Thoughts on MSOS104A vs HDO6104A-MS vs MSO56?

[Neganur]

I did notice you had the DSOS for sale. How did you find it overall?

Very happy with it, it is very nice to use and compared to the 9000-series the USB3 and fast processor is most welcome.
I mainly capture waveforms and process them in matlab so most of the decodes etc are not so super critical.

However, zone triggers (InfiniiScan option N5415B ), advanced math (user defined function option N5430B) are not in the scope by default. Of course thw most basic triggers (I2C, RS232, SPI) are missing too...can understand that the decode is out but the triggers...doh!

I can totally understand that the advanced options are costly and indeed optional but I would have assumed serial bus trigger, zone trigger and something where I can multiply with a Log(x) and Cosine using a free-form equation entry standard in such a scope.

Probe selection available is good too. I would have loved if some of the probes that worked with the 9000-series scope worked with this one too (namely 1153A, 1152A and 1155A.

It's fairly heavy though and tends to blow a lot of hot air.

One really cool feature is the offline Infiniium tool that basically runs the scope software on your computer for post processing (love it for reporting!!) but unfortunately it is a paid option (because it can run some of the paid options that the scope also uses). It would be so incredibly nice if I could just send a data capture to a customer and have them use the offline tool to see what I am talking about. Dear Keysight, release a stripped down version that can do only the basic scope functions (fft is a must)?

[Neganur]

[...] Also, I though high-res mode was 12-bits?[...]

High Resolution does 13 bits at 1.25GSa/s and below.

I'm guessing the reason you are seeing a large jump in noise when you go from 10GS/s (and above) to 5GS/s (and below) is I believe the S-Series is only 10-bits at 10GS/s and above.  Below that it runs at 8-bits.  This would explain why you see the biggest jump in your second table (the larger volt/div setting).

You're right, it switches to 8-bit below 10 GSa/s

[srce]

V/div		50		1M
-------	|	--------	|	---------
1mV	|	42.7 uV	|	135 uV
20mV	|	119 uV	|	151 uV

Thanks. That seems more like what I'd expect.

Out of curiosity, since noise seems to change with sampling rate and memory depth, I fixed the amount of memory and swept the sampling rates.

Interesting. Looks like there's a bit of a step <10GSa/s. I think I read on another thread that the resolution at lower sampling rates is 8-bit rather than 10-bit, so perhaps related to that. (Although that seems the wrong way round to me!)

edit: Ah, too slow! Already covered.

[srce]

Hi srce - a couple tweaks for the RTO2000 portion of your table (looks like you might have had an old datasheet - here is the latest version:

https://cdn.rohde-schwarz.com/pws/dl_downloads/dl_common_library/dl_brochures_and_datasheets/pdf_1/RTO2000_dat-sw_en_3607-2684-22_v1601.pdf

Thanks Rich, I've updated it.

[Rich@RohdeScopesUSA]

Hi srce - a couple tweaks for the RTO2000 portion of your table (looks like you might have had an old datasheet - here is the latest version:

https://cdn.rohde-schwarz.com/pws/dl_downloads/dl_common_library/dl_brochures_and_datasheets/pdf_1/RTO2000_dat-sw_en_3607-2684-22_v1601.pdf

Thanks Rich, I've updated it.

And I missed a couple other items:

The RTO2000 runs W7 Embedded Standard.  It comes with at least a 200GB SSD. 

For the 1mV/div setting with the 20MHz BW limit on, here is what we get (keep in mind these are also at 10div - so they will appear about 20% worse than scopes with only 8div):
20MHz BW, 1mV/div, 1MOhm input:  29uV AC-RMS
20MHz BW, 1mV/div, 50Ohm:  33uV AC-RMS

-Rich

[Neganur]

How is there less noise with 1Mohm than 50Ohm?

[Rich@RohdeScopesUSA]

How is there less noise with 1Mohm than 50Ohm?

When we were designing the front end for the RTO (and RTE/RTA/RTM for that matter), the team focused on low noise for both paths as they are general purpose scopes.  Traditionally, scopes have only focused on improving (and talking about) noise performance on the 50Ohm path so I think people are used to seeing 1MOhm have significantly more noise. 

-Rich

[Someone]

How is there less noise with 1Mohm than 50Ohm?

Rather than the worthless marketing speak above, I'd guess that the two paths have different v/div gain structure/grouping/settings. If you could get noise data plotted from multiple v/div settings you'd likely see some step changes in the channels at different points...

Actually checking the RTO2000 data sheet they have listed the 50 ohm input impedance noise for the different bandwidth models separately, but the noise for the 1M input is just a single table. There are no step changes in the data they show there. Perhaps there is a low pass filter on the 1M input path that restricts its bandwidth to less than on the 50 ohm path? But that shouldn't be making much effect at the 20MHz bandwidth limited measurement Rich presented.

[srce]

Actually checking the RTO2000 data sheet they have listed the 50 ohm input impedance noise for the different bandwidth models separately, but the noise for the 1M input is just a single table. There are no step changes in the data they show there. Perhaps there is a low pass filter on the 1M input path that restricts its bandwidth to less than on the 50 ohm path? But that shouldn't be making much effect at the 20MHz bandwidth limited measurement Rich presented.

The 1MOhm input b/w is 500MHz, whereas 50Ohm is up to 6GHz. Presumably they can use some lower noise components / different design to optimise noise given the lower b/w requirement on that path.

[Keysight DanielBogdanoff]

Given where this thread has gone, this talk from one of our designers might be interesting for you all. You may or may not want to skip the first video, it's pretty basic.
https://www.youtube.com/playlist?list=PLzHyxysSubUmxGOMVpiKLxouweh2AAlG1

[babryce]

I actually evaluated the S-Series and the RTO on site and am thankful to R&S and Keysight for providing me loaner units. I will write up a burb in a few weeks after the acquisition is over, which I think will occur just after April 1st.

[srce]

I've gone for an MSOS204A in the end. Nearly went for the Tek, as there are some quite nice things about it, but was swayed in the end by some of the better specs for the Keysight scope as well as its maturity (there were a few issues when I saw a demo of the 5 series). Looking forward to having a play 

[babryce]

I will now attempt to write my blurb as I made my recommendation for a scope.

This post will be the background and selection choice.

I really appreciated SRCE and other's comments on this thread including the company reps.

All of the scope discussed here are good. Of the biggest vendors of test gear I think we have only really left out Yokagowa.

As I mentioned elsewhere I evaluated the RTO2000 and S-Series on site. I also had access to a LeCroy WaveRunner 8000 series. I own an MDO4000 at home (that I got surplus with the SA-3 option).

So the scopes considered were basically: LeCroy WR 8000, HDO6000; Tek MSO56, MDO4000; Keysight X-Series, S-Series; R&S RTO2000, RTE1000.

As was noted at the beginning of this thread these scopes (the big 3 in the title that I was at first focusing on) are not the same. Of course they have all sorts of design choices in them.

I'm very happy that today we have a lot of choice in scopes. This seems a healthy and competitive market. I hope it is not so competitive that too much consolidation occurs as we have seen in the IC market as of late. New companies growing from the bottom as well have a very competitive T&M space.

First what do I need? Some people asked at the start of this thread. I gave the answers I could then, but I had just joined the organization. While I have 15+ years electronics experience, I did not know details of what the organization was like. Thankfully it being large, it took a bit of time for the money to become available and I had time to get some on site to look at. After a few weeks I realized that I would probably be using this scope for everything and that I would probably have it for 5-10 years. I also realized that I would probably always mostly be asked to do analog focused design with some mixed signal stuff thrown in. Most of it not to high a frequency work.

My focus being analog came up with the initial list as these all have higher resolution ADCs in them. My group only has two vendors of scopes at present: Tek and LeCroy (technically we have one Yokagowa) Neither is surprising. LeCroy has long had good relationship with particle physics folks.  LeCroy himself having a degree himself in that area. The folks that use the LeCroys are the analog designers mostly and they lean toward particle type work. The digital focused people all seem to have Tek scopes. If you need a ton of digital channels the new 5-Series might be a good fit.

Given my analog leanings my focus would be on signal integrity. Some of my choices would be arbitrary but with finite time you have to sometimes cut on something. For instance SpaceWire decode only exists on LeCroy, R&S and Keysight. Triggering only exists on R&S and Keysight.

How could I eliminate some of the scopes without a full multi-day test of each? Well given I would be using this thing effectively forever (in EE terms), I would want something that could cover any foreseeable task. That meant digital and analog work.

Although the Tek 5-Series looks impressive in some ways I think it has the following major downsides right now:

* Being very new it is not mature
* Protocol decodes are lacking
* Discounts (bang for buck) would almost certainly be lower given it is the newest thing
* Sample rate at full resolution is only just over 3 GSPS; 6 GSPS is only at 8-bits

On the positive side the MSO56 would have given me 2 extra analog channels most of the time given I will mostly do analog work even if the MSO56 is only the same mix as a normal 4 + digital if you choose to use it that way, the 2 extra analog channels look like a very good thing. If I had at more time I would have evaluated it. My biggest two reasons for not evaluating the 5-Series were the: lack of decodes, and the simple fact that with so much Tek equipment around and with quite a few new hires picking equipment someone would certainly bring this capability to the group.

I played with the Waverunner 8000 we already have to get a sense of the most up to date LeCroy software and looked at the pricing structure and got quotes for the HDO. I must say that of all the marketing I felt the 10 GSPS advertised rate being an interpolation on 2.5 GSPS was the line I was the most annoyed with. Interpolation is not sampling. For a while I was focused heavily on LeCroys because of the analog designers support of them in the group. This could have meant shared active probes and other items. But even more than with Tek, there already are new LeCroy's in the group so it did not provide any new capabilities I could not borrow on the rare occasion I might need a unique feature.

This leaves us with Yokagowa, Keysight and R&S offerings. I must admit I didn't investigate Yokagowa carefully I probably should have but I did not. On the Keysight front I've use lower end X-Series a lot. Very fine for quick bench work but not really for signal integrity and analog work. One of my biggest annoyances with them is that for me being colorblind channel 1 and 2 are the same color, and you cannot change it. One would think colorblind safe color schemes that map makers have known about forever would have reached UI designers but time and again this is not so.

So in the end the two scopes I tired out on site were the Keysight S-Series and the R&S RTO 2000.

In the end my recommendation was to select the RTO2000. Details on the next post which some might find the more interesting without the background bit in this one hence the separate post. 

[babryce]

Having given some fairly stream of consciousness background on my scope down-select I will now go into the final two scopes: The MSOS104A and the RTO2014. I will try to be terse.

Signal Integrity
As analog signal performance was core to this exercise I really focused on this when I evaluated the scopes.

Keysight has a very fancy ASIC at the core of their S-Series, that while older is still a very excellent performer. The S-Series comes fully calibrated up to the full 8-GHz (though you only can do this on 2 channels). It runs at 20 GSPS on 2 channels and 10 GSPS if you are using 4 channels. The RTO just runs at 10 GSPS for any number of channels. It is calibrated to the bandwidth you order though it is still just a software limit I believe.

I measured things like the SFDR with the S-Series and the RTO at low signal levels. I focused on repetitive signals that could be averaged as well to find the best DANL etc. The S-Series basically did better in these tests. The RTO showed spurs above the noise floor in many of these tests while the S-Series did not. Note these were not at high levels like the animation Keysight showed. The difference in the triggering systems was very noticeable. Trigger jitter while undesirable would have effectively spread the power of any component out. I did not really get to look too deeply at this in relation to phase noise measurements.

As shown in the Signal Path video, the S-Series is good at demodulating tasks. These are optional extras and not something I would be doing but a lot of care looks like it went into the S-Series's ASICs and analog design. This focus I felt was born out in the SFDR performance.

The RTO of course is well designed also but I did not feel the signal chain was as good as the S-Series. Of course it is an 8-bit converter which can process a lot more waveforms/s. They are different.

R&S make lot of their HD option which increases the ENOB of the system via digital filtering. I would call this emblematic of their approach to design. While I felt the heart of the Keysight was a very excellent set of analog and mixed signal ASICs, I felt the heart of the R&S was software/digital. In some ways this is more like LeCroy.

The HD option increases resolution for signals under 1 GHz, by applying a digital low pass filter after sampling before feeding the samples to the rest of the chain (see: High-Resolution Measurements with R&S Oscilloscopes; which compares it to a simple moving average filter).

As I am focused on < 1 GHz here this is a big deal. With HD mode on while SFDR and other tests were slightly worse than the S-Series it wasn't very dramatic. Everything on both scopes was of course inline with their datasheets.

If you had to go faster than 1 GHz and needed the best signal integrity, I would say: stop looking; go buy an S-Series. The new 5-Series doesn't have the bandwidth or sample rate. The LeCroys don't in their regular HDO series (though plenty of super fast fancy LeCroys out there that I have used in the past).

For a time I was very focused on the fact that the S-Series had better signal integrity by my testing at least.

Looking at the core specs, the upgrade path is unmatched for bandwidth at this price and the time base was excellent. I feel many people don't think about time bases enough. An error in "x" goes into "y" though the differential at the point. A good time base is super important.

User Interface

The Keysight user interface is fine. You can find most things in the menus without too much trouble and once you know where it is it is not hard to use. It has dedicated knobs for each of the 4 main channels and the digital signal bundle is on the front (the R&S MSO option is on the back if you get it).

I lot of people want dedicated knobs for each channel, but I think that might be a bad use of space if there are more important functions. I found the lack of other knobs and buttons compared to the front panel of the RTO made the S-Series harder to use.

The software for the Keysight is very mature but with that maturity comes a lot baggage. In general things are configured though dialog boxes. While you can use the touch screen to use these dialogs, they are text driven and on the smaller side. I think the UI works for the most part better with a mouse. I would say this probably is because of the legacy of the software and where it came from with touch being only added recently. Pinch and cursors work well though.

R&S have less time in the scope market (though I don't know how much Hameg is in the RTO line). The software they have created while not beautiful (looks like the 5-Series will be easier on the eyes), is clearly designed with using the touch screen most places. I appreciated the combination of most features into visual depictions of signal chains and acquisition settings together.

Fragmentation of averaging, filtering, etc is annoying. LeCroy has long put this into one big channel menu which is good. R&S is almost as good at putting it all together, perhaps better if you like graphical representation of the signal chain. While we all know what the options are for, no one gives all text slides for a presentation, more people are visual. Keysight and others should take note.

As I noted in the previous post I am colorblind (red-green), this affects perhaps 2-8% of the user market for Oscilloscopes.

R&S uses shared knobs for channels. While I doubt they had the colorblind in mind when they made the design choice, this means they backlit everything with RGB leds to match the selected channel color. This means for perhaps the first time ever, all of the colors (not just the ones I can change on the screen via menus which often is a feature on analysis scopes) actually match and I can tell them apart (the backlight matches screen color). Those with full color vision take color coding as a standard way to make things easy. Often the over reliance on it makes my life miserable. Here at least I have the ability to make it work well for me: a first. Others please do this if you cannot make things colorblind safe (which you could if you tried at all).

This is not a deciding feature, because I always have worked around this by moving the vertical offset a little to figure out which pattern is which, but it still matters.

Overall the UI for the RTO is better than the S-Series. The visual driven system with fewer text menus and drop boxes is just nicer to use.

There are some oddities in the RTO UI like channel math functions that use only one channel showing two channel inputs. Some colors in dialogs did not update with the channel color. This later issue is just a bug which I am sure they will eventually fix (I don't remember where it was).

Boot time
The RTO booted in 70-80 seconds
The S-Series booted in 220-240 seconds

The RTO and S-Series reached windows at about the same time, but the software for the Keysight is just bigger I guess. It loaded things like a Matlab kernel. I'm not sure if that occurs if you do not pay for the Matlab option or not but for these fully loaded demos this was what I saw. Boot times aren't ultra critical but that sort of time difference is obvious and probably could get annoying with time. Instrument boot time to ready varies a lot depending on what calibrations it must do etc. Worth noting though for a workhorse.

Noise
Neither scope was loud in testing under the loads I could give them, but the fans on the RTO were louder than the S-Series on my units. My old LeCroy LT344 was a lot louder than either and I did at times find it tiresome to listen to. I doubt most would be bothered by either the RTO or S-Series noise levels.

Math
As I mentioned above the S-Series has a Matlab option. That's cool but it costs extra. Normal channel math like +-*/, etc are there. Not as fancy as a LeCroy. The Matlab option looks from the datasheet nicely integrated into the traces though.

I personally started as an Engineer with Matlab, but I have mostly stopped using it in favor of Python. Python works for more things than Matlab and unless I needed a very special toolbox I would not choose to use it. While I can still write code in Matlab I try not too these days. Julia looks interesting and is like Matlab style wise maybe its fast execution would be helpful for scope like applications. Anyway... Matlab for advanced math and pay more for the S-Series.

The RTO's math can do more functions built-in and do compound expressions without chaining channels. This is good. Though I would take my data off the scope and use Python to look at it in detail for full analysis, for quick functions in real time the better math of the RTO is very valuable. This feature looks like it is built-in for the base model. It looks like the 5-Series might also have this though try as hard as I could I could not find any screen shot of it...

It is a little unclear how deep the external hooks are for the RTO. I found a Python tool, and saw the .NET/C# API along with the normal VISA like stuff. I'd love to see a direct realtime API for custom decoding and math in Python or Julia or something open and free. It might crimp the decode software market though...

Probes
Keysight has more probes than R&S but it looks like R&S has been expanding. They have the most common probes I might want, so its a draw really. Costs are almost the same.

Documentation
R&S has a proper manual for the RTO which is a few thousand pages in length. Keysight has the help file you would see in software. Well written documentation is undervalued and is frankly rare. I like single monolithic documents rather than fragmented documentation.

Option, options, options
To make the RTO2014 closer to the MSOS104A requires options. I would say the biggest one is the ovened reference (RTO-B4). I would not bother to get a scope costing this much without an excellent time base. With the time base option they are similarly good. You also need the HD mode (RTO-K17) and the Mixed signal module (RTO-B1).

Final bit
If you are going to stay below 1 GHz with these options the RTO has some advantages: faster waveform update rates, faster boot times, friendlier UI.

Above 1 GHz if signal integrity is your prime motive I would probably just select the S-Series.

For me although I was very focused on signal integrity, I felt like the easy built in math (without writing an m file), and UI would make my daily tasks faster with the RTO. Signal integrity was still good, and for the most difficult things I will still have to use RF techniques regardless.

I got some other options on my RTO quote that matched the current offers from Keysight. Some of these options on the R&S list for nearly 2x what they do on the S-Series. So think through your future need carefully! I'm not sure you have as much leverage for getting an option at a discount later.

Just ask sales folks for what you need at the price you need it, they will probably help you if they can. The Keysight and R&S sales staff were both helpful.

[Rich@RohdeScopesUSA]

Thanks babryce for your analysis and posting up your results.  There are lots of good scopes on the market these days and I've always been a fan of trying them out to see which one best fits your exact needs. 

-Rich

[exmadscientist]

Thanks for posting your thoughts on these models. It's always useful to see a head-to-head comparison from someone independent.

Although the Tek 5-Series looks impressive in some ways I think it has the following major downsides right now:

* Being very new it is not mature
* Protocol decodes are lacking
* Discounts (bang for buck) would almost certainly be lower given it is the newest thing
* Sample rate at full resolution is only just over 3 GSPS; 6 GSPS is only at 8-bits

On the positive side the MSO56 would have given me 2 extra analog channels most of the time given I will mostly do analog work even if the MSO56 is only the same mix as a normal 4 + digital if you choose to use it that way, the 2 extra analog channels look like a very good thing. If I had at more time I would have evaluated it. My biggest two reasons for not evaluating the 5-Series were the: lack of decodes, and the simple fact that with so much Tek equipment around and with quite a few new hires picking equipment someone would certainly bring this capability to the group.

You weren't missing much by skipping the 5 Series. We recently had one in for a test and it was unimpressive. "Not mature" is really probably the best way to summarize it. A kind-of-ranty summary of the 5 Series:

The good:

• The medium-resolution screen is really nice. Not quite bright enough, and not quite sharp enough (seriously, my several-years-old phone has more pixels), but it's so far ahead of everything else in this space that it's kind of sad.
• Eight channels! This is really the only thing that's truly special about this scope. Everything else is secondary.
• Good, fairly snappy performance at default settings (1Mpts/channel record length)
• Good zoom features (not, you know, any better than other recent Tek scopes, but at least they didn't regress here.)
• Dedicated memory for each channel (so enabling/disabling channels is almost entirely a display thing). Nice, but hardly essential.
• Eight! Channels!

The bad:

• Trivial to crash. It crashed a lot during testing, and I wasn't trying that hard. It only cleanly failed once (with a "please reboot me" message); the rest of the time, it just shut itself down a few seconds after hanging. If this is how bad it is now, with the latest firmware, I can only shudder to think how awful it must have been at launch.
• Terrible UI. Whoever thought up "single-tap to access useless controls you already have on the front panel, double-tap to get to the real menu" should be flogged. Just bring up the double-tap menu already, I'm always going to need it.... I could go on about the UI, but it's obvious after a few minutes' use that it's crap and they really should just sit down and watch someone try to use the damn thing.
• Insane horizontal (record length) controls. The UI ties together sample rate, horizontal scale, and record length, so that adjusting one changes the other two. It turns out to be extremely difficult and annoying to increase the record length above the default ~1Mpts/channel. It's an absolutely bizarre system, but I can see why they had to do it this way, because...
• ...the scope's deep memory performance is pathetically awful. Yes, I know, cranking the capture length up to the full 125Mpts is not something you're supposed to do often. But I had a problem where the device under test was going weird sometime after startup, so I needed to grab the full startup sequence to see exactly when it went weird. So I wanted a long, high-resolution capture. That's what the memory is for, right? But it should never take fifteen seconds to capture one single-shot waveform! (And before anyone asks, the horizontal scale was somewhere around 4ms/div, so 40ms per capture. Maybe 10ms/div, I don't remember for sure. But short enough that the capture period itself was very quick.) And the thing doesn't have the decency to give you partial updates or any kind of feedback that it's processing... it just sits there, its little green "Triggered" light on solidly. The first time I did this I thought I'd crashed it again. I'm grateful I only needed two or three of these painful captures to figure out where in the startup sequence I needed to be looking and could set up a better trigger.

The ugly:

• Working with 8 traces is pretty annoying. There's a "stacked" mode and an "overlay" mode, but that doesn't help much: if they're stacked, each trace is too small. If they're overlaid, something's always blocking something else. (Why can't we have transparent traces? It's 2018!) You end up playing the same old games as usual with offset and scale knobs.
• Crazy long boot time. But that might have been affected by crashing so often; maybe a reboot-after-crash takes longer?
• The combination of default sinc interpolation and low sample rates is not a good one. Sinc interpolation goes nuts when you have frequency content above Nyquist... and with the rates this thing likes to sample at, you're going to have a lot of aliasing if you like to use the zoom button. I'm really glad I noticed this setting before trying to figure out why the signal I was looking at seemed to be bouncing below ground! Interpolation settings should not lie to you nearly as badly as this scope's do.
• The ludicrous price tag. Enough said!

So,yeah: it's immature and not worth the current asking price. At half the price I'd be interested. The above comes across more negative than I intended, but it's really just not a revolutionary product in any respect. Certainly it's not worthy of Tek's marketing hype, but I guess Danaher is just really proud that they finally spent money on something? I think it'll actually be more interesting to see how the other manufacturers respond in their next refreshes.

Does anyone know how other scopes in this class (S-Series, RTO, etc) stack up in waveform rate when you need a deep memory capture? I'm guessing they do better than 0.07 waveforms per second, but I haven't actually tried them myself and I couldn't come up with anything when searching around. The S-Series is probably next on our tryout list, but that requires dealing with the local salesmen and that's never pleasant, not when there's real work to be done.

[Eric_S]

Working with 8 traces is pretty annoying. There's a "stacked" mode and an "overlay" mode, but that doesn't help much: if they're stacked, each trace is too small. If they're overlaid, something's always blocking something else. (Why can't we have transparent traces? It's 2018!) You end up playing the same old games as usual with offset and scale knobs.

Too bad you can't combine the stacked and overlayed modes. So that you'd have (say) four windows with two traces in each.

[nctnico]

Working with 8 traces is pretty annoying. There's a "stacked" mode and an "overlay" mode, but that doesn't help much: if they're stacked, each trace is too small. If they're overlaid, something's always blocking something else. (Why can't we have transparent traces? It's 2018!) You end up playing the same old games as usual with offset and scale knobs.

Too bad you can't combine the stacked and overlayed modes. So that you'd have (say) four windows with two traces in each.

IMHO that should be possible. Dunno for Tektronix specifically but on other scopes (Yokogawa) you can usually combine more traces in one window.

[fonograph]

One important thing that was not mentioned in this thread is DC accuracy,I believe its limited by ADC non linearity.I think you can oversample 8 bit ADC so it have 16 bit ADC like noise levels,but you cant improve linearity/DC accuracy by oversampling.The LeCroy 12bit ADC is relatively slow at 2.5 Gs/s,but its true 12 bit,without oversampling.

Even better is 14 bit Native Instruments PXIe scope,its only 1 Gs/s,but its DC accuracy is best and they have by far most detailed datasheet about signal integrity.

I am too lazy to read it again but I believe most 8 bit scopes,including RTO2000 and MSO 56 are 2% DC accuracy,Keysight S is 1%,HDO is 0.5% and  NI 14 bit scope is 0.25%

[babryce]

Interesting. I had not even considered crashes. 0 crashes of either S-Series or RTO in my testing FWIW.

If the S had crashed that boot time would have been very painful.

I probably should have looked harder at the HDO9000 not just the HDO6000 and WR 8k. We already have a HDO9k though.

Maybe an HDO8000A would work for you given you like the channel count high? LeCroy's UI is very mature at this point I feel like its not radically different since at least 2008 time frame. Sample rate is not that different from 5-Series.

The S-Series is a beast though.

[exmadscientist]

Working with 8 traces is pretty annoying. There's a "stacked" mode and an "overlay" mode, but that doesn't help much: if they're stacked, each trace is too small. If they're overlaid, something's always blocking something else. (Why can't we have transparent traces? It's 2018!) You end up playing the same old games as usual with offset and scale knobs.

Too bad you can't combine the stacked and overlayed modes. So that you'd have (say) four windows with two traces in each.

IMHO that should be possible. Dunno for Tektronix specifically but on other scopes (Yokogawa) you can usually combine more traces in one window.

I'd have thought that too, but we couldn't figure out how to do it during our demo period.

Still, we didn't explore every corner of the crap UI and so it might be buried somewhere. The Tek salesdroid's pitch had a lot of fluff about how stacked mode "maximizes ADC usage" for each channel, but the DUT on our bench right now doesn't call for much precision, so we didn't waste much time trying to get that to work out. Traditional trace stacking was just fine (if tedious).

[srce]

Interesting. I had not even considered crashes. 0 crashes of either S-Series or RTO in my testing FWIW.

In the ~2-3 hour demo I had with Tek, it crashed twice     Obviously going through all the different features of the scope in that period though.

[exmadscientist]

I probably should have looked harder at the HDO9000 not just the HDO6000 and WR 8k. We already have a HDO9k though.

Maybe an HDO8000A would work for you given you like the channel count high? LeCroy's UI is very mature at this point I feel like its not radically different since at least 2008 time frame. Sample rate is not that different from 5-Series.

The S-Series is a beast though.

We do a lot of different things. On the bench right now is a board with an interesting power stage, so voltage and current probe pairs everywhere. The high channel count scopes really shine for that kind of work. (In fact isn't that how LeCroy markets many of them?) Next month it'll be something different, so who knows?

It's also worth noting that I wasn't the one who called in the 5 Series, another engineer here was. I just got to use it for a while. I think the Tek sales reps were fairly aggressive in trying to demo it; perhaps it's not selling well? (Again, no surprise at their asking prices.) It's also the showiest scope around, and we were hoping that would help with upper management. Alas, they seem to continue keeping their heads in the usual places and being stingy. Guess we'll just have to try again in a few months!

But a "beast" scope sounds really good... right now our "beast scope" for the most demanding tasks is a mid-2000s MSO4000 (yep, the original), which is... not quite what I'd like us to have. But that's my problem, not the scope's!

[babryce]

You can improve anything that is a random error by averaging or low-pass filters etc. You cannot remove any systematic error from the signal path that way. That could be INL on a DC level or other things. The linearity of the converter is captured in the SFDR or THD numbers certainly. R&S talks about this in their white paper about their HD mode technique. You cannot exceed the number of actual bits of the converter for SFDR of course but none of the converters reach this limit. It is perfectly possible to have a noisy but totally linear 8-bit converter have better linearity than a 12-bit, though in general that wouldn't be the case.

SFDR were < 1-bit lower on the RTO in my limited testing than the S-Series. Both the RTO and S-Series are good. The HDO9k and WR8k are both nice too. The MDO4000 with the spectrum is a useful thing too. The 5-series strength on paper would either be the 8 channels or just having gobs of digital channels. There are probably situations where you want to look at more than 16-lines. They will eventually get the software sorted though if there are bad design choices like how to click that I wouldn't expect to see them change for a long time; just the crashing and adding features they didn't have time to have at the start, probably mostly as pay options.

For myself I never by new equipment, better value to buy last generation on the surplus market.

[srce]

Results:
20MHz BW, 1mV/div, 1MOhm input
Mean baseline DCVrms noise = 156 uV

20MHz BW, 1mV/div, 50Ohm input
Mean baseline Vrms noise = 180 uV

20MHz BW, 20mV/div, 1MOhm input
Mean baseline Vrms noise = 366 uV

20MHz BW, 20mV/div, 50Ohm input
Mean baseline Vrms noise = 288 uV

Thanks to you both. I think it's the AC RMS values from the screenshots that you want to promote though

Scope	BW	Vertical setting	Input	Noise AC RMS	ENOB limit based on noise
MSO56	20MHz	1mV/div	50 Ohm	70uVrms	5.2
MSO56	20MHz	1mV/div	1 MOhm	64.8uVrms	5.3
MSO56	20MHz	20mV/div	50 Ohm	102uVrms	9
MSO56	20MHz	20mV/div	1 MOhm	104uVrms	8.9
MSOS804A	20MHz	1mV/div	50 Ohm	48uVrms	5.4
MSOS804A	20MHz	1mV/div	1 MOhm	115uVrms	4.1
MSOS804A	20MHz	20mV/div	50 Ohm	260uVrms*	7.3
MSOS804A	20MHz	20mV/div	1 MOhm	139uVrms	8.2
RTO2014	20MHz	1mV/div	50 Ohm	33uVrms	6.3
RTO2014	20MHz	1mV/div	1 MOhm	29uVrms	6.4

* This looks a bit fishy to me, as it's far higher than the speced noise for the MSOS104A at 1GHz. (Which is 163uVrms). It does appear to be the MSOS804A the measurement was made on, from the 8.40 GHz at the top of the screen. But if the b/w is set to 20MHz, that shouldn't matter should it? Does one of the other b/w limiters need to be on too? For the 1MOhm screenshot, the 8.4GHz drops to 500MHz.

My MSOS204A arrived It's noisy and hot! Surprisingly it comes with Windows 10, rather than the advertised 7.

There are two b/w limiters. A global one, that be manually set in steps of 500MHz, and a per channel limiter, that can be set to 20MHz, 200MHz or a custom frequency. It seems to get the lowest noise on the 50Ohm path, you need to set both. (I'm guessing the global limit is pre-ADC and the per channel filter is just done digitally). It seems the global limit can't be adjusted manually in high res mode.

Scope	Sample rate	Resolution	BW Limit	Vertical setting	Input	Noise AC RMS	ENOB limit based on noise
MSOS204A	20GSa/s	10-bit	2GHz/20MHz	1mV/div	50 Ohm	41uVrms	5.8
MSOS204A	20GSa/s	10-bit	2GHz/20MHz	1mV/div	1 MOhm	119uVrms	4.2
MSOS204A	20GSa/s	10-bit	500MHz/20MHz	1mV/div	50 Ohm	40uVrms	5.8
MSOS204A	20GSa/s	10-bit	500MHz/20MHz	1mV/div	1 MOhm	118uVrms	4.3
MSOS204A	20GSa/s	10-bit	2GHz/20MHz	20mV/div	50 Ohm	148uVrms	8.3
MSOS204A	20GSa/s	10-bit	2GHz/20MHz	20mV/div	1 MOhm	145uVrms	8.3
MSOS204A	20GSa/s	10-bit	500MHz/20MHz	20mV/div	50 Ohm	87uVrms	9
MSOS204A	20GSa/s	10-bit	500MHz/20MHz	20mV/div	1 MOhm	147uVrms	8.3
MSOS204A	5GSa/s	11-bit	1.14GHz/20MHz	20mV/div	50 Ohm	194uVrms	7.9
MSOS204A	5GSa/s	11-bit	1.14GHz/20MHz	20mV/div	1 MOhm	203uVrms	7.8
MSOS204A	1.25GSa/s	13-bit	277MHz/20MHz	20mV/div	50 Ohm	104uVrms	8.8
MSOS204A	1.25GSa/s	13-bit	277MHz/20MHz	20mV/div	1 MOhm	153uVrms	8.2
MSOS204A	100MSa/s	13-bit	22.1MHz/20MHz	20mV/div	50 Ohm	62uVrms	9.5
MSOS204A	100MSa/s	13-bit	22.1MHz/20MHz	20mV/div	1 MOhm	101uVrms	8.8
MSOS204A	100MSa/s	13-bit	22.1MHz/20MHz	500mV/div	50 Ohm	2mVrms	9.2
MSOS204A	100MSa/s	13-bit	22.1MHz/20MHz	500mV/div	1 MOhm	2.5mVrms	8.8
MSOS204A	10MSa/s	13-bit	2.1MHz/20MHz	500mV/div	50 Ohm	985uVrms	10.2
MSOS204A	10MSa/s	13-bit	2.1MHz/20MHz	500mV/div	1 MOhm	1.14mVrms	10