Channel Sounding – Ranging Data Overwritten and No Distance Update

[witc]

Hello,

I managed to run the examples for nrf54l15 channel_sounding_ras_initiator.c and reflector on my custom hardware boards. I changed the overlay files to use my own LED and UART for logging. I have only one RF antenna. I also do not have an external LF 32khz crystal, so I added these lines to my prj.conf:

CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y
CONFIG_CLOCK_CONTROL_NRF_K32SRC_XTAL=n
CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC_CALIBRATION=y

After starting, I get some results from the initiator, but it does not work 100 percent as I expect.

At the beginning, I get this log:

D: On-demand Ranging Data notification received
D: On-demand Ranging Data notification received
D: On-demand Ranging Data notification received
D: Ack Ranging data for counter 2
I: Distance estimates on antenna path 0: ifft: 0.785345, phase_slope: 0.720688, rtt: 8.246675
I: Sleeping for a few seconds...
I: Distance estimates on antenna path 0: ifft: 0.785345, phase_slope: 0.720688, rtt: 8.246675
I: Sleeping for a few seconds...
I: Ranging data overwritten 3
D: Get Ranging Data Success
...
I: Distance estimates on antenna path 0: ifft: 0.785345, phase_slope: 0.720688, rtt: 8.246675
I: Sleeping for
D: On-demand Ranging Data notification received
D: Ack Ranging data for counter 4

But when I move the reflector farther away, it starts printing this, and the measured distance does not change anymore, even if I move the reflector:

I: Sleeping for a few seconds...
I: Ranging data overwritten 211
I: Distance estimates on antenna path 0: ifft: 0.320133, phase_slope: 1.553719, rtt: 7.424473
I: Sleeping for a few seconds...
I: Ranging data overwritten 212
I: Distance estimates on antenna path 0: ifft: 0.320133, phase_slope: 1.553719, rtt: 7.424473
I: Sleeping for a few seconds...
I: Ranging data overwritten 213

• What does "Ranging data overwritten" mean here?

• If I change the main loop delay from the original 5 seconds to for example 200 ms, I never get any measured distance in the log anymore. Why should changing the sleep time matter if the code just checks if (buffer_num_valid != 0)?

It is also strange why there is such a big difference between the results of different methods (rtt, phase, slope, etc.). Could this be caused by unsuitable hardware - for example the antenna?
My HW board:
 

Thank you for any help.

Jan.

[tesc]

Hi,

The board might give some issues, yes. Please create a private ticket with schematics and gerber files, for our review.

Have you tried with the custom board only, or do you see similar issues with an nRF54L15 DK?

What does "Ranging data overwritten" mean here?

Basically that you have gotten a new set of ranging data.

If I change the main loop delay from the original 5 seconds to for example 200 ms, I never get any measured distance in the log anymore. Why should changing the sleep time matter if the code just checks if (buffer_num_valid != 0)?

Ranging might take some time. If you decrease the timeout, you risk timing out before you get the result. In the case of timeout you will not get a result.

Regards,
Terje