Is this true for engineers? It is a very important question.
I believe it is quite true. The guys I work with scoff and snicker whenever the subject of USB scopes comes up. But they almost never say "those things are hard to use". The thing always stated is "those things don't work".
I think we all agree that a benchtop scope is better to use. The display is always there and not covered up by the debugger you've got open, and you can adjust it by feel while looking at the display.
With USB you have to grope around for a mouse and look at the control while adjusting it (I agree with the comment on "virtual knobs" - PLEASE use normal GUI elements). But we have lots of tools which are PC/USB based and we're used to it enough that were there some other compelling reason to use a USB scope, I think most engineers would consider it... except for ..
USB scopes have a strong reputation for not working reliably (or at all in some case). At least the ones many people would consider have this reputation.
And unreliability in test equipment is a "show stopper" to any professional.
High-end USB scopes can work (some of them actually do), but don't cost significantly less than a better desktop scope (often more). For most, there just isn't a compelling reason to go that way.
The benefits a USB scope offers are:
- Lower cost.
Often not true for the ones that actually work. And most companies or independent engineers would gladly pay a few $$$ more for something that is more usable and reliable.
Cost is something more important to a hobbyist.
- Small size (assuming you have a computer at the workstation anyway)
Generally not a big deal in a commercial lab setting. You make room for is a decent scope. And modern bench scopes are much smaller than they used to be.
May be more important in a portable setup, field work etc. but that is usually done with a "Scopemeter".
Again, this is more appealing to a hobbyist, who may be relegated to the corner of an apartment or other small work area.
- Ease of extracting waveform data.
Since USB scopes already have the data "in the PC" it can be much easier/faster to access it than using a USB/LAB interface with a bench scope.
But it can be done quite easily with modern bench scopes, and unless you do it a LOT (data logging etc.) generally not worth the downsides.
- Can be combined into a multi-purpose portable lab tool.
"Analog Discovery" .. example of a successful device even though it costs as much as an entry bench scope. Lots of functionality in a very small package.
Most engineers will want better versions of the functions it can perform on their bench, but still useful as a "portable lab".
Cost is high for hobbiest but not out of reach of many.
Most "Cost effective" USB scope just don't work reliably. Mainly because maker has cut corners to the bare bone, relying on unreliable streaming to a PC which "does everything". Software tends to be buggier than firmware in dedicated scopes. I've tried a number of the "streaming" USB scopes, and even with a belting fast PC they just couldn't hold a candle to my oldest/crappiest bench scope.
Unreliable triggering, missed sections in captures, not usable at all for serious work.
I do have a VDS1022I, but it's different from the others in that it does the capture/triggering inside the box. The PC is only a display. This is the only cheap (<$100) USB scope I've found which actually works. I don't use it on a daily basis, it lives in my laptop bag which I always have with me when off-site .. so now I always have a basic scope with me.
If you want to make a successful USB scope:
#1 - It HAS TO WORK! not just "mostly work" - it has to be as reliable as a bench scope.
#2 - Decent software. No "virtual knobs". Design it to be used with a mouse by someone who would really rather not be using a PC at the moment (ie: minimize "mousing around").
Support many host platforms: Win, Max, Linux, Android/IOS (tablet support) etc.
As bug free as possible.
#3 - Open interface. Document the control protocol. Not only will that get it supported by things like SIGROK, but it allows people to use it for other dedicated purposes.
I think one area where a USB scope could appeal to a professional is in automated monitoring and logging systems.
#4 - Open software. Since your hardware is a great security "dongal", why not open the software. This can go a long way as it lets people:
See how to do programatically do various functions with the scope.
Pull out code to use in dedicated (non UI) applications.
Fix bugs and change other annoyances that you might not get around to.
#5 - Offer something more - make it stand out, things like:
Isolated USB interface.
Higher then expected bandwidth, sample rate, sample size, sample depth precision etc. for the cost.
Extra test and measurement functions.
Logic analyzer.
Signal/function generator etc.
I'd love to see a low cost USB scope which ticks all the boxes. The VDS1022I comes close but you could do better: Higher bandwidth/sample rate. Deeper capture memory, Ability to trigger >=100ms, more advanced functions, open interface. Build that at the right price and "they will come" (at least I would).
Dave