[Discuss-gnuradio] DPSK Demod Problem

[Javier M. Suarez]

Hi List,
I am working with DPSK mod and demod in GNU Radio with a USRP1 RFX2200 and using UHD blocks.
First I did the flow graph without UHD blocks, here it is :

https://picasaweb.google.com/101968292957887487468/UHD_DPSK_COSINE#5751314293318063922

This is the spectrum after the DPSK MOD block:

https://picasaweb.google.com/101968292957887487468/UHD_DPSK_COSINE#5751318283072511474

 I get the output that I expectd at the end, which is the cosine at the right frequency


Now I use the UHD sink and source blocks, this is the flow graph of the TX part:
https://picasaweb.google.com/101968292957887487468/UHD_DPSK_COSINE#5751314290252431730

The spectrum that i am transmitting ( before UHD block):
https://picasaweb.google.com/101968292957887487468/UHD_DPSK_COSINE#5751318282266922114


And this is the flow graph of the RX part:

https://picasaweb.google.com/101968292957887487468/UHD_DPSK_COSINE#5751314292653491874

Spectrum that I am receiving after UHD source block
https://picasaweb.google.com/101968292957887487468/UHD_DPSK_COSINE#5751318283765888786


But at the end I dont get the output that I want. In fact, I 
cant see anything in the final scope  of the schematic, not even noise!

Anyone knows what is happening?

I know that the receiving part is working because I can see some good spectrum at the receiving

I would appreciate any help you can give me. Thanks in advance.