Hi thank you for your comment.<br><br>What do you think about the following thought:<br><br>I take two old radioscanners each  has 12.5 kHz channel pattern (&quot;Kanalraster&quot;) , Tetra uses 25 kHz.<br>Then
 I make for each scanner a FM modulation in Software or on FPGA and 
after a signal addition. Now i should have the modulated Pi/4-DQPSK 
signal back. Or haven’t I?<br><br><br>