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I am working on a Robot-project where a sub task is have to check how many and which RFID-tags are placed in a bucket.

Multiple tags will be placed into the bucket - so I run into the problem with RFID-tags colliding with each other. The reader will be connected and programmed via Raspberry Pi. From my research so far I have come up with the following 3 options: enter image description here

1 RFID reader at the buttom of the bucket. This has to be a reader able to read the multiple tags at the same time, since the tags will be laying on top of each other. Example of reader: https://www.sparkfun.com/products/14066

2 RFID reader on the side of the bucket. Should read the tags passing by as they are thrown into the bucket. Would not required that the RFID reader is able to read multiple tags at once, but the reading should be fast enough to catch them passing by. Example of reader: ADAFRUIT PN532 NFC/RFID

3 Same concept as 2 but minimizing the space and using slides to hopefully give a bit longer time for reading the tags. Example of reader: Same as in 2

I am aiming for the most simple and most secure solution.

How would you guys do this, and what kind of RFID hardware would you recommend to go with the Raspberry Pi connection.

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  • \$\begingroup\$ In RFiD world, you 3 type of hardware. The RFiD LF (about 125kHz). The RFiD HF (13.56MHz). The RFiD UHF. \$\endgroup\$ – Foxrider83 Aug 16 '17 at 12:22
  • \$\begingroup\$ I have a car that goes 100 miles an hour how do I make it go 200 mph? A: you cant you get a different car that goes 200mph. \$\endgroup\$ – old_timer Jan 19 '18 at 3:27
  • \$\begingroup\$ @old_timer. Actually a Porsche 918 hybrid has a top speed of 220 mph (750 hp), but it cost over 1 million bucks. \$\endgroup\$ – Sparky256 Jan 21 '18 at 2:34
  • \$\begingroup\$ #3 should work fine, unless your RPi software takes a really long time to read the tag. \$\endgroup\$ – Dmitry Grigoryev Jan 22 '18 at 11:09
  • \$\begingroup\$ The guys at RFID-Radar demonstrated reading of a shopping trolley full of tagged products about 20 years ago. They used what was then the less common UHF tag frequency to handle the collisions. - trolleyscan.com \$\endgroup\$ – KalleMP Jan 22 '18 at 16:34
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In RFiD world, you 3 type of hardware.

  • The RFiD LF (about 125kHz).
  • The RFiD HF (13.56MHz).
  • The RFiD UHF (444MHz or 866MHz band).

If you want to detect multiple tags, you need to have a reader with anticollition protocol. I recommend using RFiD HF because the antenna design and debug is easier than UHF. You can use the OMNIKEY multi ISO reader which is a good product. You can find it on the RFID SHOP website.

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