[SI-LIST] Re: Question of taking measurement. Thanks.
- From: Bill Wurst <billw@xxxxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Fri, 09 Dec 2005 10:46:53 -0500
Hi Peng,
The bandwidth requirement of the test equipment will depend on the
harmonic content of the signal you are observing and the level of
accuracy you require. For example, if you are measuring a sinusoid and
don't mind the observed amplitude being low by as much as 10-20%, then
BW=2*f should be fine. However, if the signal of interest is a
square-wave, then your oscilloscope should have 5-10 times the bandwidth
of the fundamental to observe a reasonable replica of the actual
waveshape. You must also keep in mind that when measuring fast edges,
the observed transition time will be increased by the bandwidth of the
instrument, and that transition times of cascaded systems add roughly in
root-sum-of-squares fashion. Your measurement technique (i.e., probe
ground inductance, etc.) will also influence high-speed measurements.
For more information on this subject, I would suggest the websites of
Agilent, LeCroy, and Tektronix.
Regards,
-Bill
/************************************
/ billw@xxxxxxxxxxx /
/ /
/ Advanced Electronic Concepts, LLC /
/ www.aec-lab.com /
************************************
========================================================
Peng Ye wrote:
> Hi everyone,
>
> To get accurate results, the bandwidth of the oscilloscope must be 2X+
> of the signal. (Please correct me if I'm wrong. Thanks.) So if I know that
> the bandwidth of my scope is not enough compared to the signal that I want to
> measure, is that any way I can still get accurate results? (This may be well
> discussed, but I have no idea about this as a new scope user. I very
> appreciate any of your answer.)
>
> Thank you very much.
>
> Yours,
> Peng
>
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