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Topic: Long range RFID or other sensor (Read 2 times) previous topic - next topic


Does anyone know if there is a long range RFID sensor available or something I could convert to do long range?

I'm looking into an idea for tracking animals. I'm thinking if I can get a long range RFID reader, I can get a general direction. Once the signal is strong enough, switch to a medium range reader, then a short range reader. The idea being that I can get at least relatively close to the area the animal would be. I don't know much about RFID yet, however.

If RFID won't work, does anyone have any suggestions of what might work?

Looking at http://www.parallax.com/product/28140 looks like this won't be strong enough to detect an animals RFID.


Forget the toys at Parallax and others. Those are 125kHz short range passive ID tag readers. At best, a range on the order of a few meters.

There are many kinds of RFID, for this I think you'd want an active tag, and the UHF tags (850-900MHz) can be read from a distance using a directional antenna. You don't switch to different readers.


"Near field UHF RFID tags contain a small silicon chip and an antenna paired onto or into an object. This allows one to create tags which can be read from inches to 10s of feet in a passive configuration, and 100s to 1000s of feet if used semi-passively (the tag still changes the RF that comes back to the reader rather than transmitting, but gets a battery to help it out) or actively (an active transmitter)."
Steve Greenfield AE7HD
CET Consumer Electronics and Computer
Please don't read your attitudes into my messages


I am looking at this device for UHF RFID tags: http://www.soliddepot.com/index.php?main_page=product_info&cPath=38_42&products_id=232&zenid=e6f5f982644a2b10965d452f53cda687

What kind of distances are you trying to achieve in your "long-range" readings?

Also, how many animals/tags would you like to scan at one time?


You can add a directional antenna to that, too, which will boost the range and allow a direction measurement to be made. Animal tracking has been done that way for decades.
Steve Greenfield AE7HD
CET Consumer Electronics and Computer
Please don't read your attitudes into my messages


I might as well state my idea here so you get an idea of what I'm trying to do. I was looking at creating a quadcopter that would follow / track an RFID tag and potentially report its position to my phone. So the distance could be pretty far or relatively close. I suppose I'm looking for max possible. I have been somewhat distracted with another idea at the moment, but maybe if this is viable for me I may come back to it


That limits the power and antenna size, then.
Steve Greenfield AE7HD
CET Consumer Electronics and Computer
Please don't read your attitudes into my messages


Interesting idea!

There are a few trade-off scenarios we should work through. First, how high do you want the quadcopter to fly? Also, is the goal of the quadcopter to locate the animal(s) or simply report what was scanned during a flyby? (i.e., if a rancher wants to locate the position of an animal the quad would need to sweep the land until the animal was found; but, if you wanted to sample the population of a wildlife refuge, you might want to set a flight path and merely report which animals were present). Each scenario may have a trade-off based on the flight time available vs the distance needing to be scanned at once. So, to stay true to my previous examples, if you were locating an animal then you would need to sweep the land (much like a Roomba). The number of sweeps would need to be compared to the range of the RFID scanner.

With that said, I don't think you will have any credible choice other than using an active UHF RFID tag to extend the range. According to wikipeida, the range of an active UHF tag is 100 meters but that probably assumes that the reader is fixed and you need to have a mobile reader. It might be possible to create an array of fixed readers/antennas to create a long range mobile reader...

Thoughts anyone?


you could  use Gsm Shield to send a text to one of these thats on the dogs collar
the tracker will reply by sms with its location
there only a little bit bigger than a sim card



The key point with RFID is that it is possible to work with devices that have no battery.   The device gets enough power from the reader device,   and that limits the range to centimetres not metres [  unless you are allowed to blast the whole vicinity with high-powered transmissions from your RFID reader ].

A device that has a GPS chip and also a GSM transmitter obviously has a battery.    If you are able to attach a big enough device to an animal for that to work,   you don't need RFID.


I was hoping to revive this thread and take it on a tangent.  I am also working to use long range UHF RFD to track wildlife, but in this case wild turkeys.  I am working with a science museum on projects to connect people with urban wildlife and we want to gather data on turkeys that live on the property using an array of readers.

Does any one have advice about how to best find a suitable tag for a turkey? I was hoping there might just be a larger version of those I have seen for songbirds. 

Also, I was hoping someone could fill me in on how things would change if I needed to track more than one bird simultaneously.

Thanks a lot.  This forum is awesome.

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