From: Barry Ma ([email protected])
Date: Thu May 25 2000 - 14:51:28 PDT
Chas,
Thanks for the information.
If it is related to a scope, please allow me to make a guess below.
What kind of scope should be used to measure a digital signal with rise time Tr?
Your 0.3/Tr might suggest that the upper limit of frequency bandwidth for a candidate scope be no less than 0.3/Tr. Vise versa, we can know what Tr signal can be well observed using a given scope.
If my guess were true, it would be interesting to put your 0.3/Tr and "Knee Frequency" together,
Fknee = 0.5/Tr (see Howard Johnson's book). They both might imply that the waveform of a digital signal could remain unchanged even if all frequencies > 0.5/Tr in the spectrum are neglected. And, on the other hand, we should take good care of all frequencies < 0.3/Tr.
Regards,
Barry Ma
[email protected]
-----------
On Thu, 25 May 2000, [email protected] wrote:
> Hello Barry,
>
> There is an old formula for calculating the bandwidth
> with respect to the rise time. It dates from Tek scope
> days I believe an it is: 1/pi*tr or about 0.32/tr.
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