nRF9160 DK + Asset Tracker v2, AWS A-GPS

[MostlyHardware]

Hello!

I am having some GPS problems with the Asset tracker v2 firmware. It can find satellites, but it doesn't track them nor do I get a GPS fix before the timeout occurs. I was thinking to enable A-GPS to speed up the fix, but since I am connecting it to my own AWS IoT instance it doesn't seem to download any A-GPS data. How can I modify the asset tracker firmware so that it downloads A-GPS properly?

Some other info:

• I have clear skies and open surroundings for the device
• If I run the GNSS firmware it gets a GPS fix within 30 seconds, so I am suspecting some kind of interference with the modem. iBasis supports PSM in my area but it doesn't seem to be activated if I read it out via modem commands.
• The original asset tracker firmware which connected to nRFcloud worked perfectly, so the device isn't faulty.

Thanks!

[MostlyHardware]

Hello,

Håkon Alseth said:

You'll need certificates for nRFCloud as well.

Two questions:

1.) Can the nRF9160 use two different certificates at the same time. I.e. connect both to nRFCloud and my own AWS IoT server?

2.) Is the only option nRFCloud to download A-GPS (or P-GPS) data? It cannot be downloaded from AWS?

Håkon Alseth said:

This is unfortunately bad news. You are not getting PSM in your current connected roaming network. I would suggest that you try to obtain a home registered SIM from your local network provider instead.

I'll try a different SIM card. What do I need to configure in the prj.conf file in order for PSM to start? Is it enough with:

CONFIG_LTE_PSM_REQ_RPTAU="11000001"
CONFIG_LTE_PSM_REQ_RAT="00100001"

Many thanks!

[Håkon Alseth]

Hi,

 

Yes, those configurations will then request PSM.

MostlyHardware said:

CONFIG_LTE_PSM_REQ_RAT="00100001"

This will give you an active time of 1 minute, which you probably do not need:

https://infocenter.nordicsemi.com/topic/ref_at_commands/REF/at_commands/nw_service/cpsms_set.html?cp=2_1_7_2_0

 

Try changing this to "00000001" instead, to give 2 seconds active time.

 

MostlyHardware said:

1.) Can the nRF9160 use two different certificates at the same time. I.e. connect both to nRFCloud and my own AWS IoT server?

Technically yes, as long as you use different sec tags for nrf cloud.

MostlyHardware said:

2.) Is the only option nRFCloud to download A-GPS (or P-GPS) data? It cannot be downloaded from AWS?

Yes, this is a feature that nrfcloud provides, and cannot be fetched with generic AWS endpoints.

 

Kind regards,

Håkon