advertising phy coded s8 long range stops at nearly 20m built

[Bjoern Gutgesell]

Hi there,
I have been testing my ble long range app with coded phy (s8), with extended advertising etc. for a few weeks now. Only adv and scan are used. Works well, only the range is almost the same as it is in the 1M phy.

I don't understand that, so I read about it at SIG.

Now I understand that on channels 37, 38, 39 (data rate is 1M phy, not 1M / 8) a pointer points to the data channel that transmits with s8 (125k)? And channels 37, 38, 39 continue to work with 1M?

Is that correct? Because if channel 37, 38, 39 still works with 1M, where is the benefit? Or did I get it wrong.

On scan_report the ch_index has values ​​between 0 and 35 and an rssi between -40db (very close) and -95db (approx. 20m built).

best regards
Bjoern

[Bjoern Gutgesell]

Hi Torbjorn,

yes there are 2-3 thin walls between the advertiser and the scanner. More walls (or on flat angle a thin wall becomes thick) reduce the range. But I expected that there is a real big difference between 1M and phy coded. So, that there is a difference with coded phy and 1M in built, like there is range one or two rooms more and not only one or two meters.

But your note with wifi is perhaps the solution. Our wifi leaves out the advertiser channels 37,38,39. But we have much traffic and rf-signals in the other channels and the extended advertisements are in the channels between 0 and 36. I will test it in the evening and shut down our wifi.

One additional question: is it possible to place the extended advertisments with channel maks in the channels next to 37, 38, 39 (like 0, 10, 11 and 36).

best regards

Bjoern

[ovrebekk]

Hi Bjoern

Doing a test without WiFi could be interesting. Long range packets are inherently more sensitive to interference, as they take a longer time to transmit over the air, increasing the chance of packet collision with other RF sources in the area.  

Bjoern Gutgesell said:

One additional question: is it possible to place the extended advertisments with channel maks in the channels next to 37, 38, 39 (like 0, 10, 11 and 36).

There is a channel_mask field in the ble_gap_adv_params_t struct, but unfortunately it only allows you to define which primary channels to map out. We don't support mapping out secondary advertising channels. 

Best regards
Torbjørn

[Gary M.]

Hi Torbjørn

Can the sd_ble_opt_set be use to set channel map for secondary advertising channels during extended advertising? Or it only works when in connections?

Best regards

Gary