Timing Advance reading too high and neighbouring cells unable to be parsed.

RE: Timing Advance reading too high and neighbouring cells unable to be parsed.

flau — Fri, 12 Dec 2025 20:37:58 GMT

My understand is that 1 TA = 16 Ts. According to the 9160 AT Commands document, the timing_advance reported is Ts. Please correct me if I am wrong. Therefore, dividing your 160 by 16 to get TA = 10. Then multiple by 78 will give you 780 meter. Am I correct?

RE: Timing Advance reading too high and neighbouring cells unable to be parsed.

Øyvind — Tue, 07 Jan 2025 09:29:00 GMT

I hope that you are able to find the solution, and we apologies for the inconvenience.

Kind regards,
Øyvind

RE: Timing Advance reading too high and neighbouring cells unable to be parsed.

Turk — Mon, 06 Jan 2025 19:50:45 GMT

OK, I’ll see if I can work out how to use lte_lc_neighbor_cell_measurement() myself but if I struggle I’ll just use have to live with the parsing errors till the function has a little more documentation. Thanks for bringing it to the attention of your developers.

RE: Timing Advance reading too high and neighbouring cells unable to be parsed.

Øyvind — Mon, 06 Jan 2025 11:45:52 GMT

No, that's is an issue that our developers will fix. They do see that the information is lacking.

That said, if you are using LTE LC, you should be using i.e. lte_lc_neighbor_cell_measurement()

RE: Timing Advance reading too high and neighbouring cells unable to be parsed.

Turk — Mon, 06 Jan 2025 10:18:35 GMT

Hey there,

oh, I didn’t even know that function existed. Are the parameters detailed anywhere? I’m struggling to find the information.

RE: Timing Advance reading too high and neighbouring cells unable to be parsed.

Øyvind — Mon, 06 Jan 2025 09:23:25 GMT

Hello, thanks for your patience.

The problem is most likely that you are directly calling %NCELLMEAS and not calling lte_lc_neighbor_cell_measurement() to trigger the measurement. LTE LC needs to know the measurement parameters to be able to parse the notification correctly

RE: Timing Advance reading too high and neighbouring cells unable to be parsed.

Turk — Tue, 31 Dec 2024 20:06:23 GMT

As for the error from your parsing code, I still have to look into that more, but have to move house in between. Any indication on how to avoid the error coming up would be helpful.

RE: Timing Advance reading too high and neighbouring cells unable to be parsed.

Turk — Tue, 31 Dec 2024 20:04:40 GMT

Some more information. I took another walk with the kit and see that TA is only reported in increments of 16. So taking my 160 figure, it’s actually an equivalent to a timing advance of 10, which is about 780m, which is much closer to the distance I was from the tower. Other pings of other towers were even more accurate. Not sure why your TA reports in chunks is of 16, but at least now I know the calculation to use.

RE: Timing Advance reading too high and neighbouring cells unable to be parsed.

Turk — Mon, 30 Dec 2024 22:38:38 GMT

Hey there,

Thanks for the reply. I am trying to get an accurate timing advance number and neighbouring cell ID's for location purposes. I'm running firmware mfw_nrf9160_1.3.7

The timing advance usually calculated out to be 78m (or so) per unit. See here:The LTE Timing Advance – WirelessMoves and 4G LTE Timing Advance Distance Calculator | 5G-Tools.com

Therefore a TA of 160 should equal a distance of around 12.5km, which is reading from the device about 12km farther than it should be. I have since done a walk to the cell tower and the TA numbers did decrease and eventually went to '0' when I was right by the tower. So it seem like it is some form of TA value, but I am not sure what the scale is (it's calculating out to about 3m per unit at present).

For the error, my probelm is that I am doing nothing but running the following command (once RRC is showing as 'Idle'):

err = nrf_modem_at_cmd(response, sizeof(response), "AT%NCELLMEAS=5,3");

and then in my handle I have this code as a place holder:

static void cellMeasHandle(const char *notif)

{

printk("cell measurement complete");

}

but get the "<err> lte_lc: Parsing of neighbor cells failed, err: -95" come up in the console. This does not happen when I run the following:

err = nrf_modem_at_cmd(response, sizeof(response), "AT%NCELLMEAS");

So I am just wondering why this error occurs for the NCELLMEAS command when I give it a 5,3 argument vs. no argument. The only other difference is I deliberately run the no argument command when RRC is 'Connected' and the 5,3 version when the RRC is 'Idle' (which I have to do to get the neighbouring cell data).

After a little more investigation, this does not occur in the Serial Terminal run from nRF Desktop (as expected as there is no parsing), and only seems to be an issue the first time the AT%NCELLMEAS=5,3 is called. Subesequent calls seem to work ok. So I think there may be an issue in the parser somewhere? I'll try and look into it a bit more when I get the chance from my end.

RE: Timing Advance reading too high and neighbouring cells unable to be parsed.

Øyvind — Mon, 30 Dec 2024 13:03:52 GMT

Hello,
Could you please provide what version of the modem FW you are running on your device? What are you trying to achieve?

[quote user=""]but I am not sure what the error -95 means[/quote]

From nrfxlib\nrf_modem\include\nrf_errno.h -

#define NRF_EOPNOTSUPP 95 /**< Operation not supported on socket */

[quote user=""]I am using an nRF9160DK and looking to get accurate Timing Advance numbers from it and also information on neighbouring cells. [/quote]

The AT%NCELLMEAS is documented here.

[quote user=""]. Am I calculating the TA wrong [/quote]

Where do you have this calculation from? I'm not aware of how to calculate this, and could not find this in the referenced 3GPP documentation.

Kind regards,
Øyvind