**.matteo wrote on Jun 22**^{nd}, 2009, 9:32am:I attached you my simple model that has just I. Just to make sure I understood correctly, are you saying that I should design a replica of my I to create a model of Q, sum them together such that I transmit I+j*Q so I get a complex number on the channel?

No.

You don't seem to understand concept of equivalent lowpass model for RF bandpass system.You have to understand this concept correctly if you use system simulator such as Agilent Ptolemy and Mathworks Simulink.

**.matteo wrote on Jun 22**^{nd}, 2009, 9:42am:Yes, you re right, I am studying it right now by myself.

I come from the math world and I need to simulate a communication system.

BPSK has always Q=0 so if I want to create a complex signal I should switch to QPSK, right?

No.

Use "Communications Blockset>Modulation>Digital Baseband Modulation>PM>BPSK Modulator Baseband".

Any modulation can be expressed as "QAM" not "QPSK".

However you don't have to use "QAM".