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I am attempting to make a grid of RFID readers that can triangulate the position of a tag within their read range.

I am currently using MFRC522 readers connected to a Raspberry Pi 4 Model B (4gb) and reading using the SimpleMFRC522 Python library.

This is great in that it lets me easily read from & write to the tags that the readers can detect.

I would like to try to triangulate the relative position of a tag by using several readers to gauge signal strength from each one, with the intention of scaling up to have a grid of readers (or antennae connected to multiplexers) that can track the position of a tag as it is moved across a larger area (think a few feet across).

Is this possible using MFRC522 readers, or is this something that could be done with other readers or a specific chip connected to other antennas? I can't see any methods to return signal data from the SimpleMFRC522 library, just read & write methods.

Is there a command I can send to the reader to return this data?

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    Perhaps you can consider two grids: RFID reader and RF detector. Or one RFID reader with a servo, another RF detector also driven by servo.
    – tlfong01
    Aug 21, 2020 at 3:15
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    Thanks for the suggestion! I am open to suggestions on how best to accomplish an accurate and fast tracking grid. Although given i want to scale it up cost is a consideration, and rc522 is very cheap to buy hence why i started there. Aug 21, 2020 at 9:34
  • You are welcome. I am just brainstorming. I only started learning RFID reader, RF detector, and GPS sensor about a year ago and have only played RFID and GPS for perhaps less than 100 hours each. I have not played with RF detector yet, because I think it is not that useful for my current project. For SimpleMFRC522, I am just scratching the surface. So I will be glad that all can join in to learn together. Cheers.
    – tlfong01
    Aug 21, 2020 at 9:41

1 Answer 1

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Question

Can Rpi4B 4GB, using SimpleMFRC522, triangluate a tag read by a grid of MFRC522 RFID readers?


Answer

Part A - RFID Reader Triangulation

rfid reader

See Refs 1, 2

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Part B - RF Detector Triangulation

RF Detector

See Refs 3, 4


Part C - GPS Satellites Multiangulation

ublox GPS-RTK2 Board (10mm accuracy) - SparkFun


And you can use a GPS board to do not only triangulation, but with 2,500+ satellites to multiangulate, to 10mm accuracy.


gps 1


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References

(1) RC522 - THM3060 RFID Reader Q&A

(2) RC522 - THM3060 RFID Reader Chat

(3) AD8632 - How Can I read data from AD8361 RF Detector - Rpi SE 2020mar15

(4) AD8632 - DIY Rpi Triple Axis RF/EMF Detector using AD8362/AD8361 - Rpi SE 2020may21

(5) RFID Range Overview - What is the maximum read distance of RFID? - SkyRFID

(6) Real-time Locating System - Wikipedia

(7) ublox GPS-RTK2 Board (10mm accuracy) - SparkFun $220

(8) Neo uBlox Neo-8M GNSS Module Tests - tlfong01, Rpi SE, 2020jul01

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Appendices

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End of answer

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