upconverting and downconverting qpsk modulated signal?

[nauman2558]

i am trying to implement upconversion and downconversion of qpsk modulated signal. i am not getting the constellation diagrame at receiver, exactly same as at transmitter side. i want to have exactly same constellation diagrame on both sides(Tx and rx). I also have to get my BER to zero or minimum which is possilble. i am not sure about the filter parameters which i have to give for upconversion and down conversion. plz have a look at my vi and guide me through this.

[snowpunter]

Try posting this in this forum, you'll probably get a much better response. I'd try and answer it but I don't have the digital option installed.

http://forums.ni.com/t5/RF-Measurement-Devices/bd-p/290