Products > Test Equipment
Let’s Talk About LeCroy Scopes, AKA… the “Wuerstchenhund Holds Court” Thread
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David Hess:

--- Quote from: nctnico on September 14, 2016, 02:31:08 pm ---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.

--- End quote ---

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:

--- Quote from: AutomationGuy on September 14, 2016, 07:18:25 pm ---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.
--- End quote ---
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.


--- Quote from: tautech on September 14, 2016, 07:24:54 pm ---
--- Quote from: Wuerstchenhund on September 14, 2016, 05:25:53 pm ---
--- Quote from: nctnico on September 14, 2016, 02:31:08 pm ---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.

--- End quote ---

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.

--- End quote ---
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?

--- End quote ---
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.


--- Quote from: David Hess on September 14, 2016, 07:35:41 pm ---
--- Quote from: nctnico on September 14, 2016, 02:31:08 pm ---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.

--- End quote ---

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.


--- End quote ---
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:

--- Quote from: tautech on September 14, 2016, 07:24:54 pm ---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?

--- End quote ---

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:

--- Quote from: David Hess on September 14, 2016, 07:27:46 pm ---
--- Quote from: Wuerstchenhund on September 14, 2016, 02:13:24 pm ---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.
--- End quote ---

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

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  :palm:


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

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.


--- Quote ---
--- Quote ---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.
--- End quote ---

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?
--- End quote ---

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.


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

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:

--- Quote from: Someone on September 14, 2016, 11:43:44 pm ---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.
--- End quote ---

:palm: 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.


--- Quote ---Keysight offer similar tools under their InfiniiScan name.
--- End quote ---

No, they don't :palm: 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.


--- Quote ---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.

--- End quote ---

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.
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