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Author Topic: Mesuring Distance up to 500m / Line of Sight available  (Read 699 times)
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Hi,

i want to display an animation on a boat floating on a river. The animation content is related to the boats distance from a certain point. During a show the maximum distance will be max. 500 Meters. Is this a GPS thing, or are there other possibilities? Laser could be an option, but it is expensive ( ca. 1000€ in these distances ) and depends on clear visibility -

Any ideas, anyone?

Best regards,
Hendrik

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500 meters can be handled by GPS, but maybe a sound pulse is an option (sound takes 1.5 second for 500 mtr).
Every second a short pulse and once per minute a longer sound pulse to sync ?
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How about a person who looks at the boat and presses a button when its time to change the animation.

Or if the schedule is pretty consistent, could you just do it as timed transitions?

Or, if that would spoil the magic, what about someone on the boat pressing a button and using an RF link?

Anything else apart from GPS is going to be pretty tricky.
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Celerity (speed) of sound is not a constant considering temp, humidity.

after 350 meters, it's not a 'VALID' value, it can change from few meter considering the climatical elements. if your'are working with big heat and sun, convection will change these values an they will be false.

25 years in the job of sound ingeneer...

This is not a good way of doing it to get right results !
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Quote
25 years in the job of sound ingeneer...

Clearly not 25 years as an English teacher smiley-wink

Sorry - couldn't resist.

It would have to be quite a loud noise to carry that distance, and it would have to bounce off something and return to get a distance measurement that was based on the speed of sound.
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@ mxwendler
What is the accuracy you need in your measurements, smaller than 1 meter 1 meter, 5 meter, 10 meter, ...?
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Quote
25 years in the job of sound ingeneer...

Clearly not 25 years as an English teacher smiley-wink

Sorry - couldn't resist.

It would have to be quite a loud noise to carry that distance, and it would have to bounce off something and return to get a distance measurement that was based on the speed of sound.

Sorry but I'm French people, I dont get all the english gramar and way of writing words as I can do it in French...
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@ mxwendler
What is the accuracy you need in your measurements, smaller than 1 meter 1 meter, 5 meter, 10 meter, ...?


this is a good question.

what we want to do is ( i hope i can explain that in words ) display a loooooooooooong--seeeeenteeeence that will be shown as a projection on the boat. imagine the boat floating on a river, at the first meters showing 'lo' then 'oo' then 'oo' then ... etc. Get the idea? You would read the whole sentence if you keep watching the boat or i you could make a long-time exposure along the whole boat trip. So if i start calculating, we have 1 pixel per cm ( 500 m distance -> 50.000 cm -> 50.000 pixels sentence length as large image which will be sampled ) and to get a reasonably sharp impression, anything that jitters below 10-20cm would be perfect ---


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10 cm on 500meter = 1:5000 = WOW!

@Grag38
How much is the speed of sound fluctuating over mentioned conditions ? 300-400 M/s ? or is it less?


@mxWendler
eh ..... How about a looooong rope and a "wheel" keeping the rope tight => counting the centimeters.
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I would have thought 10-20cm is too much to ask - it's also on water so that will make the boat go up and down (probably by 10-20cm or so).
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