DPSK mod/demod in 3-node relay with USRP2 not working

GNU Radio
1

Hi,

I have been trying to implement a relay system using DPSK modulation
scheme. I’m basically trying to replicate the decode and forward method
using three usrp2 nodes. I generate a .dat file DPSK modulation of a
random
source initially. The graph goes like this:

First time slot:
file sink --> Tx of node 1 --> Rx of node 2 && Rx of node 3

Second time slot:
Rx of node2 remodulate and store in file sink

Third time slot:
file sink --> Tx of node 2 --> Rx of node 3

Simultaneously in the third time slot, node 1 transmission acts as
interference.

Now, the issue here is that, during the second time slot, the file sink
remains blank even after demodulating and remodulating the received
file.
It does not store anything. Am i doing a mistake somewhere ? I have
attached a screenshot of my flowgraphs here.

Please help me out in solving this.

2

On Wed, Apr 3, 2013 at 6:08 PM, Vinodhini Ravikumar
[email protected] wrote:

Second time slot:
does not store anything. Am i doing a mistake somewhere ? I have attached
a screenshot of my flowgraphs here.

Please help me out in solving this.

Thanks,
Vinny

Vinny,

One thing that I recommend to people is to use your debug tools! You
can put in other GUI’s and file sinks along the path of your flowgraph
to make sure that the signal is as you would expect throughout. That
will help pinpoint where things are going wrong.

Tom