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#1 2009-09-12 05:43:44
- ishmell
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- Registered: 2009-09-12
- Posts: 4
Calculating position using RSSI (received signal strength)
I've got a few people on my RFID forum that are curious as to how to derive approximate position using the RSSI values coming from RFID reader hardware. I outlined a guess here: http://www.rfidtoys.net/forum/forum_posts.asp?TID=635 but I really have no idea how one would come up with a flexible formula that would allow for a more practical setup. Can anyone comment, either there or here?
Last edited by ishmell (2009-09-12 05:47:36)
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#2 2009-09-13 00:46:31
- integer
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- Registered: 2008-02-21
- Posts: 79
Re: Calculating position using RSSI (received signal strength)
I've got a few people on my RFID forum that are curious as to how to derive approximate position using the RSSI values coming from RFID reader hardware. I outlined a guess here: http://www.rfidtoys.net/forum/forum_posts.asp?TID=635 but I really have no idea how one would come up with a flexible formula that would allow for a more practical setup. Can anyone comment, either there or here?
Since you are looking for a two dimensional coordinate answer (x,y), only three readers are required.
Establish the location of the three receivers & triangulate the location of the transmitter.
[Aside Note: This is what the cel phone system does.]
There are many algorithms on the web for doing this.
(This is similar to the problem of trying to find the radius of a circle, given three points.)
However, you require the intersection of three (3) circles
Distance from transmitter to receiver 1:
Similar for Distance2 and Distance3
Do you need additional information to do this?
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#3 2009-09-13 06:50:51
- ishmell
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- Registered: 2009-09-12
- Posts: 4
Re: Calculating position using RSSI (received signal strength)
Thanks for the reply 
I think I understand the concept here, except for one thing... the X0 and Y0 values for the transmitter. How do you arrive at those values in order to use them in the distance calculation?
PS, thanks for all the schooling
Last edited by ishmell (2009-09-19 05:21:27)
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