Society of Robots - Robot Forum
Electronics => Electronics => Topic started by: silo_xtreme on June 28, 2009, 06:17:55 AM
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Hey All,
I'm looking to buy a new scope - however, there's quite a few options. What are your thoughts on a USB vs digital storage scope?
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Ok,
Let me summarize what I've found in the forums and perhaps answer this myself.:
USB - are slower than the traditional oscope and may not be suited for robotics.
digital storage / analog would do the job.
You should use a oScope that has 2x clock speed that you want to measure. For example, my chip is 32MHz so I would look for a 64Mhz chip.
Tektronix seems to have the best scope.
There are lots "used" Tek's on ebay.
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Well, from an ET's point of view, when diagnosing problems (especially over long distances) the usb one makes it easier to send the analyses via email. But since I'm guessing this will be only for personal local use the digital storage one would seem to be the better.
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Your 2x rule seems to be based on the Nyquist sampling theorem, which says that a signal of bandwidth B can be accurately reconstructed by sampling at a rate of 2B. However, in practice, a sampling rate higher than that is usually recommended. Normally the specs for an oscope will tell you what the max bandwidth is for the scope, especially if it is a quality manufacturer like Tek. As for clocks, if you are looking at a clock as an analog signal, for example looking at logic delays, you might want to see events on the scale of rise times and fall times, which requires a much higher bandwidth than 2x the clock frequency.
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Thanks for all of the information,
I just got a Tek 100Mhz 2 channel on ebay.
This should be enough to debug PWM, and related signals from my 32Mhz Xmega to payloads and sensors.
Then again, I could be wrong - ?
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That would be exactly my recommendation....
And new Tek have also usb stick storage with which you can track signals...
Quite helpful really to debug a lot of things!!!
Good scoping!!!! :D