Nordic Distance Measurements

RE: Nordic Distance Measurements

Simonr — Mon, 10 Jul 2023 10:28:12 GMT

Hi Franck

We haven't tested doing multiple rangings back-to-back without the syncing step, but our developer suggested trying this for ranging a single device.

Best regards,

Simon

RE: Nordic Distance Measurements

franck — Thu, 06 Jul 2023 12:47:59 GMT

Hello Simon, yes I'm using a nrf52832 so high precision is disabled (as not supported if I'm correct). This is great that if 10 is achievable, right now haven't managed to get more than 5-6/s

"One try you could probably do is to run multiple rangings back-to-back and don't go via the syncing step using the advertiser/scanner, if you are interested in ranging a single device."

-> this was my previous question, to get one synchronisation then call dm_request_add with same parameter everytime I get the result callback "Is this possible to call continuously dm_request_add on both devices everytime a timeout or a sucess result is returned ??"

Will check nrf_dm_get_duration_us api to see how long time is returned

Best regards

Franck

RE: Nordic Distance Measurements

Simonr — Thu, 06 Jul 2023 12:13:55 GMT

Hi Franck

We haven't tested a maximum on our end, but we think 10 should be possible to achieve. Did you disable high precision as well, as the "normal" precision mode should be much faster. You can also try to lower the advertising interval.

One measurement with high precision mode disabled should take ~16ms, so getting 10 measurements should in theory be possible if the delay from advertising to measurement isn't too long. Meaning you shouldn't do a bunch of other stuff over BLE as well that might increase discovery time or take up time on the radio for example.

For the measurement, there is an `nrf_dm_get_duration_us` api, that gives you the duration of the data collection for a given configuration, plus NRF_DM_PROC_EXECUTE_DURATION_OVERHEAD_US, which is the duration of the (non-high-precision) algorithms.

One try you could probably do is to run multiple rangings back-to-back and don't go via the syncing step using the advertiser/scanner, if you are interested in ranging a single device.

Best regards,

Simon

RE: Nordic Distance Measurements

franck — Wed, 05 Jul 2023 16:23:30 GMT

I played with values but did not seem to improve a lot, managed to get 4-5/secs, not sure I understood fully the parameters how to change the settings

Could you share a Kconfig file that should increase the rate

Thanks a lot

RE: Nordic Distance Measurements

franck — Wed, 05 Jul 2023 08:46:44 GMT

Hello Simon,

Thanks for your answer, I would need at least 10 values per seconds, and even more would be even better like 20 or so

Will try the tuning of the parameters

Also, power consumption is really not important for my device

Franck

RE: Nordic Distance Measurements

Simonr — Wed, 05 Jul 2023 07:51:40 GMT

Hi FrancK

[quote user="franck"]current distance measure report between 2 devices is only 2 or 3 values per seconds I would need more.[/quote]

How many reports would you need per second?

The Kconfig options CONFIG_DM_TIMESLOT_QUEUE_COUNT_SAME_PEER and CONFIG_DM_TIMESLOT_QUEUE_LENGTH define how many measurements are scheduled. The more measurements are scheduled, the more of them take place, which increases power consumption but gives more frequent rangings. At the application runtime, the additional delay of measurement execution is configured using the start_delay_us parameter of the dm_request structure. This option helps in adjusting the synchronization. The CONFIG_DM_INITIATOR_DELAY_US Kconfig option defines the initiator delay. Increasing the values of these parameters increases the latency and power consumption.

Best regards,

Simon

RE: Nordic Distance Measurements

franck — Mon, 03 Jul 2023 14:44:19 GMT

Hello Simon,

Thanks for your answer. My concern that current distance measure report between 2 devices is only 2 or 3 values per seconds I would need more. Consumption is not an issue. As which device are reflector and initiator are defined as well as BT device address. Is this possible to call continuously dm_request_add on both devices everytime a timeout or a sucess result is returned ??

What are other solution to increase the number of distance measure reported per seconds ??

Thanks

RE: Nordic Distance Measurements

Simonr — Wed, 05 Oct 2022 12:42:48 GMT

Hi Franck

What time exactly are you looking for? The minimum time between timeslots are by default set to 8ms (8000µs) with the CONFIG_DM_MIN_TIME_BETWEEN_TIMESLOTS_US. This time should also account for processing of ranging data after the timeslots. You can also define the time between the synchronization and ranging (request) with CONFIG_DM_RANGING_OFFSET_US .

Increasing this allows more ranging to different nodes, but increases latency. Regarding movement, I think the limitation or offset would be however long you move it in 8ms (time between events).

Best regards,
Simon