Default coded PHY (S=2 vs S=8) on nRF52833 for advertising and connections under ncs 3.1.0

RE: Default coded PHY (S=2 vs S=8) on nRF52833 for advertising and connections under ncs 3.1.0

Einar Thorsrud — Mon, 08 Sep 2025 14:00:26 GMT

Hi,

You are correct. I was not clear, but what I wanted to say was that you gain very little range using S=2 compared to using the normal 1 Mbps PHY. You get the downside of reduced bitrate and increased power consupmtion per transfered unit of information, but not a significant gain in range. So in practice, the choise whoudl be between 1 (or 2) Mbps PHY and S=8 Coded PHY.

RE: Default coded PHY (S=2 vs S=8) on nRF52833 for advertising and connections under ncs 3.1.0

longo92 — Mon, 08 Sep 2025 13:45:14 GMT

Thank you for the detailed answer.

I have one point I’d like to clarify: you mentioned “however, you gain very little range using S=2, so this has little practical use.”
From my understanding, when using S=2 there is a gain in bitrate but a reduction in maximum distance compared to S=8. Moreover, from a power consumption perspective, S=2 should consume less since the transmission time is shorter. Am I correct?

RE: Default coded PHY (S=2 vs S=8) on nRF52833 for advertising and connections under ncs 3.1.0

Einar Thorsrud — Mon, 08 Sep 2025 13:34:09 GMT

Hi,

[quote user=""]1. When I enable coded PHY advertising on the nRF52833, which coding (S=2 or S=8) is used by default?[/quote]

Using coded PHY, S=8 is the defaut.

[quote user=""]

2. When establishing a connection on coded PHY, which coding is negotiated by default?

[/quote]

There is no negotiation on this part. All devices supporting coded phy need to suppor both, and the header is always transmited as S=8, and this tells if the rest of the packet is S=8 or S=2 encoded.

[quote user=""]3. Is it possible to explicitly request S=2 on the nRF52833, or is only S=8 supported?[/quote]

for recent nRF Connect SDK versions, both S=8 and S=2 are supported. You can specify S=2 using the BT_CONN_LE_PHY_OPT_CODED_S2 option. For a sample, please take a look at this post. However, you gain very little range using S=2, so this has little practical use.