RFID receiver

GNU Radio
1

Hello

As a pre-project to my master-project I am considering making a RFID
receiver with gnuradio, atleast attempt to. However I recently noticed
that an RFID detector/receiver is mentioned as a project under
investigation or progress in the “Exploring GNU Radio”-document.

How far has that project progressed? If it is near completion it may not
be of such an interest as a pre-project.

best regards

Erlend Barstad Strand

2

On Tue, Sep 19, 2006 at 11:55:51AM +0200, Erlend Barstad Strand wrote:

best regards

Erlend Barstad Strand

I haven’t heard anything on the RFID front lately, so it’s a good bet
that it’s stalled, and still a good idea for a pre-project.

Eric

3

On Tue, Sep 19, 2006 at 11:55:51AM +0200, Erlend Barstad Strand wrote:

Hello

As a pre-project to my master-project I am considering making a RFID
receiver with gnuradio, atleast attempt to. However I recently noticed
that an RFID detector/receiver is mentioned as a project under
investigation or progress in the “Exploring GNU Radio”-document.

Sorry for the late reply, but I didn’t have a lot of time for keeping up
with mailinglists recently (busy with other free hardware RFID work for
http://openpcd.org).

When you talk about RFID, what kind of system are you talking about?

Which frequency? Which protocols? Magnetic coupling, backscatter or
SAW?

I have quite a bit of experience with RFID on a protocol level. My RFID
hardware related experience is limited to 125kHz and 13.56MHZ magnetic
coupling systems at this point.

I personally would love to see an ISO 18000-6 (UHF RFID) implementation
for gnuradio. The biggest challenge is the analog frontend because of
the 80dB difference between Tx and Rx. you will probably need two
antennas, and switch off / attenuate the Rx path while transmitting.

If you have any questions, just ping me.

Cheers!

4

Sitat Harald W. [email protected]:

Sorry for the late reply, but I didn’t have a lot of time for keeping
up
with mailinglists recently (busy with other free hardware RFID work
for
http://openpcd.org).

No problem…

When you talk about RFID, what kind of system are you talking about?

Which frequency? Which protocols? Magnetic coupling, backscatter or
SAW?

I have changed the focus of my pre-project sligthly, so I will not try
to make an RFID receiver this semester, I might try next though.

If I do try this next semester, it will be a RFID receiver of the ISO
14443-2 standard. The aim of the project will simply be to sniff on the
communication between a card an a reader. The reason for chosing ISO
14443-2 is simply that I have a RFID reader available using this
standard…

the 80dB difference between Tx and Rx. you will probably need two
antennas, and switch off / attenuate the Rx path while transmitting.

If you have any questions, just ping me.

Cheers!

============================================================================

We all know Linux is great…it does infinite loops in 5 seconds. –
Linus

–
Erlend Barstad Strand

5

On Tue, Oct 24, 2006 at 09:49:41AM +0200, Erlend Barstad Strand wrote:

I have changed the focus of my pre-project sligthly, so I will not try
to make an RFID receiver this semester, I might try next though.

what a pity.

If I do try this next semester, it will be a RFID receiver of the ISO
14443-2 standard. The aim of the project will simply be to sniff on the
communication between a card an a reader. The reason for chosing ISO
14443-2 is simply that I have a RFID reader available using this
standard…

ISO 14443-2 Type A or B ?

In any case, the problem is the dynamic range. Even with those
magnetically coupled systems, the field emitted by the reader is at
least 60dB stronger than the load modulation (subcarrier) that you get
back from the transponder/card.

This problem is further complicated by the fact that the reader-carrier
and the lower sideband of the transponder-subcarrier are (depending on
bit rate) 400kHz apart in the spectrum

Therefore you definitely need some very steep filter to separate the
modulated subcarrier signal from the

The OpenPCD project has developed a device for this job, which can be
used as a gnuradio frontend: http://www.openpcd.org/rfiddump.0.html

It is basically mixing the signal with a signal from a crystal
oscillator
in order to get the signal down to 10.7MHz where you can use a stock
250kHz bandwidth ceramic filter for 10.7MHz to attenuate the reader
carrier.

This might be a good starting point…

We’re currently working on dedicated (free) hardware for simulating a
14443 (A and B) transponder/smartcard, so we don’t have time to put into
the sniffing project at the moment.