Hi all,

I've demodulated an advertisement frame from a DA14580 device using the rohde and schwarz CBT BLE tester. However, I'm having trouble understanding the frame structure. I've attached a picture (in pdf) showing part of the demodulated frame.

Why are there extra bits before the 1 byte preamble?
Is a carrier tone (indicated by arrow) absolutely necessary before the actual frame?

P.S. I was able to detect the DA14580 device just fine on a BLE sniffer. So, it's working fine.

Thank you all,
Ray