Re: [Mgs] Cooling issue, revisited

[Rick Lindsay <rolindsay@yahoo.com>]

Paul and I wrote...

>> ...and not in sync with the meter's sample-and-
>> hold circuit.
>
> You wouldn't *want* a digital meter to be
> in-sync with the switching...

   Correct.  Those of us working in digital signal
analysis deal with sampling issues daily.  The problem
we face is called aliasing.  It occurs when the
sampling rate is inadequate to represent the
frequencies in the input data.  There is a frequency
called the Nyquist Frequency and that is the MAXIMUM
frequency that can be present in the input signal to
avoid aliasing.  Aliasing is the phenominon that
occurs where the input frequency is above the Nyquist
and appears or 'aliases' as a lower frequency.
   The condition you suggested is the ultimate
aliasing.  That is, when a pulsing signal is in sync
with the sampling.  That means that the Nyquist is
HALF of the input signal and therefore aliases at zero
hertz - either the sample value of 0 or 12.
   Okay, now back to your originally scheduled program
- already in progress.

rick
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