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Hi there,

I would like to be able to detect  a moving object fitted with a transmitter.
The transmitted signal would be  by receiver connected to my arduino.
 However, I want only to detect specific objects , so the signal would have a unique signature, so I can distinguish whether the moving object is or is not the type I want to identify, and how far it is

Which direction should I take?

Many thanks.

OptionB

P.S: newcomer, with RF kit on its way. I'm currently a baker making 20p profit per loaf, so urgently need a million $ invention smiley
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and how far it is
That is the tricky part, crack that one and you can give up your day job.
Finding the distance of a radio transmitter is very difficult. You can not rely on signal strength because that gets screwed up with reflections.

There have been many attempts at the commercially and they are marginally successful at best. The best system I have seen uses an Zigbee mesh of transceivers and works on a collective average from six or more receivers.
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Which direction should I take?

Select a different more reasonable project that has more realistic goals.

Lefty
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Select a different more reasonable project that has more realistic goals.
That is, without a doubt, the best advice I've seen on the forum in quite a while.
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You will need to use multiple receivers so that you can triangulate the position of the transmitting object. You can use the difference in intensity of each signal to work out a bearing.

Your Arduino will need to be able to sample both the intensity of the RF signal, and also be able record the signal so that they can be individually identified.

There are many practical difficulties in this however. Some research will give you more.
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You will need to use multiple receivers so that you can triangulate the position of the transmitting object. You can use the difference in intensity of each signal to work out a bearing.

No, at such short range the signal strength from the swarm of RF emitters will not have enough variation to be able to be used as a discrimination measurement. On this path only lies tears.

Your Arduino will need to be able to sample both the intensity of the RF signal, and also be able record the signal so that they can be individually identified.

A receiver on a single channel cannot demodulate multiple transmitters to obtain any useful information, it would like listening to twelve people talking at you at the same time. You would have to have a more sophisticated receiver that could scan multiple channel frequencies so that it could receive signals from each transmitter that were each using a unique channel frequency.

There are many practical difficulties in this however. Some research will give you more.
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This is the sort of thing I was thinking about.
www.daintree.net/downloads/.../appnote_016_sna_ti_locationing.pdf
Mind you it is not an Arduino project.


Moderator edit: link corrected.

EDIT
Thanks, it was a copy and paste from a Google hit, I guess it didn't make it.
« Last Edit: January 04, 2013, 06:23:48 pm by Grumpy_Mike » Logged

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This is the sort of thing I was thinking about.
That is irony.

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This is the sort of thing I was thinking about.
www.daintree.net/downloads/.../appnote_016_sna_ti_locationing.pdf
Mind you it is not an Arduino project.

Bad URL for some reason.  http://www.daintree.net/downloads/appnotes/appnote_016_sna_ti_locationing.pdf seems to be a correct link.

I've had this BBS software trash a URL on me before too, though I think it was an FTP link.
« Last Edit: January 04, 2013, 06:17:06 pm by JoeN » Logged

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