My sorry attempt at a review - DS1104Z - Page 1
Forum section: electronics / testgear

author: jadew
author_rank: Frequent Contributor
timestamp: January 15, 2014, 09:51:03 am
content: I wish I knew how to add a youtube video, so here's the link:The video is pretty much a fail, but it might at least offer a bit more info on the DS1000Z series. I did try to make it good, but that's all I could put together from a few hours of footage.The quality sucks too...In case the video gets automagically embedded in here, here's the description:"Sorry for my english and my crude editing skills.The review didn't came out as I expected because I found it a bit hard to express myself in english with out thinking for a second about what I was about to say.Anyway, I hope it at least gives prospective buyers an idea on what it can and can't do. I tried to cover the things that I found lacking in the other reviews that are currently out and it's made from the perspective of a DS1052E owner.Thanks for watching"

author: electronics man
author_rank: Frequent Contributor
timestamp: January 15, 2014, 12:45:35 pm
content: I recently got this scope I realy do love it ther are some problems but realy for the price it is amazing I meen4 channels for £445 is just incredible it is a very good scope rigol have set a new benchmark for spec. Even a very good agilant can't beet it memory depth it is realy amazing. It would be nice if the sample rate were higher though.

author: jadew
author_rank: Frequent Contributor
timestamp: January 15, 2014, 12:58:29 pm
content: Yeah, I enjoy it as well and yes, it could have used a second ADC, 250 Msps is a bit low.

author: marmad
author_rank: Super Contributor
timestamp: January 17, 2014, 05:06:42 pm
content: Thanks for your video! BTW, it's totally fine - and it does offer some new info on the DS1000Z. Not enough owners are publishing any in-depth info about the DSO.A couple of points and questions:1)The DS2000 allows measurements on MATH - both horizontal, vertical, and all - so if any of that is missing on the DS1000Z, I suspect it's a bug:2)As mentioned in other threads on the forum, most of the new generation of cheaper DPOs (like the Agilent X-Series, Rigol UltraVision, etc) DON'T have Alt-Triggers. I theorized that perhaps the reason it's not included is because it would be difficult to support intensity-grading of two distinct time bases at a reasonable speed. In some situations, you can at least achieve a stable display of two non-time-correlated waveforms by using one of the dual source triggers of the Rigol - such as the Delay Trigger - which allows you to trigger after edges (or other conditions) from each channel with an adjustable </>/<>/= time between them. This image shows triggering on two uncorrelated waveforms:3)Does the DS1000Z allow MATH functions using a REF waveform as a source? This is something missing from the DS2000 - and it would be nice if they would implement this function.4)In another thread about the DS1000Z, there was some discussion of the fact that the DS1000Z appears to, at many voltage scale settings, to digitally scale (like a camera digital zoom) a smaller set (< 200) of the ADC sample values to fit the screen. This can result in a display that looks like it has horizontal stripes running through it (as in the following image). Unfortunately, Rigol fails to include this info in their datasheets (the DS2000 scales the 500uV setting). Any chance you might test this with a graded signal (such as AM signal) and see how many of the main scale settings (not the fine scale, just the coarse settings) this might be visible on?Once again - thanks for your efforts!

author: jadew
author_rank: Frequent Contributor
timestamp: January 17, 2014, 07:03:52 pm
content: Hey,Quote from: marmad on January 17, 2014, 05:06:42 pmIn that case, I really hope it's a bug, but I'm worried it could be because the CPU can't handle it. I think I forgot to put that piece in the video, but I was complaining about how slow is everything (including saving a screenshot). It's possible that doing additional processing on top of the already slow MATH channel, might slow it down to a crawl.I actually took this screenshot with the Source menu opened, but it didn't show up in the screenshot (I noticed other elements don't show up in screenshots either - like the channel labels).Quote from: marmad on January 17, 2014, 05:06:42 pmNope, indeed it would have been very nice.Quote from: marmad on January 17, 2014, 05:06:42 pmI don't have a proper AM modulated signal, but I did take a look at some noise and indeed, the issue you're talking about is apparent on the lowest voltage scale (1mV/div).I couldn't reproduce the exact thing you have in your screenshot (which looks like digital zoom), however I got something similar, but I don't think it's proof of digital zoom but rather an intensity grading issue. The reason for that is because there are visible spikes in my screenshots that are smaller in amplitude than the region with the same color grading, while the fact that most spikes are about the same amplitude could be due to the repeating nature of the noise:Now... this one is the only one I could get that I'm positive it has digital zoom:And a little zoom inside it:

author: Dongulus
author_rank: Regular Contributor
timestamp: January 17, 2014, 07:14:17 pm
content: Your English speaking is fine and you are perfectly understandable. Hearing yourself speaking always sounds worse than what someone else hears.Thanks for the review. I've had my eye on this series of scopes and it helps to see one in action. I've had my concerns with the usability of the UI and it appears to be okay. It's good to know that it does have some quarks when there is a lot of menus, measurements, and multiple waveforms on screen.

author: jadew
author_rank: Frequent Contributor
timestamp: January 17, 2014, 07:49:06 pm
content: @ Dongulus,Thank you for the encouragement.I'm not sure if this particular bit of information is apparent in the video, but I'm very happy with it and I think it's a great oscilloscope. It does fine with all 4 channels active, the problem seems to be when it's doing extra stuff.If I were you, I'd hold off for a bit longer from buying one right now and see if the little issues it has will be fixed with a firmware update or a new hardware revision.

author: marmad
author_rank: Super Contributor
timestamp: January 17, 2014, 08:11:11 pm
content: Quote from: jadew on January 17, 2014, 07:03:52 pmWell, even on the DS2000, getting the Measurements menu to switch to the MATH channel (change color) is a little erratic. After you've turned on the MATH function (BTW, they won't work for FFT) sometimes you have to first press one or two CH buttons and then press the MATH button to get the measurements menu to switch. So if you haven't tried this yet, try turning on MATH then alternate between pressing CH1, CH2, and MATH button. Even if the DS1000Z can't handle doing ALL measurements for MATH, you'd think it could handle a maximum of 5.QuoteThanks for testing that. From other tests it seems as if the DS1000Z is doing it (digital zoom) a smaller amount at other scales too - but if it's not noticeable in the displayed image (which always gets upscaled by at least a factor of 2x for the 400 vertical pixels anyway), at least it won't be visually distracting.

author: jadew
author_rank: Frequent Contributor
timestamp: January 17, 2014, 08:29:05 pm
content: Quote from: marmad on January 17, 2014, 08:11:11 pmTried it, didn't work.Quote from: marmad on January 17, 2014, 08:11:11 pmI see, so the 2 pixels I was seeing in there are nothing out of the ordinary.I took a better look at the screenshot you showed me and while the general feel is that of pixelation both vertically and horizontally, it still shows fine detail on the margins, which might mean that they're not doing any digital zoom and it's in fact just a case where their intensity grading algorithm fails.

author: nctnico
author_rank: Super Contributor
timestamp: January 17, 2014, 08:39:55 pm
content: Quote from: marmad on January 17, 2014, 08:11:11 pmIt would be nice to test again with a sine wave. If the signal is being scaled up then it should be visible. Perhaps it takes different frequencies to make the effect visible. Rigol could use oversampling on longer timebase settings.

author: marmad
author_rank: Super Contributor
timestamp: January 17, 2014, 08:49:40 pm
content: Quote from: jadew on January 17, 2014, 08:29:05 pmWell, the stripes are caused by scaling the sample values. When digital scaling is present, it's apparent (at the smaller scales) on the DS2000 when you turn off Vectors and look at the Dots. Interpolation plus intensity-grading tends to hide it more.EDIT:Perhaps they've gotten more clever with how it's implemented on the DS1000Z series.QuoteOn the DS2000, 250 ADC values are ALWAYS mapped to 10 divisions (the 8 you see +/- 1 above/below) - UNLESS: you are at the 500uV scale (which is 1mv x2) - or any fine vernier scale (e.g. 2.2V) - which is mathematically derived (as opposed to a fixed resistor on the PCB) - i.e. digital zoom. This chartposted by syncindicates that the DS1000Z is doing some mathematical scaling at other settings and based on other factors (such as number of channels on).

author: electronics man
author_rank: Frequent Contributor
timestamp: January 17, 2014, 09:35:58 pm
content: Talking About the slow maths functions I was doing FFT on a sine wave that was increasing in frequency fairly slow I was just increasing the freq using the encoder on my function gen and the the FFT was realy slow to update I it took about 5 or 6 seconds to update each time. I would like to see if rigol will correct this with new firmware. I can't comment on other things as this is my first dso

author: Pasky
author_rank: Regular Contributor
timestamp: January 17, 2014, 11:07:10 pm
content: Is the 1000z basically a 2000 series with a signal generator?

author: marmad
author_rank: Super Contributor
timestamp: January 17, 2014, 11:34:53 pm
content: Quote from: Pasky on January 17, 2014, 11:07:10 pmNo, the DS2000 has more bandwidth, more memory, more features, faster hardware, etc. - but they share a certain amount of the hard and soft tech - as do all of the UltraVision series of DPOs.

author: Mark_O
author_rank: Frequent Contributor
timestamp: January 18, 2014, 02:29:07 am
content: Quote from: Pasky on January 17, 2014, 11:07:10 pmNo, not at all. It's more of a scaled-down 2000, less expensive, with twice the channels.Either can have a signal-gen, as a purchase-time option (-S models).

author: Mark_O
author_rank: Frequent Contributor
timestamp: January 18, 2014, 02:31:48 am
content: Quote from: marmad on January 17, 2014, 11:34:53 pmHey! With your DS2000 more, more, more mantra, you left out "more money" and "lesschannels".

author: electronics man
author_rank: Frequent Contributor
timestamp: January 18, 2014, 12:40:33 pm
content: Yeah and 24Mpts is still massive compared to other scopes whitch may only have a few meg

author: marmad
author_rank: Super Contributor
timestamp: January 18, 2014, 01:14:55 pm
content: Quote from: Mark_O on January 18, 2014, 02:31:48 amWell, unless you believe more of something is cheaper than less, that seems obvious.As far as the efficacy of those 4 channels go, it really depends on what your work is. The effective reliably-interpolated maximum analog bandwidth of the DSO when using 4 channels is ~25MHz (well, ~31.5MHz if you're charitable), and it's clear from the OPs video that the UI is a bit on the slow side. Definitely handy for certain situations (like 4-channel protocol decoding) - but it's not a 4-channel100MHzBW DSO.

author: cybermaus
author_rank: Frequent Contributor
timestamp: January 18, 2014, 05:24:39 pm
content: Quote from: jadew on January 17, 2014, 07:49:06 pmGlad to hear you say so, I had the impression the device was being bashed a little in this thread, and I am quite happy with it myself.I come directly from a Analog CRO, so I may not know precisely what the norm is for DSO or what to expect. And I agree, maybe the UI could be faster. Especially when you do math or if it has a difficult trigger.But I am quite happy with it, I am convinced it is a step up from most other DSO targeted to the hobbyist like DS1054 or Owon SDS or Hantek clones. (not sure about Owon TDS)Sure a DS2000 would be better, and even better yet would be two DS2000 or a DS4000. But where does it end? If you compare it, compare it against its correct pricerange, and I still believe it then is the best choice. @Marmad: Don't go telling people a entry level Volkswagen is junk just because you own a top level Audi.

author: marmad
author_rank: Super Contributor
timestamp: January 18, 2014, 06:23:24 pm
content: Quote from: cybermaus on January 18, 2014, 05:24:39 pmWell, I'm not trying to do that! Sorry if it came across that way; I think the DS1000Z is a great bargain - and I'm a fan of Rigol's entire UltraVision line. But with new products in general - and new Chinese products specifically (since most manufacturers from there seem to be a little reticent about admitting faults or weaknesses), it's important for prospective buyers to know as much as possible to make informed choices - and that includes the bad as well as the good. There are plenty of things wrong with the DS2000 too - just read awhile over in the other thread.I was never making a value comparison of the DS1000Z to the DS2000 - I was only interested to know what FW changes/additions/omissions Rigol had made when they developed the newest addition to the UltraVision line. Each product fits a different segment of the market.

author: Hydrawerk
author_rank: Super Contributor
timestamp: January 18, 2014, 06:32:40 pm
content: Quote from: marmad on January 18, 2014, 01:14:55 pmIsn't there an equivalent sampling feature? With that you can have a 100MHz oscilloscope with only 250MSa/s. Like that old HP 546000 series. Well, they say nothing about it...http://www.rigol.com/prodserv/DS1000Z/

author: nctnico
author_rank: Super Contributor
timestamp: January 18, 2014, 10:01:42 pm
content: Quote from: Hydrawerk on January 18, 2014, 06:32:40 pm250Ms/s is enough for 100MHz but it depends on the interpolation whether you get a pretty picture or not. The more pressing problem is aliasing and I'm pretty sure you'll see lots of aliasing on this scope with 4 channels on. An interesting tests would be to feed the scope 62.5MHz (and a little bit) and display 1, 2 and 4 channels.

author: marmad
author_rank: Super Contributor
timestamp: January 18, 2014, 10:15:17 pm
content: Quote from: nctnico on January 18, 2014, 10:01:42 pmBy "pretty picture" do you mean a reasonable facsimile of the waveform?The sampling rate is almost certainly too low for reliable sin(x)/x - and 2.5 samples per period are not enough for an accurate linear reconstruction, pretty or not.

author: jadew
author_rank: Frequent Contributor
timestamp: January 19, 2014, 05:13:42 am
content: Quote from: nctnico on January 18, 2014, 10:01:42 pmAny particular reason why you picked that frequency? I can't do 62.5, but I can do 64.As for equivalent sampling - I haven't found that yet.

author: cybermaus
author_rank: Frequent Contributor
timestamp: January 19, 2014, 07:09:13 am
content: exactly 1/4 of 250 sample.If you are *exactly* exactly, it would not show any artifact, but near the sampling frequency, so if you have 62.49 (or of the actual sampling is 250.01) some interesting things may show.

author: marmad
author_rank: Super Contributor
timestamp: January 19, 2014, 03:07:33 pm
content: One nice feature that the DS1000Z has - which both the DS2000/4000 are missing - is the ability to manually turn ON/OFF sin(x)/x interpolation. On the 2000/4000, this is always automatic.I'm curious if this puts the decision on which interpolation to usefullyin the hands of the user - or whether the DSO sometimes overrides the setting. As usual, Rigol's documentation is lacking.

author: cybermaus
author_rank: Frequent Contributor
timestamp: January 19, 2014, 08:58:12 pm
content: Yes, I do seem to have full control over sin(x)/x on/off (aquire menu), as well as separately over dot/vector (display menu).EDIT: correction: I can only control sin(x)/x when displaying 3 or 4 channels. On all timescales, with 3/4 channels I can turn it on/off, with 1/2 channels, I cannot control it and is is grayed out "on"In dot mode sin(x)/x does not do anything of course. But to be honest I am not so sure sin(x)/x is useful for vector either. I may try to keep it off just because of the notion that it saves on CPU power.Screenprints: 1, 2, 3, 44-channel on (so 250Ms per channel) feeding one of them a 12.5+25MHz input sine1: Dot mode (either sin(x) on or of, does not matter), single shot2: Dot mode (either sin(x) on or of, does not matter), run/stop on full frame-rate (so sort of with equivalent sampling)v3: vector mode, sin(x) on, single shot4: vector mode, sin(x) off, single shot5: vector mode, sin(x) ??, run/stop (forgot how it was set)Bonus: Dot mode with only one channel

author: marmad
author_rank: Super Contributor
timestamp: January 19, 2014, 09:15:09 pm
content: Quote from: cybermaus on January 19, 2014, 08:58:12 pmAssuming that the DS1074/1104Z have a similar input filter to the DS2072/2102, you would probably be best served by not using sin(x)/x when sampling rates <=250MSa/s (unless you use the 20MHz BW limit). But for the 500MSa/s and 1GSa/s rates, the sin(x)/x interpolation will give you more accurate waveform reconstruction with smaller sample sizes.

author: Mark_O
author_rank: Frequent Contributor
timestamp: February 13, 2014, 08:40:47 am
content: Some confusing commentary here.Quote from: marmad on January 18, 2014, 01:14:55 pmHuh? I don't recall you suggesting the "effective reliably-interpolated maximum analog bandwidth" of the DS2072 (modded to 200MHz) was only 100MHz? (Whose max sampling rate with 2 channels enabled is 1GHz.) So why have you chosen to select a 10x oversampling qualifier here?QuoteAgain, why? If running at it's max 250MHz sample rate, that's certainly adequate for 100MHz on all 4 channels. When sampling slower, of course, it's not.Quote from: nctnicoI understood what you meant, though marmad did not. If it does sin(x)/x properly (and perhaps it doesn't??, which would explain marmad's comments), then you get the "pretty picture", aka, accurate waveform display, you referenced.QuoteWhy are you sure there will be lots of aliasing? While it's certainly possible to have the sample rate set too low, while examining a signal source with high-frequency components that will cause aliasing, that's true ofanyscope.Quote from: marmadI agree with the later, but don't understand the former?

author: mrflibble
author_rank: Super Contributor
timestamp: February 13, 2014, 12:07:17 pm
content: Thanks for this video!I found your English easy enough to follow, so wouldn't worry about that.As a prospective 1074Z buyer I like to know all the good & bad before I really really buy one, and your video highlighted a few things I hadn't seen in other vids yet. GUI sluggishness would be a bit of a concern, because that is one of the many reasons why I'm looking for a new scope. The old one is very nice, but it's got the drawbacks of all the old DSO's: low memory depth, and bleeping slow CPU (68020). Now the 68k was great fun in the Amiga era, but uhm, yeah... it's a bit slow compared to modern stuff.

author: marmad
author_rank: Super Contributor
timestamp: February 13, 2014, 03:51:03 pm
content: Quote from: Mark_O on February 13, 2014, 08:40:47 amActually, I've been suggesting exactly the same problem for the DS2000 when it's bandwidth is300MHz; 200MHz is not an issue for it since it doesn't attempt to do sin(x)/x interpolation at sample rates below 1GSa/s (which puts the Nyquist frequency at 500MHz).Themajor stipulationfor sin(x)/x interpolation (which is a mathematical formula imposed on the sample points as opposed to just connecting the dots) to function correctly (i.e.notintroduce errors into the reconstruction) is that NO components above the Nyquist frequency be present in the sampled signal. That is the MAIN rule thatmustbe followed (to reap the benefit of a lower sample rate to frequency ratio) - there are reams of literature about it.At 250MSa/s, the Nyquist frequency is 125MHz - and according to BW tests I've read about for the DS1000Z - frequencies >=125MHz do not seem to be adequately attenuated to make sin(x)/x interpolation a reliable option at that sample rate (i.e. there's no way to know for sure if it's introduced errors in the waveform).So, just as the DS2000automaticallyswitches to linear interpolation at sample rates <=500MHz, I would suggest a DS1000Z owner that wants reliable signal reconstruction should switch to linear interpolation at sample rates <= 250MHz -or else- bandwidth-limit the signal to 20MHz. Either of those options, obviously, reduces the "effective reliably-interpolated maximum analog bandwidth" of the DSO when using all 4 channels.QuoteYou mean adequate when using an input filter designed to properly attenuate signals >=125MHz, don't you? Not only that, but a 2.5:1 ratio is actually fairly 'bottom-end':From a LeCroy document on sin(x)/x interpolation:"SinX interpolation works very well only when this ratio is greater than 2:1. 3:1 is a good ratio, with 4:1 usually working almost perfectly."Again, the original 200MHz DS2000 only uses sin(x)/x when the ratio is 5:1 or greater.QuoteI understood him perfectly fine, but I think he's wrong - at least in terms of the DS1000Z. He either doesn't understand how errors can be introduced into sin(x)/x reconstruction, hasn't thought about the filter roll-off of the DS1000Z, believes a sample rate 2.5x the highest frequency is good enough for linear interpolation, or is just speaking in non-specific, general terms. I'm guessing the latter, since that seems to be his MO on the forum in numerous threads.In theory, 250MSa/s is (just) fast enough for a sin(x)/x reconstruction of 100MHz - but in the real (Rigol-designed-input-filter) world, I don't believe it is.

author: Mark_O
author_rank: Frequent Contributor
timestamp: February 14, 2014, 01:26:52 am
content: marmad, thanks for taking the time to clarify.Quote from: marmad on February 13, 2014, 03:51:03 pmYes, I did see that. Which most would apparently prefer to ignore. "Hey! I've got a 300MHz scope!"QuoteThanks. I wasn't aware of that. So it does linear reconstruction for 200MHz signals, when sampled at 500MSa/s.I wondered how that differed from the 1000Z though, also in linear mode for 100MHz signals, sampled at 250MSa/s? You wrote, "...2.5 samples per period are not enough for an accurate linear reconstruction, pretty or not."[This is one example of what puzzled me about your original posts. You appeared to be singling out the 1000-series for criticisms, that applied equally well to the 2000; which you'd never been concerned about. E.g., I had never heard you say about a DS2202,"it's not a2-channel200MHz BW DSO".But of course, the DS2000 goes one step further, by offering double the sample rate, because it's not trying to mux one ADC 4 ways (to save costs). So there you get 5 samples per period, instead of 2.5, and that's enough for reliable sin(x)/x reconstruction of a 200MHz signal. So now I understand what you were getting at.]QuoteYep. Thanks for the review of Sampling Theory 101.QuoteYou may be right about the 1074Z, rated at 70MHz, but actually only -3dB ~90MHz. You're certainly correct about the "100MHz" 1104Z, which is actually -3dB at ~160MHz. 250MSa/s is nowhere near adequate for sin(x)/x curve-fitting you can believe in, on a real or modded 1104Z. And therefore shouldn't be used in 4-channel mode.QuoteIt would certainly be nice to have some better control over the BW Limiting, especially considering the realities of sampling constraints. It's too bad the attenuator chip Rigol uses has only 20MHz and 100MHz rolloffs, at the low end. 80MHz and 50MHz would be handy to have.QuoteYes. And, yes.QuoteThanks! I've read a lot of LeCroy's stuff, but don't recall this. I liked the "usually", and "almost", with 4x.I would have expected them to say, "works very well" with >2.5:1 though, rather than 2:1. LeCroy uses good filters, but they're not brick-wall (because they'd introduce too much phase-shift in the pass-band).QuoteAfter reading your additional commentary, I'd have to agree with that conclusion.Thanks again.

author: marmad
author_rank: Super Contributor
timestamp: February 14, 2014, 04:38:19 pm
content: Quote from: Mark_O on February 14, 2014, 01:26:52 amWell, whenever I'm using linear interpolation rates (<= 500MSa/s on the DS2000), I'm assuming that the effective reproducible bandwidth is 8-10x less than the sample rate. Fortunately, because of the memory depth of the DS2000, I can use the maximum sample rate (1-2GSa/s & sin(x)/x) with both channels on down to 2ms/div, if I so desire. But, as you mentioned, because of the single ADC, this is impossible on the DS1000Z with 3-4 channels on.