Problem with Packet Decoder and DPSK

Hello,

I am a relative beginner with gnuradio and am currently trying to set up
a DQPSK system using a USRP2 and a USRP N210 , both with uhd and WBX
Daughterboards and on Ubuntu 10.04. We made a simulated version which
worked perfectly, packet encoder/decoder and everything. The
constellation and waveforms appear as they should.

However, when I implement the actual system on the USRP’s (shown in
figures 1 and 2), the packet decoder refuses any output, despite the
input looking very correct from the DQPSK Demodulator.

Any help would be appreciated, thank you.

-Scopat J.