[Discuss-gnuradio] Using a MPSK Demodulator or 4QAM for oQPSK

[Marius]

Hi!

I found a comment in the source code of the MPSK block, that it could
be used for oQPSK demodulation. I think this block is very interesting
implementation, however I'm not sure which parameters I should use for
oQPSK. In the gr-ieee802_15_4 implementation from Thomas Schmid he
uses a Quadrature Demod with an MM Clock Recovery where the parameters
are:

omega = self.sps
gain_mu=0.03
mu=0.5
omega_relative_limit=0.0002
gain_omega = .25*gain_mu*gain_mu        # critically damped

This works just fine - with a Quadrature Demodulator.

Can somebody suggest parameters for the MPSK Block, or give me some
hints how I can calculate/test them at least? The MPSK block uses a
Costas Loop for Demodulation, so the approach is quite different here.
Also I wonder whether it's possible to use a 4QAM Demod, because
practically a 4QAM mod produces the same wave-form like a QPSK.
Practically at least ,)

Best,
Marius