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
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
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? 
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On Oct 28, 2008, at 4:10 PM, George N. 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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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?
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.