Let’s Talk About LeCroy Scopes, AKA… the “Wuerstchenhund Holds Court” Thread

[David Hess]

Well, that is not surprising, considering that the Rigol DS1000z is a $400 scope with very limited functionality. I already said that for low end scopes PD is sometimes the only option. But we're not talking low-end scopes here.

It was surprising to me but only because I had studied the user manual which implied something very different.  Marketing triumphs over engineering.

There really is no alternative to evaluating an oscilloscope in person with a collection of problems to solve.

and I would rather have all three than a long record length if it means a faster update rate with lower blind time.

Great. But this tells me that you somehow missed the whole point I was making, which is that the lack of PD on the WS3000 is made up by other tools. Don't take this the wrong way but you sound like the type of person that if sat in front of a modern high end scope and asked to find and measure a glitch would resent to persistence mode and cursor readouts.

There's a reason why a modern mid-range or high-end scope has advanced toolsets, which is that you don't have to rely on crutches that pretty much only exist because of limitations in test gear 20 years ago.

I did *exactly* that while evaluating a Tektronix MSO5204 and its "advanced toolset" was not able to make the kind of glitch measurement I was interested in which would have been trivial on a oscilloscope with delta delay capability.  I could not get it to work and the Tektronix sales engineers could not get it to work although together we managed to crash the DSOs user interface a couple of times.  Or does the MSO5000 series qualify as a budget low end DSO?

This experience among others with modern mid-range DSOs has led me to distrust the advertised capabilities of all of them.

These days, scopes come with reasonably large sample memories, which means even in normal mode you can run the scope at full sample rate for longer timbases. Also, modern scopes tend to come with a much larger sample rate to BW ratio (the 750Mhz WS3074 samples at 4GSa/s, the 1Ghz DSOX3104T at 5GSa/s), which means there is lots of room for the sample rate to drop without losing any details. With its 10Mpts memory, even the 750MHz WS3 can aquire a 5ms period at sufficient sample rate (2GSa/s). And the lower the analog bandwidth the further the sample rate can be dropped without losing detail.

I am not sure if this is what you meant to say.  That modern DSOs typically come with a large maximum sample rate to bandwidth ratios makes no difference when the sample rate is limited by record length unless they have peak detection, delayed sweep/acquisition, or something similar going on between the digitizer and acquisition record.

The point is that back then in 1996 a standard 100Mhz DSO like the HP 54622A came with 200MSa/s sample rate, while a modern day equivalent samples at 2Ghz or more. The large oversample ratio on modern scopes means it doesn't necessarily have to run at full sample rate to get all the details, meaning on a scope that lets you manually select the sample rate you can simply drop the sample rate to extend the acquisition period even more.

I think that may have been Tektronix's theory when they released the TDS700 series without peak detection.

With delayed sweep/acquisition capability, the record length is of less importance for making the maximum sample rate available.

[David Hess]

You are missing my point slightly. For a first cursory look at a signal I'd like to see it's extremes at all timebase settings (even the slowest ones and roll mode) and for that peak detect is the only option. Sometimes I have to look at signals from systems which are slow but can have glitches. Even worse: I have no idea what to expect. So I set the scope to roll mode with peak detect on to get a feel for what a signal does (amplitude and if there are pulses at all) over a period of seconds to minutes. From there I can switch to triggering on glitches etc.

I use peak detection in the same way and if I had a DSO with DPO mode, I would probably use that instead as required.  I have been told a couple of times now that DPO mode is intended for quantifying signal irregularities so that advanced triggers can then be setup to capture them.

[Someone]

In WaveScan you can assign limits to any math function like rise time, peak width, duty cycle, RMS and so on ... on a trace and when the limits are -touched the trace will be stored. I am sure you can find any peak with WaveScan.
That way you can leave your scope running for days and review the stored anomalies next day. The high end scopes probably have  much more math functions.

Except you won't find the peak/error/glitch with certainty. The scope is hunting through the captures offline to look for anomalies, which relies on the speed you are able to search. This will never be as fast as realtime capture and accumulation, which although it still has a dead/blind time is much smaller than offline analysis.

You are missing my point slightly. For a first cursory look at a signal I'd like to see it's extremes at all timebase settings (even the slowest ones and roll mode) and for that peak detect is the only option. Sometimes I have to look at signals from systems which are slow but can have glitches. Even worse: I have no idea what to expect. So I set the scope to roll mode with peak detect on to get a feel for what a signal does (amplitude and if there are pulses at all) over a period of seconds to minutes. From there I can switch to triggering on glitches etc.

I'm sorry and maybe I still miss your point but that sounds like a perfect scenario for WaveScan (which is *not* a trigger btw, it's more like a search tool/glitch finder, and it finds stuff that triggers won't). Instead of going through various time base settings I'd just enable WaveScan and let it search for deviations, and then just let it run for a while (5 seconds, 30s, a few minutes, ten days, whatever is appropriate). WaveScan will tell me exactly what went wrong at which point in time.

What features does Wavescan offer over a Mask test?
Sounds from what you describe it's much the same thing. 
Can it be used over non-repetitive waveforms or a continuous data stream?

Wavescan is the offline analysis built into most Lecroy scopes it takes the capture and then searches through it, if it finds events you can tell it what to do with them. Mask testing can be done offline like this, or it can be done much faster in hardware, but mask testing cannot do all the advanced analysis of wavescan so they can miss or capture different characteristics. Keysight offer similar tools under their InfiniiScan name.

You are missing my point slightly. For a first cursory look at a signal I'd like to see it's extremes at all timebase settings (even the slowest ones and roll mode) and for that peak detect is the only option. Sometimes I have to look at signals from systems which are slow but can have glitches. Even worse: I have no idea what to expect. So I set the scope to roll mode with peak detect on to get a feel for what a signal does (amplitude and if there are pulses at all) over a period of seconds to minutes. From there I can switch to triggering on glitches etc.

I use peak detection in the same way and if I had a DSO with DPO mode, I would probably use that instead as required.  I have been told a couple of times now that DPO mode is intended for quantifying signal irregularities so that advanced triggers can then be setup to capture them.

Mr W is for some reason opposed to this method of working. The rest of us get on with life and use realtime modes to get a quick look at the signal before deciding what to do. Accumulating a large amount of captures in an eye diagram or even just free running you can gain some understanding of what needs a more detailed investigation.

[Wuerstchenhund]

What features does Wavescan offer over a Mask test?
Sounds from what you describe it's much the same thing. 
Can it be used over non-repetitive waveforms or a continuous data stream?

Yes it can.

WaveScan is pretty much an automated anomaly finder. It can learn how the signal works and then identify pretty much any kind of anomaly, even those that are difficult to trigger on. That includes data streams for a wide range of standards (provided you have the serial decode and analysis option for that standard of course). Other than Mr S. claimed, WaveScan *does* work in real-time (although it can also be used post-acquisition).  It's a pretty unique tool, and none of the other manufacturers offer anything similar. Keysight has InfiniiScan on the Infiniium Series, it can't do even half of what WaveScan does, it's slow, and of course it's a paid-for option.

As stated above, the WaveSurfer mid-range scopes have a slightly cut-down version of WaveScan (not all functions as the high-end scopes), and I'm not sure where exactly the differences are (documentation isn't exactly a strong point of LeCroy, they could learn a thing or a hundred from Keysight here), but I'm pretty sure for the stated case where people use PD, WaveScan on the WS3k would have no problem finding the anomalies.

[Wuerstchenhund]

Well, that is not surprising, considering that the Rigol DS1000z is a $400 scope with very limited functionality. I already said that for low end scopes PD is sometimes the only option. But we're not talking low-end scopes here.

It was surprising to me but only because I had studied the user manual which implied something very different.  Marketing triumphs over engineering.

Well, it's Rigol, what should I say. That's the company that wants $9k for a 1GHz DS9104 where basic functions like ETS still don't work 7 years after the scope came to market 

There really is no alternative to evaluating an oscilloscope in person with a collection of problems to solve.

No, there never is. Which is why I'd always recommend to get some loanders and take the scopes for a spin around the block before committing several grand for what should be a tool that works for you.

There's a reason why a modern mid-range or high-end scope has advanced toolsets, which is that you don't have to rely on crutches that pretty much only exist because of limitations in test gear 20 years ago.

I did *exactly* that while evaluating a Tektronix MSO5204 and its "advanced toolset" was not able to make the kind of glitch measurement I was interested in which would have been trivial on a oscilloscope with delta delay capability.  I could not get it to work and the Tektronix sales engineers could not get it to work although together we managed to crash the DSOs user interface a couple of times.  Or does the MSO5000 series qualify as a budget low end DSO?

I'm sorry to have to say this but Tektronix is shit. I have a MSO3054 (or had, until a week ago), and I've seen the MSO4k and MSO5k Series, and they are pretty much the same. These scopes are slow, they still can't produce decent waveform rates in normal mode, and their toolset is pretty basic. The few times we had a Tek representative inhouse, we saw pretty much the same as you. I felt sorry for them because they have to go out and sell that crap.

This experience among others with modern mid-range DSOs has led me to distrust the advertised capabilities of all of them.

Well, the lesson here is just don't buy Tek. They were great 30yrs ago when analog scopes were a thing but their DSOs are nothing to write home about. When I got my MSO3054 I really wanted to like it, but seriously it's so bad using it you lose the will to live. The UI is dreadful and must have been designed by someone who genuinely hates humans. It's really that poor. No wonder why Keysight pretty much owns most of the T&M market.

[Wuerstchenhund]

Wavescan is the offline analysis built into most Lecroy scopes it takes the capture and then searches through it, if it finds events you can tell it what to do with them. Mask testing can be done offline like this, or it can be done much faster in hardware, but mask testing cannot do all the advanced analysis of wavescan so they can miss or capture different characteristics.

No, WaveScan is *not* just an off-line tool (although it can be used post-acquisition), like mask testing it works real-time as well.

Keysight offer similar tools under their InfiniiScan name.

No, they don't InfiniiScan is a far cry from what WaveScan does. It's pretty much a flexible trigger which you have to setup to look for specific issues (which means you already have to know what you're looking for). It's a lot more flexible than a conventional trigger, but it's nothing like WaveScan.

Of course, If you had ever *used* InfiniiScan and WaveScan yourself you'd know that, and maybe then you wouldn't feel the need to come to these threads and spew the always same nonsense about things you don't understand and you've clearly even barely read about. I have InfiniiScan on my work DSO91304A (it's pretty much on all our Infiniiums), and while it adds some really useful functionality (like the zone triggers) it's in no way a full substitute for or in any way equivalent to WaveScan.

Mr W is for some reason opposed to this method of working. The rest of us get on with life and use realtime modes to get a quick look at the signal before deciding what to do. Accumulating a large amount of captures in an eye diagram or even just free running you can gain some understanding of what needs a more detailed investigation.

That condescending statement just shows that you really have no idea what WaveScan is (aside from I guess you could find with a quick google search). Since you seem to be made of Teflon (nothing sticks), I'm not going to repeat all the info that is given here and in the old WaveRunner 8000 thread again, as clearly you come to these threads not to contribute but because you have some hidden agenda.

Just let me say this, that one sign of a good engineer is eagerness to learn, and that includes functions and capabilities that new tools can bring to the table and which could make life easier (and then make an informed choice wether it helps for his own tasks or not). The average engineer sticks to what he learnt in his youth and avoids change or spending time on learning new stuff wherever possible. Both categories are easily recognizable.

Of course, there's nothing wrong with wanting to stick with what you know. Just buy tools that support your way of working and live on happily. But don't come here and try to BS others that show more interest in what is available in modern tools and who want to see if they can use it for their benefit.

So If you want to contribute positively you're welcome. But if you continue with your obvious 'agenda' then don't get surprised if some of the Mods will have a serious talk with you.

[Someone]

Wavescan is the offline analysis built into most Lecroy scopes it takes the capture and then searches through it, if it finds events you can tell it what to do with them. Mask testing can be done offline like this, or it can be done much faster in hardware, but mask testing cannot do all the advanced analysis of wavescan so they can miss or capture different characteristics.

Not this again 

Why is it that you always show up to these threads and spread nonsense that shows that you've actually no idea what you're talking about? Someone clearly has a hidden agenda here.

And No, WaveScan is *not* just an off-line tool (although it can be used post-acquisition), like mask testing it works real-time as well.

Its not running in the acquisition memory at sample rate, its run on the general purpose processor, offline, as you say it can be run on acquired data exactly the same way. It can be used in realtime at a diminished capture rate which is addressing the questions posed by other users although not your narrative.

Mr W is for some reason opposed to this method of working. The rest of us get on with life and use realtime modes to get a quick look at the signal before deciding what to do. Accumulating a large amount of captures in an eye diagram or even just free running you can gain some understanding of what needs a more detailed investigation.

That statement just confirms that you really have no idea what WaveScan is (aside from I guess you could find with a quick google search). Since you seem to be made of Teflon (nothing sticks), I'm not going to repeat all the info that is given here and in the old WaveRunner 8000 thread again.

Just let me say this, that one sign of a good engineer is eagerness to learn, and that includes functions and capabilities that new tools can bring to the table and which could make life easier (and then make an informed choice wether it helps for his own tasks or not). The average engineer sticks to what he learnt in his youth and avoids change or spending time on learning new stuff wherever possible. Both categories are easily recognizable.

Of course, there's nothing wrong with wanting to stick with what you know. Buy tools that support your way of working and live on happily. But don't come here and try to BS others that show more interest in what is available in modern tools and who want to see if they can use it for their benefit.

You could certainly reference that thread where you consistently claimed realtime use was stupid yet failed to suggest alternatives, and didnt come up with any examples at all, sure. Everyone would love to see some new tools and ways to use them but you wont share.

[JPortici]

Another nice feature on the WS3000 would be a SENT decoder.

Agreed. only option i'd really "miss" over a MSO3000T (that i already have on a 200€ picoscope + whatever price pc though)

Direct replay from a trace to the build in function generator would be nice.

+1 on that too, much faster than capture, download, load on another AWG

[Wuerstchenhund]

And No, WaveScan is *not* just an off-line tool (although it can be used post-acquisition), like mask testing it works real-time as well.

Its not running in the acquisition memory at sample rate,

*Nothing* runs in the acquisition memory in a scope, it's a store for sampled data

its run on the general purpose processor

On a LeCroy X-Stream scope (which the WS3000 is, X-Stream lite) *everything* runs on the main processor. Which is the main reason why these scopes are so fast.

Which you should know by know as this has been excessively discussed in the past already.

offline, as you say it can be run on acquired data exactly the same way. It can be used in realtime at a diminished capture rate which is addressing the questions posed by other users although not your narrative.

WTF are you talking about? WaveScan directly uses life acquisition data, there's nothing inherently "offline" to it as you claim. The update rate goes down (naturally because of the processing required), by how much depends on the circumstances (i.e. what WaveScan settings, scope generation and CPU cache size and speed). Nevertheless it scans all acquired data.

As to my "narrative", all I said was that the tool you clearly know jack shit about should be a sufficient replacement for situations where people tend to use Peak Detect.

You could certainly reference that thread where you consistently claimed realtime use was stupid yet failed to suggest alternatives, and didnt come up with any examples at all, sure. Everyone would love to see some new tools and ways to use them but you wont share.

I have no idea what you're talking about. But in any case, if you feel that something that has been discussed in another thread needs further discussion then this will happen there and not here, which seems to be your modus operandi to stir up trouble.

[nctnico]

WTF are you talking about? WaveScan directly uses life acquisition data, there's nothing inherently "offline" to it as you claim. The update rate goes down (naturally because of the processing required), by how much depends on the circumstances (i.e. what WaveScan settings, scope generation and CPU cache size and speed). Nevertheless it scans all acquired data.

As to my "narrative", all I said was that the tool you clearly know jack shit about should be a sufficient replacement for situations where people tend to use Peak Detect.

The thing is that peak-detect combined with roll mode will show all peaks. If Wavescan is an acquire-process-acquire-process- system then it will have a considerable blind time. IMHO you are too much focussed on finding glitches in known signals but you have to take a few steps back to a signal you know nothing about and want to get a feel for. Without peak detect this is nearly impossible and it sounds to me Wavescan isn't solving that. Compared to the Lecroy Wavesurfer 3000 it seems the R&S RTM2000 series is in the same price range and it does have peak detect.

[Wuerstchenhund]

Wavescan sounds like a perfect tool for letting the scope find 'errors' in a signal. However every now and then I find myself in a situation where I hook up a scope to a system and I have no idea what to expect so the first thing I want is a slow recording (seconds per divisions) of some signals which may be interesting. Roll-mode or long time/div with peak detect are really crucial because that way I have both an overview of what happens on a long timescale and an indication if there is or isn't something happening on shorter timespans. From your description I don't see how wavescan can do the same but then again I have never seen Wavescan in action.

I still believe WaveScan could help here, as it can find errors you don't know are in the signal.

Obviously you have adapted your way of working to your tools, but if you ever have the chance just give it a try.

[Wuerstchenhund]

I would like to have WaveScan on FFT which would include math functions on a FFT trace.

WaveScan on FFT is unlikely as FFT is processed data (and WaveScan works with the original sampled data).

I haven't tried on the WS3000 but as to math on FFT, you should be able to use the FFT trace (which is just a math trace like any other math function) as an input to another math function.

Another nice feature on the WS3000 would be a SENT decoder.

LeCroy has stated they'll expand the options for the WS3k depending on customer feedback (they already implemented CAN and FlexRay which were both missing when the scope came out) so they might as well implement SENT if enough people show interest.

One thing about the WS3000 which annoys me is the autosetup which probbaly breaks sampling for a few seconds each time its triggered. I could not yet find out when the autosetup is triggered. There is a button for autosetup on the scope but it has no use for me since the scope starts it automaticly.
The autosetup is realy helpfull and gives real good results but it interrupts sampling.

the scope should not start auto setup by itself, only if you press the button (if it does then there's something wrong with your unit).

The WS3000 does a self-cal cycle after a certain amount of time running but that is once only.

Direct replay from a trace to the build in function generator would be nice.

As with SENT, ask LeCroy, they might just implement it in a next software release.

[Wuerstchenhund]

The thing is that peak-detect combined with roll mode will show all peaks. If Wavescan is an acquire-process-acquire-process- system then it will have a considerable blind time. IMHO you are too much focussed on finding glitches in known signals but you have to take a few steps back to a signal you know nothing about and want to get a feel for.

I do, and that's what WaveScan can be used for. It can find problems you didn't know where in the signal. You seem to think that you have to know the problem for it to work, but you don't.

Yes, the blind time will be higher than with PD in roll mode. But then all roll mode tell you if there are any drop-outs or if there aren't (and that only if you didn't miss anything), you still haven't analyzed the problem.

Without peak detect this is nearly impossible and it sounds to me Wavescan isn't solving that.

It's difficult to do remotely (and I don't have a WS3000 at hand anyways) but I'm still confident I could find with WaveScan anything you find with PD.

Just out of interest, what frequencies/pulse widths/PRFs are we talking here? You mentioned H-Sync/V-Sync which suggests some kind of video signal?

Compared to the Lecroy Wavesurfer 3000 it seems the R&S RTM2000 series is in the same price range and it does have peak detect.

The RTM2000 is a very nice scope (and yes, it does have PD), however it has a max update rate of some 11k wfms/s, a much smaller screen, and you only get 128k FFT, plus options and probes are pretty expensive (and probe selection is very limited). However it does have some nice features (like dimmable LED indicators), it's really very silent, and even comes with a Z input (brightness modulation for true X/Y/Z mode) which is a rarity on DSOs. It also has a memory search tool that helps to find certain glitches and runts post-acquisition.

Some time ago I bought a RTM1054 (500MHz 4ch) 2nd hand which for the price (<$2k) was an absolute bargain. The RTM2000 is pretty much the same plus a few improvements (128k instead 64k FFT, 10M instead of 8M, MSO option, more serial decode standards) but the platform is the same (BlackFin based). The scope is now with someone else who talked me into selling it to him and he's quite happy. I'm not sure I'd have paid the $6k or so R&S wanted for it when new.

I know we talked about this and you had some problems finding representation in your country but if you have the chance then I'd recommend to get loaners and spend some time exploring the various tools like WaveScan in your test environment. I might well be that I'm wrong and WaveScan can't help in your situation (although I doubt that), but I'd really recommend to give it a try.

The worst thing with WaveScan is that it is so poorly documented by LeCroy (like a lot of things, unfortunately).

[AutomationGuy]

I don't know the insightes of the WaveSurfer3K but technicaly it should be possible to implement WaveScan at least partly in FPGA and process all data in real time. How many math functions are implemented in VHDL could depend on the scope price. There might still be some functions implemented on an "offline" CPU. That would make WaveScan run "offline" in just some configurations. Many might run in real time.

I know there is a limit on high speed signals but in many usecases WaveScan could run in real time. Especialy on video or audio signals.

LeCroy will not publish its scope insights. Especialy not for marketing reasons.

I just need occasionaly peak position and peak width in numbers on an FFT to quickly read out without fiddling with cursors. A math function could implement that. If FFT could be implemented in VHDL plus math that could even run in real time in WaveScan.

WaveScan might not be fast enough to always catch all anomalies but its so quickly configuered and can run for days which saves so much time for me to find problems.

[Someone]

WTF are you talking about? WaveScan directly uses life acquisition data, there's nothing inherently "offline" to it as you claim. The update rate goes down (naturally because of the processing required), by how much depends on the circumstances (i.e. what WaveScan settings, scope generation and CPU cache size and speed). Nevertheless it scans all acquired data.

As to my "narrative", all I said was that the tool you clearly know jack shit about should be a sufficient replacement for situations where people tend to use Peak Detect.

The thing is that peak-detect combined with roll mode will show all peaks. If Wavescan is an acquire-process-acquire-process- system then it will have a considerable blind time. IMHO you are too much focussed on finding glitches in known signals but you have to take a few steps back to a signal you know nothing about and want to get a feel for. Without peak detect this is nearly impossible and it sounds to me Wavescan isn't solving that. Compared to the Lecroy Wavesurfer 3000 it seems the R&S RTM2000 series is in the same price range and it does have peak detect.

This is the important point for everyone to understand, searching the acquired data after the fact looking for anomalies has a much higher blind time than looking at realtime or your extreme example of peak detect in roll mode which theoretically has no blind time if you check the screen at least once per horizontal period. Different ways to look for different characteristics, and all useful techniques.

I don't know the insightes of the WaveSurfer3K but technicaly it should be possible to implement WaveScan at least partly in FPGA and process all data in real time. How many math functions are implemented in VHDL could depend on the scope price. There might still be some functions implemented on an "offline" CPU. That would make WaveScan run "offline" in just some configurations. Many might run in real time.

Yes, this is the approach taken by some other manufacturers with hardware mask testing or advanced triggers. Lecroy goes further and offers a very unique triggerScan mode where it will step through a list of triggers to test against but sadly doesn't apply them in parallel so the blind time becomes proportional to the number of features you are looking for exceptions on (similar scaling for wavescan). So its about evaluating the possibility for different tools to a) see the anomaly, and b) the rate at which it can check for that specific anomaly amongst all the other possible anomalies it is looking for.

More advanced searches can be conduced offline, so they increase the ability to detect anomalies, but they capture slower and with higher blind times than simpler tools such as mask testing or visual assessment of an eye diagram. None of the tools are better for all situations no matter how much Mr W says so.

[David Hess]

*Nothing* runs in the acquisition memory in a scope, it's a store for sampled data

While literally true, this statement is misleading; operations like digital triggering, peak detection, timebase decimation, and DPO functions work on the non-trivial real time subset of samples in parallel with or between the digitizer and acquisition memory limited only by logic resources.  While I expect designers attempt to make this subset of samples as small as possible because logic costs more than memory (memory is incredibly cheap in all respects), it always exists unless none of these operations are present like on very early or very cheap DSOs.  What gets stored in the acquisition record has been processed except in trivial cases or apparently if you are LeCroy.

As to my "narrative", all I said was that the tool you clearly know jack shit about should be a sufficient replacement for situations where people tend to use Peak Detect.

I am not interesting in "sufficient" replacements; I am interested in superior replacements which if they do not cover all previous applications, at least do not preclude them using the older method.  DPO is usually but not always a superior replacement for peak detection so the later is still needed.  I am not sanguine that WaveScan is a superior replacement for either.

Marketing said the same thing about large acquisition memories replacing the need for delayed acquisition and peak detect yet the result has been lower performance or outright uselessness in a minority of applications which older DSOs without large acquisition memories have no trouble with; if a DSO misses the long tail of applications, then that is not an improvement no matter how much marketing tries to convince otherwise.  For instance if a current DSO cannot capture the jitter on a GPS pulse per second output at a sampling rate commensurate with its bandwidth, then I am not interested in it no matter how good its automatic measurement capability, touch screen, "one true knob" user interface (HP), and dual aspect ratio display (LeCroy) is.

Dig up Bob Colwell's Stanford lecture where he mentions "Blue Crystals" for an example of marketing driving development to its detriment.  If you cannot find it, I can provide it as a bittorrent link.  Marketing reminds me of the law aphorism about pounding the table but suitably modified:

If you have the record length on your side, pound the record length.  If you have the WaveScan on your side, pound the WaveScan.  If you have neither on your side, pound the table.

Your comment about LeCroy designs originating with physics applications where all original data is preserved and then analyzed fits with how WaveScan is described as working however I do not think that model is necessary or even suitable for design, development, and troubleshooting.

It would be interesting to consider how a modern DSO could work to provide superior performance to older designs.  Processing after acquisition strikes me as insufficient by itself unless either deadtime is acceptable or processing occurs in real time in which case why is there an acquisition record at all?

[Wuerstchenhund]

What gets stored in the acquisition record has been processed except in trivial cases or apparently if you are LeCroy.

That is right, because other scopes use 'destructive' acquisition modes (destructive as in the original sample data is destroyed) when not in normal mode.

It's still only data though 

As to my "narrative", all I said was that the tool you clearly know jack shit about should be a sufficient replacement for situations where people tend to use Peak Detect.

I am not interesting in "sufficient" replacements; I am interested in superior replacements which if they do not cover all previous applications, at least do not preclude them using the older method.

That is fine, but if you follow the discussion then you should realize that it was meant as a "replacement" at a functional sense, not literally, i.e. if you were given the WS3000 you could get the same results as when given a scope with Peak Detect.

It certainly didn't mean people like nctnico should rush out and buy one, besides that I've regularly pointing out that no scope should be bought without a test drive. If you had say a DSOX3000T and it fits your needs then it would be silly to sell it and buy a WS3000 instead. But if you're in the market for a scope in that class then the WS3000 is certainly worth consideration, and while it lacks some features it brings others that, while perhaps using a different approach most EE's would take, can replace many of them plus bring further benefits (you may or may not use, but that's up to you).

DPO is usually but not always a superior replacement for peak detection so the later is still needed.  I am not sanguine that WaveScan is a superior replacement for either.

It isn't, because WaveScan is not meant to replace DPO, a mode Tek had to implement because their scopes architectures suck so badly that they can't get decent update rates in normal mode without using some tricks. Other scopes have had persistence mode for years, and so does the WS3000.

Marketing said the same thing about large acquisition memories replacing the need for delayed acquisition and peak detect yet the result has been lower performance or outright uselessness in a minority of applications which older DSOs without large acquisition memories have no trouble with;

Well, PD is in pretty much any big brand scope aside from LeCroy, so I must have missed when a manufacturer claimed it's no longer needed because of memory lengths. What has happened though is that the need for PD has reduced a lot, simply because of ever increasing sample meory sizes.

Your comment about LeCroy designs originating with physics applications where all original data is preserved and then analyzed fits with how WaveScan is described as working however I do not think that model is necessary or even suitable for design, development, and troubleshooting.

That may be your opinion, but in reality there are many areas where having the original sample data retained so you can run various analysis modes in parallel is a big advantage. You'll find LeCroy scopes in pretty much every segment of high tech, often simply because no other scope including Keysight can offer the same performance or capabilities.  And that has been the case pretty throughout their existence.

If that architecture wouldn't work for their customers then I'm sure LeCroy would have already given up on it because implementing a design as on other scopes where sampling modes can be destructive would make it a lot easier for them.

[David Hess]

DPO is usually but not always a superior replacement for peak detection so the later is still needed.  I am not sanguine that WaveScan is a superior replacement for either.

It isn't, because WaveScan is not meant to replace DPO, a mode Tek had to implement because their scopes architectures suck so badly that they can't get decent update rates in normal mode without using some tricks. Other scopes have had persistence mode for years, and so does the WS3000.

*All* DSO architectures suck badly if they cannot process the data from the digitizer in real time.  That does not make them useless but it prevents them from replacing an analog oscilloscope like the Tektronix 7834 fast storage oscilloscope.

Persistence has nothing to do with DPO operation.  The earliest non-vector DSOs Tektronix made included it but without DPO operation, it was no faster than non-persistence operation which is to be expected.

If I were designing a DPO mode, I would halve the acquisition memory by dividing it into two banks, fill one bank with the real time histogram, and swap banks allowing the histogram to be processed for display while filling the other bank.  To take maximum advantage of this, the acquisition record length *must* be limited to provide the maximum trigger rate because otherwise multiple triggers will be present in each histogram.  That is not fatal but it effectively creates blind time for data which is not going to be displayed anyway.  It also shows why a short record length may be used in DPO mode without any drawbacks except of course for not being able to see the original data which will be required in specific applications.

If I care about the original data, record it in parallel for display as needed like when a secondary trigger condition is satisfied.  With increasing integration, memory for an extended record is the cheapest thing to add.

Your comment about LeCroy designs originating with physics applications where all original data is preserved and then analyzed fits with how WaveScan is described as working however I do not think that model is necessary or even suitable for design, development, and troubleshooting.

That may be your opinion, but in reality there are many areas where having the original sample data retained so you can run various analysis modes in parallel is a big advantage. You'll find LeCroy scopes in pretty much every segment of high tech, often simply because no other scope including Keysight can offer the same performance or capabilities.  And that has been the case pretty throughout their existence.

Many areas like physics?

Apparently then LeCroy oscilloscopes are found in every segment of high tech except those I have worked in.  When evaluating equipment, LeCroy has always been close to the bottom for me.  These days based on historic reputation which may or may not be deserved, I would group them with the likes of Rigol.  Pointing out other manufacturer's flaws does not make them better; just because I am not a fan of current Tektronix designs does not lead me to default to LeCroy.

If that architecture wouldn't work for their customers then I'm sure LeCroy would have already given up on it because implementing a design as on other scopes where sampling modes can be destructive would make it a lot easier for them.

I do not believe this at all.  LeCroy has specialized in a specific DSO design to the exclusion of markets where their reputation is poor anyway.  It is easier for them to accept the status quo than to pursue those markets.  I am sure they also had patent conflicts with other manufacturers which made certain designs more attractive than others and marketing is going to push what you have.

[Wuerstchenhund]

Your comment about LeCroy designs originating with physics applications where all original data is preserved and then analyzed fits with how WaveScan is described as working however I do not think that model is necessary or even suitable for design, development, and troubleshooting.

That may be your opinion, but in reality there are many areas where having the original sample data retained so you can run various analysis modes in parallel is a big advantage. You'll find LeCroy scopes in pretty much every segment of high tech, often simply because no other scope including Keysight can offer the same performance or capabilities.  And that has been the case pretty throughout their existence.

Many areas like physics?

That was where they started decades ago. It's hardly their main market.

Today this are areas like storage technologies (LeCroy scopes were and still are standard in the labs of most hard disk and other storage manufacturers), and high speed communications/networking (guess what one of the target market for the 100Ghz scope is) or aerospace/defense (for example, LeCroy is the *only* scope manufacturer that even offers procotol support for standards like SpaceWire or EFABus/STANAG3910). They have "scopes" with up to 80 channels, sampling rates of 240GSa/s and inter-channel jitter of less than 130fs. You think this is for physics when the majority of options are for communications, Vector Signal Analysis and other EE related stuff?

Apparently then LeCroy oscilloscopes are found in every segment of high tech except those I have worked in.

Well, then I guess that was either in different fields which didn't require as cutting edge in a scope. Or maybe it wasn't as high tech as you think it was.

When evaluating equipment, LeCroy has always been close to the bottom for me.  These days based on historic reputation

"Historic reputation"? Which was what exactly?

which may or may not be deserved, I would group them with the likes of Rigol.

Really? Rigol which really has nohing that isn't bottom-of-the-barrel? You compare the company that makes the fastest, most advanced scopes you can find, and which supports their scope longer than any other manufacturer with a CHinese B-brand that required Agilent to teach them so that they come up with the bug-ridden products they offer today?   

If that isn't a stupid statement then I don't know what is.

Pointing out other manufacturer's flaws does not make them better; just because I am not a fan of current Tektronix designs

And still that's the vendor you seem to go to for new scopes, which i guess is because you trust them based on the great analog scopes they had.

It's no secret that Tektronix scopes are crap. That's why pretty much no-one who knows a bit about the T&M market buys them unless they have no choice.

does not lead me to default to LeCroy.

So what, I never expected it did, nor do I care. Why should I, it's your business what you buy and what not, not mine. I obviously don't even know what you work on so I couldn't even recommend something even if you asked (although my gut feeling is that whatever it is it should be as close to an analog scope as possible).

Juts to be clear, I don't want to "convert" anyone, and as stated nor do I suggest that if you have a decent scope already to dump that and buy a LeCroy. All I do is show some alternative about scopes not too many people here know much about, so people know there are alternatives to the trotten path of pretty much only Keysight. You're completely free to ignore that of course and consider only those manufacturers that you trust personally, even if it's what today is pretty much the bottom scrape of all the big brands.

If that architecture wouldn't work for their customers then I'm sure LeCroy would have already given up on it because implementing a design as on other scopes where sampling modes can be destructive would make it a lot easier for them.

I do not believe this at all.  LeCroy has specialized in a specific DSO design to the exclusion of markets where their reputation is poor anyway.

Which are? You already stated something about "poor reputation" so it would be helpful if you could provide some details.

It's clearly not digital storage, communications and aerospace/defense, so what are these markets where they have a poor reputation?

It is easier for them to accept the status quo than to pursue those markets.

Again, what are these markets?

I am sure they also had patent conflicts with other manufacturers which made certain designs more attractive than others and marketing is going to push what you have.

What "patent conflicts" are these? Can you provide some links please?

[Someone]

Juts to be clear, I don't want to "convert" anyone, and as stated nor do I suggest that if you have a decent scope already to dump that and buy a LeCroy. All I do is show some alternative about scopes not too many people here know much about

Then how about instead of using one sided feature comparisons you show some of these unique features and how they're used. Telling everyone you have a secret technique/feature that makes all other scopes pointless while failing to tell anyone else either how it solves problems better or even what that feature or technique is just makes you look like a you're here to be intentionally obtuse and blustery.

Even when presented with well described examples of how people use peak detect to learn about signals, you immediately dismiss them without capturing all the requirements:

Even with long memory I use peak detect often at low sweep rates to make sure I don't miss a narrow pulse c.q. see a trace which has all the expected elements and nothing missing or malformed due to aliasing. It is true that timing information is lost but when looking at (for example) video signals it is nice to see the hsync and vsync pulses are all there. To me having no peak detect is a show stopper.

I understand. Well, on a LeCroy scope I would rather use WaveScan for that.

Your scenario is actually not too unsimilar to a pet project of mine, where one element relies on a set of (unevenly spaced) sync pulses. To find out if pulses are missing or out of spec I just throw WaveScan at it and let it run for a while, it then tells me any pulses were missing/out of spec, and if so presents me with a nice histogram showing when exactly that happened. If I wanted I could even set it up to do specific measurements on malformed pulses, or just let it do some screen shots everytime a deviation occurs, or do a range of other stuff.

It's pretty handy, and helped me to identify a problem where the sync generating unit producted malformed pulses in varying periods. It also helped me finding the source of a problem where the sync providing element occasionally threw out malformed pulses. With WaveScan and the statistics function I found out that the timing depended on the operating mode of that unit, i.e. power load, and that it was a flaw in the PSU which caused it.

Granted, on a entry-level scope which doesn't have any advanced functionality, PD is probably the best (only?) way to do that.

Peak detect runs at the acquisition sample rate, and as discussed can have zero blind time. This can be very important to quickly assess the signal especially in something as complex as video. But without any examples or evidence you claim that a technique with substantial blind time (still unquantified) would be a much better way to do it, and then continue to argue on and on about it. The simple answer is to provide some figures of the blind time and the capabilities of the wavescan triggers then we can see what applications it might be superior for. But until then you're just broadcasting your unsubstantiated view and we're all sceptical.

Analog (even some digital) video signals are good candidates for visual assessment or mask testing due to their structured frames which are complex enough to only be decoded by specialist signal analysers (from Tek). We know of two tools which work for this, a fast realtime scope, or the video analysers.

[heavenfish]

There're two primary usecases for oscilloscopes. First it's a validation tool that people use it to view the waveform or make measurements to see whether your circuits work as expected; second it's a troubleshooting tool that people use it to find bugs by looking for a abnormal signal or incorrect cmd being sent through serial buses. Though the later seems need more advanced features sets in oscilloscopes, an oscilloscope still needs some basic things to do what it was invented for: waveform visualization.

Wavescan can help to debug and find any glitches from video waveforms or any other waveforms. But if a student or technician wants to show an entire frame of video signal on the screen, just show, there's no better way than simply using peak detect mode.

This doesn't mean Lecroy did anything wrong. In the end, no product can meet everybody's need and make them all happy. It's about the choice of the company and the product manager. Which features are more important for the applications and customers they focus, or easier to implement with their technology.

[mjames]

What are the general differences between the different types of Lecroy scopes, i.e., WavePro vs WaveRunner vs WaveSurfer, etc.?

Thanks,m
-- Mark

[2N3055]

What are the general differences between the different types of Lecroy scopes, i.e., WavePro vs WaveRunner vs WaveSurfer, etc.?

Thanks,m
-- Mark

On LeCroy web site, they have all the info you need, including comparison tables for exactly that.. Shortly, they range differ in capabilities and frequency ranges while keeping similar look and feel...

[Wuerstchenhund]

What are the general differences between the different types of Lecroy scopes, i.e., WavePro vs WaveRunner vs WaveSurfer, etc.?

WaveSurfer are upper midrange scopes with BWs of up to 1GHz, which are usually built on some kind of embedded platform (SOC or x86), and with a more limited set of functionality. These are intended to be flexible general purpose scopes for tasks which don't require extended analysis capabilities.

WaveRunner are lower high-end scopes with BWs up to 4GHz, built on Windows (x86), and with notably expanded capabilities over the WaveSurfer. The WRs are intended as debugging and analysis scopes. There also is an 8 channel variant, which is also sold together with advanced power analysis software as Motor Drive Analyzer (MDA).

WavePros are mid-high-end scopes with BWs up to 8GHz, also built on Windows (x86), with some additional features over the WaveRunner. These scopes are often used for serial data analysis and compliance testing. There also are special application variants for hard disk manufacturing (DDA, Disk Drive Analyzer).

WaveMasters are upper high-end scopes with BWs up to 30GHz, other than that they are similar in functionality to the WavePro. There also are special application variants for comm systems testing (SDA, Signal Data Analyzer).

LabMasters are modular ultra-high-end scope systems with BWs up to 100GHz and up to 80 channels. The functionality is similar to WavePro/WaveMaster.

HDOs are high definition scope models (although other LeCroy scopes are now HD as well) which are positioned between WaveSurfer and WaveRunner.

Everything else below WaveSurfer is just re-badged kit from other brands (Iwatsu in the past, Siglent today).

[Sighound36]

If there is anything in particular you would like to know happy to help, we own few Lecroy scopes including a Wavepro HD, 8000MDA and a couple of Waveunner runner HD's plus some 6000's