I tried doubling both, the sample rate to 8MHz and Omega to 4, but still no progress. The setup is simply the 802.15.4 PHY block connected to a USRP source, listening for an over the air transmission. Can you give some insight on how you picked the other MM Clock Recovery params? Is there any other dependence in the PHY block? The papers and guides I looked at explain what the MM params are but don't give much intuition for choosing them.
Additionally, based on posts in this thread: https://lists.gnu.org/archive/html/discuss-gnuradio/2015-07/msg00585.html
I thought it would be better to replace the MM CR block with a polyphase clock sync block, as "M&M block isn't great in fading environments", and I would like to receive possibly weak signals,
Again, works for 4 MHz sample rate and 2 samples per symbol, but not 8 MHz rate and 4 samples per signal. What do you think?