Unreliable Ranging Behavior and Inconsistent Frequency on NORAB126 (NCS v2.9.0)

[Luis Santos]

Hello,

I'm working with Distance Measurement (nrf_dm) using the NORAB126 module on nRF Connect SDK v2.9.0 and nRF Connect SDK v3.0.1.

I'm facing an issue where, occasionally and randomly, the devices stop performing ranging between them. Once this happens, the only way to resume distance measurements is by restarting one or both devices. I've tried adjusting the following configuration parameters, but the problem persists:

• CONFIG_DM_INITIATOR_DELAY_US

• CONFIG_DM_MIN_TIME_BETWEEN_TIMESLOTS_US

• CONFIG_DM_TIMESLOT_QUEUE_LENGTH

• CONFIG_DM_TIMESLOT_QUEUE_COUNT_SAME_PEER

• CONFIG_DM_RANGING_OFFSET_US

Despite these changes, the behavior remains the same — ranging between peers stops unexpectedly and only resumes after a reset.

Additionally, I noticed that the distance measurements occur at around 4 times per second when the devices are close. However, the measurement frequency appears to vary randomly.

My questions are:

1. Is there a known issue that could explain why ranging suddenly stops and only recovers after restarting the device(s)?

2. Is there a way to set or control the number of distance measurements per second (i.e., define a fixed ranging frequency)?

Any insights or recommendations would be greatly appreciated.

[Elfving]

Hi Luis,

Is there a known issue that could explain why ranging suddenly stops and only recovers after restarting the device(s)?

Are you seeing this with the default samples for this as well? 

Are you seeing any info on logs as to why this is happing? If not, could you try increasing the logging level?

Is there a way to set or control the number of distance measurements per second (i.e., define a fixed ranging frequency)?

I do not think there is any easy way to change the frequency, unless you make that yourself. Though you can eg. use dm_request_add() at a certain frequency, and control the schedualing with the configurations you mentioned. I might be missing something here, though let us start with the first problem.

To increase the amount of samples you can queue more. 

Regards,

Elfving

[Luis Santos]

Any update?