125 kbps PHY Rx Sensitivity Not As Low As It Should Be

[GaryS]

Hi - 

In reading through the data sheets for the Nordic chips that support the low-rate (125 kbps) BT 5 PHY, I'm seeing Rx sensitivity numbers around -103 dBm. For the 1 Mbps PHY, it's around -96 dBm. I would expect the Rx sensitivity for 125 kbps to be 12 dB lower than 1 Mbps, i.e., -96 - 12 = -108 dBm. 9 of the 12 dB comes from reducing the bit rate by 8x, the other 3 dB comes from coding gain added to the low rate S=8 PHY. Why are you guys leaving 5 dB on the table? This is a big miss, in my opinion, since 5 dB amounts to almost a 2x range increase outdoors!

Do you have any plans in the future to improve the PHY performance to make up for the 5 dB shortfall?

Thanks,

Gary Sugar

[run_ar]

Hi,

Unfortunately, BTLR125kb does not categorically add 12 dB of sensitivity. For 1 mbit we where already applying some methods to improve the range, so we do not get the theoretically maximum improvement compared to our 1mbit performance. Regardless you can find more details on BTLR here: https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/testing-long-range-coded-phy-with-nordic-solution-it-simply-works-922075585