# RFID at 2.4GHz simulation-Encoding, Modulation techniques (grc implementation)

Hi everyone,
i’m an undergraduate student of ee and currently i’m working on my
thesis
which is related to an RFID standard simulation in GNURadio.

I don’t have a USRP device yet, so i’m just working on the grc tool with
default signal sources.

As i figured out, there are already some pre-installed blocks for bpsk
or
gmsk simulation methods that i need in my thesis.
Although, i also need ASK simulation.
I implemented it with a square and cosine source multiplication and i
think
it works properly. What should i take care of?

Also, i have to implement manchester and fm0 encoding. I started the
implementation by creating an edge detecting circuit. Before carrying
on,
i’d like to ask you if i’m on the right path (i mean creating boolean,
mathematical functions between sources and constant numbers) or i have
to
change the way of thinking.
Finally, is it necessary to use code for any of this techniques i
mentioned
above, or it is possible to manage it just with grc blocks?

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On Sat, Apr 27, 2013 at 4:31 AM, stefosee [email protected] wrote:

I implemented it with a square and cosine source multiplication and i think
Those are all very vague questions. I think you’re going to have to
get a good start on things yourself, first, then come back with any
specific questions you have.

Tom

Hello again,
I’ve already implemented the modulation schemes i’m writing above, plus
the
manchester encoder.
No i’m trying to design the biphase space (fm0) encoder.
For the manchester i used 2 square sources, one for the data and another
one
for the clock with the double frequency and i use an XOR between them.

So, for a clock:
10 10 10 10 10 10 and data 101110:
11 00 11 11 11 00 i have an output like that:
01 10 01 01 01 10 which is the expected one.

Assuming that it works right, now, i’m trying to design the fm0.
I know its harder because each output is related to the previous one.
Is there any fm0 already implemented? Or is there any link to help me do
it?

TIA

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Sent from the GnuRadio mailing list archive at Nabble.com.

stefosee wrote

Assuming that it works right, now, i’m trying to design the fm0 encoder.
I know its harder because each output is related to the previous one.
Is there any fm0 already implemented? Or is there any link to help me do
it?
TIA

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Could anyone help me with the building of the biphase space encoder