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Re: [rtl] Release 9F Problems...
Kurt,
Please see the end of my scope page (www.med.uvm.edu/~gaffney/scope.html)
for a look at the characteristic frequency of the square wave. I think
this is what you wanted to see; it does provide a nice look at the spread
around the schedule. Thanks for your advice.
What I'm sort concerned about is the occaisional outliers seen on the
time trace. This would be related to the spread around the characteristic
frequency in the PDS. It looks to me like these blips are on the order of
10 microseconds or longer, this means that the 40 microsecond schedule is
blown. If the bit pattern must be written at within a 50 microsecond cycle
this means that system will fail during these longer blips.
I'll be purchasing a faster computer, and trying interrupt driven
scheduling as well as Mantegazza's variant. Do you or other on the list
have experience meeting a tight schedule (<=50 microseconds) in a manner
which never fails?
Thanks again for your suggestion,
-Don
On Fri, 2 Oct 1998, Kurt Rosenfeld wrote:
>
> On Fri, 2 Oct 1998, Donald Gaffney wrote:
> I don't
> > know how good the FFT gizmo is on this scope, I may need a real analyzer
> > to do this - as the digital storage shows the trace is not really
> > stationary - won't that mess up an FFT?
>
> It won't mess up an FFT as long as the window includes many pseudo-periods
> worth of the sampled signal. Perhaps, the representation that would be
> most meaningful to people (personally I do robotics) would be the
> probability density function of the time between one rising edge and the
> next rising edge. I think that the FFT would give, for comparison
> purposes, the same information; a tight first peak corresponding to a tight
> PDF. This issue is the essence of why we are all interested in RTLinux,
> isn't it? -kr
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