[Discuss-gnuradio] O-QPSK demodulation

[Anh Duc Nguyen]

Dear all,

I am struggling with O-QPSK receiver that I hope I can utilize GnuRadio radio for it. However, after doing quite a lot of search, I am still stuck, making no headway. Some results I could find are:

1. The mpsk_receiver states he can do OQPSK demodulation (based on the comments in the source code and in some documents e.g., Simple GNU Radio User manual); however, I can not figure it out how he could do it

2. The second approach used in UCLA Zigbee (https://www.cgran.org/wiki/UCLAZigBee) with the links among O-QPSK <-> MSK <->FSK then FSK Demod is used to accomplish O-QPSK demodulation. The problem here is with this direction, we can only handle the case O-QPSK with half-sine pulse shaping - then OQPSK becomes MSK, a special case while I wish could do general OQPSK. One question also strikes my mind is with this approach, where is the parameters for the root raised cosine (rrc) filter?

Can anyone kindly show me the way to solve my problem: OQPSK demodulation using GnuRadio, or just tell me if I missed or misunderstood something?

I would like to thank you very much in advance,

Nguyen Anh Duc