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I am planning to buy an oscilloscope. I always used oscilloscopes which come with an LCD display. But I found there are USB oscilloscopes as well which can be connected to PC and get data from the PC. Since I already have a laptop I felt like that's a better choice.

But is there any disadvantage in terms of accuracy/efficiency for USB type?

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    \$\begingroup\$ Let's clarify here. The USB type scope that connects to a PC gets control from the PC but not data. Instead the scope supplies capture data to the PC. \$\endgroup\$ – Michael Karas Jul 30 '17 at 20:59
  • \$\begingroup\$ There are "USB 'Scopes" that are have no display or controls themselves, but use a program on a PC as the display/control panel. \$\endgroup\$ – Peter Bennett Jul 30 '17 at 21:05
  • \$\begingroup\$ @PeterBennett: Yes, that's what I meant. \$\endgroup\$ – InQusitive Jul 30 '17 at 21:07
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    \$\begingroup\$ The USB scopes I have seen are not as robust as standalone oscilloscopes. They have more limited voltage range. Also, most USB scopes are lower in bandwidth. On the other hand, they often can be used as data-loggers, also, which is nice. They are likely cheaper than a standalone scope with similar bandwidth and number of channels. \$\endgroup\$ – mkeith Jul 30 '17 at 21:08
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    \$\begingroup\$ Already selecting the "best answer" after only 20 minutes is somewhat limiting - give other people a chance to try and help, and consider coming back later to select the answer you like most. \$\endgroup\$ – Joren Vaes Jul 30 '17 at 21:14
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Although this is a very opinion-based matter, there are two things to keep in mind. I presume here, with "USB scope" you refer to an oscilloscope that has no display or controls, and requires a computer to operate. I presume you do not mean an oscilloscope that can be connected to a computer, since any modern scope is capable of doing this.

USB scopes are often made to a price - they are aimed at entry-level buyers, who consider 500 USD/EUR/Whatever too much. Hence, they will, in my experience, be of lower quality. Exceptions to this exist - I've heard many good things about the picoscope, and of course there are devices such as the NI virtualbench that are excellent products (however I think this is not the price range you had in mind when asking this question).

The main difference is in the interface. In the end, most oscilloscopes are the same (to the untrained eye): Apart from a bandwidth difference between models, digital scopes are just fancy analog-to-digital converters with trigger systems and a screen. But this latter is key: The triggering system, its capabilities, and the software to control the entire thing is what makes-or-breaks an oscilloscope - esp. to someone who is at the knowledge level to ask this question. For every day, hobby use, I much prefer the physical nature of oscilloscope control knobs. Fiddling about with mouse sliders and such just never seems to work fast for quick-and-dirty measurements.

And finally as a sidenote: Consider the lifespan of a product and its dependence on a second system. If you purchase a USB oscilloscope, there is a good chance you won't be able to use it in 10-15 years. No more driver updates, computers (in whatever form they are then) no longer have USB interfaces, the software doesn't support your device, etc.. A "classic" oscilloscope is fully integrated and stand-alone. As long as the thing powers on, you know it will be able to take measurements. You need not rely on the support of the device on a second system.

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    \$\begingroup\$ We bought a picoscope at work. The software is a bit wonky, but it is a decent unit. Has worked reliably for us. The software UI does not use typical oscilloscope nomenclature, so it is hard to figure out how to do the stuff you want to do. \$\endgroup\$ – mkeith Jul 30 '17 at 21:16
  • \$\begingroup\$ Most of the scope work I do is either in the "get a visual idea of the signal", for which a simple analog scope suffices, or using complex measurements that you set up ahead of time. I would guess that a USB device might work well for the latter? \$\endgroup\$ – Joren Vaes Jul 30 '17 at 21:21
  • \$\begingroup\$ It does have the ability to save and load setups easily. So that might help. The picoscope we bought had 2 analog and quite a few digital inputs. That was important to us in our specific application. I don't remember how fancy the triggering is. We just used simple triggers. \$\endgroup\$ – mkeith Jul 30 '17 at 21:29
  • \$\begingroup\$ I dont have much experience with other scopes, but is is very easy to write your own software to interface with a picoscope. \$\endgroup\$ – Matt Jul 31 '17 at 0:45
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A USB scope can be useful as a lower cost alternative to a non-USB scope. But it will tie up your laptop if at the same time as testing electronics you wish to look at schematics.

Also be aware that the typical modern standlone LCD screen scope that is in the typical hobbiest or single engineer budget price range is going to have more features that the software than goes with the USB type scopes. One reason for this is that the standalone scope manufacturer is able to protect his software investment whereas if a USB scope manufacturer makes very nice PC based scope software there will be rip-off manufacturers that make clones of their hardware and pirate and distribute the software. (Case in point a constant problem being suffered by the folks that make the Saleae brand if USB logic analyzers).

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  • \$\begingroup\$ +1 True, but most seasoned enthusiasts (at least those who came to the point of having a need for oscilloscope) usually have several old laptops, so dedicating one old Win-XP laptop for the scope purpose serves also the concern about the software - you set it, and use for life. Manufacturers of standalone scopes must follow the insanity of Windows upgrades and (frequently idiotic) "feature improvements", which may render old good scopes nearly useless - recent Agilent/Keysight updates are in case, introducing horrible user-control latencies. \$\endgroup\$ – Ale..chenski Jul 31 '17 at 0:05
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If you're travelling around a lot, some people prefer a USB oscilloscope. But, if you're spending the majority of your time in the same place, engineers almost universally prefer a stand-alone benchtop scope.

Pros of USB oscilloscopes:

  • Smaller & more portable
  • Sometimes cheaper
  • Sometimes more integrated capabilities

Pros of Benchtop oscilloscopes:

  • Dedicated controls (knobs, buttons, ect.) + streamlined GUIs vastly improve usability
  • Often better specs - bandwidth, waveform update rate, max input voltage

This talked about in more detail in the "5 Common Mistakes People Make When Buying a Low-Cost Oscilloscope" here:

https://www.keysight.com/main/editorial.jspx?cc=US&lc=eng&ckey=2830640

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    \$\begingroup\$ For those readers who don't want to supply their personal details on the website form which is linked in this answer, a Google search gives a direct link to the same document on the Keysight website at this address: literature.cdn.keysight.com/litweb/pdf/… \$\endgroup\$ – SamGibson Aug 8 '17 at 18:12
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    \$\begingroup\$ Perfect, thanks! I didn't realize it was a gated link. \$\endgroup\$ – Daniel Bogdanoff - Keysight Aug 8 '17 at 19:45

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