nRF9160 Not connecting over LTE on custom board

RE: nRF9160 Not connecting over LTE on custom board

RodWatt — Tue, 25 Feb 2020 12:58:02 GMT

Just to to update the ticket, I have tried the system in Germany with a different NB-IOT SIM and it worked fine! Thanks again Kaja for all your advice during the antenna design and layout,

RE: nRF9160 Not connecting over LTE on custom board

RodWatt — Thu, 20 Feb 2020 18:24:38 GMT

Hi Heidi,

Sorry just checking, is that a typo? I guess the _GPS text should not be there?

CONFIG_LTE_NETWORK_MODE_LTE_M=n

Thanks,

Rod

RE: nRF9160 Not connecting over LTE on custom board

RodWatt — Thu, 20 Feb 2020 13:00:15 GMT

Hi Heidi,

Thank you for the update. I will go ahead and try and get a Vodafone SIM and make the changes to the config file as detailed below.

When LTE Link Monitor connects over NB-IOT, does the LTE icon go green?

It would be really cool if this icon changed depending on the connection type!

Thanks,

Rod

RE: nRF9160 Not connecting over LTE on custom board

Heidi — Thu, 20 Feb 2020 12:42:13 GMT

Hi Rod,

Unfortunately, according to the iBasis coverage list, iBasis (the SIM that comes with the DK) does not have coverage for NB-IoT in the United Kingdom at the moment. I suggest finding a local network provider (for example Vodafone) with support for NB-IoT and using their SIM card instead. This explains why you weren't getting a signal.

When you do get a hold of a new SIM card:

Yes, you can still use LTE Link Monitor to connect with NB-IoT. You can do one of the two suggestions listed below:

1. You can change the AT%XSYSTEMMODE setting to NB-IoT, and run AT+CFUN=0 to make sure the configuration is saved by the modem after every reboot of the device.

2. You can change the configuration in the application you're running on the device by setting the following configs in the prj.conf file like so:

CONFIG_LTE_NETWORK_MODE_LTE_M_GPS=n
CONFIG_LTE_NETWORK_MODE_NBIOT=y

Best regards,

Heidi

RE: nRF9160 Not connecting over LTE on custom board

RodWatt — Wed, 19 Feb 2020 13:50:06 GMT

Thanks Kaja,

Yes, I appreciate that I need to turn the circuit. I am not sure if you saw my update below ? I have realised that my board has the NBIOT only part fitted so I can not use LTE.

Am I correct in saying that I just need to change the AT%XSYSTEMMODE setting to enviable NBIOT?

I live in Cambridge, do you know what the NBIOT coverage is here?

I will go back to the DK and verify that I get a NBIOT connection. What is the best way of doing that?

Rod

RE: nRF9160 Not connecting over LTE on custom board

Kaja — Wed, 19 Feb 2020 13:40:49 GMT

Hi Rod,

yes you talked to me about the HW. But as I said in the previous answer, you need to tune the antenna for your specific board.
The impedance of the antenna will change from design to design, because things are not always exactly the same.

If you have a look at this:
devzone.nordicsemi.com/.../9160Ant.pdf

This just means that you have to adjust the values of the matching components, so that the antenna is matched to 50 Ohm, withing your chosen freq. band, based on your specific board.
What I have done, is added ground on the DK, to have the same placement as in your design, just to see how "de-tuned" the antenna gets.

We still get okay signal strength, and connection shown in the LTE Link Monitor: devzone.nordicsemi.com/.../log_5F00_dk_5F00_jordplan.txt

What freq. are you using?

Best regards,
Kaja

RE: nRF9160 Not connecting over LTE on custom board

RodWatt — Wed, 19 Feb 2020 11:29:37 GMT

Hi Kaja,

Ok, a bit more investigating and it looks like my board has the NBIOT only part fitted. I have an nRF9160-SIBA fitted. (I see the nRF9160DK has the - SICA fitted) So, am I correct in saying that my board will only support NB-IOT? (and not LTE?)

Can I still use the LTE Link Monitor to connected to NB-IOT?

What changes do I need to make to the AT commands?

Thanks,

Rod

RE: nRF9160 Not connecting over LTE on custom board

RodWatt — Mon, 17 Feb 2020 12:56:03 GMT

Hi Kaja,

I am using the exact same antenna as used on the nRF9160DK. I spent a lot of time back and forth with one of your apps people on reviewing the layout and design so am confident/hopeful that its OK.

Do you see anything in the log file that would suggest Im getting any signal.?

One of things I thought I could try would be to plug in an external antenna. As with the NRF9160DK, I have added an RF switch (like J1 on the DK) . Is there one you could recommend? I have tried to find one on line but cant seem to find one compatible with the connector, J1 on the DK. Do you know what you call that connector? A search for MM8130-2600 doesn't seem to help.

Regards,

Rod

RE: nRF9160 Not connecting over LTE on custom board

Kaja — Mon, 17 Feb 2020 12:44:29 GMT

Hi Rod,

it might be that the antenna is too close to the ground to the right, but the antenna datasheet does not specify anything in this regard so it is hard to say. Have you had the antenna manufacturer look through the design as well?

You might just need to tune the components values on the matching network.

Best regards,
Kaja