NRF9160 Modem Band Scan

RE: NRF9160 Modem Band Scan

Thomas — Fri, 06 Nov 2020 02:15:45 GMT

That does not work so it seems we have to stick with power hungry timeouts for the time being. Thank you for the information and for chasing this up anyway Hakon.

RE: NRF9160 Modem Band Scan

Hakon — Thu, 05 Nov 2020 13:03:25 GMT

They confirmed there is no other way than using +CEREG notification.

RE: NRF9160 Modem Band Scan

Hakon — Fri, 30 Oct 2020 14:51:18 GMT

I don't know, but I doubt it. I will ask R&D and see if they know something about this.

RE: NRF9160 Modem Band Scan

Thomas — Wed, 28 Oct 2020 02:51:40 GMT

I am already doing something similar, is there no smarter/power efficient way to do it? Modems we have used in the past automatically switch between the two.

RE: NRF9160 Modem Band Scan

Hakon — Tue, 27 Oct 2020 16:52:45 GMT

If you have LTE_LINK_CONTROL=y enabled you can use LTE_NETWORK_USE_FALLBACK=y to change from CAT-M1 to NB-IoT after LTE_NETWORK_TIMEOUT seconds. If you know the time it usually takes to find a network then you can use that as a timeout.

RE: NRF9160 Modem Band Scan

Thomas — Mon, 26 Oct 2020 13:35:46 GMT

Hi Hakon,

I am watching it on a power analyser. I can see it attempt scans on an exponential back off schedule dependant on XDATAPRFL. For example in ultra low power mode it attempts a scan, then retries in 20 seconds, 20 seconds, 40 seconds, 40 seconds, 5 minutes then retries every half an hour.

RE: NRF9160 Modem Band Scan

Hakon — Mon, 26 Oct 2020 13:23:11 GMT

[quote user="Thomas2197"]But it seems CEREG does not transition from mode 2 to mode 0 if a scan fails?[/quote]

What do you mean by "if a scan fails"? As far as I know the modem will keep searching until it finds a network. How do you know it is failing?

RE: NRF9160 Modem Band Scan

Thomas — Fri, 23 Oct 2020 15:40:34 GMT

Hi Hakon,

Sorry for the misunderstanding. We sell our products globally so we don’t know whether an end user will be requiring NB-IoT or CAT-M1 so we need to switch between the two if the device is not registering. So I was hoping to find a way to determine when the modem has finished doing a band scan on one technology so I can swap to the other. But it seems CEREG does not transition from mode 2 to mode 0 if a scan fails?

RE: NRF9160 Modem Band Scan

Hakon — Fri, 23 Oct 2020 11:58:33 GMT

It can usually take several minutes to get an LTE connection. You can reduce the time it takes by applying bandlock if you know which band to use. What operator/SIM are you using?

RE: NRF9160 Modem Band Scan

Thomas — Fri, 23 Oct 2020 03:00:47 GMT

Hi Hakon,

From what I see it just stays in mode 2, and does not transition to mode 0?

RE: NRF9160 Modem Band Scan

Hakon — Thu, 22 Oct 2020 12:41:15 GMT

Hello,

you can use the +CEREG command to check the connection status. <stat> should be 0 if it is not searching, 2 if it is searching, and 1 or 5 if it is registered.