Re: [Discuss-gnuradio] About the RFX 2400 daughterboard

[Eric Blossom]

On Tue, Jun 02, 2009 at 09:10:07PM +0200, Ankit Saf wrote:
> So I had a few questions about the RFX 2400 daughterboard, and this what
> Matt Ettus had to say in his email...
> 
> >
> > 1.What is the maximum distance I can place two USRPs with the RFX 2400 
> > daughterboards, both communicating with an antenna, to ensure proper 
> > transmission, provided they have some line of sight available?
> 
> That depends on many many factors, including modulation, antennas, data
> rate, environment, other interferers, how well you've written your code,
> etc.  It is impossible to give a proper answer to your question, but I
> can tell you that a few feet sounds like you are doing something worng.
> 
> > 2. I've tried adjusting the gain in the receiver (the maximum gain I could 
> > use at the receiver for this was 89) and the amplitude in the transmitter 
> > (while using the benchmark_tx.py and benchmark_rx.py programs) to maximize 
> > this distance, but I can only go as far as a few feet apart. Is there any 
> > other way to adjust the gain? Also, the CRC32 was false for all packets 
> > received. Is there a way to fix that, or should that not be an issue?
> 
> There is a lot of work involved in creating a proper AGC system for your
> individual application and system.  More gain is not always better.
> 
> > Finally, I am trying to implement a simple direction finding algorithm 
> > using two antennas as receivers in one USRP. Are you aware of any other 
> > similar work that has already been done in the field?
> 
> Yes, quite a bit of work has been done on this, and I believe at least
> one paper was published.
> 
> 
> To update on the first question...I was using the benchmark_tx.py to
> transmit and benchmark_rx.py on another USRP to receive, with pretty
> much default settings and carrier frequency of 2.45GHz.
> Any comments on that?

What kind of antennas are you using?

Eric