Advertising not linked state

[m1zol3]

Hello everybody, I am currently experimenting with BLE on the nRF51-Ek. At measurement on the oscilloscope, the BLE protocol shows a behavior that I do not quite understand or i do not know in which documentation i can read up on it. Here is a picture to illustrate my problem. Three flanks are generated in not linked state. (3 times TX an RX, on the picture is dB=-40). Does anybody have an explanation for it or better a link tot he documatation where this is described?

Many thanks

ble.png

[Ulrich Myhre]

Hi

This is quite normal.

Advertising in BLE works like this: For each available channel (default 37, 38 and 39) send an advertisement, then wait for a scan request or connect request to come ~150 us after. If this request arrives, and the peer is in the whitelist (in cases where whitelist is being used) then the advertiser will either: send a scan response and continue to the next channel OR go into a connection with the peer and stop the advertiser.

I would recommend reading an introduction to BLE - or even the spec itself - if you are interested in deciphering more scenarios like this.

[m1zol3]

Thank you.