[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Discuss-gnuradio] OFDM implementation

From: Tom Rondeau
Subject: Re: [Discuss-gnuradio] OFDM implementation
Date: Fri, 15 Jun 2007 11:22:30 -0400
User-agent: Thunderbird (Windows/20070326)

Brett Trotter wrote:
Tom Rondeau wrote:
Just the status report from the work done the past couple of weeks on OFDM. With Matt Ettus, Bob McGwier, and Eric Blossom, we successfully transmitted and received OFDM over the air with BPSK, QPSK, and 16QAM. I have merged the code into the trunk so others can use it, though I currently restricted the subcarrier modulations to use only BPSK or QPSK (M-QAM will be coming soon I hope). It's not complete; specificially, it lacks an adaptive equalizer over the entire packet and channel coding. Other features should be coming over time, too.

If you're interested, and for the good of the community, I have posted the presentation I gave last week to the address@hidden Symposium about the implementation details of the system. This includes the block-diagram representations of the flow graphs for the transmitter, receiver, and, most importantly, the synchronizers used in the system. I have made it available in both PPT and PDF format (the PPT opens just fine in the latest version of Open Office for those without MS Office). You can find it under the Presentations link on the front page of Trac (Johnathan, Eric, if you have a better place to put this kind of information, let me know; this seemed like a good place to start).

I seem to be having trouble- I've tried the usual suspects for arguments but

address@hidden ofdm]# ./benchmark_ofdm_tx.py -f 13M -s 300 -i 200 -M 1
Traceback (most recent call last):
  File "./benchmark_ofdm_tx.py", line 217, in ?
  File "./benchmark_ofdm_tx.py", line 190, in main
    fg = usrp_graph(options)
  File "./benchmark_ofdm_tx.py", line 56, in __init__
    self.txpath = transmit_path(self, options)
"/root/gnuradio-normal/gnuradio-examples/python/ofdm/transmit_path.py", line
44, in __init__
    self.ofdm_tx = \
  File "/usr/local/lib/python2.4/site-packages/gnuradio/blksimpl/ofdm.py",
line 88, in __init__
    self._pkt_input = gr.ofdm_bpsk_mapper(msgq_limit,
options.occupied_tones, options.fft_length)
line 7060, in ofdm_bpsk_mapper
    return _gnuradio_swig_py_general.ofdm_bpsk_mapper(*args)
TypeError: ofdm_bpsk_mapper expected 5 arguments, got 3

What options does it really need?

even if i go nuts and specify nearly everything with defaults
./benchmark_ofdm_tx.py -f 13M -s 300 -i 200 -M 1 --tx-amplitude=12000 -m
bpsk --fft-length=512 --occupied-tones=200 --cp-length=128

I still get the same 'got 3'

What'd I miss?

It's a SWIG problem. You'll probably need to clean out your gnuradio-core/src/lib/swig directory (make distclean inside it works and prevents you from having to build the whole thing again).

We switched the interface by handling the insertion of known symbols in another block, so we went from 5 inputs to 3. Try again after cleaning up the SWIG files and reinstalling.


reply via email to

[Prev in Thread] Current Thread [Next in Thread]