[Discuss-gnuradio] about bluetooth

[Thom L]

Hi,

I try to understand how exactly bluetooth works using a phone and usrp b200.

When I send data (audio) from the phone to the computer with bluetooth on I see quite easily the 'frequencies hopping' in waterfall.

When I choose an 'active' channel the output of Quadrature Demod bloc show something which could be data ( CH2 - green - see attached):

https://drive.google.com/open?id=0B-yiBccj_WYCX1V4MHMyWnd1RlU

What I do not understand is that the signal changes alternately between the two figures which seem to be two different types of modulations to send the data (the first part of the green signal CH2 is always the same).
From all my readings on the subject the modulation used for bluetooth from version 1 to 4.1 would be the GFSK (in my opinion the first figure).
My phone is a samsung of 2013 (galaxy note 3), I do not think it is compatible bluetooth 5?
Has anyone ever worked on the subject and would have an idea to help me?

here my flowgraph:
https://drive.google.com/open?id=0B-yiBccj_WYCUDZYSVdRcWlESkE

Thanks

Best regards,

Thomas