Re: [Discuss-gnuradio] tunnel.py distance problem

[Eric Blossom]

On Wed, Nov 07, 2007 at 08:38:51AM -0800, Marko Simunac wrote:

> Hi,

> I am using tunnel.py to transfer text files between two USRPs. It
> only works when the two USRPs are almost right next to each other,
> max distance is 5 inches, after that the ping fails and tunnel stops
> working. I am using the Flex 400 daughterboards and am assigning a
> carrier treshold of 90(-c 90) to get rid the BBBBBBs. Can someone
> help me to increase the distance between the two USRPs, and
> theoretically what is the max distance between the two USRPs that
> tunnel can work?

Not sure about the theoretical maximum, but as described in the
README, I usually have them about 3 meters apart.  What kind of
antennas are you using?  What data rate are you using?  what
modulation are you using?

Try this:
 
  * start benchmark_tx.py on one machine
  * run usrp_fft.py on the other machine

and confirm the the received spectrum looks reasonable.  
You'll want to experiment with the received gain setting.

Eric