[nRF9160] How to have gps and lte concurrently working

[Augustin Bricout]

Hello,

I am developping a project on with the nRF9160 and I would like to have the LTE and GPS working concurently. I managed to have both working separatelly on my custom board but I can't figure how to have them both. I started from the simple mqtt example then I integrated the GPS part to it.

I changed the configuration of the modem so that they both should be available "AT\%XSYSTEMMODE=1,0,1,0" but then only the LTE is available.

Do you have any advice for this use case?

Thank you by advance,

Augustin

[Håkon Alseth]

Hi,

 

I changed the configuration of the modem so that they both should be available "AT\%XSYSTEMMODE=1,0,1,0" but then only the LTE is available.

This systemmode is correct given that you need M1 and GPS. There is however one restriction with the current modem fw (v1.0.x): You have to be in PSM mode for the GPS to be available for the application.

Here's an example that does this: https://github.com/Rallare/fw-nrfconnect-nrf/tree/nrf9160_samples/samples/nrf9160/udp_gps

 

Note that some providers limit the use of PSM with roaming SIM cards, so if you are seeing issues, please post the return from these two AT commands after requesting PSM:

AT+CEREG=5

AT+CEREG?

 

Kind regards,

Håkon

[Augustin Bricout]

Hi,

Thank you for your answer, I wil try this.

I have a sim card SFR in NB IoT. Do you know if the PSM is supported with this sim?

Augustin 

[Håkon Alseth]

Try running the sample, and then use LTE Link Monitor to issue the AT commands that I listed in my previous post.

That should give you something back, and if you post the returned string (preferably the whole .log file), I can help you parse it.

 

Kind regards,

Håkon

[Augustin Bricout]

Hello,

Here is what I get from using my Ibasis sim card

AT+CEREG?
+CEREG: 5,5,"644A","01296A04",7,,,"00001000","00101011"
OK

AT+COPS=3,2
OK

AT+COPS?+COPS: 0,2,"20801",7
OK

AT%XCBAND%XCBAND: 20
OK

AT+CGDCONT?+CGDCONT: 0,"IP","ibasis.iot","10.160.166.180",0,0
OK

AT+CGACT?
+CGACT: 0,1
OK

I didn't manage to have the sample working with the SFR NB IoT sim card yet, if I do I'll tell you.

Augustin

[Håkon Alseth]

Here is the AT command doc for CEREG:

https://infocenter.nordicsemi.com/topic/ref_at_commands/REF/at_commands/nw_service/cereg_read.html?cp=2_1_6_8_1

The two last parameters are related to the PSM interval, where 00001000 is the "active time", and 00101011 is the "periodic TAU" (the interval).

The periodic TAU is defined using "GPRS Timer 3" in the 3GPP specification, where "001" is the prefix for 1 hour intervals, and "01011" is the timer value. The TAU is then 1 hour * 11 = 11 hours.

The Active time is defined using "GPRS Timer 2" (note: this has different prefix values!), where "000" is defined as a multiple of 2 seconds, timer value "01000" = 8, active time = 2 * 8 = 16 seconds.

The GPRS timers are defined in 3gpp TS 24.008 v15.5.0, chapter 10.5.7.5.

 

It looks like you are entering PSM successfully, with a periodic tau of 11 hours, and an active time of 16 seconds.

 

PS: to change to NB1 systemmode, please see the AT%XSYSTEMMODE at command: https://infocenter.nordicsemi.com/topic/ref_at_commands/REF/at_commands/mob_termination_ctrl_status/xsystemmode_set.html?cp=2_1_3_29_0

This should be done prior to issuing AT+CFUN=1.

 

Kind regards,

Håkon