Robert McGwier wrote:
Like all things in branches, until they are not in branches, this is
absolutely development code and here is no guarantee of completeness
or even correctness. It is the reason for doing this kind of work in
branches rather than imposing it on everyone in the trunk.
In the gnuradio-examples/python/ofdm directory, the only functional
up-to-date file as of this moment is ofdm_benchmark.py. It does a
loopback through noise test.
ofdm_benchmark_tx.py calls upon a tx_pick_bitrate which is missing
from the single computer where Tom, Matt, and I did the work. I will
make sure that this is not an accidental omission that was actually on
Tom's laptop when he arrives tomorrow.
We are attempting a very difficult thing which requires some delicacy
and art. We want to be able to come up with a compact description of
any kind of constellation, cyclic prefix size, or complete absence of
cyclic prefix and then have support for the requirement for sync
channels of several types. At the same time, we have the design goal
for this to be reasonably efficient and even dynamic. We have chosen
not to take the fast road to a single exemplar but to abstract as much
of this as possible believing this will aid experimentation and serve
the greatest possible good.
I have been so busy for the last few weeks that all of this slipped
out of the sieve that is left of my mind ;-).
When Tom and I can get some work done tomorrow, one of the things we
will be planning is the next big steps in the ofdm tree. You may
expect nothing to work until we say it does work.
Bob
A quick look showed that pick_bitrate.py was not checked into the
repository, this has been corrected. However, I don't think we've ever
tested running the OFDM modulator with the USRP yet, as the
benchmark_ofdm_tx.py is meant to do.
The pick_bitrate.py file was copied over the digital examples; it will
probably be modified in the future for OFDM-specific operation.
To test the OFDM system, we were using a loopback mode using
benchmark_ofdm.py, which calls upon receive_path_simple and
transmit_path_simple, which bypass the calls to the USRP and connect
directly to each other. A checkout and install had this working with no
issues. You should just be able to run:
./benchmark_ofdm.py
With no argument and you'll see a stream of packet info being spit out.
You can change a lot of the parameters now, including the SNR.
As Bob said, this is development code. We have no synchronization in the
receiver yet, so this will definitely not work over the air yet.
Tom
_______________________________________________
Discuss-gnuradio mailing list
Discuss-gnuradio@gnu.org
http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
