Re: [Discuss-gnuradio] Considering OFDM implementation on GNU Radio

[Eric Blossom]

On Mon, Jun 07, 2004 at 01:41:01PM -0400, David Beberman wrote:
> 
> 
> I've been interested in the GNU Software Radio project for a couple
> months or so.
> 
> I've just downloaded and gone through some of the current
> source code.  The examples are fairly straight forward.  From those
> and using them as a guide to explore some of the classes, I think
> I have a good handle on how the system works.
> 
> (Did I miss some notes on system overview on the project website
> or in the doc directory?  If not, and I manage to write something that
> works, I might take a crack at writing a short intro.)

We need a good intro... 

I'll be releasing a version of GNU Radio 2.x for alpha testing soon.
The details are different, but the same basic data flow idea holds it
all together.

> I'm going to attempt to put together a rudimentary OFDM radio capable
> of transmitting and receiving OFDM bursts.  Unfortunately, I am not a DSP
> expert with experience in OFDM.  I am familiar with the concepts involved
> and have done some simulation code before.  I'm going to try to do
> simple QAM modulation on the carriers.
> 
> I haven't started to look at the drivers for ADC/DAC and radio board
> support yet, but I expect I'll be writing my own drivers for
> whatever boards I can lay my hands on anyways.

Interfacing to new hardware shouldn't be a problem as long as the
hardware can continuously stream data.  The GNU Radio glue code will
be on the order of a couple of pages.

> Please let me know if anybody has done anything like this before.
> In particular, I could use help with frequency offset error
> estimation and correction, time synchronization, and bit slicing the
> QAM signals efficiently.

This would be a great project.  I know others have looked at it, but
as far as I know nobody's actively working on it.

> David Beberman

Eric