Forum: GNU Radio RFID data packet

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Ffba6254119073ff7c78bbd73d2f9f1d?d=identicon&s=25 Andrea Farulli (Guest)
on 2008-10-24 12:16
(Received via mailing list)
I have to develop a system for RFID operating in the 433 MHz frequency
band (ISO 18000-7) transmission with the GNU radio python framework.
I succeded transmitting a simple message with bfsk modulation using the
gr.cpfsk_bc block with the proper parameter (carrier frequency,
frequency deviation, bitrate).
I'm trying now to implement the data link layer according to which data
is sent in packet format, a packet is comprised of a preamble, data
bytes and a final logic low period. Data bytes are sent in Manchester
code format.
The problem is: the length of the preamble pulses and the lenght of the
data bit period are different, but I can only specify one bitrate in the
gr.cpfsk_bc block (well not exactly the bitrate, the modulation index
and the number of output samples per input bit, which depend on the
bitrate).
Have I to vary the bitrate according to which part of the packet I am
transmitting? Or have I to choose one bitrate and to vary the sequence
of symbol to reproduce the proper period length?
Are there any helper function int the framework to do the job? What the
simple_framer block exactly does, are there other blocks dealing with
framing.

Andrea
787e7c36ae21bdf3707062b0d857ab51?d=identicon&s=25 C.cc Jay (cjay)
on 2008-10-28 12:18
Dear andrea

I want to develop ISO 14443-A,
Can you tell me, how to find ASK100% python module. Or I must rewrite
this part of the code.


Andrea Farulli wrote:
> I have to develop a system for RFID operating in the 433 MHz frequency
> band (ISO 18000-7) transmission with the GNU radio python framework.
> Andrea
Ac73d95c8ccddff9ecae369bcb80a923?d=identicon&s=25 George Nychis (Guest)
on 2008-10-29 00:12
(Received via mailing list)
C.cc Jay wrote:
> Dear andrea
>
> I want to develop ISO 14443-A,
> Can you tell me, how to find ASK100% python module. Or I must rewrite
> this part of the code.
>

Dan,

Do you know if any of the RFID code done at UDub/Intel is going to be
published soon? :)

- George
3dfb724cefc1eddbade1e8bd1ee6131f?d=identicon&s=25 Dan Halperin (Guest)
on 2008-10-29 01:57
(Received via mailing list)
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On Oct 28, 2008, at 4:10 PM, George Nychis wrote:

> C.cc Jay wrote:
>> Dear andrea
>> I want to develop ISO 14443-A,
>> Can you tell me, how to find ASK100% python module. Or I must
>> rewrite this part of the code.
>
> Do you know if any of the RFID code done at UDub/Intel is going to
> be published soon? :)

I hope so! I know it's in the roadmap. The author (not me ;) is on
post-NSDI vacation right now.

Note his code is for the EPC Gen 2 915 MHz standard. I suspect it may
be different than the above mentioned standard (433 MHz) but I know
basically nothing about RFID.

- -Dan
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Ffba6254119073ff7c78bbd73d2f9f1d?d=identicon&s=25 Andrea Farulli (Guest)
on 2008-10-30 04:08
(Received via mailing list)
C.cc Jay wrote:
> I want to develop ISO 14443-A,
> Can you tell me, how to find ASK100% python module. Or I must rewrite
> this part of the code.
>

Sorry, I don't know the python module you are talking about.
My question to the gnuradio mailing list was essentially the same of
yours. To deal with packets I found only the simple_framer and
simple_correlator blocks in gnuradio python framework. Am I wrong?
787e7c36ae21bdf3707062b0d857ab51?d=identicon&s=25 C.cc Jay (cjay)
on 2008-10-31 09:10
Andrea Farulli wrote:
> Sorry, I don't know the python module you are talking about.
> My question to the gnuradio mailing list was essentially the same of
> yours. To deal with packets I found only the simple_framer and
> simple_correlator blocks in gnuradio python framework. Am I wrong?

Yes, I find same file simple_framer.h and simple_framer.cc in
/gnuradio-core/src/lib/general

Another module, packet_sink(), I still trying.
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