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- DuncanR
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Offline - From: Up and down East Coast Aus
- Registered: 9/16/2015
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Stripchart Advanced Channels - TWDPeriod and TWSPeriod
If they are what I hope they are, good - but I can't find any explanation of what they are. So waht are they>
- Fergal
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Re: Stripchart Advanced Channels - TWDPeriod and TWSPeriod
Well from the Help text:
Twd Period: Period of the dominant wind shift.
Tws Period: Period of the dominant tws cycle.
So hopefully that is what you were hoping for!!
- DuncanR
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Re: Stripchart Advanced Channels - TWDPeriod and TWSPeriod
G'day Fergal, you did werll to find that - I couldn't. This is what I thought in concept, but what does that actually mean? I think a worked example from Nick might be needed, especially as I couldn't make it work on last week's logfile - nothing shows up.
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Thread Starter- Fergal
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Re: Stripchart Advanced Channels - TWDPeriod and TWSPeriod
Duncan
I tried it on some old log files and wasnt successful either, the numbers just dont get populated. It would be useful value to have, our main trimmer is fixated on wind shift patterns and I'd love to be able to validate some of his statements with some numbers.
Actually, I've now left it run for a while and the values are populated but it doesnt make much sense to me.
Does anyone have any guidance?
F.
- DuncanR
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Re: Stripchart Advanced Channels - TWDPeriod and TWSPeriod
Ok Fergal, you have done better than I have, and being fixated on oscillating versus permanent shifts is OK, and to find out to track even better!
I take it the above numbers are live?
Looking for the next contribution.
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Thread Starter- Nick
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Re: Stripchart Advanced Channels - TWDPeriod and TWSPeriod
Good morning,It is one of those things that is there because it could be done. Whether or not it is useful is another matter.These numbers are essentially just the main period of the wind oscillations. As background, it is a Fourier transform () of the wind track data.Just looking at the code, it may not handle 0-360 for TWD.
- DuncanR
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Re: Stripchart Advanced Channels - TWDPeriod and TWSPeriod
Ahhh .... a Fourier transform. I very, very vaguely remember that from Uni - verty vaguely!
Nick, I take it then it is the dominant period of time or direction from the start of data recording on that day?
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Thread Starter- Nick
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Re: Stripchart Advanced Channels - TWDPeriod and TWSPeriod
It uses the same data as the track data winds, so it limited to the length of that.
- GRaines77
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Re: Stripchart Advanced Channels - TWDPeriod and TWSPeriod
My experience with the Fourier transform is that it converts a time domain function in to the frequency (or period) domain. For time histories, we normally plot the parameter as a function of period. It would be interesting to see the shape of a Twd transform funtion this way. In the above example, for Twd, I assume that whatever Twd is at the time, the transform is then giving the period of that Twd. I have normallly tried to evaluate Twd oscillations, while racing, by a visual process looking more for the period of change of the Twd, such that I can report up that the Twd oscillation is approx. X degrees with a period of approx. Y minutes to try to help the tactitian get in phase with the shifts. So to me, it is the period of Twd change, which might be the slope of the transform function. Thoughts?
- DuncanR
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Re: Stripchart Advanced Channels - TWDPeriod and TWSPeriod
Crikey, I've just written significant shifts in a notebook, verified what appears to be happening on Stripchart to reinforce my observations, then called a tactical huddle. This has had little to do w maths.
What interests me about this topic is the way in which we form conclusions, and trying to make that more systematic - if you believe a shift is going to happen, you'll go looking for data to einforce that conclusion. This has to do w psychology and neural nets, not maths.
Graines, your writings indicate that you know something about the topic. Can you do a worked exaple to inform we mortals or soft arts practitioners?
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