Tek MDO3000 or Agilent DSOX3000 - Page 1
Forum section: electronics / testgear

author: Sal Ammoniac
author_rank: Super Contributor
timestamp: September 24, 2014, 06:24:12 pm
content: The current special offers on the Tek MDO3000 and Agilent DSOX3000 series are coming to the end very soon and I'm still sitting on the fence trying to decide which way to go.I already have a spectrum analyzer, so the SA in the MDO3000 is not a deciding point for me. I'm an embedded developer and spend most of my time writing and debugging firmware for various MCUs and mostly use a scope to find noise on ADC inputs, slow rise time on I2C lines, etc. I have dedicated logic analyzers too, so the mixed signal and protocol decoding capabilities of the Tek and Agilent scopes really aren't big selling points for me either.The two differences that seem important to me boil down to the waveform update rate and the memory depth. The Agilent does 1,000,000 updates a second, while the Tek does 280,000 -- how much of a difference does that make in everyday use?The Tek seems to have a big advantage in memory depth with 10 Mpts versus only 2 Mpts for the Agilent. Again, how important is this difference in everyday use?I've read numerous forum and blog posts saying the Tek scope has a sluggish UI that often locks the user out while it's processing a capture -- is this still an issue, or has it been fixed in a new firmware release?The current special offers pertain to features I really wouldn't use much, but having them anyway would probably add to the resale value of the scope if I decide to sell it and upgrade in the future. If I'm going to get one of these, I want to take advantage of these offers while they last, unless someone has some inside info on what the next special offer may be... Last year Agilent had an offer where the next higher bandwidth scope was priced the same as the lower bandwidth model (e.g. the 350 MHz model for the same price as the 200 MHz model). That kind of special offer would be more important to me than more bandwidth on the built-in SA or a free protocol analyzer.

author: eurofox
author_rank: Unknown
timestamp: September 24, 2014, 07:28:42 pm
content: I'm a very big fan of my MSOX3001, the serial decoding work like a charmDo not compare the 2M segmented memory from the Agilent with the memory of the TekI got a Tektronix scope before, the major difference for a user is that the Agilent menus are very intuitive and that is not always the case with Tektronix.In Europe the Agilent support is simply excellent.

author: David Hess
author_rank: Super Contributor
timestamp: September 24, 2014, 08:28:56 pm
content: Quote from: Sal Ammoniac on September 24, 2014, 06:24:12 pmI would say none unless you are glitch hunting. The update rate per second may severely depend on horizontal time/div setting though so that should be checked if possible to see how consistent the advertised high update rate really is.Segmented acquisition memory may be a substitute for high waveform acquisition rates.QuoteAgain I would say none unless you have a specific need for high single shot sample rates at slow horizontal time/div settings which the shorter but still long record length will not satisfy.

author: don
author_rank: Regular Contributor
timestamp: September 25, 2014, 01:39:39 am
content: I'm in the same boat as you after trying rigol ds4000 and siglent sds2000. I now have an mdo3000 on order but looked at dsox 3000 ( and am intrigued by lecroy wavesurfer 3000). I use the mdo4000 which is very similar to mdo3000. I guess its what you are used to and need, but I'll highlight pros of tek that are very basic but impact my work flow:-two very nice large cursor knobs. Very smooth, and can work in all modes (seems obvious but you'd be surprised). No button pushing to switch and has a fine / course button. Just clear menus and you have two cursor knobs-great auto switching roll mode (down to 40ms) with zoom. Some scopes disable zoom in roll mode. I use roll mode extensively and want it to behave like regular single aquisiton when it comes to analysis-measurements can be gated by screen, entire waveform or cursors. There are no changes as you zoom like agilent-pan/zoom is nice featureI don't find the UI sluggish with my usage profile. If you are doing something extreme perhaps (someone mentioned 50s to decode 8500 I2C transactions) but just a 10M capture with a couple measurements will not be an issue with zooming / panning and navigation. Dave's latest video on polar heart rate monitor has the mdo3000, might get a read from that.There are many other criteria, but for me I capture and analyze. I want all features to be there when analyzing. I'll take up front processing if this enables more analysis capability or consistency of operation. I want to use 10M rolle mode with peak detect, add measurements, zoom, cursors, screen capture w/o issue. I really just want the basics to be there with no surprises. I only use segmented memory for decoding else I use persistence (can't do on MDO but can on agilent) For decoding large amounts I would use a different tool, so instead prefer tek 10M to agilent 2M . Really comes down to what is important to you.One quick comment on SA - it has 3GHz capture bw. So in one capture you get full 3GHz spectrum. Great for debugging noise sources compared to a traditional SA with only 10-20MHz capture bw that must be swept.

author: EEVblog
author_rank: Unknown
timestamp: September 25, 2014, 02:36:42 am
content: Quote from: Sal Ammoniac on September 24, 2014, 06:24:12 pmYou can't compare the two here really. The Agilent is superior not only on the numbers, but because it's always on and working at the fastest rate.The Tek only gets it's claimed rate in FastAcq mode which you have to select, and you then only get a small memory size of a few K.Indeed, the Agilent has no memory depth or fast mode settings, it "just works".So for everyday use looking at signals without fuss, I think the Agilent is the clear winner.But the Tek does better analysis on the full memory depth (one of the reason why it can be slow)

author: HighVoltage
author_rank: Super Contributor
timestamp: September 25, 2014, 10:13:40 am
content: After considering also the Tektronix scope, I went with the Agilent MSO 3000 X Series and I love it. I got the official option pack and one feature that I did not even expect to be useful is "Segmented Memory" and now I use it all the time. I am very happy with the Agilent scope and can only recommend it.

author: don
author_rank: Regular Contributor
timestamp: September 25, 2014, 01:41:29 pm
content: Regarding memory depth, the tek is up to 10M on all channels in all modes and user selectable. So you can do 4 analog and 16 digital all at 10M.Agilent is 2M for one or two channels, 1M for three or four or channels in single acquisition. Memory is not selectable. If in run/stop mode vs single, memory is further halved to 1M for two channels and 500K for four channels. If digital is added i believe it is halved yet again. so you can be down to 250k - 500k vs 10M on tek. You can get 4M option to double these .So you need to see what's important - update rate or memory depth. Also consider what you need update rate for. Update rate is about 3x on agilent. For my use I let a scope run and walk away. I rarely use it and most of the time my trigger is much slower than the update rate of scope.

author: MarkL
author_rank: Unknown
timestamp: September 25, 2014, 04:27:20 pm
content: Quote from: don on September 25, 2014, 01:41:29 pmThe Agilent/Keysight scope under consideration does not reduce memory beyond 2x for analog channels. One acquisition engine is shared between channels 1&2, and another between 3&4. So, it's either 1Mpts or 2Mpts per analog channel depending which channels you have on. Each digital channel is always 1Mpts.All those numbers are doubled with the DSOX3MEMUP option, as you mention.The DSOX3MEMUP and every other decode and upgrade key is being offered now as a bundle for the cost of a single option. But that offer is only running for a few more days until Sept 30.

author: MarkL
author_rank: Unknown
timestamp: September 25, 2014, 05:24:20 pm
content: Quote from: MarkL on September 25, 2014, 04:27:20 pmAfter looking again at the Agilent datasheet, there was some squirrelly language surrounding the digital channel numbers. I did a quick test to find out exactly what it's doing.This is with SINGLE capture, the MEMUP option, and examining the number of points recorded for each channel via the SCPI commands. You are correct that RUN mode vs. SINGLE will halve these numbers again, but that's already a well known behavior.Chan1 on, chan2 off, digital off: 4Mpts on chan1.Chan1 on, chan2 on, digital off: 2Mpts each on chan1 and chan2.Chan1 off, chan2 off, digital on: 2Mpts on Bus1 (as the digital channels are called on SCPI).Chan1 on, chan2 off, digital on: 2Mpts on chan1, 250k on Bus1.Chan1 on, chan2 on, digital on: 1Mpts each on chan1 and chan2, 250k on Bus1.What surprised me was the drop to 250k digital points if *any* analog channels channels are on. And it doesn't seem to matter which or how many digital channels (D0 through D15) are on.My apologies for the previous mis-statement, and thank you Agilent Marketing for the crisp specifications.

author: don
author_rank: Regular Contributor
timestamp: September 25, 2014, 10:36:28 pm
content: Its worth noting that while Tek architecture is often said to be old, there were clear design tradeoffs agilent and tek made. Mdo3000 has 20-40x the memory of agilent (depending on 4M option or standard) as you add channels , or change acquisition. That's very significant, and may be why tek is sticking with their architecture. Hard to justify agilent 3x improvement in update rate at the expense of memory -- at least for how I use scopes

author: andrewwong2000
author_rank: Contributor
timestamp: September 26, 2014, 05:11:42 am
content: Before I even bought an MSOX for the speed and convenience, I'd already planned for a logic analyser (Saleae Logic Pro) to allow for embedded micro deep serial decodes.As usual, you need more toys er tools and one size doesn't fit all MDO, MSOX or whateverSent from my iPhone using Tapatalk

author: MarkL
author_rank: Unknown
timestamp: September 26, 2014, 10:44:20 am
content: I ended up with the same combination for the same reasons: MSOX3104 + Saleae Logic 8. They complement eachother's capabilities very well.

author: trevwhite
author_rank: Frequent Contributor
timestamp: September 26, 2014, 10:57:26 am
content: I have a MSO-X 3024A and I just love the speed of it. The speed at which it decodes everything and its responsive interface is great. Can always do with more memory but I agree that the PC analysers can be used for looking at a lot more information and they have a better interface as well with mouse and the screen to work through the data.I am not sure I like the scope probes that came with the MSO-X though. The hooks do not seem to stay on that tight.

author: EEVblog
author_rank: Unknown
timestamp: September 26, 2014, 12:27:44 pm
content: Quote from: don on September 25, 2014, 10:36:28 pmAgilent have had and still have the cheap fast real time update market to themselves since the released the X series. But the Achilles heel is that 4M on-chip ASIC memory. It was plenty 4+ years ago when released, but now it's looking long in the tooth, and they know it.

author: MarkL
author_rank: Unknown
timestamp: September 26, 2014, 12:48:08 pm
content: Quote from: trevwhite on September 26, 2014, 10:57:26 amI definitely don't. They're too big and bulky for fine work. I replaced all four with N2894A 2.5mm tip probes. (That's a 4000X probe though, N2873A 2.5mm is the recommended one for 3000X.)One thing I'll grant Tek is that they make much better probes.

author: David Hess
author_rank: Super Contributor
timestamp: September 26, 2014, 12:53:10 pm
content: Quote from: MarkL on September 26, 2014, 12:48:08 pmAgilent's 5mm probes appear to be the same ones that Texas makes or sells and Agilent's 2.5mm probes look like the 2.5mm probes that PMK makes.

author: MarkL
author_rank: Unknown
timestamp: September 26, 2014, 01:43:24 pm
content: Quote from: EEVblog on September 26, 2014, 12:27:44 pmMaybe they know it, but they continue releasing new scopes using the same basic design, albeit faster. Even the brand new 6000X series has 4Mpt memory. The target market segment maybe doesn't care so much about the next doubling or quadrupling since it's diminishing returns and then you step up to the next class instrument. I think the target market is more sensitive to fast response and usability, and apparently BW since that's where the new products hit. More memory might be good for churning up replacement sales, but I don't think Keysight feels pressured to do it.Look at Tek. They're still selling the 10kpt TDS3000 series with the same acquisition engine after 15 years. Now *that's* long in the tooth.

author: David Hess
author_rank: Super Contributor
timestamp: September 26, 2014, 02:46:50 pm
content: Quote from: MarkL on September 26, 2014, 01:43:24 pmThis might be a processing limitation and not a memory limitation. Retaining the current fast response and usability with more memory may require faster logic that is not available on an economical ASIC.

author: don
author_rank: Regular Contributor
timestamp: September 26, 2014, 11:52:37 pm
content: Quote from: MarkL on September 26, 2014, 01:43:24 pmI believe the 1M waveform update is a bit of a marketing gimmick, and most people do not realize how much memory they are leaving on the table as a result. The sample rate is only 2GS/s. You need a triggerable event at least ever 1us. That means the memory depth is only 2k at best (people say tek's 10k is small). There is a pretty limited use case in my opinion where you need or can even use the 1M waveform update. It's not like you can update 1M waveforms per second at 1ms per division.Note that none of agilents high end scopes have 1M update rate. Instead, they all have more memory and 100k or 400k update rates (and only in segmented memory...). In other words, agilent does not market their high end scopes for waveform update rate. Why? There is a point of diminishing returns on update rate, and I'd guess the majority of users are much better served with a longer record length. I guess it depends on what you do, but I know where I work record length is much more important than update rate and used daily by most engineers that are on the bench. On the rare occasion we need a faster update rate we let it sit longer and go do something else. But you can't do anything to create more record length. Tek had 400k update rate almost 20 years ago and basically stopped there. Because they couldn't do it? Doubtful. Probably because they feel they reached the practical limit of usefulness. So now their economical scopes have a good update rate (280k) and decent record lenght (10M on all channels, all the time). I think that beats the agilent 3000x hands down -- unless you always work where you can trigger at 1M waveforms per second.

author: MarkL
author_rank: Unknown
timestamp: September 27, 2014, 01:24:09 am
content: I wasn't thinking of update rate, but I agree with you that's another area of diminishing return. Update rate is a marketing term, and it takes very specific conditions to generate that number. What really matters is the dead time while the scope is processing between captures. That's the number I'd like to hear, but I guess it's not as exciting sounding because it doesn't end with a lot of zeros.I'm also not saying that long capture memories aren't useful either. There's really no substitute in some applications. It's obviously important in your work.My point was that Agilent seems to have found a sweet spot with this shared 4Mpts ASIC design, and I think they're going to milk it for as much as they can by expanding in areas other than just making the record length longer. There's a heck-of-a-lot of measurement and compliance capability you can bring to the lower cost market that will fit in 4Mpts that was once the exclusive domain of much more expensive scopes. And the fast response of the UI inherent in the design makes it that much more attractive.

author: don
author_rank: Regular Contributor
timestamp: September 27, 2014, 02:58:35 am
content: All true. And the x series is over 3 years old. Will be interesting to see if they merge the design with their high end scopes as tek has done or keep their current approach for this segment. Thinking about it, it's funny because the scope is very responsive. And user sees 1M waveforms per second spec. One almost reinforces the other to show how good/fast it is, and slower scopes processing 20-40x the data are classified as old and out of date in comparison even though apple to oranges. Just different design targets and customers. Hopefully customer understands needs and if they don't know might as well take the faster scope for general useability.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: September 27, 2014, 03:40:49 pm
content: Quote from: don on September 26, 2014, 11:52:37 pmIndeed. The waveform rate is an important factor when the aim is to "see" things like rare glitches on the screen (i.e. using a DSO in a similar way as an old CRO). But no-one buys a high end scope for merely *looking* at a signal, and these scopes have other (more advanced) ways to capture glitches and such than relying on persistence mode and waiting for the user to see it.

author: don
author_rank: Regular Contributor
timestamp: September 27, 2014, 04:10:15 pm
content: Quote from: Wuerstchenhund on September 27, 2014, 03:40:49 pmYes, and a simple deep memory approach to glitch hunting is to trigger on a high level system failure (reset or such) and monitor all activity on suspected signals leading up to. This gives you system insight of all activity vs looking at a 100ns slice of time.Does anyone have usage patterns where they glitch hunt (and successfully find glitches ) more than you would use deep memory? Trying to think of real world uses cases beyond demo board. I do look for glitches and such, but they are usually on signals synchronous to much slower triggerable events and cannot make use of 1M waveform update rate.

author: nctnico
author_rank: Super Contributor
timestamp: September 27, 2014, 04:28:00 pm
content: I don't see the point of having an ultra high waveform capture rate to look for glitches. If I assume there is a narrow pulse I set the trigger condition for a narrow pulse. Wide pulses vice versa. If I want to see if a signal stays within boundaries I use the infinite persistance mode and let is run for a while. No need to stare at a screen without blinking my eyes. IMHO the whole waveform capture update rate has become a magic marketing number.

author: David Hess
author_rank: Super Contributor
timestamp: September 27, 2014, 04:55:48 pm
content: Quote from: nctnico on September 27, 2014, 04:28:00 pmIt is more useful when you suspect a problem but do not know what to specifically trigger on. A specialized trigger is always going to win this race.I agree it has become a marketing number but there is a big difference between the 45 to 90 waveforms per second which used to be common in DSOs and the fast rates available now even at the low end.

author: Neganur
author_rank: Unknown
timestamp: September 30, 2014, 08:35:09 pm
content: Quote from: MarkL on September 27, 2014, 01:24:09 amWell, anything that is used to promote product features is a marketing term no? How would a "dead time war" be any different from update rate.Quote from: MarkL on September 27, 2014, 01:24:09 amI'm not sure what you mean. Doesn't a higher update rate automatically mean that the dead time will be shorter too? Isn't a higher update rate always preferable when you want as little dead time as possible? Have a look athttp://literature.cdn.keysight.com/litweb/pdf/5989-7885EN.pdfthey're explaining it very well in my opinion: (example attached picture)

author: alex.forencich
author_rank: Frequent Contributor
timestamp: September 30, 2014, 08:59:35 pm
content: Quote from: nctnico on September 27, 2014, 04:28:00 pmIf the update rate is low, infinite persistance will not help as you are still likely to miss an infrequent glitch during the dead time in between captures. Fast update rate doesn't just mean it will appear on the display more often, it also means you will capture it more quickly with infinite persistance on.

author: nctnico
author_rank: Super Contributor
timestamp: September 30, 2014, 09:05:44 pm
content: My point is: you shouldn't hunt glitches by just staring at the screen and wait for a glitch to get caught. Just setup a trigger which doesn't trigger on a valid signal and let the oscilloscope run for a while. The trigger condition never misses a glitch because it has no dead time and the waveform update rate becomes completely irrelevant.

author: alex.forencich
author_rank: Frequent Contributor
timestamp: September 30, 2014, 10:10:04 pm
content: Quote from: nctnico on September 30, 2014, 09:05:44 pmRight, but this most likely won't work for all glitches. If you know enough about the glitch to figure out how to trigger off of it, then this works.

author: nctnico
author_rank: Super Contributor
timestamp: September 30, 2014, 10:33:54 pm
content: You just have to turn your assertion around: you always know what the normal/expected signal looks like so anything but the normal/expected signal is a glitch.

author: David Hess
author_rank: Super Contributor
timestamp: September 30, 2014, 10:41:15 pm
content: Quote from: alex.forencich on September 30, 2014, 10:10:04 pmWhich was my point earlier. Any oscilloscope with a low waveform acquisition rate and special triggers can capture a glitch if you already know what you are looking for. If you do not know the glitch characteristics, then it takes a high waveform acquisition rate to find them unless it is common.Even with a high waveform acquisition rate, it can take minutes to hours to days to find the initial glitch so minimizing dead time can be crucial. At low waveform acquisition rates, you have to find another way. Luckily good design practices minimize this problem.

author: don
author_rank: Regular Contributor
timestamp: September 30, 2014, 10:42:19 pm
content: Quote from: alex.forencich on September 30, 2014, 10:10:04 pmEven a high update rate needs a trigger. How do you know where to set your trigger? If right after a rising / falling edge like demos then great. But if you are dealing with bus contention or something well before / after trigger, 1 M waveforms at the wrong trigger won't help since you only get something like 2k memory depth at 1M waveforms/ sec. if i dont know the trigger, then deep memory capture on high level system trigger is my preferred approach, or play with different triggers. If you don't see anything with 1M waveforms then what? You can't say its good. Likely you'll resort to different triggers anyway that will work.high update rate fans...try deep memory and triggers...you'll like it

author: nctnico
author_rank: Super Contributor
timestamp: September 30, 2014, 11:02:18 pm
content: For really complicated things like bus contention I pull out my Tektronix logic analyser. The sheer power of the trigger system on that machine dwarfs anything I've seen on an oscilloscope so farAnd it also has really deep memory with store-changes-only 'compression'.Anyway, even with high capture rates there is still a chance you miss the 'glitch'. With a proper trigger condition the chance you catch a 'glitch' is 100% but sometimes it takes some work to come up with a good trigger condition.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: October 01, 2014, 05:34:21 am
content: Quote from: David Hess on September 30, 2014, 10:41:15 pmNo, it doesn't. With a good DSO you don't even need to know what you're looking for. Just set the scope to trigger on any deviation from the expected waveform and it will happily show you any glitch that is there.Sitting in front of a scope in persistence mode and waiting for a glitch to show up may have been a good way in the 80's when CROs were still a thing but nowadays there are much more sophisticated methods to find signal deviations. Why do you think high end scopes can get away so easily with low waveform rates? It's because you don't hunt for glitches the old way, you set up how the signal is supposed to look like and then trigger for any deviations. Even my 11yrs old LeCroy WaveRunner LT264M can do that, and this scope does have some low wfm rates (see my review). Newer LeCroy scopes have something calledWaveScanwhich makes it even easier to find glitches, and scopes from other manufacturers do have somewhat similar tools. There's really no need to have a scope sitting in persistence mode waiting for a glitch to appear.BTW, this is one of the reasons why I disagree with the common belief that the first scope for a starter in EE should really be an analog scope. While many think that this will teach newbies how to use a scope properly, in my opinion it only does introduce outdated methodologies that are later difficult to let go. Instead of starting with an obsolete piece of technology it's better to start with a DSO and learn how to handle that like a DSO and not like a modern variant of a CRO.

author: nctnico
author_rank: Super Contributor
timestamp: October 01, 2014, 08:01:59 am
content: +1

author: David Hess
author_rank: Super Contributor
timestamp: October 01, 2014, 12:49:23 pm
content: Quote from: Wuerstchenhund on October 01, 2014, 05:34:21 amThis is something I was distantly aware of but left out because DSOs which support it are relatively expensive. If it is a characteristic of a good DSO, then most people are going to be using bad ones.QuoteI was thinking of DSOs and not analog storage oscilloscopes although I picked up a Tektronix 7834 for exactly this purpose at home because it was the least expensive high bandwidth alternative that I could find. Even now an Rigol which could replace it is in the $2500 to $4000 range.QuoteWhat is the least expensive DSO which can do this? LeCroy's web site is not very helpful unless you want to examine every series for the features you want.QuoteI do not disagree but starters in EE usually face budget restrictions which until recently would restrict them to rather primitive DSOs that are worse than analog CRT oscilloscopes in some respects. When I needed a storage oscilloscope for work about 15 years ago, my boss provided a Tektronix 464 (!) and then later a Fluke ScopeMeter which ended up being used in production anyway so I was still stuck with the 464.On a different subject, does CRO refer to any oscilloscope, analog or digital, which uses a CRT? I always find the term terribly ambiguous in some contexts.

author: MarkL
author_rank: Unknown
timestamp: October 01, 2014, 01:42:41 pm
content: Quote from: Neganur on September 30, 2014, 08:35:09 pmYes, to both questions. The update rate is 1/(capture_time+dead_time). Dead time is simply the time when not capturing. My preference is to not have the two numbers convolved since it's more meaningful for me.The dead time should be roughly a fixed number for a given number of points to process (including math, protocol decoding, etc.). From the chart, the MSOX3000 has about 1us dead time, the Wavesurfer 2ms, and the TDS3000 1.3ms. I'm not sure where to pin the DPO3000 since it drops at one point dramatically with the capture time, which I wouldn't expect. Looks like it might be a bug or some strange architectural limitation.When taking measurements (with any equipment) it's important in interpreting results to be cognizant of what you might *not* be seeing. On scopes, knowing the dead time can help gauge that uncertainty (along with BW, noise, trigger sensitivity, probing inaccuracies, etc etc). It's just part of knowing the limitations of your equipment.A short dead time can help bring an anomaly to the surface more quickly, but as other posters have pointed out, it's not the only tool in the bag. Glitch triggers, persistence, test masks, and if you have control over the DUT software, software generated triggers are extremely useful. It really depends on the situation.

author: XFDDesign
author_rank: Frequent Contributor
timestamp: October 01, 2014, 02:36:54 pm
content: For what it's worth, my finding is that Agilent now provides a much better support model than the Danaher-Tektronix does. My place of work uses mostly HP gear (plenty of which still has HP branded on it), and when some pieces of test gear go down or we need to buy an option, Agilent will happily sell us the option or the repair.Contrast to my home TDS5032B scope of 2005 vintage, and Tektronix would not even sell me the software key to buy the Jitter Analysis software (a thing which occupies no shelf space). Their repair options are essentially the price of a brand new Rigol scope of greater capabilities to boot. When I bought my TDS5000 I did so because it had, at the time, crazy deep memory.There are a number of things that you get with very deep memory that sit outside of the glitch hunt everyone seems to be hung up on. First and foremost, aliasing is less likely to be a measurement error. The 10k points on the TDS3000s easily let you get screwed on this front, by essentially down-converting higher frequency business at a much lower frequency. The experienced engineer will be cognitive of this kind of thing, but if a less experienced engineer has parts singing at higher frequency and they see a pretty sine wave at 50kHz, they're not getting good feedback. More datapoints means more information is put on the screen; they'll likely see the "bar of noise" that would lead to turn down the time base to smaller values.More datapoints also permits the user to do more with the acquired data; if they wish to perform some post-signal-processing on the PC, they can do so and do it with more signal content. This gets pretty important when they wish to spit the result back out through some D/A box.In my case, I've begun needing to perform a jitter analysis on an OXCO product I'm making. Tek doesn't want my money anymore, but I'm not up the creek completely as I can perform deep memory captures on the waveform (and again) then post-process that data on the PC to determine the RMS jitter.

author: eurofox
author_rank: Unknown
timestamp: October 01, 2014, 04:00:01 pm
content: It seems that the like or not Agilent/Keysight and Tektronix get emotional hereI'm the happy owner of a DSOX3001 with Lan interface and genuine full options.I got Tektronix scopes mainly before, I like the 2465B, one of the best analog scope ever build but the newer generation of Tektronix oscilloscopes is different, I got a new TDS3054 that I sold a few months later, I disliked very much this scope, I replaced it by my 2465B.I bought later a TDS784B second hand, a good scope but small screen, no serial decoding.When I decided 6 months ago to update my gear I decided to buy an Agilent oscilloscope after hesitating a lot between Agilent or Tektronix or maybe R&S.The Agilent/Keysight service is simply 1st class, I cannot say that from TektronixIt is not easy to compare both scope because +/- points on both sides but the Agilent GUI is always very responsive, is not the case with the Tektronix, the Agilent does all decoding by hardware and is not the case of the Tek.With respect to the memory, finding glitches in a huge amount of data in memory is not easy, is not even sure that it is captured, it is smarter to select the right trigger to capture the glitch.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: October 01, 2014, 04:21:04 pm
content: Quote from: David Hess on October 01, 2014, 12:49:23 pmNot really. The functionality has been available for more than 15 years, and nowadays there are plenty of opportunities to get an advanced scope in good condition for relatively little money.QuoteNot necessarily. I have very limited experience with low end scopes but from what I know even many cheaper scopes come with better triggers and pass/fail testing.And I'd say rather than most people using bad DSOs I think it's more a case of many people using their DSO like an old analog scope because of their training, maybe coupled with a certain hesitation to let go of old habits that decades ago were useful but nowadays aren't really appropriate any more.QuoteThe least expensive scopes are probably the 9300 Series and the WaveRunner 1 LT Series which can often be found dirt cheap on ebay.For brand new scopes LeCroy's advanced range starts with the WaveSurfer 3000, which I think starts somewhere around the $3200 mark.QuoteYes, but only if they insist to buy new. The second hand market has quite a lot to offer on much more advanced scopes than your cheap entry level gear. For example, for roughly the price of a Siglent SDS1072 (70MHz 2Ch) I got a WaveRunner 2 LT264M, with 350MHz bandwidth, 4 channels and lots of advanced functionality (this is the scope I reviewedhere). And for my WaveRunner 64Xi (600MHz 10GSa/s 25Mpts) I paid less than a new DSOX3024 would have cost me.There are enough deals out there if you have a little bit of patience and know what you want (i.e. do some research before buying). It's not really rocket science.And they learn properly how to drive a modern DSO instead of beginning their career with learning inappropriate and outdated methodology with a piece of museum gear (analog CRO).QuoteYou're right, it is. With 'CRO' I meant analog scopes, not DSOs with CRT.

author: David Hess
author_rank: Super Contributor
timestamp: October 01, 2014, 08:16:46 pm
content: Quote from: Wuerstchenhund on October 01, 2014, 04:21:04 pmEven what I would consider the low end now comes with advanced triggers in addition to level/slope triggers which is nice.Doesn't pass/fail and mask/limit testing require a previous trigger? This would limit it to the waveform acquisition rate preventing them from being a substitute for the right trigger.My experience at the high end has been limited to evaluation.QuoteI think the best deals I have picked up are a 300 MHz 500 MS/s Tektronix 2440 digital storage oscilloscope and a 14 GHz analog/digital sampling oscilloscope. I get most of my development work done with a Tektronix 2230 but I could use an MSO. For now I get by with a word recognizer on my 2440.I looked through the LeCroy documentation on the LT264M and concerning WaveScan, TriggerScan, and WaveStream and did not find:Quotein the sense of replacing high waveform acquisition rates and persistence. In LeCroy's advanced trigger setup instructions, they specifically recommend:TIP: Use Persistence to reveal the glitch shape, then match the trigger level to the level atwhich the glitch appears.- Page 112 Waverunner Operating ManualLeCroy advertises WaveStream for finding aberrant waveforms to determine suitable trigger settings:WaveStream is most helpful in viewing signals that have signal jitter or signal anomalies, or for applying a visual check before creating an advanced trigger or WaveScan setup to locate an unusual event.I think we are talking past each other about different things and applications.QuoteI have always been leery of high performance test instruments available on Ebay which lack service documentation which will be the case for anything introduced after about 1990. Manufactures are increasingly proving zero support for out of production products.Research before buying is not enough especially for a starter in EE who lacks experience. This is one reason I almost universally recommend inexpensive instruments to start out with. The other is that starters in EE are prone to expensive mistakes and it is better to make those with inexpensive equipment.QuoteI am not convinced this is a problem except for marketing getting in the way although . . .When I was evaluating the Tektronix MSO/DPO5000 series, I asked how to go about using it to make measurements which were easy on some of my analog oscilloscopes and the application/sales engineers were sure it could be done but could not figure out how. A couple times we either ended up placing the oscilloscope into an unrecoverable state requiring the setup to be reset or locking it up requiring a cold boot. Maybe this is just a Tektronix or embedded Windows 7 or early firmware problem.QuoteIt gets even more confusing with the term DSO. Does that mean digital storage oscilloscope or digital sampling oscilloscope? To me the two are very different if only because I have some of the former and one of the later. Even worse, some old digital storage oscilloscopes do not use sampling because their high speed ADCs do not require it.If I ask a manufacturer's representative about high bandwidth digital sampling oscilloscopes, they always start with digital storage oscilloscopes and I end up having to explaining the difference.

author: don
author_rank: Regular Contributor
timestamp: October 01, 2014, 10:50:50 pm
content: Quote from: eurofox on October 01, 2014, 04:00:01 pmI've had excellent experiences with support from both Tektronix and Agilent. Original question was asking about update rate importance and memory depth importance on tek mdo3000 and agilent 3000x so just trying to circle back to that.Tek has clear advantage on memory. 20-40x that of agilent because it has 10M on all channels all the time. Agilent can be as low as 250k with 2M or 500k with 4M option . Likely a cost of architecture for high update rates. But agilent advantage on update rate is much smaller. About 3x at 1M/s vs 280k/s for tek. Point being that memory depth can be used to capture large records and then search for anomolies post capture with waveform search (can scan for runts / glitches) or visual. You can trigger on a system reset and scan through captured data. I'm not familiar with trigger capability of agilent, but will assume the same as tek (obviously setting trigger is preferred). I use its of memory and rarely use fast update rates.Personally I don't see hw decoding or GUI speed as that significant ( satisfied with tek). At least not enough to trump tek's memory, cursors, measurents on waveform data, teks auto roll mode or waveform inspector (zoom). For my usage at least. But for those not knowing what to buy or significance of specs, info from different perspectives can be usefu.Both are fine scopes, just different usage models. . .

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: October 02, 2014, 02:48:10 pm
content: Quote from: David Hess on October 01, 2014, 08:16:46 pmIt probably depends on the implementation. For example, WaveScan on LeCroy XStream scopes doesn't require a previous trigger.QuoteThe WaveRunner LT Series predates XStream (Windows) scopes (WR LT run VxWorks), and therefore don't have WaveScan, TriggerScan and WaveStream.QuoteProbably because at that time when these scopes were new (1998 - 2003) a large portion of users came rom analog scopes. Also don't forget that on these scopes many of the advanced functionality was contained in options (which mostly came with separate manuals), and not all of them were even available when the scopes came out.I'm also not a great fan of LeCro's documentation, which is often put together in quite a sloppy manner where sections are copied across from other/older scopes. Agilent is light-years ahead in this respect.QuoteWaveStream (which has been introduced in 2005 with the WaveSurfer Xs and the WaveRunner Xi) is LeCroy's equivalent of Tek's DPO. When selected it limits signal processing and brings the data to the screen faster. The adjustable persistence makes it really 'feel' like an analog CRO. WaveStream is an addition to existing functionality, the standard persistence modes (2D and 3D) are also still there of course.The main reason this was implemented is because a certain competitor managed to make the wfm rate a major marketing argument (around the same time LeCroy also started listing the max trigger rate in their brochures, which they usually didn't do before). WaveStream also made the transition easier for people coming from analog scopes and making the switch to a modern advanced DSO.WaveStream does show some glitches which wouldn't necessarily show up so quickly when the scope is in normal operating mode. However, (like a true analog CRO) it doesn't show all deviations that might be there. On the other side, WaveScan (which is available on all XStream scopes) *does* exactly that, in addition to capturing things that would show up on WaveStream. So in the end it's much more useful and quicker to simply use WaveScan in the first place.In addition, the XStream scopes with WaveStream don't reach their highest trigger rates in WaveStream mode anyways but in Sequence Mode. The WaveRunner 64Xi for example is specified with up to 1.25M wfm/s (didn't check). Not too bad for a scope which was introduced in 2005.QuoteService Manuals including schematics are freely available for LeCroy 9400, 9300, LC, WaveRunner 1/2 LT, WavePro 900 and WaveRunner 6000(A) Series. This covers most of their scopes from around 1990 to 2006. I'm sure LeCroy will make more scopes available as time goes by.LeCroy also gurantees support for their scopes for 7 years after a Series was EOL'd, and even after that does perform best-effort maintenance/repair. You can still send in a 9300 Series scope for repair, and this series was terminated around 1998.QuoteI agree with that the original investments should better be limited, but I do disagree that research is difficult. For advanced big brand scopes there really are only three contenders: Agilent, Tektronix and LeCroy. And with all three manufacturers there's enough information and experience out there to get a good picture.QuoteProbably a firmware bug. A scope shouldn't crash or become unrecoverable, no matter if it runs Windows or not.I do have similar experiences with Tek's sales droids not knowing how to drive their equipment. But I admit they are fast to try to sell you something if you dare to download anything from the Tek website, even though the checkbox for wanting to be contacted by Tek remained unticked. They really seem to be desperate.QuoteIt's mostly'Digital Storage Oscilloscope'these days. The old sampling scopes (using ETS) are a thing of the past unless you need a scope over 65GHz where a few scopes which haven't been refreshed in roughly a decade remain available (and which should disappear soon when 100GHz realtime scopes appear on the market).