Modulation Schemes

Hello all, I’m new to GNU Radio and was wondering what kind of
modulation
schemes were available. I know that GMSK is the default scheme for the
“…digital/benchmark_tx.py” file. I saw that the schemes are derived
from
the “modulation_utils” file. I’m not sure the available options though.

Also, when the benchmark_tx.py script transmits from a file, how does
the
data in the file get transmitted. For example if file.dat is
transmitted
with contents “5123645AY…”, are these converted to binary 1’s and 0’s
using ASCII or Hex conversion and then modulated and transmitted?

Any help will be greatly appreciated. Thanks all.

Dumezie

Look into the directory
/usr/local/lib/python2.x/site-packages/gnuradio/blks2impl/ . It has many
modulation schemes already implemented in Gnuradio. GMSK is infact the
default scheme but one can choose various other provided in this
directory.

Bye
Ali

Regarding your other question I think the following line in GMSK.py does
the
work.

Turn it into NRZ data.

self.nrz = gr.bytes_to_syms()

Each byte is converted to a symbol of -1 or +1. I do not know any more
detail. Correct me if I am wrong.

Thanks
Ali

If it’s done using -1 and +1, how are the numbers in the files converted
to
1’s and 0’s. NRZ encoding converts binary 1’s to a + voltage and 0’s to
a -
voltage. For example, how would a “5” or even a “Z” in the .dat file be
converted to binary 1’s and 0’s.

Thanks all

Dumezie

From: Murtuza [mailto:[email protected]]
Sent: Tuesday, September 09, 2008 4:13 AM
To: Dumezie M.
Cc: [email protected]
Subject: Re: [Discuss-gnuradio] Modulation Schemes

Regarding your other question I think the following line in GMSK.py does
the
work.

Turn it into NRZ data.

self.nrz = gr.bytes_to_syms()

Each byte is converted to a symbol of -1 or +1. I do not know any more
detail. Correct me if I am wrong.

Thanks
Ali

On Tue, Sep 9, 2008 at 3:56 AM, Murtuza [email protected] wrote:

Look into the directory
/usr/local/lib/python2.x/site-packages/gnuradio/blks2impl/ . It has many
modulation schemes already implemented in Gnuradio. GMSK is infact the
default scheme but one can choose various other provided in this
directory.

Bye
Ali

On Mon, Sep 8, 2008 at 11:34 PM, Dumezie M. [email protected]
wrote:

Hello all, I’m new to GNU Radio and was wondering what kind of
modulation
schemes were available. I know that GMSK is the default scheme for the
“…digital/benchmark_tx.py” file. I saw that the schemes are derived
from
the “modulation_utils” file. I’m not sure the available options though.

Also, when the benchmark_tx.py script transmits from a file, how does
the
data in the file get transmitted. For example if file.dat is
transmitted
with contents “5123645AY…”, are these converted to binary 1’s and 0’s
using ASCII or Hex conversion and then modulated and transmitted?

Any help will be greatly appreciated. Thanks all.

Dumezietho


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Mir Murtuza Ali
Graduate Student
Center for Wireless Communications
University of Mississippi
University, MS 38677
Ph : (M) 662-202-5472 , ® 662-513-9903