Longer Range RFID

Thread Starter

Nuno Silva

Joined Sep 26, 2016
7
Hi.
I am planning to build a raspberry pi controlled cat door. I want to allow the entrance/leaving of a cat based on it's proximity. I figured out that the way to go was RFID. However, since a cat can't be taught to go near the RFID reader to unlock the door, and since all RFID readers I have found have a very small range (up to 3cm) this doesn't work.
I was hoping that some of you knew any option to either extend the range of a MIFARE RC522 or any other similar option with a higher range even if a little bit pricier.
Thanks
 

GopherT

Joined Nov 23, 2012
8,009
Hi.
I am planning to build a raspberry pi controlled cat door. I want to allow the entrance/leaving of a cat based on it's proximity. I figured out that the way to go was RFID. However, since a cat can't be taught to go near the RFID reader to unlock the door, and since all RFID readers I have found have a very small range (up to 3cm) this doesn't work.
I was hoping that some of you knew any option to either extend the range of a MIFARE RC522 or any other similar option with a higher range even if a little bit pricier.
Thanks
Look for Active RFID. They have a battery, Chip and antenna coil and, therefore, Much more range. The passive RFID are energized by the reader coil the range is much less. Just antenna (also functions as energizing coil) and chip.

Good luck.
 

RichardO

Joined May 4, 2013
2,270
However, since a cat can't be taught to go near the RFID reader to unlock the door, and since all RFID readers I have found have a very small range (up to 3cm) this doesn't work.
Maybe you need to train the cat better. :D

I worked with a gal whose cat rang the doorbell to get in! There was a railing next to the doorbell button. The cat found out that if it jumped up on the railing and rubbed against the button somebody would come to the door.
 

Thread Starter

Nuno Silva

Joined Sep 26, 2016
7
Look for Active RFID. They have a battery, Chip and antenna coil and, therefore, Much more range. The passive RFID are energized by the reader coil the range is much less. Just antenna (also functions as energizing coil) and chip.

Good luck.
Can I use an active tag with any normal reader if the frequency is the same?
 

Thread Starter

Nuno Silva

Joined Sep 26, 2016
7
Maybe you need to train the cat better. :D

I worked with a gal whose cat rang the doorbell to get in! There was a railing next to the doorbell button. The cat found out that if it jumped up on the railing and rubbed against the button somebody would come to the door.
Well it's for a school project so I can't train all the cats in the world :-D Thanks anyway,
 

inwo

Joined Nov 7, 2013
2,419
I just got in a rfid system that worked from >5M. Had to adjust to minimum. Now about 1M.
As per GopherT active system.
Found it on Ebay.
 

GopherT

Joined Nov 23, 2012
8,009
Can I use an active tag with any normal reader if the frequency is the same?
I think the passive systems work on higher frequencies (in general) that active systems. Lower frequency yields better battery life for the tag than a higher frequency - if I remember correctly.
 

Thread Starter

Nuno Silva

Joined Sep 26, 2016
7
I think the passive systems work on higher frequencies (in general) that active systems. Lower frequency yields better battery life for the tag than a higher frequency - if I remember correctly.
Yes that's true. I researched deeper and found that they wouldn't work together. Back to square one I guess, since an active reader is too expensive for the project...
 
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