Author Topic: Regular oscilloscopes versus USB oscilloscopes  (Read 3360 times)

birrbert

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Regular oscilloscopes versus USB oscilloscopes
« on: December 15, 2013, 07:34:36 AM »
Dear Forum, dear Martin!

Is there a chance to test some USB oscilloscopes? I would highly value your professional opinion about them (i.e. advantages and disadvantages).

For example, which statement do you agree with?
1. there are occasions when a USB oscilloscope could come in handy (e.g. when beginner's budget is low).
2. these devices should be forgotten and it's better to buy a "real" oscilloscope.

Moreover, I think I read somewhere that ambitious DIY people can make use of there desktop or laptop PC's sound car, but I don't remember the details. What do you think about that?

Thanks!

edit:
OK, I should've searched first. :)

- EEVblog #13 Part 1 of 2 - Digital storage Oscilloscope Tutorial
- EEVblog #13 Part 2 of 2 - Comparison of PC Based Oscilloscopes

Still, there are many opinions or disagreements amongst specialists and I would like to hear those too. Besides, Dave Jones made the videos 4 years ago.
« Last Edit: December 15, 2013, 08:10:54 AM by birrbert »
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SeanB

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Re: Regular oscilloscopes versus USB oscilloscopes
« Reply #1 on: December 15, 2013, 08:32:33 AM »
USB scopes have a place at the bottom end of the markey, but most are a big compromise between usability and bandwidth, as they are both constrained by the USB bus bandwidth and power available. This leads to a scope with limited bandwidth, likely less than 10MHz and a limited input voltage range as well. As well they are connected to the host computer ground, and have noise problems.

With USB3 there is a possibility to have a decent processing engine in the host computer and good bandwidth with having enough power down the cable to provide decent processing and an isolated input section. This will then make a software scope much more useful.

As to using a sound card there are programs out there that do this, often used for SDR as a final decoder, and they are useful if you want to analyse audio, but are limited by the onboard ADC of the sound card and it's noise and sampling rates. Very usable for audio work though with a decent 24 bit 96kHz sound card with low noise. Regular PC sound card will give at best 10 bits of usable data and often only a single sampling rate of 44.1kHz and an often very poor input anti aliasing filter.

ProBang2

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Re: Regular oscilloscopes versus USB oscilloscopes
« Reply #2 on: June 29, 2014, 10:11:37 AM »
[...]
Moreover, I think I read somewhere that ambitious DIY people can make use of there desktop or laptop PC's sound car, but I don't remember the details.
[...]

Just for fun:

http://www.zeitnitz.de/Christian/scope_en?PHPSESSID=cp8r7bflv6vqt32d5tihut3st4

This program acts with your sound-card as an oscilloscope and includes a function-generator.
It is free granted for private an non-commercial use. The technical restrictions are well known, I suppose.
Perhaps itīs in some kind useful for you...
Anyhow, sometimes itīs just nice to play with it.

Greetings,


Hartmut
If you think, my english is bad, then you should read my french. :(