Peak jitter roughly 0.23 ppm including sum of all individual errors in whole setup. Including also of course oscilloscope trigger jitter. It is also fun, perhaps lack of enough experience for doing labs, you use relatively low signal amplitude - or in this case better say wrong V/Div setting in scope. Is it designed error or just random "who cares" error. What is reason you have selected trigger position far from middle position in rising edge. (in this case nearly nonsense but leat for me it tell something even when not explained why. With some frequencies it may affect more than with others but as we know final result is sum of ALL errors. Still I believe these some erros are not important in "big image".)Also one side note. I have never understood why time position (delay) is displayed from center of screen. This is really stupid. But yes, these design engineers do not have 50 years of experience about using oscilloscopes. Right place where is time zero is trigger position where ever user have set it to fixed display position or fixed time position.. This is zero reference. Period.Back to this jitter.Oscilloscope nominal trigger jitter we can just ignore, it is under 10ps (RMS!) if signal 6 div and risetime 2ns.But if oscilloscope run with its own reference clock its jitter need take to count.Even if it run with external clock its jitter need take to count. Including scope freq locking quality to this ext ref.If we thing 10MHz. Just for imagine something... Think if frequency "jitter" 0.2ppm Peak. So this 10MHz is sometimes up to 2Hz too high and sometimes 2Hz too low and mostly less off.0.23ppm Peak in your image (If I look it right where is trigger and where is your zoomed window position. These photograps are so unclear / this is why mostly screen dump png is far better and also very small data size and lossless.)Here is one old image from tests I have done. There is lot of images but as told this time I do not have more available.For understand better this image it need more explanations due to fact in this image there is two different SA settings in one image. I do not explain here butblue trace can see part of SDG1000X near carrier "jitter".As can see, even with 10Hz RBW it can clearly see from around -35dBc that used tcxo and/or PLL is not at all best possible.(we know SSA RBW shape factor is bit under 1:5. Of course with 1Hz RBW, if used, it can see starting from much higher level from carrier but because 10Hz is enough for detect this and 1Hz RBW is really LOT of more slow and testing time is limited....) If I remember right it can clearly see full level using 1Hz RBW and long time peak hold. After then it can see it is more wide than 1Hz RBW shape is even there in carrier peak level. It have clock jitter and it is not much better than its specs. And do not directly believe it is better with External clock until enough accurate and reliable tests. Average freq is totally other question. Of courseitis as Ext ref is.Because topic name is about harmonics here some images what are not whole OT.Harmonics + non harmonics, 3, 3.7, 7, 9 and 10 MHz (note freq scale)Harmonics + non harmonics, 10, 14.2, 21.2, 28, 30 MHz (note freq scale)Harmonics + non harmonics, 30, 31.5, 40.8, 52 and 60 MHz (note freq scale)In all images SDH1062X run with its own reference and SA run with its own reference what is LOT of better than SDG reference..In First image compared signal is from HP High Grade OCXO what have very low jitter and pn. Enormous amount better short time than my any crap Rb or some short time crap poor trimble GPS. Only one I have is better than this, it is HP Symmetricom GPS with "famous" HP DOCXO what I have made even better than out from factory (better optimized Owen temperature control fine matched for this individual xtal used there) But this was cold in this time and not want wait one month... for stabilize.About specs. If look SDG2000X its reference initial is more than 10 times better accuracy.Then if look example some jitter specs. SDG2000X square (cycle to cycle) just 150ps RMSBut if look 1000X there is cycle to cycle 300ps + 0.05ppm of period RMS.Now there is used 10MHz but delay is long. It is nearly same if use square with long period. So this part is here roughly in 2ns class RMS! (0.05ppm from 45000000ns is 2.25ns. and now, this is RMS, not Peak!So my conclusion is, until know more: roughly this jitter you have detected now is more like in normal and somehow in specified class than individual failure.Least if I see this kind of specifications I do not wonder if I find these results you have found.Who ever have SDG2000X, it is different animal.Attached your image with text what is based for my opinion. If I have mistake when I read your image please correct me.

author: mawyatt
author_rank: Super Contributor
timestamp: October 04, 2020, 02:58:08 pm
content: Interesting analysis rf-loop.I did not know just how good the SSA3021X Plus 10MHz reference oscillator was, but assumed it was the best I had available. So thanks for confirming this, again another pleasant surprise from SiglentThe AWG from the SDS2102X Plus DSO isn't bad, and certainly not as bad as what Johnny has shown. Makes me wonder if the SDG1032X and the AWG from the SDS2102X Plus are similar in design/components and maybe even XO. From what little experience I've had with Siglent gear, I haven't seen the kind of "specmanship" we see from other lower cost suppliers, if anything they seem to do very well with performance things that don't show up in the core specs, and why I suspect a defective XO.I didn't consider the SDS2102X Plus AWG for precision use (why I got the SDG2042X), and I would not consider the SDG1032X AWG for precision use either, but would not expect this level "jitter" from either AWG and another reason I suspect that he has a defective XO in his AWG.If someone that has this SDG1032X AWG and could do a simple test we would all know and I could quit "speculating" about the defective XOBest,

author: DL2XY
author_rank: Regular Contributor
timestamp: October 04, 2020, 04:29:52 pm
content: Just for reference a jitter test taken somehow to extreme.1Hz square wave taken 1s after trigger (next rising edge) with 1ns/div resolution, acumultated over 5 minutes.Used Equipment: SDG6052X, SDS2054X+ and EFRATOM MFS Rubidium normal (R&S).SDG6052 drift and 1s jitter with internal XO:SDG6052 drift and 1s jitter with external 10Mhz (MFS):10 MHz MFS drift and 1s jitter directly measured. (MFS [ Specified attachment is not available ] and SDS2054):The difference between internal and external clock is not really that big, about a half of total jitter and drift seems to belong to scope timebase.

author: mawyatt
author_rank: Super Contributor
timestamp: October 04, 2020, 05:09:45 pm
content: I think these delayed or "zoom" type jitter measurements are asking a lot from the scope trigger and sweep performance. Triggering and waiting 1ms, 50ms even 1s and looking for ns randomness seems difficult for any DSO much less a modest priced DSO. Actually impressed they can do this well.If you think about what's happening, the trigger circuit is trying to trigger on exactly the same sampled voltage, but noise, quantization and other things place some randomness on this, then the delay circuit must wait the prescribed delay period which is DSO clock dependent and subject to some jitter, then the sweep starts for the display which is also subject to some uncertainty. Sure all these are created from the sampled data from the ADC, but still subjected to the ADC clock jitter which is based upon the DSO clock.I see very little evidence of jitter from any source; SDG2042X, SDS2102X Plus DSO AWG or SSA3021X 10MHz reference regardless of the delay, so the DSO must not have much jitter on it's clock either.I don't see any difference between using the delay "Holdoff" trigger or "Zoom" feature.Here's using the Zoom with delay of 1s on SDG2042X AWGThe SSA3021X Plus 10MHZ reference with 1s delayThe SDS2102X Plus AWG with 1s delayBest,

author: TurboTom
author_rank: Super Contributor
timestamp: October 04, 2020, 06:18:04 pm
content: A modern DSO is very well suited for that job since all the processing stages after the sampling engine are completely deterministic. Everything relates to the quality of the sampling timebase and possible jitter in the ADC's sampling section (which should be neglible in case of the ADC08D1000, TI specifies a sampling aperture delay jitter of 0.8ps rms, its chinese copy MXT2001 that's probably used in the SDS2000X Plus shouldn't perform much worse).So either a high quality reference or possibly an external ref input, combined with a properly designed PLL (Rigol delivered a major failure here almost a decade ago...) is mandatory for these kinds of measurements. Otherwise, when measuring half-way decent frequency sources, all that one will see on the screen of his scope is the scope's own timebase jitter.

author: mawyatt
author_rank: Super Contributor
timestamp: October 04, 2020, 06:58:16 pm
content: Since everything is based upon the ADC captured data and time reference to the ADC clock, any randomness in the ADC clock or input signal will appear when compared to a uncorrelated signal like we are doing. At least we "assume" these are completely uncorrelated and hopefully no subtle non-linear effects like injection locking are taking place.Anyway, whatever reference and up-conversion PLL the SDS2102X Plus is using is certainly working well as shown. Resolving 1ns after 1,000,000,000ns is impressive!!Wish there was a means to adjust the DSO internal reference frequency like the SDG2042X has, or allow an external reference input, but that's a very minor point.Best,

author: DL2XY
author_rank: Regular Contributor
timestamp: October 04, 2020, 07:28:36 pm
content: Quote from: mawyatt on October 04, 2020, 05:09:45 pmSorry for disagreement, but holdoff delay is totaly different to timebase delay.Holdoff: delay>arm>trigger>sample ...Timebase delay: arm>trigger>delay>sample ...So with holdoff you will get the samples immediately after trigger, but we want the samples at defined time behind trigger.The use of zoom is just a workaround to get the delay as high as one second at 1ns timebase.

author: mawyatt
author_rank: Super Contributor
timestamp: October 04, 2020, 08:10:39 pm
content: Quote from: DL2XY on October 04, 2020, 07:28:36 pmDon't think we have a disagreement, as mentioned both show about the same result.Zoom to 5ns/div from 1s sweepHoldoff for 1s of 5ns/div sweepBest,

author: TurboTom
author_rank: Super Contributor
timestamp: October 04, 2020, 08:52:59 pm
content: ...just to show what the "jitter cross correlation" of two really good oscillators looks like on a moderately fast scope, the MSO4000. In this screenshot, the internal HP 10811 OCXO of a 53310A is providing the external reference to the scope while my Efratom LPRO101-based Rb standard is connected to channel 1 of the scope. I arranged it that way because the square output of the Rb standard is really fast and provides good steep slopes for superb observability of the trigger crossing width. Prior to taking the measurement, the oscillators had been running for only about 20 minutes, so they didn't even reach thermal equilibrium.As arranged by the previous contributors, the display window is delayed by one second vs. the trigger point and the scope is running with infinite persitance for approx. five minutes, recording a trace every second. Unforunately, the scope hasn't got those nice histogram functions or colour grading features but the cursor measurement shows a 260ps peak-to-peak jitter width.

author: mawyatt
author_rank: Super Contributor
timestamp: October 04, 2020, 09:37:30 pm
content: That looks very good indeed for the Rb standard and the HP external referenceHow does this compare with the scope using it's own internal reference?Best,

author: TurboTom
author_rank: Super Contributor
timestamp: October 04, 2020, 11:04:36 pm
content: Quote from: mawyatt on October 04, 2020, 09:37:30 pmThis is something I specifically left out... When the engineers at Rigol designed that scope, they must have had something in mind like this: "If we provide an input for an external reference, why should we install a good internal one..."Actually, hardly seen a scope with worse internal reference jitter. In the view as attached to my last post, the slope would be all over the place if run on the internal reference.

author: mawyatt
author_rank: Super Contributor
timestamp: October 04, 2020, 11:32:43 pm
content: Sorry, I don't know anything about Rigol, maybe a replacement oscillator with a better, lower jitter one would help?Wish Siglent had a means to adjust the reference frequency like they have with the SDG2042X, and/or an external reference input.Best,

author: tautech
author_rank: Super Contributor
timestamp: October 05, 2020, 12:07:02 am
content: Quote from: mawyatt on October 04, 2020, 11:32:43 pmAll/any SDS2000 series DSO's have never had Ext clock references however the SDS5000X does.

author: rf-loop
author_rank: Super Contributor
timestamp: October 05, 2020, 03:09:31 am
content: Quote from: TurboTom on October 04, 2020, 08:52:59 pm"Efratom LPRO101-basedRb standard"So, do it mean LPRO is main reference inside some Rb standard and is disciplining something what is short time better than LPRO itself. If (when) this is case, do you know what OCXO is before output and how LPRO discipline it.Three decade count of LPRO101 (second hand) what I have seen long time ago, some even repaired and most of them calibrated, have never been in this "jitter" class. Most of them are really crap when we talk short time stability (depending highly also individual LPRO), even when longer time average is semi good or good in 5*10 exp -11 class (factory initial). (yes in previous life I have been time nutter)Inside LPRO there is only crap cheap "OC"XO and cotrol loop is "hopeless" if think short time jitter. They are mainly made/used for time keeping and there they meet standards. But using LPRO is possible to make better freq standards...Of course also 260ps P-P jitter is not good but is it random symmetrical jitter or how much it include LPRO and 10811 drift due to very very short time after power up. But yes, some 10811 versions are good and best versions some individuals are very good, nice reference for many purposes. But of course if they are long time power off they need long long time before they come back near or fully to individual nominal ageing curve (xtal ageing retract)"moderately fast scope"what is this meaning in this test setup where you get under 300 acquisitions in 5 minute?

author: rf-loop
author_rank: Super Contributor
timestamp: October 05, 2020, 03:38:48 am
content: Quote from: mawyatt on October 04, 2020, 05:09:45 pmCan you now carefully explain what are these images showing.What have 1s delay and where and after then explain how it trig after holdoff.My eyes are far over best before date so perhaps I can not see something important...I believe I see only rising edge trig just in trigger time position and as we know Siglent this scope trigger jitter is inside 10ps rms class.Even if you run random time hopping signal you must get this when you look just this edge what is triggering and edge shape stay enough constant and amount of noise is enough low.P.S. I know exactly what is trigger Holdoff (what can not generate trigger jitter at all and if holdoff time itself have jitter or inaccuracies also it do not generate time jitter what you can see in this kind of test what are in images. It do not work so at all.After delay it wait NEXT trigger event in signal and trig perfectly to this point including fine interpolation between raw samples and fine positioned then in display buffer)I think this is now good to handle just for basics how oscilloscopes works for avoit next thinking trap in future.. With scope is easy to do mistakes in some tests. It is very important to understand how oscilloscope works.With holdoff. After last trig it start holdoff time and during this time it do not listen trigger engine for acquisition trig. After time is full it start listen again trigger engine. If trigger Holdoff timer have jitter or not it do not produce visible jitter at all. If holdoff time have big jitter or signal have jitter still in trigger time position they are positioned in image to same position. Independent of if your signal is random hopping or holdoff time have enormous time jitter and drift etc. Of course if we go to some special rare situations all can happen depending how it is programmed there deeply inside trigger engine.But time delay after trigger trigger position inside this one acquisition... it is very different and it can tell truth added with some errors. Example if you look pulse to pulse jitter you set trigger to rising edge and you look next edge position what is delayed one period after trigger. You see pulse to pulse jitter. You can zoom to this next rising edge and your zoom window center is delayed one pulse period from trigger position. If you look position 1s after trigger position you see jitter over this time time period.But if you stay looking in trigger time position and look it, zoomed or not, and you set trigger Holdoff time to 1s or what ever you do not see signal or holdoff time jitter. You see just as your images here show, even if your example square wave signal is random time/freq hopping.Holdoff is, with other words, delay time after last trigged event beforeenablenext possibility for trig.Delay after trig done is very different and it can have negative or positive delay. If this time have jitter it can see signal trigger position jitter just same as if signal itself have jitter what can see in this delayed position.If this Holdoff timer itself have jitter or not it is not normally visible in this kind of situation.

author: TurboTom
author_rank: Super Contributor
timestamp: October 05, 2020, 09:23:12 am
content: Quote from: rf-loop on October 05, 2020, 03:09:31 amIn my LPRO100 based reference oscillator is no post-processing circuitry contained that would affect short term phase noise / allan deviation. I read about the sortcomings of using an Rb oscillator module directly and probably all your assumptions regarding the situation of such units in private ownership fit my Efratom module as well -- I repaired it myself. I've got other Rb modules (Temex LPFRS) that perform considerably worse. Do you actually have some hands-on experience with an LPRO100?Nevertheless, its performance (also short-term phase noise wise) is better than any other reference oscillator that floats around in my basement lab, inside some gear or externally. And this includes the HP 10811, after "moderate" warm-up periods of a few hours, though they are close. As yet, since I received the 53310A with the ovenized timebase option only shortly, I didn't bother to give it a really long time heat-up period. Since I haven't got much experience with this HP oscillator yet, it may also be a rather poorly performing one. For whatever reason, the LPRO101 that I've got appears to perform (much) better than average. Or all the other references that I've got are really crappy...The "moderately fast" oscilloscope helps a lot visualizing the fairly steep slope of the input signal without much smear and as such makes the cursor measurement possible at all.I may try another test by supplying both the reference and the input signal from the same source. This will show how much the internal processing (sampling clock PLL) of the scope contributes to the jitter.

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: October 05, 2020, 01:23:15 pm
content: Quote from: 2N3055 on October 03, 2020, 11:18:56 pmYeah, me too.John

author: mawyatt
author_rank: Super Contributor
timestamp: October 05, 2020, 02:57:43 pm
content: Quote from: rf-loop on October 05, 2020, 03:38:48 amThese are intended to show the effects of scope introduced jitter, and I know exactly how Holdoff works at least in the old Tek analog scopes, assumed the DSO works similar and why I indicated as you highlighted above!!I don't see any difference between using the delay "Holdoff" trigger or "Zoom" feature.I've been using analog Tektronix scopes since 1966, and about 40 years ago actually studied how the triggering was achieved in the Tek scopes. They had an almost amazing ability to capture signals, and found out they were using the fastest ECL logic chips available. These were used as analog limiters and comparators, not the intended logic use, although they did use some as logic functions. In these old analog scopes the Holdoff function could not achieve a 1 second delay with a 5ns/div scale factor (not enough range), and neither could the B Delayed function since the update rate would be 1 second and you can't "see" the result because of the finite CRT phosphor persistence. I believe the old Tek analog scope B delayed function is similar to the way the Zoom function works on the DSO for the scope time base. On some of the old Tek scopes (like the 2465) you can select to "Retrigger" on the B Delayed function which allows a Holdoff like behavior but with more range, although you are still limited by the trace persistence issue.Anyway, all this tells me that the oscillator used for timing and ADC capture in the DSO is very good from a jitter standpoint, and why I stated such. If the delayed retriggered (Holdoff) and triggered then delayed but not retriggered (Zoom) trace look the same then the scope is doing it's job quite well thank youI just did a quick test on my Tek 2465 using the B delayed function with the AWG waveform at 10MHz. With the sweep set to 1ms/div and B Delayed sweep set to 10ns/div the trace has considerable jitter due to the scope clock and circuitry, using the retrigger feature (like Holdoff) locks the trace in with no apparent jitter. This is the best I could do because the trace is very faint (had to darken the room), and my eyes aren't good eitherHere's couple photos on the Tek 2465, 1st is B Delayed (~7.1ms), note the significant jitter introduced by the scope.2nd is delayed (~7.1ms) with retriggering enabled, note the lack of jitter.Best,

author: mawyatt
author_rank: Super Contributor
timestamp: October 05, 2020, 03:36:30 pm
content: Quote from: tautech on October 05, 2020, 12:07:02 amCan you loan me the price difference between these 2000 and 5000 series scopes, so I can get one with an ext ref inputOr maybe a big discountBest,

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: October 05, 2020, 04:22:47 pm
content: Quote from: mawyatt on October 02, 2020, 11:31:37 pmAll of which leads me to conclude that I'm simply seeing the effect of a faulty cheap DDS type of smd xo rather than some feature of a particularly cheap 'n' nasty dds type smd xo. After looking at the datasheet for the Silicon Labs one dollar 50 cents in 1000 off quantities dds smd xos (justhowcheap were those earlier dds type xos, famed for this very effect?,I can't really see Siglent skimping on such a vital part of their low jitter strategy. I can well imagine a company like Feeltech opting for the ancient dds versions at 10 cents each but not Siglent.Torturing a poor defenceless DSO into revealing this particular flavour of jitter by zooming into a 100ns window some 45 to 50ms to even as much as 1000ms after the trigger event when you happen to have at least one low jitter reference signal (a 10MHz gpsdo, a DOCXO or, better yet, an Efratom LPRO-101 oreven betteran LPRO-101anda gpsdo) to hand to do this the "Easy Way"(tm) just seems so masochistic an act of folly to my mind.I do agree however, that when dealing with such an unusually jittery signal, you need to be doubly sure that what you're seeing isn't the result of a very flawed test set up. In my case, I had two independent and uncorrelated 10MHz references, the RFS and the GPSDO to trigger from with the other acting as a referee to validate the results.I even went so far as to run the 100ns zoomed window delayed from the trigger event by 50ms test, aka "Doing it the hard way" (I wasn't sure I could use as long as a 1s delay for this test but even so, the framerate was going to be rather glacial to say the least and the infinite setting on persistence didn't seem to be working).The 50ms delay was sufficient to show enough of this jitter and I did question the timebase jitter by triggering from one then the other of my references to see how much jitter, if any, was present in the timebase itself (and, for that matter, between the two references) with the indication being that what small (tens of ps worth of?) jitter appeared to be all down to the DSO's timebase with none observable between my two uncorrelated references. From these 'sanity checks', I think I can safely conclude that the DSO's contribution to the jitter displayed on the AWG's signal was less than 1% of the total.As I've already mentioned, this method is the resort of the man who has absolutely no access to an independent low jitter source of test signal to use the "Easy Test" method. Such an independent test source doesn't even need to be a highly stable GPSDO or RFS or DOCXO type just as long as it can remain frequency stable to within +/-1Hz for more than ten seconds at a time and has negligible jitter of its own. A salvaged DIP14 XO in the range 5 to 15MHz could suffice for this, even if plugged into a solderless breadboard as long as it's protected from random air draughts (a bit of rag or a cardboard box or WHY).Anyway, all that aside, I'm returning my new toy as "Unfit for purpose" for a full refund. Incidentally, itispossible to apply a 1mHz offset to a 10MHz frequency setting (and a 100uHz offset to a 9MHz setting) with the SDG1000 and 2000 X series of AWGs despite the displayed frequency being rounded to 10.000000MHz when the "MHz" suffix stamps all over the last three digits after pressing the MHz button. You need to use the external 10MHz clock option to eliminate the jitter and lock it to your reference source before the effect of these tiny frequency changes can be observed.I first tested this by entering 10.000000000 until it wouldn't accept any more zeroes followed by a single backspace to replace the final zero with a "5" before hitting the MHz button. I saw a slow but quite discernible drift to the left despite the display now showing 10.000000MHz.When I tried this trick using 9.9999999999 and moving back one digit to enter a "5" expecting to see a similar drift to the right, I'd overlooked the fact that I'd gained an extra digit's worth of resolution and had entered a 500uHz reduction rather than the 5000uHz increase I'd applied to the 10MHz setting which resulted in only a tenth of the drift rate to the right that I'd been expecting. However, after a minute or so, I did see a rightward drift and only then did the penny drop.The result of this test strongly suggests that, given a re-write of the frequency entry algorithm in the GUI, it could be made to emulate the Feeltech's 14 digits of resolution frequency entry. complete with the selected digit being remembered between each adjustment session. The frequency setting algorithm as it stands is an insult to the AWG's capabilities and whoever was responsible for that execrable effort in data entry programming should be hanging their head in unmitigated shame.It is only with that thought of a possible re-write of the frequency input algorithm in these two series of AWG that I'm even entertaining spending yet another 200 plus quid on an SDG2042X to get hold of a more upmarket AWG thatdoesoffer a little more improvement versus the SDG1032 which, surprisingly offers so muchlessEven if my unit hadn't exhibited this nasty and insidious jitter on its internal clock reference, I think I'd have been returning it as "Unfit for purpose" anyway.John

author: TurboTom
author_rank: Super Contributor
timestamp: October 05, 2020, 04:51:52 pm
content: Couldn't agree more with you on the U/I shortcomings of Siglent's AWGs. Even their top end model that I've got (SDG6000X) shares the same troubled user interface. It all gets down to usability of the instrument without having to look at the display all the time. The plain and easy rule when changing parameters incrementally is "stay on the digit" whatever decimal's carry is going on. Moreover, when switching between parameters to adjust alternatingly for example amplitude and frequency (or whatever other parameter may be of interest), remember the digit that the cursor had been on when leaving the parameter. There are a few more things (like the choice to set limits for the adjustable range of a parameter) that would be really nice to have. I wonder if Siglent will actually address this - if they do, these instruments would surely gain even more popularity. If not, well, other manufacturers aren't sleeping...Cheers,Thomas

author: mawyatt
author_rank: Super Contributor
timestamp: October 05, 2020, 05:19:17 pm
content: Quote from: Johnny B Good on October 05, 2020, 04:22:47 pmAs I've mentioned a few times, this I believe is the source of your observed excessive jitter.QuoteEven extending this to 1 second and using the DSO "Zoom" feature shows no excessive jitter with the SDG2042XQuoteYep, that's the way to get more digits with the SDG2042X as well, they don't show on the display tho.QuoteBTW I used the "sliding waveform" method mentioned in a separate post to quickly align the SDF2042X Internal Reference (has internal control DAC), this achieved a 0.002ppm deviation from my stable SSA3021X Plus 10MHz reference (previously indicated as a good reference) for > hour quick test. I'm sure it's not that good over a longer period, but plenty good enough for my immediate needsBest,

author: mawyatt
author_rank: Super Contributor
timestamp: October 05, 2020, 05:38:12 pm
content: Quote from: TurboTom on October 05, 2020, 04:51:52 pmAgree, this isn't the best implementation of a UI, and some parts are quite annoying, not limited to just the rounding of the frequency display. Since this is evidently a common interface with all the AWGs, maybe Siglent will address some of these shortcomings in updated firmwareAnyway, with the performance I've seen and the chips used (shown in teardown) in the SDG2042X I honestly have few complaints, and outside a larger screen, all with the UIBest,

author: tautech
author_rank: Super Contributor
timestamp: October 05, 2020, 07:54:04 pm
content: Quote from: mawyatt on October 05, 2020, 03:36:30 pmOf course the SDS5000X was a totally new design and a new venture into higher BW's for Siglent and the SDS2kX Plus was a follow on using a very similar form factor but with shared controls to keep size and costs down.In a recent chat with the product manager he disclosed the the 2kX Plus rear housing isexactly the sameas used for earlier 2k products which I'd never noticed before.So this means 2kX Plus is the same physical size as Siglents earlier 2000 products.

author: rf-loop
author_rank: Super Contributor
timestamp: October 06, 2020, 03:03:34 am
content: Quote from: mawyatt on October 05, 2020, 02:57:43 pmI have also much over 50year experience with many kind of oscilloscopes etc. In history including these 2465 and if go more far in history also other models. Also couple of 7000 series "RollsRoyces" and also couple of Hewlett-Packard ones. And of course Solartron ones etc. And then some total hobby ones like example most crap shit Heathkit what I get when I was young after my grand father frustrated I always mess his professional instruments.But I have never ever messed and mixed basic fundamentals between digital scopes and analog scopes. This is also one reason I still sometimes use analog scope for some purposes due to fact they are fast never ever fool me by aliasing and always things can fast set withoit searching any menu system finding this and that setting.Now I can see here that something is wrong in thinking scope itself timing jitter and some DUT timing jitter and how to detect if there is and roughly how much.I do not agree your explanations and tests here based to your words and 5 images.As far as I understand your explanation and SDS2000XPlus images you did not detect any jitter. Even when you say there is 1s delay. (but I can not see any delay there)In every image your timebase delay is Zero! Also when you set trigger Holdoff to 1 second what is just nonsense in this meaning. Even if your scope have enormous reference clock jitter with timebase delay zero and what ever trigger holdoff time you can not detect this jitter at all.Also I can see @DL2XY note this to you but it looks like you know about oscilloscopes so much that of course you are right... and your answer is... as can see images have no difference even if Holdoff is 1 sec or not Holdoff. But you forget that of course they are same because Holdfoff do not affect anything but slower wfm/s rate in this case.Here is just two of these images just for example and because SSA3000X ref clock is most less jittering signal thing in your displayed set of things and this is what is best for analyze - if you want - your scope timebase jitter. (But not as you have done it with Trigger Holdoff 1s what do not accumulate time base or DUT time jitter at all to display).@myawatt:The SSA3021X Plus 10MHZ referencewith 1s delay[ Attachment Invalid Or Does Not Exist ]@myawatt:Here's using the Zoom with delay of 1son SDG2042X AWG[ Attachment Invalid Or Does Not Exist ]Now it is possible that I do not understand your scope screen image information related to your words because I do not have SDS2000XPlus here my position now.Scope screen display time delay zero when I look it with my old eyes. Your image looks like it is just in trigger time position. Not delayed. So if this is case it do not accumulate also any possible time jitter in DUT signal or in scope timebase. It can not as long as you look trigged position.If you take even 200ms long capture with this 10MHz signal and zoom(!) to example 100ms delayed position AFTER trigger position then there is jittering DUT and Scope timebase producing jitter what is accumulated over this 100ms time. And if not see jitter take more long capture and go to example 1s position after trigger and zoom to this position, zoom in to fastest time scale it can. If still can not see any jitter then need very very hard explanation why not and what is fooling us.Please draw me free hand image and/or some other method.Please, teach me so that also I understand where is this said 1 second delay in both of these images. Between what and where and how it produce displayes time jitter if jitter exist.

author: rf-loop
author_rank: Super Contributor
timestamp: October 06, 2020, 03:12:35 am
content: Quote from: rf-loop on October 06, 2020, 03:03:34 am

author: TurboTom
author_rank: Super Contributor
timestamp: October 06, 2020, 10:26:43 am
content: I actually wanted to stay out with further posts regarding the signal / TB jitter issue since it's somewhat off-topic but @rf-loop made me reconsider, and he is right. I didn't understand where the jitter/delay is in your scope screen shots as well. The functions of the "good old time"scopes basically make it very clear: timebase B delayed by A or "zoom" mode without retrigger is the actualy "delayed timebase mode", where a single trigger event causes the whole trace display sequence to happen and thus will accumulate the TB A (or signal, whichever is predominant) jitter.Anything that just delays the trigger arm function for the "display timebase", will not accumulate any jitter since the triger event for the display timebase will be on-screen. These are holdoff or anything that incorporates a re-trigger function (as it's called on the analog flagships).Since in my previous post, I mentioned to try to measure the 1s delayed performance of my MSO4000, I won't retain it from you. Here I decided to disable the vector display but rather have dots displayed since this reveals some more information. This first screenshot shows again the measurement of the HP 10811 (reference) vs. my Efratom LPRO101:And now, I used the LPRO101 to supply both the scope's reference signal as well as the input, so this should depict the scope's own one-second delay jitter:Both measurements were taken over approx. the same time of a few minutes and with the instruments warmed up for maybe an hour. It's quite curious to see the individual "islands" of the sample locations not completely bleeding into each other in the latter measurement. But it also shows that this kind of measurement (at least with the gear used) is not accurate enough to quantitatively characterize the jitter characteristics of two fairly good oscillators. I only wish the MSO4000 had density colour grading, in these kinds of measurements this feature would be really useful!

author: rf-loop
author_rank: Super Contributor
timestamp: October 06, 2020, 12:26:36 pm
content: Quote from: TurboTom on October 06, 2020, 10:26:43 amExcellent. Thanks.But... is it also so that this 1 second delay is exactly based to its reference clock. Now your oscilloscope reference clock is based (with some sidenotes) to same signal what you use for input. If you use LPRO or good 10811 as input and give scope run with its own reference you see this reference jitter what is totally much much more. I believe can not stay in this display width at all.What is this tiny jitter we see here, roughly perhaps 100-200ps class depending what amount trigger jitter is included.I believe it include many things.Freq locking quality to ext ref signal, some jitter/PN generated in PLL etc system what clock ADCs and acquisition, some part come from trigger itself jitter (I do not know how it fine interpolate trigger between sample points (inside 250ps interval) and position signal inside this sample interval. In image looks like it do not make very fine fine interpolation and positioning. Last bright dots related to trigger (time) position.So we do not even know sure if it display some trigger or is it mainly trigger jitter due to some lack or lousy fine positioning.If it is mainly trigger jitter it is not very good but if it is mainly system other kind of "jitter", not bad when external reference is in use. Without external reference situation is sure totally different.But, it have Ext ref input.Scopes what do not have... there is good and important to know its time jitter when it run based to its own reference because there is not any choice. (except if user do HW modification for better internal or ext ref)

author: mawyatt
author_rank: Super Contributor
timestamp: October 06, 2020, 03:39:53 pm
content: Quote from: rf-loop on October 06, 2020, 03:12:35 amObviously the second image is incorrect, as there is no "Zoom" feature enabled in the display, so I must have used the incorrect image fileI've also discovered the DSO "Zoom" feature does not work exactly like the Tek B Delayed function since the trace starts with 0 delay and begins at the center of the display, thus invoking Zoom does not introduce any delay and this is subtly displayed above the lower Zoomed trace window. I'm not sure if another means is available to introduce a long delay, but the <> Knob is hopelessly inadequate if a large between Zoom timebases is required. The only way I could get this to work was use the finger "gesture" method, which was trying indeedEventually I was able to get ~1/2 second delay with a normal timebase of 100ms/div and still have a 5ns/div Zoom timebase. As expected the 1 sec delayed trigger shows no jitter, the Zoom trace shows a small amount of jitter with a delay of ~1/2 second.As mentioned I'm impressed with this DSOs ability/performance in every aspect of it's use and behavior as I learn more about it's capabilitiesHopefully someone can point out a better method to achieve these widespread time bases with the Zoom feature, I suspect thereISa better methodEdit: Just found the Zoom Timebase window that shows up on the waveform has numerical entry for the delay. It allows a 1 second delay with a 5ns/div timebase. So I'll add a third image with 1 second delay with 5ns/div Zoom timebase and 100ms/ normal timebase. So there IS a better method10MHz reference with 1 second Delayed Trigger10MHz reference Zoomed with ~1/2 second delayAdded 1 second Zoom delay.BTW I saved up and purchased a Heathkit scope when I was 12~13, this was the original tube versionBest,

author: rf-loop
author_rank: Super Contributor
timestamp: October 07, 2020, 06:23:31 am
content: Quote from: mawyatt on October 06, 2020, 03:39:53 pmNow it looks better.But as previously told first image can not accumulate any jitter related to waiting time. It can not see in image but I assume you have again used Trigger Holdoff and of course this Holdoff time do not accumulate any jitter due to zero delay when next trigger event after Holdoff time elapsed. Result looks same if Holdoff or not, exept delay next displayed acquisition.DPO zoom have nearly nothing to do with analog scope zoom even when result may looks like somehow same kind of image.This is also small Achilles heel in conventional DSO and more modern DPO (or SPO like Siglent name it) but mostly there is way to walk over this. But dual independent beam dual time base dual delayed trig - just forget with these digitals.This, and most other simple ones, DPO can only do one whole sweep based to one trigger engine trig and nothing else.For Zoom window we take only more or less long part from this one acquisition and from time position how user set zoom window position. There can not generate example other delayed trig for zoomed detail. There is not second "Timebase" where scope sweep part of trace more fast or do sequentially slower sweep and then for zoom faster sweep for adjusted position. No, DPO do not at all have other than just one "timebase" so it is even bit wrong to name horizontal axis adjustment as timebase. It is only time scale. With Zoom there is just this same original one "sweep" aka acquisition in memory. When we zoom, we only take part of this acquisition in memory and show it using different time scale on display. And in this case now here, time jitter come only visible using this zoom so that we look other memory position than trigger position. There we can see if signal detail exist sooner or later. After then we know that oscilloscope timebase have jitter or signal under test have time jitter or both have time jitter. For know more we need know scope timebase jitter. If we know it is far less than signal under test we can name this observed jitter is signal under test jitter + error from scope timebase jitter. If we Know signal jitter is example "zero" after then we can tell that jitter we have seen is oscilloscope own jitter in timing.In your images (zoomed ones) can see quite small time jitter.Now small problem there is that slope is very slow for this purpose.Decimated samplerate is 100MSa/sIt mean that there is decimated sample interval 10ns. In Zoomed window there is only 5 samples in one acquisition and rest visible things are interpolation. Due to lack of knowledge about just this Siglent model I can not estimate what is perhaps possible trigger/fine interpolation/display positioning jitter amount and what is timebase related jitter and signal jitter. I believe trigger engine just after ADC use full non decimated samplerate but this is only now hope and believe. But so or so, it can say -- scope timebase jitter is small! Better than I expect. And it is good to know due to fact it do not have ExtRef input.Oh well, example Hethkit IO-12 and perhaps even one bit older.. is still deeply "burned" in my memory, I can even remember smell of it and my first old Collins Rx from 40's.

author: mawyatt
author_rank: Super Contributor
timestamp: October 07, 2020, 01:06:29 pm
content: Quote from: rf-loop on October 07, 2020, 06:23:31 amIf you recall, the original intent of these screen captures was to show that the DSO was not introducing significant jitter because the Holdoff is retriggered and the Zoom is not.QuoteThe core fundamental difference between the analog scope and the DSO regarding triggering is, the DSO must decide the triggerafterthe signal has been captured by the ADC, the analog scope can trigger essentiallyinstantlyon the signal and in the case of the dual timebase can have two entirely different timebase sweeps with continuous resolution between them, whereas the DSO is limited by the prior sampled signal by the ADC. So in effect the ADC clock becomes the controlling singletimebasein the DSO, and the memory depth becomes the limiting factor between using delayed functions like Zoom to try and emulate the analog dual timebase. The analog scope has limits also since with very large differences in the dual timebases the CRT update rate limits one's ability to "see" the signal, and one reason (the main reason was to capture single or infrequent events like "glitches") why Tek developed the long persistence phosphor CRTs and later the special Micro-Channel Plate CRT.QuoteYes the jitter is very small indeed, so I can feel confident when observing jitter from other sourcesQuoteYes the jitter is very small indeed, so I can feel confident when observing jitter from other sourcesThe sample rate and memory depth place limits on these, so higher sample rates require deeper memory or faster main timebase. I think this SDS2102X Plus DSO achieves a good compromise considering the cost.Maybe Siglent will consider an ext ref for this level scope in the future, and the ability to tune the internal reference with a DAC like the SDG2042X AWG. These additions shouldn't cost much to implement.QuoteHave fond memories of that period of time including my Heathkit VTVM. At 8 years old I knew what I wanted to be, an EE, and have had a fun career which is winding down now, faster than I would like thoBest,

author: rf-loop
author_rank: Super Contributor
timestamp: October 09, 2020, 01:51:53 pm
content: Just for fun.In this thread was FeelTech FY6600 told and also some words about more new FY6900.I was bit interest to see what it is.This is not after DIY modification project. This is out from box, as it is. I like instruments are ok out from box. I have other things to do than playing with DIY boxes.Here first old image about SDS1032X. CH1 10MHz sine CW out.Also SDG1032X is some off from 10MHz but I remember it is much better than specifified. But in this image I believe it is connected to ext reference from SA. This is not so important here.Yes in home I have LOT of better images and data.But then this FY6900I have not often seen this dirty output.Totally shit. And I mean this AM modulation what must not be there at all or so small that with this system I use here can not detect it. But this modulation is high... it is totally so bad that I try find if there is some external reason what disturb now things but with many kind of cross check my conclusion is that it come from FY without any doubt. I have also tried full isolation (and signal from antenna to antenna... just same result. )Other thing is that it is out from box initially 30ppm off. Specs max limit is 20ppm. In one hour it drift roughly 5ppm.These freq accuracy things are not so severe but this AM modulation is terrible. And of course it continue more wide that just this 1kHz span... bit less amplitude but 5kHz offset and still high. What a fuck they have done or forget to do.But it looks that it have roughly 50ohm internal output resistance (yes I say output resistance and not impedance because I do not know enough due to total lack of test instruments in my situation just now). But something weird there is in output amplifier... when it drive some load it is perhaps warming and level start drift down..Still if look price, under 80 Euro... even there is missing lot of features and performance what example SDS1032X have it still can do some things quite well. This frequency full resolution adjust I like.But this really dirty sine CW.... bhuuhhh... for what it can use?Who knows if there is some simple trick inside what cause this and is easy repairable.1.9Hz RBW as can see 30ppm off (304Hz)

author: mawyatt
author_rank: Super Contributor
timestamp: October 09, 2020, 02:15:20 pm
content: This looks horribleIs the Feeltech AWG the one that uses an R2R ladder network that's directly driven from the FPGA outputs, rather than using a proper DAC?Quality high resolution, high frequency DAC's are costly, but the use of the mentioned design practice to replace the DAC would help explain this. The FPGA supply noise levels and non-linearity introduced by using the direct FPGA drive for the R2R network are going to make creating a quality waveform almost impossibleBest,

author: rf-loop
author_rank: Super Contributor
timestamp: October 09, 2020, 03:18:12 pm
content: Quote from: mawyatt on October 09, 2020, 02:15:20 pmAfaik 2x 14 bit DAC. I believe FeelElec is just overall this bit "better" manufacturer.What I have here is just for fun because it was so dirty cheap and I was bit interesting to look it after I have read many peoples talk about these 6600, 6800 and most new 6900 what may have some advantages over these others/olders. Model is FY6900-40M FW V 1.3.1 Later some day when I carry it to my homeland I will look more carefully and deeply some "performance" things. I think there is something bad in internal power supply and power sharing. Perhaps HW design error or least poor desing...

author: radiolistener
author_rank: Super Contributor
timestamp: October 10, 2020, 01:58:05 am
content: PSG9080 10 MHz sine:

author: Fretec
author_rank: Contributor
timestamp: October 15, 2020, 05:53:09 pm
content: Wow, that FY6900 output signal is really very bad.

author: Electro Fan
author_rank: Super Contributor
timestamp: October 22, 2020, 01:23:47 am
content: Is it the conclusion of this thread that a 1032x has too much/unacceptable jitter and that the next solution up to bat is a 2042x, or is there some other conclusion/recommendation (maybe a Rigol DG1022Z generator, or something else) in the $300 - $500 range? Or is this thread possibly a bit tough on the the 1032x ok (ie, it's "fit enough for use" in the ~$300 neighborhood)?

author: rf-loop
author_rank: Super Contributor
timestamp: October 22, 2020, 03:26:35 am
content: Quote from: Electro Fan on October 22, 2020, 01:23:47 amThis have so many times handled that I do not explain so much images exept if someone ask some detail.Of course if we compare clock jitter to other clock what is DIY assembled example in some Feeltech generator we can say Siglent internal reference have more jitter.Out from box example FY6900 freq accuracy is with one word:Horrible and sinewave is so dirty that it can not use for any kind of serious work as also shown here previously. Of course if someone do same DIY work for Siglent he can also install there even best possible high end DOCXO. But when need better frequency accuracy and stability it have also input for external 10MHZ reference.Square cycle to cycle jitter. Note frequency, it is selected so that it is not "golden frequency" for lowest jitter.Here in this image jitter is roughly 170ps Peak (340ps Peak to Peak) specs limit is 300ps RMS what is far higher what is peak depending jitter ditribution and how much data (how long time) we collect.Previous rising edge (trigger) is left side out from image.Square cycle to cycle + width jitter. Note frequency, it is selected so that it is not golden frequency for lowes jitter.DG1032ZSDG1032Xhttps://siglent.fi/pic/SDG1000X/SDG1000X-1Hz-Pulse-duty0-001-fall-zoom.pngPulse width jitter. 1s period pulse. Pulse width 10000ns falling edge slope zoomed. Infinite persistence. Jitter roughly in 200ps peak to peak. 10/90 Ft 2.9ns.5.1kHz Note. 1st harmonic (fundamental) level is higher. So level distange to 2ns harmonic is not accurate and perhaps more than displayed 66dBc. This is due to fact that 5.1kHz is out from SSA frequency range and it start attenuate more and more when go under specified 9kHz.3.7MHz30MHzIn this last image pulse period is continuously 1sAll time scope have been with infinite persistence.First there have been 50ns pulse. Sfter bthen pulse width is adjusted slowly with very small increments to 100ns. After then adjusted for 300ns. After then 200ns width and then started to ajust slowly with very small increments falling edge slope to 150ns fall time.In this image continuous 1kHz freq and 100ns width. After then width have adjusted 8 steps using 1ns steps and finally 10 steps using 0.1ns steps.There can see small jitter, roughly p-p 200ps.If look shape in zoom window top and bottom there can see this "EasyPulse" technology produced some kind of risetimejitter or wobbling or undulating how it need name I do not know. But partially reason is also when I "wrong use" oscilloscope. Analog input stage is highly overdriven because I want better image for show these pulse width steps and if whole signal top and bottom is in image this falling edge slope looks very different in this time scale 2ns/div. This is for show these steps, not for show whole edge shape.Continue in next msg due to forum image limits

author: rf-loop
author_rank: Super Contributor
timestamp: October 22, 2020, 03:27:24 am
content: Continue...I have lot of more tests but these tests data are not with me here far from my homeland.And example if use for some under 30 or 60MHz works with some radio things, example for filters adjustment or other things. Siglent AM modulation is made like real RF generators. And you can even use two independent channel AM with independent modulations. Also same for dual sideband DSB. Sad it do not have single sideband SSB.In SDG1000X channels can also combine.scope Ch2 is 400kHz sine out from generator Ch2. 400kHz sine is also AM modulated with some audio as can see level change due to persistence. It is trigged to this 400kHz HF.Generator CH1 have other higher frequency with lower levelOscilloscope Ch1 is coming from generator CH1 what is inside generator combined CH1 and CH2 signal. Freq. are selected so that no sync what can also seen due to scope persistence.But, of course all depends what are user needs related to jitter and other things.SDG2000X series internal reference is better than SDG1000X.Do this tell enormous jitter. Imho, not.

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: October 24, 2020, 12:01:50 am
content: Quote from: Electro Fan on October 22, 2020, 01:23:47 amSince it was me that had brought up the issue of 'jitter' with a recently purchased SDG1032X which I've now returned. I can tell you that I finally concluded that the problem had been down to either a faulty XO chip or a fault in the supporting circuitry or just a dry joint, broken capacitor or whatever.Aside from that, courtesy of the use of an external 10MHz reference clock, there doesn't seem to any jitter issue other than what is entirely expected of DDS and sharp edged arbitrary waves. This model uses a special circuit for square waves to eliminate the DAC clock jitter issue that would otherwise afflict them in cheaper designs such as those Feeltech/FeelElec FY66/68/6900 models.If jitter is your only concern, then worry not.John