regarding nrf_dm code is not proper

RE: regarding nrf_dm code is not proper

Mathew A — Wed, 05 Jul 2023 14:20:19 GMT

ok Simonr,

thank you so much for your patience and feedbacks

i will do the calibration as well and if possible I will post the results

Thanks

A. Mathew

RE: regarding nrf_dm code is not proper

Mathew A — Wed, 05 Jul 2023 14:14:32 GMT

thank you Simonr for the testing

RE: regarding nrf_dm code is not proper

Simonr — Tue, 04 Jul 2023 08:02:50 GMT

Got some information from the devs on this issue as well, and they strongly recommend doing the calibration as well.

The standard deviation for the IFFT libraries is ~70cm or so, while for the high precision it is 27cm. Usable resolution for high precision measurements will then be ~50cm and ~1m for standard measurements, so what you're seeing is not too off it seems here.

Best regards,

Simon

RE: regarding nrf_dm code is not proper

Simonr — Mon, 03 Jul 2023 14:15:19 GMT

Hi Mathew

I can confirm that I see similar results on my end with a Dongle and DK, and I've asked the developers if they have any ways to improve this. From my testing it seems to provide the same accuracy at longer distances too though, so missing with ~50cm at 10m seems okay. One thing that came to mind, that I'll test myself tomorrow as well, could be to follow the zero-distance calibration mentioned in the documentaiton here.

As for measuring the distance between phones that don't have nRF devices in them I'm afraid will be out of our scope. The best suggestion I have is adding a tag or similar you can attach to your phone with nRF SoCs that does this distance measurement, and communicates with "its" phone through an app over BLE.

Best regards,

Simon

RE: regarding nrf_dm code is not proper

Mathew A — Sat, 01 Jul 2023 02:21:56 GMT

thanks Simonr,

Thank you so much for your replies.

ok Simonr once you get back to work, update me about the results and please give some idea how to measure the distance of the mobile phones if any alternate way available.

Thanks in Advance

A. Mathew

RE: regarding nrf_dm code is not proper

Simonr — Fri, 30 Jun 2023 11:09:37 GMT

Hi Mathew

Sorry, there's been a misunderstanding here. The Direction and Distance Finding Service (DDFS) is only a custom service that allows publication of distance, azimuth and elevation measurement data. So it will not let the nRF52/53 device to connect to a phone and calculate the distance to the phone directly. The DDFS lets you forward the data from I.E. the distance measurement sample between two nRF devices. Most phones (if not all) today does not support the Direction Finding feature in BLE, and our distance measurement can only be used between two devices.

I will have to get back to you next week with test results with a Dongle and DK from my end. We're moving into the summer vacation period here in Norway, so we'll be short on staff for the coming ~4 weeks, and delayed replies must be expected.

Best regards,

Simon

RE: regarding nrf_dm code is not proper

Mathew A — Thu, 29 Jun 2023 14:35:57 GMT

hi Simonr,

thank you so much for your replies.

please test the DK and dongle distance code, and give me feedback

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/libraries/bluetooth_services/services/ddfs.html#ddfs-readme

their is no separate code for direction and distance measurement code only nrf_dm is available.

inside the code service_ddfs_init() the function as been intialized but how to change the code for direction and distance finding and for measuring the mobile signal what uuid should be present in the nrf_connect_mobile app.

so please give me clear idea so that i will give a try.

Thanks in Advance

A. Mathew

RE: regarding nrf_dm code is not proper

Simonr — Wed, 28 Jun 2023 13:00:57 GMT

The Nordic Distance Measurement library is developed specifically for the nRF52 and nRF53 series, and we will not provide any support to port it to other products. To get these results on a phone, you will need to have an application that also connects to one of the nRF5x devices running the distance measurement application that can forward the location data to the phone over BLE. That's the solution we've been using for demos at least.

An alternative could be to use the Bluetooth Direction and Distance Finding service that the Distance measurement sample also uses. As this is a Bluetooth LE service, phones should be able to connect to and support this service as well I believe.

I don't see why you get such bad results though. I will try to reproduce this on my end with a Dongle and DK as well and get back to you.

Best regards,

Simon

RE: regarding nrf_dm code is not proper

Mathew A — Tue, 27 Jun 2023 15:20:27 GMT

thanks for the reply Simonr,

I don't have any extra DK, i am having two dongle boards, so i will test with dongle to dongle, i think so i need to do some averaging and then correct the offset as given in the document, so i will give a try.

my aim of the project is to sense the distance of the device and to make the relay on or off. This aim has to be implemented with dongle and with the mobile device.

I will test the code with averaging and try to get the near by values and will post the result.

so as i told my aim of the project i need to implement the distance measurement with the mobile devices, is their any method or we can modify the code ?if so please let me know how we can get the distance from the mobile.

Thanks in Advance

A. Mathew

RE: regarding nrf_dm code is not proper

Simonr — Tue, 27 Jun 2023 09:29:02 GMT

Thank you for the clarification. This does indeed seem worse than expected. Do you have an extra DK so you can test using two DKs instead of just the Dongle? Also, what version of the nRF Connect SDK are you working on here?

Unfortunately there isn't anything to do in HW to optimize the nRF52840 Dongle further, and it's not really meant to be an end product but rather a development tool. If you're planning on a commercial end product I think it will be worth it to use either your own HW or buy a dongle/module from a third party with a better antenna than the nRF52840 Dongle.

Best regards,

Simon

RE: regarding nrf_dm code is not proper

Mathew A — Sat, 24 Jun 2023 08:12:15 GMT

Hi Simonr,

Thanks for the reply and sorry for the late reply, The distance between both devices antenna is around 55cm and the distance between two Duts is 50 cm, so i have attached the outputs of the both the devices so please have look and let me known on what way we can solve the issues.

if i decrease the distance then some near by values are getting but if any blocks that values are not proper.

The environment i am working is 10x10 room, might be some headphones ble signals are present.

how to optimize the nrf52840 dongle antenna?

this is the output from the nrfdk

this is the output from the dongle

this the work environment setup has been made for testing.

my prime aim of the project is to use dongle and detect the mobile distance.

so please have a look and give me some solution.

Thanks in advance

A. Mathew

RE: regarding nrf_dm code is not proper

Simonr — Wed, 21 Jun 2023 13:09:37 GMT

Have you measured the distance between the devices antenna to antenna, and have you measured the exact range between the two DUTs? Can you share some details about your testing environment? It seems strange that the RSSI would be the most accurate parameter. Are there a lot of other 2.4GHz devices in your proximity? Is there anything physically between the two DUTs?

It's also worth noting that the antenna on the nRF52840 Dongle is not very well optimized for high performance in terms of antenna performance, so that may be a factor as well.

Best regards,

Simon