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Rangefinding device for my dog, (telemetry/radio/range finder/outdoors) Answered

I know a fair amount with electronics, so i was PRETTY frustrated when i looked around online for a method of rangfinding that i could build into a small device. I have been wanting to have a project for awhile, so i am not just going to buy one.
Anyway the inspiration comes from me and my dog, you see, hes a Jack Russel, and very eager, he loves to chase rabbits but i can never find him after he has run off into the forest, by that time he is too far away to hear me.I want him to chase rabbits because he loves it, but i can't use a lead because it gets caught on everything(Trees, plants, thorns and general vegetation).So i had an idea, if i could just have a device that would tell me how far away he is, then i could just use that to work my way towords him.The process seemes quite simple to me, give him a transmitting collar, and have a device that recieved that signal, and could use the basic distance = speed x time sum to work out how far away he is, then display it.
Apparently, either nobody has ever tried this, or i just ain't searching for the right thing.I know radio waves seem to be optimal, seeing as he won't be more than 1KM away from me, but again, i don't really know where to look to find the parts, or how to build the thing in the first place.
So please, if anyone could help me out, please do.My physics teacher is a real **** and refuses to help me.So you guys are all i have to ask.
Thanks.

/James

PS: My dog would be REALLY happy too, he hates being on a lead all the time, and if i could get this done, i will post pictures of him, apparently hes really cute.

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LargeMouthBassBest Answer (author)2011-03-06

It seems like the timing for this would have to be fairly accurate to be used to determine distance. Every 100 meters would amount to only approximately a 330 nanosecond differnece between the signals.

GPS satellites have atomic clocks and regular corrections and upates to maintain their accuracy.

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user

Jesus, well there goes that plan
The only other thing i can think of is still using a radio transmitter but have the reciever work out which direction the transmitter is.
However i have a feeling this will just be even more difficult.
Sigh...

Thanks anyway

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user

Determining the direction should be much easier, if you are using a directional antenna with the receiver. Google on "transmitter hunting" or "fox hunting" as it is sometimes called.

There are many amateur radio publications on this that would have good material. Even if you have no other interest in amateur radio or intention of getting a licence, the therory would all be applicable. There are some books from ARRL on the topic that would be a good resource.

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user

Wow those key words took me straight to it, thanks.
If i manage to get one up and going i will do a instructable on it. Thanks alot.
=)

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microbot (author)2011-04-19

Some German School kids made one of these. I am looking for it, not having luck yet. They used two frequencies. One initiates the other. Seems fairly simple. The Article may have been on Hackaday or Makezine. Will post if I find.
Good Luck!

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Kiteman (author)2011-03-06

Haven't you thought of training him to return on a whistle?

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Nero57James (author)Kiteman2011-03-06

I don't really have the time, and i would rather make something instead.

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Kiteman (author)Nero57James2011-03-06

In that case, you're searching for wildlife telemetry, and devices such as these collars.

You will have to remember the law regarding types and sizes of collar that can be worn by your dog, and the kinds of signal that are legal (UK standards as an example)

If you're going totally DIY, amateur rocketeers have similar problems, and a more DIY approach.  (Link).

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Nero57James (author)Nero57James2011-03-06

Well the rocketeering website was interesting, but only really had links to places to buy kits for FM transmitters to transmit a sound from a microphone.Or really long explanations on how a radio transmitter with a microphone works.All i really need is like a beep every 2 seconds on a frequency that could be tuned into.Then provided i had them synced to the same time, then i could work out a distance.
I tried googling "wildlife telemetry", but it was all just items to buy, no explanation or even a basic kit, which i would have been ok with.i don't get why its so difficult to do something that seems so simple.I just need to know how to build it.Thats all.
i would really rather not go looking for a dog trainer and a "silent whistle" when i could have a much more satisfying project like this, i want to learn about this kinda thing, and getting a dog trainer ain't gonna do that.Using it for my dog is just a practical application for it, along with the inspiration.

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Nero57James (author)Nero57James2011-03-06

And even if i did have the time, i can't whistle and i don't know how to train my dog to do that.

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Kiteman (author)Nero57James2011-03-06

Buy a silent whistle? Make a silent whistle?

(And there are loads of people "out there" who can help you train your dog.)

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rickharris (author)2011-03-06

Invest the time you take to make it to train your dog properly He will be MUCH happier.

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