Combining GNSS and CoAP client in nRF Connect SDK — GNSS fix not read, CoAP request not sent

RE: Combining GNSS and CoAP client in nRF Connect SDK — GNSS fix not read, CoAP request not sent

dejans — Thu, 09 Oct 2025 06:39:01 GMT

Hi Arun,

You can do your own tests. When testing, ensure that there is no interference from the laptop. First scenario would be to walk with your device in the open sky. Second scenario would be to walk the same route with your device in the pocket (or in a bag) enclosed in described casing. I assume you have already provided results for the second scenario. There you got very poor C/No level of 25 dB-Hz. This is almost as if your device is indoors. I would expect that you get better result if device is in open sky environment and not enclosed in a casing.

Best regards,
Dejan

RE: Combining GNSS and CoAP client in nRF Connect SDK — GNSS fix not read, CoAP request not sent

Arun538 — Wed, 08 Oct 2025 17:36:01 GMT

Hi Dejan,

The case is made of Acrylonitrile Butadiene Styrene(ABS) material, printed using a standard 3D printer.

Best regards,

Arun

RE: Combining GNSS and CoAP client in nRF Connect SDK — GNSS fix not read, CoAP request not sent

dejans — Wed, 08 Oct 2025 13:54:27 GMT

Hi Arun,

Which material is this 3D-printed case made of?

Best regards,
Dejan

RE: Combining GNSS and CoAP client in nRF Connect SDK — GNSS fix not read, CoAP request not sent

Arun538 — Wed, 08 Oct 2025 11:34:14 GMT

Hi Dejan,

Ok, I will test the device without the laptop as you suggested.
I also wanted to confirm one more thing — my DK is enclosed in an ABS 3D-printed case, and I usually keep the device in my pant pocket or in a bag while walking. In that setup, is it still possible to get a GNSS fix, or will the enclosure and placement affect the signal reception?

Best regards,
Arun

RE: Combining GNSS and CoAP client in nRF Connect SDK — GNSS fix not read, CoAP request not sent

dejans — Wed, 08 Oct 2025 09:25:26 GMT

Hi Arun,

Constant speed movement should not pose a challenge to GNSS. There seems to be something else that is creating interference in your case. If there is no degraded sky view while walking, the problem might be caused by the placement of your DK while walking. Did you place your DK close to the laptop while walking? If yes, that is mostly likely causing no-fix situation.

Best regards,
Dejan

RE: Combining GNSS and CoAP client in nRF Connect SDK — GNSS fix not read, CoAP request not sent

Arun538 — Tue, 07 Oct 2025 12:44:57 GMT

Hi Dejan,

I have already tested the standard GNSS example, but I’m unable to get a valid fix while walking. The fix works reliably only when the device is stationary outdoors. It seems that the GNSS is struggling to maintain continuous tracking while in motion.

Could you please clarify if the nRF91 GNSS is expected to work reliably while walking or during motion? If so, is there a recommended configuration or mode to enable continuous tracking while moving?

Best regards,
Arun

RE: Combining GNSS and CoAP client in nRF Connect SDK — GNSS fix not read, CoAP request not sent

dejans — Mon, 06 Oct 2025 13:28:35 GMT

Hi Arun,

With regard to use of A-GNSS or P-GPS you can look at the following samples:
nRF Cloud Multi Service
Modem Shell
Location
GNSS

Best regards,
Dejan

RE: Combining GNSS and CoAP client in nRF Connect SDK — GNSS fix not read, CoAP request not sent

Arun538 — Mon, 06 Oct 2025 11:47:35 GMT

Hi Dejan,

Thank you for the clarification.

I have not yet enabled A-GNSS or P-GPS. I am currently testing with standard GNSS mode. I will try enabling A-GNSS and P-GPS as you suggested.

Regarding the fix issue — when the device is stationary outdoors, I get a fix successfully and it updates continuously.
However, when I start walking or moving, the fix is sometimes lost, and occasionally it does not recover until the device stops moving again.

It looks like GNSS is struggling to maintain continuous tracking while the board is in motion.

Also, if you have any example code or reference project for A-GNSS or P-GPS integration, it would be very helpful.

Best regards,
Arun

RE: Combining GNSS and CoAP client in nRF Connect SDK — GNSS fix not read, CoAP request not sent

dejans — Mon, 06 Oct 2025 10:03:55 GMT

Hi Arun,

Operation modes for GNSS sample mention this
"By default, the sample runs in continuous tracking mode. In continuous mode, GNSS tries to acquire a fix once a second."

Have you considered using A-GNSS / P-GPS? You can find configuration for A-GNSS and P-GPS in the documentation.

[quote user="Arun538"]It seems that GNSS fix is lost or not acquired reliably when the device is in motion.[/quote]

Are you not getting fix at all or sometimes? Can you elaborate?

Best regards,
Dejan

RE: Combining GNSS and CoAP client in nRF Connect SDK — GNSS fix not read, CoAP request not sent

Arun538 — Mon, 06 Oct 2025 08:48:31 GMT

Hi Dejan,

Yes, I have reset the DK board and waited, but the behavior is the same. I can get a fix reliably only when the device is stationary outdoors.

For outdoor testing, I was in an open area with minimal obstructions (no tall buildings or dense trees). When moving, I carried the board in my hand while walking at normal pace. I have tested only while walking so far.

It seems that GNSS fix is lost or not acquired reliably when the device is in motion. Could this be due to the GNSS configuration? Is there a recommended mode or setting for continuous tracking while moving?

Best regards,
Arun

RE: Combining GNSS and CoAP client in nRF Connect SDK — GNSS fix not read, CoAP request not sent

dejans — Mon, 06 Oct 2025 08:31:17 GMT

Hi Arun,

Have you tried to reset your dk board and wait longer time until you get a fix?

In indoor environment, it is not expected that you can get GNSS fix reliably. You can look at cellular or wi-fi locationing (SSID Wi-Fi locationing) as an alternative. Additional information can be found in Location Services. Can you provide details about your outdoor environment? When moving, where and how have you kept the board? Can you provide more information about the type of movement? Did you test GNSS sample only when walking?

Best regards,
Dejan

RE: Combining GNSS and CoAP client in nRF Connect SDK — GNSS fix not read, CoAP request not sent

Arun538 — Fri, 03 Oct 2025 17:29:48 GMT

Hi Dejan,

Yes, that’s correct. When the device is outdoors and stationary, I can get a fix. But when the device is outdoors and moving (even while walking), it cannot get a fix — it just keeps logging “searching for satellites.”

I also tested the same unmodified GNSS example indoors, but I’m not able to get a fix there either.

Best regards,

Arun

RE: Combining GNSS and CoAP client in nRF Connect SDK — GNSS fix not read, CoAP request not sent

dejans — Fri, 03 Oct 2025 09:51:08 GMT

Hi Arun,

[quote user="Arun538"]When I mentioned “not working,” I meant that while the device is moving (even walking), the GNSS is not able to get a valid fix, and I only see repeated logs about searching for satellites. When the device is stationary outdoors, I can get a fix within a reasonable time.[/quote][quote user="Arun538"]Because when I test indoors, I don’t get location, but outdoors it works.[/quote]

Is it that when the device is outside and moving (as well as inside), it cannot get a fix?
In your testing, did you use your own application or (unmodified) GNSS sample?

Best regards,
Dejan

RE: Combining GNSS and CoAP client in nRF Connect SDK — GNSS fix not read, CoAP request not sent

Arun538 — Fri, 03 Oct 2025 04:02:21 GMT

Hi Dejan,

Thanks for your response.

When I mentioned “not working,” I meant that while the device is moving (even walking), the GNSS is not able to get a valid fix, and I only see repeated logs about searching for satellites. When the device is stationary outdoors, I can get a fix within a reasonable time.

I don’t see any fix flags set in the moving case. The environment is outdoors (open sky), and I’m testing while walking in an open area without tall buildings nearby.

Do you think additional configuration is required for GNSS to track properly while the device is moving? Or is there a recommended mode that works better?

Best regards,
Arun

RE: Combining GNSS and CoAP client in nRF Connect SDK — GNSS fix not read, CoAP request not sent

dejans — Wed, 01 Oct 2025 13:16:03 GMT

Hi Arun,

[quote user="Arun538"]when I am moving (even while walking), it is not working or giving a fix.[/quote]

What is the difference in cases when "it is not working" and not "giving a fix"? Can you provide additional details? Do you have any logs which you can share?

Can you also provide more information about your testing environment?

Best regards,
Dejan

RE: Combining GNSS and CoAP client in nRF Connect SDK — GNSS fix not read, CoAP request not sent

Arun538 — Wed, 01 Oct 2025 03:44:28 GMT

Hi Dejan,

I tested the GNSS example, and it works when the device is kept outdoors in a static position. But when I am moving (even while walking), it is not working or giving a fix.

Can you please tell me what might be the problem and suggest any solution?

Regards,

Arun

RE: Combining GNSS and CoAP client in nRF Connect SDK — GNSS fix not read, CoAP request not sent

dejans — Wed, 24 Sep 2025 06:01:38 GMT

Hi Arun,

You can look at cloud assistance, location based on cells and location based on Wi-Fi networks.

Best regards,
Dejan

RE: Combining GNSS and CoAP client in nRF Connect SDK — GNSS fix not read, CoAP request not sent

Arun538 — Tue, 23 Sep 2025 17:46:38 GMT

Hi Dejan,

My project requires indoor location. Is there any possible way to get or read GNSS-based location indoors? Please suggest any alternative solutions.

Regards

Arun

RE: Combining GNSS and CoAP client in nRF Connect SDK — GNSS fix not read, CoAP request not sent

dejans — Fri, 19 Sep 2025 10:32:27 GMT

Hi Arun,

GNSS description provides this information
"GNSS signals do not usually penetrate ceilings or other structures that well. For best GNSS performance, the DK should be placed outside on a flat surface in an open space far from sources of interference and other structures that can block the satellite signals."

In GNSS guide, you can find that "GNSS is designed to be used with a line of sight to the sky. Therefore, the performance is not ideal when there are obstructions overhead or if the receiver is indoors."

You can also look at troubleshooting and why I cannot get GNSS fix.

Best regards,
Dejan

RE: Combining GNSS and CoAP client in nRF Connect SDK — GNSS fix not read, CoAP request not sent

Arun538 — Fri, 19 Sep 2025 07:40:04 GMT

Hi juha,

I can get location and send it to the CoAP server. Thank you for your support.

Last thing I want to confirm: does GNSS only work outdoors?
Because when I test indoors, I don’t get location, but outdoors it works.

Regards,

Arun

RE: Combining GNSS and CoAP client in nRF Connect SDK — GNSS fix not read, CoAP request not sent

Juha Y — Wed, 17 Sep 2025 13:36:10 GMT

Hi, Are you familiar with the Cellular IoT Fundamentals online course?

https://academy.nordicsemi.com/courses/cellular-iot-fundamentals/

Lesson 8 show how to build a simple tracker with nRF91 device.
https://academy.nordicsemi.com/courses/cellular-iot-fundamentals/lessons/lesson-8-cellular-fundamentals/topic/lesson-8-project-description/

Best regards,

Juha

RE: Combining GNSS and CoAP client in nRF Connect SDK — GNSS fix not read, CoAP request not sent

Arun538 — Wed, 17 Sep 2025 09:48:24 GMT

Here are the details of my application logic and how I combined the two samples:

Starting point: I used the coap_client sample from nrf/samples/nrf9160/coap_client as the base.
Integration:
1. I added the GNSS initialization and event handling from the gnss sample.
2. In my main thread, after LTE link is established, I start GNSS (nrf_modem_gnss_start()).
3. When a GNSS fix event arrives, I parse latitude/longitude from struct nrf_modem_gnss_pvt_data_frame.
4. I format latitude/longitude into a JSON string (e.g. {"lat": xx.xxxxx, "lon": yy.yyyyy}).
5. I send that JSON via CoAP POST to my IPv6 server (dev-iot.imsafe.app:5683).
Changes made:
- Added GNSS related Kconfig options (CONFIG_NRF9160_GPS, CONFIG_MODEM_KEY_MGMT, CONFIG_GNSS_SAMPLE_ASSISTANCE_NONE, etc).
- Modified main.c to include both GNSS event handler and CoAP send logic.
- CoAP sending is triggered only when a GNSS fix is available.

Current behavior:

LTE attaches successfully (CEREG: 5).
After that, GNSS events never arrive.
CoAP messages are never sent because no fix is received.

I’m not sure if my current integration is correct.

Can you please tell me the correct way to read GNSS location data (latitude & longitude) and send it to a custom CoAP server?

Do you have any example code for this?

RE: Combining GNSS and CoAP client in nRF Connect SDK — GNSS fix not read, CoAP request not sent

dejans — Wed, 17 Sep 2025 08:43:07 GMT

Hi Arun,

Can you describe details of your application logic?

How did you integrate 2 samples? What was your starting point? Which changes did you make to the samples?

Best regards,
Dejan

RE: Combining GNSS and CoAP client in nRF Connect SDK — GNSS fix not read, CoAP request not sent

Arun538 — Wed, 17 Sep 2025 03:53:52 GMT

Hi, thanks for the quick response.

Here’s my setup:

Board: nRF9151 DK
SDK: nRF Connect SDK v3.0.0
SIM/network: Jio NB-IoT (India)
Server: IPv6 CoAP server at dev-iot.imsafe.app:5683
Environment: Tested outdoors, GNSS works when I run the standalone GNSS sample.

Here is the complete application log from boot:

*** Booting nRF Connect SDK v3.0.0 ***
*** Using Zephyr OS v4.0.99 ***
[00:00:00.305] <inf> coap_client_sample: Starting GNSS + CoAP client
[00:00:00.312] <inf> coap_client_sample: Bringing network interface up
[00:00:00.320] <inf> coap_client_sample: Waiting for network connectivity
+CEREG: 2,"C094","00482492",9
+CSCON: 1
+CEREG: 5,"C094","00482492",9,,,"11100000","11100000"
+CEDRXP: 5,"1001","1001","0011"
<no further GNSS or CoAP activity>

When I run the GNSS sample alone → I get fixes.
When I run the CoAP client alone → I get responses from the server.
When I combine them → neither GNSS events nor CoAP requests happen.

My goal is:
To get latitude & longitude from the nRF9151’s GNSS and send that data via CoAP POST to my server.

Regards

Arun

RE: Combining GNSS and CoAP client in nRF Connect SDK — GNSS fix not read, CoAP request not sent

dejans — Tue, 16 Sep 2025 15:49:07 GMT

Hi Arun,

Can you describe your setup and provide complete application log?

Best regards,
Dejan