Rigol Oscilloscopes With(out) Bode Plot Feature? - Page 1
Forum section: electronics / testgear

author: jackbob
author_rank: Regular Contributor
timestamp: March 28, 2019, 07:07:52 am
content: Call it a gimmick or novelty, but I find the bode plot feature on these newer scopes to be quite useful. While I realize there are pieces of equipment specifically for this purpose, I think the feature is good enough for most cases and nice to have, just as FFT is a decent poor man's replacement for a spectrum analyzer. I know Dave has done a video of how to obtain crude bode plots on an oscilloscope using a function generator with a frequency sweep but really, why? I mean this is such a basic feature for any scope with a signal generator onboard, it is merely just software.Keysight's entry-level 1000X scopes include this feature, hell even Siglent has the feature on their budget scopes, even ones without onboard waveform generators. This brings us to the elephant in the room, Rigol. Am I completely missing this feature or does Rigol not include this on their scopes? For years I have been getting by the ds1054z, an almost unbeatable scope for the money. We have scopes from Siglent today for the same price but with this feature and more. Granted, the 1054z is a bit of an older scope and I wouldn't necessarily expect this feature on such a budget scope at the time it came out, but this could have been added through firmware updates. Considering how poorly FFT was implemented on this scope, this feature couldn't perform any worse.Jump many years later and Rigol rolls out their new mso5000 series scopes. Hard to resist for the base price, can be loaded up to $5k+ for features (we all know ways around this though), and lacks this basic bode plot feature! Rigol what gives? Really they implement all these niche but appreciated features such as power analysis but cannot implement a simple bode plotter? A scope with 4 channels, 2 wave gens, and all the hardware necessary to get the job done yet they skip this feature? WHY?? It's not even an optional add on or anything. Is this feature buried in the menu somewhere? I cannot find any mention of it in the user manual. It must not exist. This can and should be implemented in a future firmware update.Does anyone else feel the same about this feature? Are there any threads on the forum where Rigol's engineers are known to roam and take notes?

author: David Hess
author_rank: Super Contributor
timestamp: March 28, 2019, 06:00:38 pm
content: It is especially dumb for an oscilloscope which also has a built in signal generator.But almost as dumb is discarding the phase results of the FFT function because combined with differentiation or an impulse generator, a bode plot can be generated from the transient response of a system in one shot.

author: jackbob
author_rank: Regular Contributor
timestamp: March 28, 2019, 06:35:02 pm
content: I agree they could show the phase results in FFT just as easily. Why do most scopes leave this out? I haven't worked with any scope that offers phase results in FFT. It can't be a technicality, it must be a marketing technique. If you add all these features, especially as scopes become more powerful and capable with these features, then why would one pony up the extra $$ for spectrum analyzers or network analyzers? I am aware these silly side features are not a replacement for these pieces of dedicated equipment in certain applications. But really for the hobbyist/amateurs, these capabilities would clean the market, not everyone has endless cash for some of the more expensive specialized equipment.

author: Fungus
author_rank: Super Contributor
timestamp: March 28, 2019, 06:41:25 pm
content: Quote from: jackbob on March 28, 2019, 06:35:02 pmYep, it has to be down to marketing.The same thing happened with Serial decoders. They used to be optional but now they're standard everywhere. Some people are still holding out on CAN bus (because that's "professional") but even that's appearing in low end 'scopes now.I'm sure every 'scope will have Bode plots as standard soon.

author: thm_w
author_rank: Super Contributor
timestamp: March 28, 2019, 08:43:50 pm
content: Quote from: jackbob on March 28, 2019, 07:07:52 amWe don't know of any Rigol reps that actually post here. So best bet is probably contact sales, let them know you are interested in purchasing MSO5000(s), but you are concerned there is no bode plot feature and if they are considering adding it in the future.

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 29, 2019, 03:09:41 am
content: you can bode plot with since the DS1052E and FG and a PC. but then if you want to trade EUR7K for that on brand name, thats fine.

author: EEVblog
author_rank: Unknown
timestamp: March 29, 2019, 03:12:50 am
content: Quote from: jackbob on March 28, 2019, 07:07:52 amThe Keysight 1000X was the first to do this. I had an original prototype unit and I thought it was one of the compelling features of the new scope.

author: jackbob
author_rank: Regular Contributor
timestamp: March 29, 2019, 07:12:33 am
content: Quote from: EEVblog on March 29, 2019, 03:12:50 amHmm I didn't realize this feature was so new, perhaps because it just seems so rudimentary I thought it had been on scopes for longer. Given the ease this feature could be added and the value it brings especially for hobbyists, I would have expected Rigol who used to completely own the hobbyist scope market to add such a feature.This makes me wonder now who got it first, Keysight or Siglent? This budget end scope market has really become quite competitive and when one rolls out a scope with specific features and specs for X dollars, it's not too much later before other brands start to follow with a similar product. In this case I wonder if Keysight was putting their 1000x series together and saw Siglents bode plot feature and thought they should include it as well.

author: rstofer
author_rank: Super Contributor
timestamp: March 29, 2019, 07:21:15 pm
content: I ask because I know diddly about this feature: Is the frequency scale logarithmic? Is the vertical scale in dog Biscuits? Am I going to be able to physically read the values for the grid lines?When I think Bode' Plot, I have an image burned into my brain about how the amplitude and phase plots should look.Within it's frequency range, I rather like the way the Analog Discovery 2 (and Waveforms) creates the plot. It looks like that mystical burned image.It just seems to me that scope screens are too small to present a properly formatted FFT or Bode' Plot. Given computer control and data capture, it would be easy enough to use the data and something like Octave/MATLAB to make the proper plot.There's nothing quite like a 27" screen when it comes to plotting. Unless it is a 34" screen...I don't think I would spend any extra money on a scope that did FFT or Bode' Plot. But that's just me because, obviously, other people think it is a worthwhile feature. The DS1054Z FFT seems rather crude but it's just an entry level scope.

author: nctnico
author_rank: Super Contributor
timestamp: March 29, 2019, 07:45:49 pm
content: Quote from: rstofer on March 29, 2019, 07:21:15 pmMost oscilloscopes don't have the required accuracy to justify a very detailed FFT or Bode plot. The best oscilloscopes have a DC accuracy of around 1.5%. AC isn't specified at all except for the -3dB bandwidth. So all you'd be looking at is the limit of the ADC and analog front-end. Still Bode plots and FFTs are perfectly usable. Real circuits usually have large component variations so the FFT and Bode plots offer enough accuracy to verify whether your circuit meets the design criteria or not. Still it seems in general Rigol is not the brand to look at when looking for a good FFT feature.

author: rstofer
author_rank: Super Contributor
timestamp: March 29, 2019, 09:14:42 pm
content: So, qualitative versus quantitative. That's pretty much all you get with a scope anyway. "It's about..."I just wasn't interested in a linear frequency scale because the shape of the graph would be all wrong. It wouldn't look anything like my mental image.

author: nctnico
author_rank: Super Contributor
timestamp: March 29, 2019, 09:25:08 pm
content: Quote from: rstofer on March 29, 2019, 09:14:42 pmBut you can still use the cursors and check the amplitude / phase at certain frequencies to see if the result matches the calculations in case the oscilloscope doesn't support a log frequency scale. I haven't played with Bode plotting on an oscilloscope yet but I would assume a log frequency scale and log amplitude scale would be supported.

author: David Hess
author_rank: Super Contributor
timestamp: March 29, 2019, 11:43:56 pm
content: Quote from: EEVblog on March 29, 2019, 03:12:50 amCleverscope has had this feature since at least 2013 and SysComp Design has had it since at least 2006.Tektronix DSOs had this capability 30 years ago using the impulse or step response method I outlined. LeCroy has supported it in the same or multiple forms almost as long.

author: EEVblog
author_rank: Unknown
timestamp: March 29, 2019, 11:59:11 pm
content: Quote from: jackbob on March 29, 2019, 07:12:33 amI'm pretty sure Siglent copied Keysight.The Keysight was released in Feb 2017, but I was given the prototype by a guy in a trench coat in the back alley at the Electronex show in Sep 2016

author: EEVblog
author_rank: Unknown
timestamp: March 30, 2019, 12:05:18 am
content: Quote from: David Hess on March 29, 2019, 11:43:56 pmYeas, but they aren't the low cost bench scopes we are familiar with today.I think some other USB based scopes with function gens also had them.But Keysight were the first to include it in an entry level bench scope with function gen sweep.

author: jackbob
author_rank: Regular Contributor
timestamp: March 30, 2019, 12:16:43 am
content: Quote from: Mechatrommer on March 29, 2019, 03:09:41 amIs this true? Has anyone else been able to achieve this? Although I feel the DS1052E is a bit outdated, this makes me wonder if they have this functionality on other scopes when connected to a computer. Even if I have to connect the scope to a computer, it's a bit clunky but it's better than manually adjusting function generator parameters, logging data point by point and plotting.

author: vk6zgo
author_rank: Super Contributor
timestamp: March 30, 2019, 02:14:12 am
content: Everybody loves to call amplitude/frequency sweep measurements "Bode Plots", where they are nothing of the sort.A Bode Plot is an idealised response curve, usually repeated in both amplitude/frequency & phase/frequency forms .They are drawn as straight lines, with 3dB points shown as sharp angles, as are the changes in phase angles.It is a long time ago, but I remember calculating these "break points" given a mathematical expression for the required response.(Wouldn't have a clue how to do it now-------30-odd years of lack of use does that).An amplitude/frequency sweep, on the other hand, shows the response of a real device, where the changes in amplitude are gradual.Such sweeps seldom include a phase/frequency display.As an old fart, I find the tendency to use sloppy terminology annoying.By the way,"Get off my lawn!"

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 30, 2019, 03:18:53 am
content: Quote from: jackbob on March 30, 2019, 12:16:43 amwell... i'm glad you asked...https://www.eevblog.com/forum/beginners/goltek-bode-plotter-pc-sw-(for-ds1000ed-andor-hantek-dds3x25)/?topicscreendated March 2012, but it worked on 3x25 FG only as thats what i have. any other programmable FG i believe can do as well... err, dont get DS100E just because of that thread, get the newer DS1000Z, can do as well...Quote from: vk6zgo on March 30, 2019, 02:14:12 amiirc we can determine system stability from bode plot when respond is over unity (greater than one) and phase is more than 180 degree, but i dont think memory serve me well, anybody can read the literature in internet now easy. i dont use my bode plotter much, i guess it was just a demonstration that it can be done (given you have some programming skill), fwiw, ymmv.

author: rf-loop
author_rank: Super Contributor
timestamp: March 30, 2019, 07:29:56 am
content: Quote from: EEVblog on March 29, 2019, 11:59:11 pmCopy what? Quite a hard accusation or suspicion.Perhaps Keysight copied some others idea that also oscilloscope may have SFRA.Perhaps also Siglent think same, independently of each others. If only copy idea that oscilloscope may have SFRA is it copying. Perhaps like Nissan or Lamborghini copy Ford.Why I think this?IF Siglent have copied Keysight this model perhaps then they release something total junk crap.But because they did not copy they make something what is even some amount useful and not only for tell students that in the world there is also "BodePlot" and studets roll they eyes.If you look Keysight scope time of release status (attached data sheet detail) you can easy see that this is really not copied by Siglent. Exept if you think that because BMW put 4 wheels under car then Nissan copy BMW and also do same - yes this level perhaps but more I believe that both have independently same idea. SFRA / BodePlot have been as long as I remember. Even I have owned (in history) real bit different "BodePlotter" ... Rohde&S SWOB. Perhaps Siglent get idea from R&S what is more like, as they have also copycat (not copy) some other features from R&S (clearly).So, if you look this Keysight data sheet from release time.. you can see 10 samples / decade (later they have improved it bit because 10pts/decade was really like bad joke. Also it have 20Hz 20MHz limits and also it have only 1 channel.Siglent have max 501 samples even down to 500Hz Span (1Hz step). Example, we have quite narrow 1.4MHz CW filter what need look... say example its width is 300Hz... If now take exaple 1000Hz Span so that 1.4MHz is center it can do samples 2Hz steps. (what can do system with 10 samples/decade).If have some bit more complex circuit it can also take simultaneously 3 independet out from DUT.Who can think Siglent copycat Keysight and then result is so much different and totally in different higher level of performance SFRA in Siglent SDS1004X-E. (but it do not have internal SG)Also freq range is depending used external SG so it can do far more than 20MHz.Of course also Siglent SFRA performance is far below real SFRA analyzers. First thing is poor dynamic range with its ADC. So, for look and adjust example high quality IF filters where stop band need be really far far below pass band it is just impossible to look this stop band. It is not tool for this.Attached Keysight model (release time) data sheet detail about BodePlotSiglent copycat this? Must have a really good ability of imagination.

author: ebastler
author_rank: Super Contributor
timestamp: March 30, 2019, 07:40:54 am
content: Quote from: EEVblog on March 29, 2019, 11:59:11 pmOr this might simply mean that you don't know any trenchcoat guys at Siglent.How would you know when Siglent started prototyping this feature? It's kind of an obvious idea, once you have combined a scope and function generator in one device and look for "what's next" after you are done with FFT...

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 30, 2019, 08:10:52 am
content: Quote from: David Hess on March 28, 2019, 06:00:38 pmiirc i did play with this method while developing bode plotter, using square waves, we'll need few cycles for faithful FFT result. but the result was not as neat as classical sweep method. maybe the setup was poorly controlled.

author: Fungus
author_rank: Super Contributor
timestamp: March 30, 2019, 11:13:31 am
content: Quote from: rf-loop on March 30, 2019, 07:29:56 amSiglent defense league!Maybe they copied their marketing strategy, nothing technical at all.(we were just saying this is probably a marketing decision not to do it)

author: nctnico
author_rank: Super Contributor
timestamp: March 30, 2019, 11:36:53 am
content: Quote from: EEVblog on March 29, 2019, 11:59:11 pmI'm not so sure Siglent copied Keysight. At least not after the Keysight 1000X scope was released. IIRC Siglent quickly came up with an FRA feature which performed significantly better compared to Keysight. Siglent must have been working on this for a long time.

author: Fungus
author_rank: Super Contributor
timestamp: March 30, 2019, 01:25:42 pm
content: Quote from: nctnico on March 30, 2019, 11:36:53 amBut ... if they didn't release it then it was for marketing reasons.When Keysight released theirs with the feature, Siglent followed, ie. they copied them.(just like Rigol 'copied' Siglent by giving away the serial decoders as standard after Siglent did it).

author: nctnico
author_rank: Super Contributor
timestamp: March 30, 2019, 01:32:42 pm
content: Quote from: Fungus on March 30, 2019, 01:25:42 pmDid it ever occur to you that manufacturers can work on the same feature at the same time? They both have the same information about the market so it is likely managements of two different companies came to the same conclusion. You can't add a complex feature like FRA into existing oscilloscope firmware in a couple of weeks. Perhaps Siglent pushed the release schedule a bit but AFAIK Siglent's FRA feature worked quite well out of the box. This is rather unique for them so Siglent must have put a lot of effort into the development and done more testing than usual.

author: tautech
author_rank: Super Contributor
timestamp: March 30, 2019, 01:45:49 pm
content: Quote from: Fungus on March 30, 2019, 01:25:42 pmCopied ?Nahimproved !Examples from forum screenshots at about the same time:Notice the graticule on graticule implementation.Just 2 traces showing of a possible 3

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 30, 2019, 02:46:17 pm
content: it took me couple of days, 1 or 2 weeks at most for my bode plotter iirc, nothing too hard...translated from mandarinQuotefrom autumn in my liver...

author: rf-loop
author_rank: Super Contributor
timestamp: March 30, 2019, 03:14:10 pm
content: Quote from: rstofer on March 29, 2019, 07:21:15 pmUser can select log or lin frequency scale.Vertical scale also can select log or linear.-Display mode can be Vin/Vout OR Vout.Some random examples (test setup and scope settings are not optimal - lack of time)

author: rstofer
author_rank: Super Contributor
timestamp: March 30, 2019, 05:09:49 pm
content: Thanks for the education!That SDS1204X-E that I want is looking better all the time! I'm assuming I can use my SDG2082X as the signal source, right? The scope controls the generator?I know, RTFM. I'll get right on that as soon as I finish reading the comics.

author: rf-loop
author_rank: Super Contributor
timestamp: March 30, 2019, 05:30:40 pm
content: Quote from: rstofer on March 30, 2019, 05:09:49 pmYes, just connect scope example with USB cable with generator. No need do anything but turn SDG power on. Scope BodePlot take full control.But then note. BodePlot UI is not very user friendly. It need some exercises before user can get all out from it. I hope Siglent develop this UI for better usability. Of course after have some experience all can do and find optimal settings and can handle it quite easy. Anyway, it's a little clumsy. UI could have made a lot more user friendly. Example some display runtime adjustments etc need some workout and experience how it can control when it is running.

author: Martin72
author_rank: Super Contributor
timestamp: March 30, 2019, 06:08:27 pm
content: Quote from: jackbob on March 28, 2019, 07:07:52 amBode-Plot function will be implemented on the 5000 (I ask them for it)…..

author: David Hess
author_rank: Super Contributor
timestamp: March 31, 2019, 10:41:06 am
content: Quote from: Mechatrommer on March 30, 2019, 08:10:52 amThe impulse method does not have the dynamic range of the swept sine method but many systems do not require greater dynamic range and it is faster which is convenient when making real time adjustments. It can also work with a single shot measurement which is invaluable when dealing with slow systems like oven controllers.

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 31, 2019, 12:13:34 pm
content: Quote from: David Hess on March 31, 2019, 10:41:06 ami'm not sure my result is something dynamic range related. i dig back my bode plotter and i still have result comparing sweep and square + fft (single capture) method. in fact, the feature is included in the software all this long i've already forgotten (3rd picture). the test was on a simple 4.7uF capacitor, 1st picture is sweep method, 2nd picture is fft method. but i'm not sure if you are talking about the same thing, but i cant think of any other method for single impulse capture other than it has to go through FFT to extract all frequencies component for analysis/plot.since you mentioned real time, i've forgotten how many points i used in the FFT implementation, but bigger points/bins count means slower operation hence not real time. real time needs smaller bins and that means greater spectral leakage in FFT. i think my problem was leakage or/in FFT implementation throwing harmonics/frequencies element's phase and magnitude out , this certainly needs more time for R&D or a paid paper somewhere. maybe some sort of averaging can fix that, but then again, averaging is not real time, for an affordable grade hardwares. fwiw ymmv..

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 31, 2019, 12:41:22 pm
content: or maybe i was just talking about a different thing... or maybe square wave is not an ideal signal for this...

author: jackbob
author_rank: Regular Contributor
timestamp: April 03, 2019, 07:45:21 am
content: Quote from: Martin72 on March 30, 2019, 06:08:27 pmI sure hope so. I have a new MSO5000 on my bench waiting for the update

author: EEVblog
author_rank: Unknown
timestamp: April 03, 2019, 08:04:49 am
content: Quote from: rf-loop on March 30, 2019, 07:29:56 amNo it's not, there is nothing wrong with copying/matching afeaturethat competitor brings out, that's normal business practice.BTW, Siglenthavecopied the UI of Keysight gearcompletelyin previous products, down to every menu option and screen layout.QuoteOf course they did, SFA in a scope is not new, Keysight didn't invent it. But what they did do was to introduce it into an entry level bench scope.Siglent have been working on the same thign at the same time, but I believe Keysight beat them to market, and first to market wins innovation bragging rights, and everyone else "copied"/"followed".QuoteChill out, you seem to be caught up on the word "copy", it's no big deal to copy a feature, in fact it'sexpectedthat a competitor do so.Ford puts airbags as standard in entry level cars, Nissan copies, etc etc.

author: EEVblog
author_rank: Unknown
timestamp: April 03, 2019, 08:16:47 am
content: Quote from: ebastler on March 30, 2019, 07:40:54 amI don't know.As I said in a previous post, it doesn't matter, first to market gets bragging rights and everyone else "copied", that's how it works.

author: nctnico
author_rank: Super Contributor
timestamp: April 03, 2019, 09:51:43 am
content: Quote from: jackbob on April 03, 2019, 07:45:21 amI hope you have time...

author: Martin72
author_rank: Super Contributor
timestamp: April 03, 2019, 05:16:26 pm
content: Always negative, hm?If everything comes in a right way, it won´t be soo long waiting for it.But I don´t have a problem to wait a little bit longer, if their priorities lies more to the bugs as to additional features ( like bode-plot is one).

author: nctnico
author_rank: Super Contributor
timestamp: April 03, 2019, 05:32:26 pm
content: Not negative. Just being realistic... look at the threads about the DS1000, DS2000 and DS4000 series. It has taken Rigol literally years to make these scope relatively bug free and deliver on the promised features.

author: 2N3055
author_rank: Super Contributor
timestamp: April 03, 2019, 05:45:23 pm
content: Quote from: nctnico on April 03, 2019, 05:32:26 pmSo did R&S for RTB2000.......

author: Fungus
author_rank: Super Contributor
timestamp: April 03, 2019, 06:00:56 pm
content: Quote from: nctnico on April 03, 2019, 05:32:26 pma) Not true. My DS1054Z has been relatively bug free and had all features since three months after launch date (unless you count spelling mistakes in the menus as major bugs)b) Why do you even go into "Rigol" threads? It seems to distress you.

author: dkggpeters
author_rank: Contributor
timestamp: April 03, 2019, 07:08:00 pm
content: Quote from: rf-loop on March 30, 2019, 05:30:40 pmOr you can connect using a network. All my Siglent test gear is on the network.

author: dkggpeters
author_rank: Contributor
timestamp: April 03, 2019, 07:13:22 pm
content: Quote from: EEVblog on April 03, 2019, 08:04:49 amThe buttons are different colors. We all know that button color is where it is at.

author: Martin72
author_rank: Super Contributor
timestamp: April 03, 2019, 07:32:34 pm
content: Quote from: 2N3055 on April 03, 2019, 05:45:23 pmSo did R&S for RTB2000.......And so did Lecroy for WS3000......and still it isn´t bug-free.

author: Mechatrommer
author_rank: Super Contributor
timestamp: April 04, 2019, 12:39:57 am
content: Quote from: Fungus on April 03, 2019, 06:00:56 pmmaybe you have not into great depth usage of the scope other than normal usage like we did in CRO age. i for one found few bugs on ni-visa usb communication, others figured in linux usbmtc what? others reported others bugs that i may find minor issues, its true Rigol did fix some of them, fixing major issues obviously normal usage like CRO day usage should be fixed quickly, but for minor delusive features bell and whistle things, it can take months or years of time (not sure if ni-visa usb stuffs is fixed to the date i havent checked). but try asking Rigol to add "new feature" like Bode plot into DS1000Z series, or even ask to show serial data of whole captured in memory (not whats displayed on lcd alone). the same case with this 5000 series is a suspect same situation. asking new feature not originally speced to come in is like an hopelessly eternal wait, if not they try to sell you license at a fortune. not specifically to Rigol, it can be any brand. ymmv.

author: JPortici
author_rank: Super Contributor
timestamp: April 04, 2019, 07:29:22 am
content: Quote from: EEVblog on April 03, 2019, 08:04:49 amtrue datoh, how many thimes this have happened..

author: IDEngineer
author_rank: Super Contributor
timestamp: May 27, 2019, 05:49:39 pm
content: Quote from: David Hess on March 28, 2019, 06:00:38 pmWhich leads me to the question I've been researching a bit lately. There are few scopes that have integrated Bode plot features, and apparently even fewer than include frequency-phase- most seem to just do frequency-amplitude. Proper FFT's yield phase data too, so why not display that?For that matter, it appears even dedicated spectrum analyzers (at least the lower end ones) don't offer to display phase. A quick scan of (for example) Rigol SA's doesn't reveal any way to select phase as a displayed parameter.What am I missing here? Phase response is not exactly a new concept.

author: David Hess
author_rank: Super Contributor
timestamp: May 27, 2019, 07:08:01 pm
content: Quote from: IDEngineer on May 27, 2019, 05:49:39 pmBecause DSO designs are dumb. I suspect it is the marketers who are responsible.QuoteCommon spectrum analyzers are scalar instruments so the phase information is not available.For the phase information, something more along the lines of a network analyzer is required. But a network analyzer lacks the selectivity of a spectrum analyzer so that by itself is not enough. There are some instruments however which combine the capabilities of both.

author: 2N3055
author_rank: Super Contributor
timestamp: May 27, 2019, 07:15:19 pm
content: Quote from: IDEngineer on May 27, 2019, 05:49:39 pmPicoscope FRA shows both phase and gain. Keysight 3000T also has it, together with variable signal/frequency.. As far as I know Siglent 1000X-E has it too, it also have phase, variable level, and also something no other can which is multiple channels simultaneously... I presume Siglent 5000X will have the same (when it's available, if not already).And SA+TG is not a VNA. That is why TG+SA makes SNA (scalar vector analyser, only gain), while VNA (vector network analyser) has gain and phase.

author: David Hess
author_rank: Super Contributor
timestamp: May 27, 2019, 07:51:27 pm
content: Quote from: 2N3055 on May 27, 2019, 07:15:19 pmMy first impulse (1) was to call shenanigans but a review of the Keysight 3000T user manual shows that it does support the needed FFT magnitude and phase function as well as FFT after differentiation so this DSO just moved to the top of my list. The manual even mentions aligning the trigger so they had this application in mind. All other modern DSOs may bow down before it.Based on the Siglent 1000X-E manual, the Siglent does not return FFT phase results. Get thee behind me, Satan!(1) Get it? Impulse?

author: tautech
author_rank: Super Contributor
timestamp: May 27, 2019, 08:22:39 pm
content: Quote from: David Hess on May 27, 2019, 07:51:27 pmCorrect X-E doesn't for FFT but they do for FRA/Bode plot and up to 3 phase results are available as 2N3055 mentioned.From a year old post using earlier FW than now available,https://www.eevblog.com/forum/testgear/siglent-sds1204x-e-released-for-domestic-markets-in-china/msg1436912/#msg1436912Bandpass passive filter, ch4 full response, ch2 high pass

author: 2N3055
author_rank: Super Contributor
timestamp: May 27, 2019, 08:55:07 pm
content: Quote from: tautech on May 27, 2019, 08:22:39 pmI could see this being interesting to look at several stages of active filter at the same time on single correlated screen.Or a test of an active crossover and plot 3 frequency bands simultaneously so you can see overlap.Also, since Siglent uses external SG, in theory you could go quite high in frequency withSDG5000SDG6000 and SDS5000X....Another interesting thing about that scope.Keysight 3000T FRA app is very nice and works real good. It maxes out at 20MHz because of siggen.EDIT: yes Tautech I meant SDG6000, not SDG5000 . Even more stupid mistake since I have it on the desk

author: tautech
author_rank: Super Contributor
timestamp: May 27, 2019, 09:03:54 pm
content: Quote from: 2N3055 on May 27, 2019, 08:55:07 pmOf course you mean SDG6000X ^Performa01 has the 500 MHz version and of course a pre-production SDS5104X.................

author: alsetalokin4017
author_rank: Super Contributor
timestamp: May 27, 2019, 09:27:37 pm
content: ...

author: 2N3055
author_rank: Super Contributor
timestamp: May 27, 2019, 09:29:58 pm
content: Quote from: tautech on May 27, 2019, 09:03:54 pmWell I have the SDG6000 but no SDS5000X...Which, as the time goes by, I itch more and more to compare it to my MSOX3000T to see how it fares.Unlike specification comparisons, I would like to make direct comparison how it is when doing real world tasks, like measuring, decoding, how good is MSO integration etc etc.From what I tried quickly, it felt real nice and quick... But I would like to try side to side comparison.For instance, I have a NFC devkit on my desk now. Keysight 3000T has NFC triggers, but if you capture whole packet it starts undersampling severely. I have to enable peak detect mode to see propper amplitude of signal. There is even a trick that Keysight devised to route trig out (that works at full sample rate) back to second input channel as a decoded signal, and then you use that to decode with Manchester decode.That kind of thing happens all the time. It would be much better if it had more memory. I use Picoscope quite often because of that.Having both good responsive scope and long mem would be nice...

author: IDEngineer
author_rank: Super Contributor
timestamp: May 27, 2019, 09:59:56 pm
content: Quote from: tautech on May 27, 2019, 08:22:39 pmVery impressive. I don't need a scope in the range of the 1000X-E series but for this feature, alone, I might buy one. I already have a Siglent SDG sitting right here on the bench, it might appreciate another member of the family.I understand the difference between SNA's (SA's) and VNA's but if the SA in question is not "real time" (i.e. swept oscillator + mixer) then it's almost assuredly doing (inverse) FFT and the phase data is right there, waiting to be displayed.EDIT: I presume the firmware is shared across all models of the 1000X-E line? Or do you have to dig through the specs of each model to confirm that each specific combination of bandwidth and channel count have the Bode Plot feature? The 1104X-E is many tens of percent cheaper than its 200MHz 1204X-E sibling and 100MHz should be plenty for a "Bode Plot Instrument" on my bench.

author: 2N3055
author_rank: Super Contributor
timestamp: May 27, 2019, 10:04:42 pm
content: Quote from: David Hess on May 27, 2019, 07:51:27 pmWell you are correct 3000T has FFT gain/phase. I believe we had a discussion about that once. In meantime I got the 3000T that got on top of my list too..Not perfect though, I have to be careful when it starts undersampling, sampling rate drops really quickly because of small mem. But, when poking around unknown signals , I just switch on peak detect. That way I don't miss that there is something there. But, my Picoscope with 512 MPoints gets fair amount of use when 3000T memory won't do...But we are discussing FRA function, and in that regard, Siglent seems to have good idea how it should look. I didn't test it in detail myself, so no idea how good is code quality, but very good concept.(1) I had to integrate that charge a bit before I detected the pun...

author: 2N3055
author_rank: Super Contributor
timestamp: May 27, 2019, 10:07:53 pm
content: Quote from: IDEngineer on May 27, 2019, 09:59:56 pmWell, it doesn't have two inputs to synchronously sample both input and output to be able to get accurate phase/gain.

author: IDEngineer
author_rank: Super Contributor
timestamp: May 27, 2019, 10:08:26 pm
content: BTW, there's a sort of appnote on Siglent's website illustrating the use of the Bode plot feature. Only one channel for each of amplitude and phase, but still.http://old.siglentamerica.com/USA_website_2014/Documents/Other/Bode-plot-application.pdf

author: IDEngineer
author_rank: Super Contributor
timestamp: May 27, 2019, 10:11:13 pm
content: Quote from: 2N3055 on May 27, 2019, 10:07:53 pmTrue. I was thinking of SA's I've used that do have two inputs to do the comparisons (old ham radio back in the day). I actually have a small DDS-based PC-hosted unit for working on antennas and even THAT has two inputs.In the back of my mind it seems the plot could show phase relative to the start of the sweep, perhaps, and that could be done with a single input. After all, even real time SA's are displaying amplitude and they are only processing a single input, so the displayed amplitude is relative to some baseline - not a real time comparison against another input. For many applications I think a relative phase display would be sufficient.EDIT: I wonder if this could be done with the math/equation features on a regular scope. My Rigol DS4000 understands phase, for example... I need to dig into what it exposes in math equations. Perhaps it's possible to hack your way there, if you're patient for the math to be processed. Not sure it supports a log X axis but if the SG generates a log sweep you'd end up with the same display format.

author: 2N3055
author_rank: Super Contributor
timestamp: May 27, 2019, 10:29:02 pm
content: Quote from: IDEngineer on May 27, 2019, 10:11:13 pmSA has absolute level calibration. Phase is always relative relationship. A timing relationship between two edges of signal. Sweep start means nothing in that regard.Picoscopes have FRA app written that uses scope as sampler.I still have to test it in detail at low frequencies with 4262 16 bit scope. With 3406D it works real nice.

author: IDEngineer
author_rank: Super Contributor
timestamp: May 27, 2019, 10:34:40 pm
content: Quote from: 2N3055 on May 27, 2019, 10:29:02 pmIf it's a swept sine, the zero crossings would give you that reference. You could resync no less frequently than every 180 degrees and accuracy would be dependent upon purity of the original sine and whatever distortion the circuit under test imposed upon its output. The effect of distortion could also affect a true two-input VNA, though for different reasons since it has a realtime reference input.I'm just saying a modest Bode Plot feature that includes phase could be achieved in this manner. Wouldn't duplicate the results of a Keysight VNA, but wouldn't duplicate its price either.I'm still impressed that two pieces of equipment from Siglent, totaling under $1K, can give you an amplitude+phase Bode Plot out to tens of megahertz.

author: David Hess
author_rank: Super Contributor
timestamp: May 28, 2019, 12:52:34 am
content: Quote from: tautech on May 27, 2019, 08:22:39 pmThe FFT method works with single shot acquisitions and in real time albeit with lower signal to noise so it is more useful for slow systems and for real time adjustments.Swept measurements I can do semi-automatically almost as fast as these DSOs can do it automatically so this feature as not as useful for me.

author: David Hess
author_rank: Super Contributor
timestamp: June 01, 2019, 04:32:20 am
content: Quote from: David Hess on May 27, 2019, 07:51:27 pmI went through the Keysight 3000T user manual in detail and am not quite so impressed now. It seems like either Keysight deliberately crippled its functionality or whoever decided to add support for FFT phase results did not understand their application and just included them as a "checkbox" item.But it is a start.

author: vr2whf
author_rank: Contributor
timestamp: January 23, 2020, 08:23:13 am
content: https://chipsnwafers.electronicsforu.com/2020/01/18/rigol-expands-its-portfolio-with-customisable-digital-oscilloscopes/"The BodePlot function has now been integrated into all MSO5000 series oscilloscopes. Both the MSO8000 and MSO5000 models have been expanded with a 12-bit high-resolution mode. "It seems not an official source. Anyone can verify it?

author: EEVblog
author_rank: Unknown
timestamp: January 23, 2020, 10:44:01 am
content: Quote from: jackbob on March 28, 2019, 07:07:52 amMore importantly, their new scopes don't have hires boxcar averaging!I've kind convinced myself (based on zero evidence) that it must have been a goof in their new ASIC and they didn't want to respin it, so they just left out the feature

author: EEVblog
author_rank: Unknown
timestamp: January 23, 2020, 10:46:36 am
content: Quote from: IDEngineer on May 27, 2019, 10:34:40 pmThe analog discovery does this for 1/4 the price and at higher resolution.

author: Sighound36
author_rank: Frequent Contributor
timestamp: January 23, 2020, 01:04:25 pm
content: Quote from: vr2whf on January 23, 2020, 08:23:13 amI would suggest that the 12 bit high resolution mode is correct for the 5000 & 8000 but as far as the bode plot function goes it's located could be a little beyond me

author: vr2whf
author_rank: Contributor
timestamp: January 23, 2020, 03:15:04 pm
content: Quote from: Sighound36 on January 23, 2020, 01:04:25 pmThe news came out 4 days ago. Not sure if Rigol has planned a firmware upgrade to introduce the Bode Plot function to MSO5000.

author: Sighound36
author_rank: Frequent Contributor
timestamp: January 23, 2020, 03:27:21 pm
content: Hello vr2whfI know Martin72 did make a point of mentioning it to the German Distributor a while back, I have both a 5000 and 8000 series and they have high rez and precision modes, but currently no bode plot facility which in fairness they really should have from the start point of the models inception, however we live in hope

author: IDEngineer
author_rank: Super Contributor
timestamp: January 23, 2020, 09:02:22 pm
content: Quote from: EEVblog on January 23, 2020, 10:46:36 amGood point! Might justify Yet Another Equipment Acquisition. "No, really dear, I NEED this."

author: Martin72
author_rank: Super Contributor
timestamp: January 23, 2020, 09:12:25 pm
content: Quote from: EEVblog on January 23, 2020, 10:44:01 amToday (after firmware updates) they got a hires mode or do you mean something different ?QuoteYep, statement was, bode plot will come…But also the next update will come in may (2019)...

author: thm_w
author_rank: Super Contributor
timestamp: January 23, 2020, 11:14:13 pm
content: Quote from: EEVblog on January 23, 2020, 10:44:01 amThey added it in the last FW, it just doesn't work well at all... eg its say 8->9-bit, not very useful compared to 8->12-bit.But I 100% agree its probably some ASIC screw up, now they have to figure out how to re-implement it in the FPGA or in software.Having it in the ASIC HW would have been a great feature. Sampling at 8-10GS/s you'd get ~4x oversampling or more with basically no BW/CPU penalty.Hell the STM32 ADC's have the same feature of HW oversampling for some years.

author: EEVblog
author_rank: Unknown
timestamp: January 24, 2020, 03:27:49 am
content: Quote from: thm_w on January 23, 2020, 11:14:13 pmWhen you spend years developing an ASIC to be one of the "big boys" and compete with the likes of Keysight that have done it in their ASIC for eons, you'd think it'd be a basic requirement.But then Rigol release several model scopes using the new ASIC and the Hires feature is mysteriously absent, only to now surface more than a year later in a firmware update...

author: qft1967
author_rank: Contributor
timestamp: January 26, 2020, 12:01:55 pm
content: I wrote a Python script to use my new Rigol DG811 (Upgraded to 100 MHz) and the DS1054z to perform a 'Bode Plot'. The noise performance is actually pretty good. At the higher end it is limited by crosstalk between Channel 1 and 4. Crosstalk between CH1 and CH2 was horrible, but between CH1 and CH4 quite accetable. I think this plays in the same class as the Siglent, and the speed is also similar. Depending on the memory used, it takes the following amount of time per point:Speed and Bandwidth at 250 MSa/s:6k: ~1 s per point RBW: 40k Hz at 250 MSa/s:60k: ~1 s per point RBW:4k Hz at 250 MSa/s:600k: ~2 s per point RBW:400 Hz at 250 MSa/s:6M: ~20 s per point RBW:40 Hz at 250 MSa/s:Attached you see the noise floor once for 600k Memory, and one for 6M Memory. Blue is gain and grey is phase.

author: rstofer
author_rank: Super Contributor
timestamp: January 26, 2020, 05:42:06 pm
content: You can get a nice magnitude/phase versus frequency plot (I'm going to continue calling it a Bode' Plot) with the Digilent Analog Discovery 2 and on a far bigger screen than a scope. But only up to 10 MHz. Still, for my needs, this is more than adequate.And, yes, in college we drew the 'curves' by hand and did the calcs with a slide rule. I blessed the day when I installed the IBM Electronic Circuit Analysis Package on the IBM1130 (circa '71). Now I could get actual plots. Sure, it turned the homework into a full time project but the plots looked really nice.

author: Sharp
author_rank: Contributor
timestamp: September 29, 2021, 01:03:25 pm
content: Hi guysI hope one of you experienced guys can help me… I’m looking into designing a low pass filer using my Rigol MSO5000 Bode Plot feature for the first time.When I use LTSpice to simulate a LC filter I get a different result compared to my MSO5000.BTW is it right that you only can use the Rigol probes in times 1 and not in times 10 setting ?source 1V, coil: 0.010mH, 0.63 ohm and capacitor: 4,468 uF with ESR 6.2 ohm

author: Fungus
author_rank: Super Contributor
timestamp: September 30, 2021, 10:45:36 am
content: Quote from: Sharp on September 29, 2021, 01:03:25 pmNo.Normally you work in 10x mode.1x mode is the exception as it severely reduces the bandwidth. In 1x mode you normally enable the 20Mhz limiter on the 'scope.

author: Sharp
author_rank: Contributor
timestamp: September 30, 2021, 01:09:16 pm
content: @Fungus thank you for your replyBut when I use my probes in times 10 mode the Bode plot looks very strange, but when I switch to times 1 mode it looks “normal” That’s why I’m confused…

author: thm_w
author_rank: Super Contributor
timestamp: September 30, 2021, 09:09:18 pm
content: Post screenshots of what you are talking about. Also post the circuit and graph of the bode there.You could manually sweep through the frequencies using the built in AWG too, and see if its doing what you think it should be doing. eg stop once you hit -3dB, is that the same -3dB as the bode result shows?

author: Sharp
author_rank: Contributor
timestamp: October 03, 2021, 08:20:26 pm
content: @thm_wThank you for your reply - I found the error - Error 40 - My mistake