NRF54l15 best accuracy possible

[Triscuit]

Hi,

I found that the NRF 54l15 can only estimate distance based on channel sounding and RSSI. On the bluetooth website it mentioned channel sounding accuracy being around 20cm. But when I test it myself it is up to 50cm and then sometimes 1m off. Since 54l15 only has channel sounding and RSSI to get distance, is combining the two of them to achieve 2cm accuracy possible? Is there any way to make the NRF 54l15 achieve 2cm accuracy? Thank you so much in advance.

[Simonr]

Hi

I don't know if I can do the "expert" tag justice, but I'll try to help to the best of my abilities.

Phase based ranging with one antenna, will per specification not be more accurate that 50cm. We are constantly working on improving our ranging algorithm and are looking into using multi-antenna solution that will likely improve accuracy, but down to 2cm accuracy will not be feasible with channel sounding I'm afraid. That exactly is the use case you're looking at here, and what range and environment will the device be operating in and requiring 2cm accuracy at?

Best regards,

Simon

[Triscuit]

I am trying to create a trilateration system and it will be outdoors, I am not too sure what range. I already kind of knew it would not be possible, I just wanted some confirmation. Thank you so much for the reply.

[ignatious-p]

Hi Simon, 

Simonr said:

Phase based ranging with one antenna, will per specification not be more accurate that 50cm.

Could you kindly point me towards the resources where I could find more on the theoretical limitations of BLE Channel Sounding? I am currently referring to the Bluetooth Core Specification v6.0 and also the Ranging Service and Ranging Profile documents.

Simonr said:

We are constantly working on improving our ranging algorithm and are looking into using multi-antenna solution that will likely improve accuracy

Will it be as accurate indoors as it is outdoors?

[Simonr]

Hi

Sorry, that number is not from the specification, but rather from Bluetooth's own marketing documents: https://www.bluetooth.com/blog/bluetooth-channel-sounding-how-it-works/ 

It will not be as accurate in a noisy indoor environment with lots of line of sight obstructions as it will be outdoors in a line of sight and interference-free environment. We still have not conducted thorough testing to provide any numbers on what the expected range/accuracy exactly will be for different environments I'm afraid.

Best regards,

Simon

[ignatious-p]

Hi Simon,

Simonr said:

Sorry, that number is not from the specification, but rather from Bluetooth's own marketing documents: https://www.bluetooth.com/blog/bluetooth-channel-sounding-how-it-works/ 

I see, that must've slipped past literature review on my end. Thanks for sharing! It seems that there is no information on the theoretical maximum resolution available, but it should be something that can be calculated. Let me look into it.

Simonr said:

It will not be as accurate in a noisy indoor environment with lots of line of sight obstructions as it will be outdoors in a line of sight and interference-free environment. We still have not conducted thorough testing to provide any numbers on what the expected range/accuracy exactly will be for different environments I'm afraid.

This is expected and that's what I am studying for my masters. Indoor environments including hospitals, warehouses and perhaps even underground environment. Is there any chance I could get in contact with someone from your end to work more closely on this? 

[Simonr]

Hi Ignatious

If you have specific questions, please open a separate DevZone ticket on that with questions you'd like answered by experts, and we can forward those to the people working closest on it. 

Best regards,

Simon