RFID limitations?
  • Is it possible to use one RFID implant (125kHz) to contain more than one access ID?

    For instance if I cloned my gym transmitter to my tag, could I also copy my Kevo RFID fob data to the same implant and operate both or would it require an entirely separate implant for each?

    Thanks in advance. I have a feeling I know the answer but wanted to make sure.
  • aviinaviin June 2016
    An RFID, when powered up, spits out its ID.  Assuming a chip was made that could contain multiple IDs, there would be no way for the chip to know which ID to provide a given query.  Supposing someone packaged two chips into a single implant, if both were operating on the same frequency, both would output their ID when queried, but then you run into something called "collision".  The reader will likely have difficulty separating the two outputs and neither one would likely be able to act as an access key to anything.

    I imagine, though, if you were to package one low frequency chip with one high frequency chip, you could likely make use of both from one implant.  But why bother?  If my 13.56 chip experiences a hardware failure, do I really want to have to buy a new 125 chip, too?  That's what would happen if both were in one implant.  That's just personal opinion, however.  Others may disagree.
  • AlexSmithAlexSmith June 2016
    @PostHumanist What @aviin said is almost entirely correct. The only thing I'd point out is that most RFID readers have an anti-collision algorithm, so having more than one chip sending it's ID should not be a problem (although some cheap readers don't handle collisions properly).

    Having said that, this is something I've been thinking about for a while. It would be possible to build a single implant which stored multiple IDs, and then sends them one after the other. It could take a few seconds if there were lots of IDs, but it would let you have one chip which works with multiple systems.

    The only reason I've not actually built this is the amount of time it would take to make build it and make it implantable, but if someone with electrical engineering/microprocessor skills wants to work with me to make this happen, I've got the design sorted out.
  • The only reason I asked is I've been assigned an ID number by my gym which is contained on a 125kHz fob. I would like to implant and clone this so I don't have to take my keys with me anymore.

    I also have a Kevo smart lock as part of my automated home. It too has a 125kHz fob. In order to operate both doors (Gym and home) I would either need to:

    A.) Program both IDs onto a single implant
    B.) Implant two chips, each in a different location to minimize signal collision
    C.) Modify my Kevo to be the same ID as my Gym fob
    D.) Ask if my gym can reassign my ID (to be the same as the Kevo fob)

    So you see, I think it's a worthy endevour to allocate enough memory to contain multiple IDs in a single transmitter provided no collision occurs.

    I intend to operate at least 6+ RFID interfaces and may very well require 6 implants if I cannot modify the pre-assigned ID.
  • trybalwolftrybalwolf June 2016
    Does your door lock system not allow you to add your own keys? If you could... Heh. Just read "C.". Seems you have worked out all the possibilities.

    I would most recommend asking the gym about using a different key (your implant).

    At the very least you could put a LF tag in each hand. You could also consider doing one in the webbing, and the second on the outside edge where people have been putting the m36's.
  • ThomasEgiThomasEgi June 2016
    Option A would be to build your own tag with multiple keys stored on it and cycling through the send keys at low rates. Like send key 1 for 50ms, wait, send key 2 for 50ms, wait etc. If the readers can tolerate unknown/wrong numbers without going into angry-mode that'd probably work.
  • I've had another thought after reading the theory of operation of RFID communication and how it's utilized in entry systems.   Because I don't have access to the computer at my gym where the FOB data is input or stored, I will attempt to clone that to my implant.  That will be my identifier code and I will then program that same ID number to all subsequent entry systems (in my own home).

    This should allow me to enter as I please nearly every place I need RFID access with only one transponder.