AVR-Chat

Awhile back, when developing a homebrew logging system, I ran acorss the
documenting what temperature the wort reached a certain temp.

At first I thought of recording the temperature every minute. Then, for me,
I had a brain storm. In a loop continue taking the temperature readings.
When the temperature increased by 1 degree F log the temp and time. For
those that are familiar with homebrewing know that the wort, in an all-grain
brew, starts at well above 100 F. Probably above 112 F. Going from 112 F to
a boil at 212 F, we are talking about 101 readings.

I didn't read all the thread on this but somewhere I saw someone talking
about 100%. If you only log the time when a certain amount of change is is
make you should know ahead how many readings you will have logged.

This may give you a different approch to documenting when changes happen.
Doing this you will probably have to log both the time and reading because,
like the temperature above, sometimes the temperature would increase 2
degrees.

Hope I'm not being redundant,
Mike

----- Original Message ----- 
From: "Robert Adsett" <subscriptions@aeolusdevelopment.com>
To: <AVR-Chat@yahoogroups.com>
Sent: Wednesday, July 14, 2004 11:39 PM
Subject: Re: [AVR-Chat] Re: variable/constant input from a PC ?


> At 10:35 PM 7/14/04 +0000, you wrote:
> > > The bigger issue I see is you are talking about an awful lot of
> >data for
> > > the students to analyze.  For the 1/min you are talking about 42000
> > > points.  Will your spreadsheet (or whatever analysis program)
> >handle
> > > that?  And if it does will it do it w/o slowing to a crawl?  It
> >would be
> > > easy to create a dummy data file to check that out.
> >
> >
> >oh, so you're saying there are leaves on those twigs ?
>
> I'm not sure we've got to the leaves yet.  BTW, I just checked the
> spreadsheet I use for this sort of thing and it has a max of 8K rows.  If
I
> want to seriously play with the data the program I use for that has an
even
> smaller limit.
>
>
>
> > > One last data question.  What are you trying to track with the
> >brightness
> > > measurement?  Do you really expect to see a significant change in 1
> > > minute?  I would have guessed a 5 minute period made more sense
> >(maybe even
> > > longer at night).
> >
> >A bush in shade will see light when the blocking thing moves
> >relitaive to the sun.  Imagine tree or tree trunk that acks like
> >gnomon.  as the Earth rotates, the Gnomon will appear to move and the
> >plant will be blocked for some period.
> >
> >How much sun a leaf gets from being in shade vs a cloudy day.  That
> >sort of thing.
>
> Yep, I'm just questioning the need for a 1 minute resolution.  Assuming
you
> are at a reasonable mid latitude, taking measurements in the winter with
> the day getting no shorter than about 8 hours (I'm making this up as I go
> along). 1 minute represents 1/480 or a little more than 0.2% of the
> daylight hours.  Do you reasonably expect to see the difference from even
a
> 1% drop in light?  Or perhaps more to the point what is the minimum light
> difference you expect to cause a difference in what you are measuring?
>
> In either case you will need a low pass filter to avoid aliasing (now we
> are getting to the leaves). Given the time scales the larger part of that
> is most effectively done in software.
>
> You can quite easily track the average exposure during the sampling period
> (It could even be a no-linear 'average' like an RMS) without needing to
> store results from high frequency sampling.
>
> What I'm getting at is if one plant is exposed to 50% intensity for 5
> minutes and another to 100% for 2.5 min and 0% for 2.5 minutes can you
tell
> the difference in the plants responses?
>
> Actually I wouldn't be surprised if you could get away with even longer
> sample intervals.
>
> Robert
>
> " 'Freedom' has no meaning of itself.  There are always restrictions,
> be they legal, genetic, or physical.  If you don't believe me, try to
> chew a radio signal. "
>
>                          Kelvin Throop, III
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
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