[Discuss-gnuradio] Problem DPSK Mod/ Demod - UHD USRP1 Blocks

[Javier Suarez]

Good morning,

I am working in digital communications specifically with dpsk modulation in gnu radio.
I  made a very simple dpsk modulation and demodulation testing flow graph
.
this is the flow graph that I made for the transmitting part:

https://picasaweb.google.com/101968292957887487468/DQPSKMODULATION#5733510080875799138

And the transmitted spectrum, before the UDH USRP1 sink block  is : 

https://picasaweb.google.com/101968292957887487468/DQPSKMODULATION#5733510073889925042

And for the receiver I did this:

https://picasaweb.google.com/101968292957887487468/DQPSKMODULATION#5733510072472332802

I receive this spectrum after the UHD-USRP1 source block:

https://picasaweb.google.com/101968292957887487468/DQPSKMODULATION#5733510074110374626

I hope to see any spectrum there! Also I hope to see a kind of 
cosine signal in the scope at the final of the flow graph but I see 
nothing!

I dont know what I am doing wrong.  I am transmitting 16
 samples/symbol with a symbol rate of 125 ksymbols/seg which is equal to
 a sample rate  of  2
 Msamples/s at the  TX and RX UHD - USRP block.The center frequency of 
the UHD-USRP1 block was set at 2.4 GHz because the daughter board is a 
RFX 2400. 

Also  when I run this program, I can see in the terminal :

UOUOOUOUOUOUOUOUOUOUOUOUOUOUOUOUOUOUOUOUO

Please, I hope anyone can help me. I have working on this for a long time and I dont know what else to do. Thanks!!