USRP as relay


I have been trying to make the USRP work as a relay for quite some time
and not been able to do so. I want to transmit whatever data the USRP
has received.

I have been working on for reception of my audio files.The
flow graph is connected like :

self.u = usrp.source_c(0,decim);
fg.connect(self.u, self.chan_filt, self.packet_receiver)

The reception of packets is perfectly fine in this case. Now, the
curious thing which is happening is that when i also make the usrp as
the sink and connect the flow graph as

self.dst = usrp.sink_c(0,interp);
fg.connect(self.u, self.chan_filt, self.packet_receiver)
fg.connect(self.u, self.dst);

then i also stop receiving any packets. I am not able to understand why
is this happening. At least the reception of the packets should not have
changed, leave aside the retransmission part. I am using a single Flex
900 board so i dont think that might be causing the problem.I dont think
that making the connection as

Data from usrp ----> Data to usrp

is wrong. If its so,then let me know and is it necessary to put some
kind of filter between the 2 to make it working. Also, i dont think that
making the flow graph as

Data from usrp----> data demod -----> data remod ------> Data to usrp

would make any difference. I also want to retransmit at a different
frequency. So, is it necessary to demod and remod or whether just
setting the usrp at that retransmission frequency would solve my

Reading from the previous archives i have found that it should not be
much of a problem in making such a thing work but somehow its not
working in my case.

I would be very grateful if somebody could help as its been quite long
since i am stuck onto this problem.

Pratik Hetamsaria