PHY coded and Coexistence

[damien5606]

Hello,

I'm testing PHY coding (for long range), I'm pretty surprise from what I get when I scan the RSSI of bluetooth channels (with Nordic app).

This is my set up:

M1 is the central, S1 is the peripheral sending 1ko/s. (with uart exemple) I use softdevice 140 V5 alpha.2

M3 is the RSSI scanner connected to "Nordic app RSSI Viewer" Here are the results I get for phy= 1mbps (Short Range) and for phy=125kbps (coded-Long Range):

1. Short Range
2. Long Range

Can you explain me why the long Range mode trash all Bluetooth channels ? this is one link (S1-M1) so my data received is what I expected (1ko/s) but when I use 10 links, the data rate drops dramatically.

Regards,

-Damien

[MartinBL]

Are you using the same connection intervals (CI) in both of those tests? I have done some tests myself and when I use coded phy and 400ms CI the RSSI viewer looks like your top most picture. If I use coded phy and 7.5ms CI it looks more like the image at the bottom. This is probably because the channel selection algorithm is designed to change channel between each connection events. Since you have turned on "Channel Scan Repeat" in the RSSI viewer you will get sort of an average view over the last couple of connection events, which manifests itself as the "ripple" in the RSSI plot.