[Discuss-gnuradio] DQPSK Transmitter and Receiver

[devin kelly]

Hello Everyone,

I've made a basic DBPSK transmitter and receiver.  I can receive ASCII strings fine and the spectrum looks exactly as it should.

However, if I swap the DBPSK modulator/demodulator for the DQPSK modulator/demodulator, my system breaks.   I can no longer receive the same strings and the spectrum looks very strange.  It's much wider and triangular shaped.  

Same goes for the D8PSK system and the D16PSK system I recently was asking about.  

I believe marcin_w asked a similar question a few days ago and I haven't seen a reply yet (am I wrong?)  My question is, should I be doing something different?  Do I need to add in some extra block when I switch from DBPSK to DQPSK?  While searching old posts, I found some people talking about DQPSK not working correctly, but that was about a year ago.

Any help would be greatly appreciated.

Devin