Is there a way to 'capture' what frequency an RFID or transponder emits at?


#1

I don’t know much about electronics so the phrasing probably isn’t right, but essentially I have a key fob for getting into my apartment complex. I have a read/write device that worked in my previous complex but doesn’t work for my new one, I guess it’s a different frequency. How would I figure out what frequency it’s at so I can find a tool to duplicate it for me to an empty fob like with the old one? The complex won’t give me a second one so I have to make my own.

Also is it possible to do the same for a transponder/gate clicker? Like does a device exist that cycles through a bunch of frequencies until it reacts to whatever one the transponder is emitting and then tell you that frequency?

I’ve tried Google for this but I don’t think I know the right terminology to bring up the results I want.


#2

Yes, and it comes in two flavors, $30 and $150.

For the $30 option, look at “RTLSDR”. Basically, you get a very specific piece of hardware called an SDR. You can use a computer and a program to look at the wireless spectrum and see what frequencies are being transmitted on.

The problem is, for RFID specifically, the powered transmitter part is the badge reader not the badge, so you’ll have to take your laptop to the reader and sit there for a couple hours finding out what signal it’s sending out.


#3

Is there a device that just sends a bunch of frequencies to the RFID until one reacts?


#4

That’s a good question I don’t know the answer to. You could technically build it with a TX and RX capable SDR, but that’s the $150 option.


#5

you’ll probably have an easier time just tracking it down from the specifications.

any identifying marks on the fob? how about model number etc on the reader?

note that it’s definitely not as simple as “sending a bunch of frequencies”, even the dumbest RFIDs engage in communication with the reader and some employ unbreakable cryptography making them all but impossible to clone.


#6

#7

I’ve got a reader that will spool thru 10 different frequency and encodings. If you want to bring it by DMS some evening, I’ll be happy to see if it will read your fob.


#8

That’d be helpful. I was looking at one of those on Amazon but wasn’t sure I wanted to drop $60 on it.

you’ll probably have an easier time just tracking it down from the specifications.

any identifying marks on the fob? how about model number etc on the reader?

Only ‘DKS’ on the fob. I haven’t cracked it open yet as I’m in the process of moving and it needs a small screw driver to do it. Just hasn’t occurred to me to try it while at the space and I haven’t found what box I put my screwdrivers in yet.


#9

probably this then.

also, there are services that will do this for you for a pretty reasonable cost.