Products > Test Equipment
True analog scopes
tggzzz:
Overall your points have some validity, but most don't stand up to detailed examination. Using strawman arguments doesn't help your contentions.
--- Quote from: baldurn on December 22, 2022, 10:16:39 pm ---
--- Quote from: tggzzz on December 22, 2022, 07:35:56 pm ---
Your list with my response...
Single shot capture The USP for storage scopes; agreed
Zooming on a captured waveform Analogue scopes have delayed trigger. (Some digitising scopes cannot zoom - useless!)
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This is just so much easier on the DSO. Delayed trigger also does not exactly do the same thing. Segmented capture? Searching for events matching a pattern? Dual view of zoomed out and zoomed in view?
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Of course it isn't the same thing. Nonetheless the many of the advantages can be obtained by using analogue scopes with digital domain tools. In most cases the digitising scopes triggering filtering and searching digital domain information is worse that the alternative.
Use the right tools for the job; a jack-of-all-trades tool is often poorer than the combination of appropriate tools.
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--- Quote ---Programable triggers of many kinds I've found those to be good when playing around, but insufficient for normal jobs
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There is just stuff you can not do without. Runt triggering for example is not easy or impossible on many analog scopes. Means you are simply not going to get the job done. Or that you have do something contrived and complex instead of something easy on the DSO.
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Runt pulses are part of ensuring signal integrity, and a scope is the right tool for that. Once signal integrity is assured, flip to debugging in the digital domain with logic/protocol analysers.
It is possible, with skill, to use an LA to trigger on runt pulses.
It is often possible to create the conditions under which runt pulses are repetitive, and therefore not requiring storage scopes.
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--- Quote ---Serial decoding Digital domain tools are much better: protocol analysers and printf(). Some digitising scopes only decode what's on the screen, which is useless
MSO Scope plus logic/protocol analyser is usually sufficient. Where not, there's a fair chance a digitising scope won't be either
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You can always get more (digital!) instruments but the point is that the modern DSO is very versatile. It will usually do the job. It might not be the best for every job, nothing is. It is a function the analog scope simply does not do (again).
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I disagree that a DSOs "versatility" means it can usually do the job. It may be able to do your jobs, especially if they are relatively undemanding. My professional experience is littered with cases where tools ran into a brick wall and other tools had to be used instead. Often I had to create a my own custom tool for the job at hand. Using combinations of tools is standard operating procedure. But then I suppose if all you have is a digitising scope, then everything "looks like a nail".
"Swiss army knife" tools (i.e. tools with a principal purpose and other things added) tend to be substandard in all but their principal purpose.
I prefer to use the best tools for any given job.
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--- Quote ---Statistics displayed on screen Some analogue scopes display some stats on screen. While digitising scopes appear to have more complex stats, their accuracy in the context of the specific waveform has to be verified. Too many scope's firmware has been found to have subtle bugs
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There is no comparison. The old cheap analog scopes do not display any stats at all (only more advanced expensive ones do). Talking about bugs in firmware is just handwaving. The stats a very useful. Not because you can't do without but because it is so easy and its just there. No need to calculate something yourself when the machine does it.
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Strawman argument; nobody claimed grotty analogue scopes displayed stats.
The "old advanced expensive" ones are often cheaper than most modern digitising scopes. To take one example, a fully working 345MHz Tek 2465 or 485 costs £300-£450. What does a new >350MHz digitising scope cost?
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FFT 8bit ADCs are limited toys w.r.t. FFTs. 14bit is much better, and even then it would be better to use a sound card for audio or dedicated spectrum analyser for RF. Some digitising scopes only do an FFT of what's on the screen, which is useless
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I just compared FFT on my new Siglent SDS2104X HD with my spectrum analyzer. It was damn impressive. But even with the cheaper entry level scope SDS1104X-E you get 1 Mpts FFT which will help the average HAM operator to verify his transmitter just fine. I also find it very useful for teaching.
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Including noise floor, intermod products, phase noise, harmonics and other spurii? I doubt it.
See David Hess' points about RBW etc.
--- Quote ---Could you use a sound card? Possibly but when you are done spending the day setting that up, the guy with a DSO just pressed a few buttons on his DSO to the job done. Not to mention that the sound card is yet another digital solution, it is limited to audio frequencies and usually requires additional hardware anyway.
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None of that invalidates my statement, and I don't understand what point you are trying to make.
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--- Quote ---Network connectivity In most cases a convenient feature rather than a sigificant benefit
Programability by scripting / remote control I don't know how you can usefully script looking at an analogue waveform to find something unexpected.
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Not useless just because you have no need for networking. There has to be a reason that all modern instruments come with it. What might it be?
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Ah, youngsters. I wonder how long it will be before you understand how marketing works (hint: checkbox specifications)
How, exactly, do you use scripting as described with analogue waveforms? I don't think scripting is as useful as you imagine (production tests excepted).
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--- Quote --- For digital signals use a digital domain tool: a decent logic analyser or protocol analyser will have far superior triggering and filtering[/b]
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Again the DSO is a versatile tool. It might not be the best but it can do a lot of stuff for free. Even the entry level scopes have this stuff. And sometimes it is just important to have the analog and digital signals on the same screen - nothing does that better than the DSO. The analog scopes does not do it at all.
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Unconvincing argument.
Often there simply isn't space to have all the signals on the screen simultaneously. Combinations of tools ameliorate that by using "complex" filtering and triggering to not display irrelevant data.
Analogy (in the nowledge that all analogies are dangerous!): I use a car to travel on roads and ships to travel on water. An amphibious car would "do it all", but it would not be the best choice.
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--- Quote --- Much better display Analogue displays are usually sufficient for analogue waveforms. For digital domain analysis, a digitising scope's screen quickly becomes a limiting factor; better to use the better triggering/filtering in a logic/protocol analyser, or offline post-processing in a computer
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"sufficient" does not equal "good". Lets just admit that the small CRTs are horrible and that the new breed of entry level scopes with 10 inch touch screens are just so nice that you would think it came straight from Startrek... are there uses where an even bigger screen is better? Of course, that is why all new DSO are network connected so you can bring that right to your huge 30 inch desktop.
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... and let's just admit that a scope's screen isn't up to the job of displaying lots of complex digital signals, whereas a logic or protocol analyser's superior triggering and filtering will remove the unimportant stuff and allow you to concentrate on the useful stuff.
You use the "DSOs may not be good but they are sufficient" argument elsewhere. "Physician, heal thyself".
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--- Quote ---Auto setup Ah, the "I don't know how to work it / I don't know what I'm expecting to see" button beloved of those that like the "Tesla full self-driving (beta)" way of using an instrument :)
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That is right. Beginners love that button. Sure sometimes they love it too much. Someone here claimed the analog scope is so easy because every lever is visible and right there. Well tell you what - the beginner just presses that one hated button and usually he gets what he wants. Not sure why it should be hated when its helps people.
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Too often it gives them what they ask for, but they haven't asked the right question.
Too often it gives them what they ask for, but they don't understand the limitations of the answer.
Too often it gives them what they want, not what they need.
Too often it discourages sanity checking and/or verifying the validity of a result.
There is no substitute for thought and understanding.
In the case of "full self driving (beta)" there is no subsitute for being awake and actively monitoring the vehicle's actions.
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--- Quote ---Multiple acquisition modes, Math modes I've never found those necessary, but provided an 8bit ADC isn't a limitation then it could be an advantage
Mask tests useful for production tests, less so for exploratory design
Power analyses / other kinds of analyses I use a DMM or the relevant special tool for those
Bode plot Severely limited by 8bit DACs, not just a simple digitising scope, can be achieved other ways
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That is pure rubbish. Bode plot is _very_ useful. It seems to be doing the job excellently for most purposes and 8 bit does not matter at all.
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That first sentence is yet another strawman argument; unimpressive.
The 8bits can be a killer, e.g. when assessing filter stop-band performance behaviour.
--- Quote ---Again the versatile tool DSO does it, but is not the only instrument or maybe the best instrument, but why should that take anything away if it solves the job? Never seen an analog scope that could do bode plot.
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See examples in other people's posts, and stop using strawman arguments.
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--- Quote ---The list just continues. There is so much the analog scope can not do. Especially the analog scopes available cheaply.
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The cheap digitising scopes are severely limited; they look enticing, but are disappointing when you look in detail.
Your other points are strawman arguments addressed previously.
--- Quote ---And THAT explains why nobody is producing analog scopes anymore.
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No. The main reason is economic: it is now far cheaper to make a new digitising scope than a new analogue scope.
Good old analogue scopes are far cheaper than decent new digitising scopes.
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The new entry level DSOs from Siglent and Rigol et al are fantastic devices. You are not going to find an analog scope + something that replaces all of what the DSO also does for anything less. That would be true even if the analog scope was free which is why everyone ends up with a DSO in the end.
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Strawman arguments and non-sequiteurs. Unimpressive.
tggzzz:
--- Quote from: alm on December 22, 2022, 10:56:57 pm ---
--- Quote from: baldurn on December 22, 2022, 10:16:39 pm ---The new entry level DSOs from Siglent and Rigol et al are fantastic devices. You are not going to find an analog scope + something that replaces all of what the DSO also does for anything less. That would be true even if the analog scope was free which is why everyone ends up with a DSO in the end.
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The Analog Discovery probably comes the closest, and can be bought a lot cheaper than decent entry-level DSOs during sales or on the used market. It contains a DSO, but not a very good one. It is quite nice for bode plotting and FFT due to its 14 bit resolution.
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I currently have two Digilent Analogue Discoveries, like them and wheel them out when I need their capabilities. (Must sell one of them :) )
The 14-bit ADC/DAC was a key benefit making me think they are worthwhile. 8bits was, um, uninticing.
--- Quote ---I think few people will argue that a modern DSO isn't much better than most analog scopes for at least 99% of use cases. But an analog scope is still infinitely better than not having a scope, and can still do a lot of useful work. Unless you have a financial interest in selling DSOs, then obviously it's a lost sale either way. In some economies, analog scopes might be available cheaply, while entry level DSOs may not be affordable.
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That's pretty much my position, but I would significantly reduce that 99% figure because I use combinations of tools. I have more than a hammer in my toolbox :)
tggzzz:
--- Quote from: BillyO on December 22, 2022, 11:21:30 pm ---
--- Quote from: baldurn on December 22, 2022, 10:16:39 pm ---Never seen an analog scope that could do bode plot.
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How do you think they were done in 1976?
I'd use my scope and an S-100 computer system running CP/M and wrote my own BASIC program to crunch the numbers and print the graphs.
DSOs are great, but we got by just fine without them. We designed and built aircraft, spaceships, cars, particle accelerators, stereos, TVs, F1 cars, Lamborghini's, satellites, radio transceivers, X-ray machines, CT-scanners, computers, etc..
We also wrote real software in C and assembler that ran word processors, spreadsheets, and engineering applications on 8-bit computer with 65,536 bytes of memory.
Today we have DSOs and people writing buggy, bloated slow as f**k code that requires a million times the processor power and memory to do essentially the same thing. We're now just learning again how to put men on the moon.
Progress.
Don't get me wrong, I love me DSOs - all 4 of them, but rather than wait a minute for them to boot and then spend another 2 minutes getting lost in badly written menu systems, when I have to have a look at something right now, I usually head for my old Tek 465.
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Just so.
Except I prefer 2465 and 485 to a 465 :)
Too many youngsters fall into the trap of "I don't know how to build pyramids, therefore they didn't know how to build pyramids (hence aliens must have done it)".
tggzzz:
--- Quote from: baldurn on December 22, 2022, 11:23:10 pm ---
--- Quote from: alm on December 22, 2022, 10:56:57 pm ---Any sweep function generator with any half-way decent scope with a second channel or external trigger input can do it:
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I can tell you that trick is nothing like the real thing.
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Ditto using a digitising scope alone, vs a scope plus logic/protocol analysers and printf() statements.
Physician, heal thyself.
BillyO:
--- Quote from: tggzzz on December 23, 2022, 01:03:50 am ---Except I prefer 2465 and 485 to a 465 :)
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As would I if I had either.
--- Quote from: tggzzz on December 23, 2022, 01:03:50 am ---Too many youngsters fall into the trap of "I don't know how to build pyramids, therefore they didn't know how to build pyramids (hence aliens must have done it)".
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Yep, and there is a growing (or is that groaning?) number of them that think the earth is flat. :palm:
Heaven forbid they solve an engineering approach for themselves instead of pouting that their scope won't do it for them.
Anything to be anti-boomer.
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