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.
Quoteand 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.
QuoteQuoteThese 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.
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.
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.
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?
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.
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?
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.
QuoteThere'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.
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.
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.
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.
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.
Another nice feature on the WS3000 would be a SENT decoder.
Direct replay from a trace to the build in function generator would be nice.
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.
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.
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.
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 would like to have WaveScan on FFT which would include math functions on a FFT trace.
Another nice feature on the WS3000 would be a SENT decoder.
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.
Direct replay from a trace to the build in function generator would be nice.
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.
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.
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.
*Nothing* runs in the acquisition memory in a scope, it's a store for sampled 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.
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;
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.
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.
QuoteYour 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.
QuoteQuoteYour 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.
QuoteIf 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.
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
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.
What are the general differences between the different types of Lecroy scopes, i.e., WavePro vs WaveRunner vs WaveSurfer, etc.?
Thanks,m
-- Mark
What are the general differences between the different types of Lecroy scopes, i.e., WavePro vs WaveRunner vs WaveSurfer, etc.?