GPS slow fix and unstable

[taitk]

Hi zone,

 I've just got nrf9160dk and test gnss feature. Issue is:
 1. Device get long time to fix. Even which many SVs in tracking and using

2. After got fix, device keep lost-fix and re-fix.

Is this normal or not? Please help me figure out

P/s: pre-condition: mfw 1.3.0, external antenna, antenna out side the windows (direct to sky) 

[Håkon Alseth]

Hello,

 

Your picture shows that you are tracking many satellites, but using 4.

If we decode the strings:

https://www.trimble.com/oem_receiverhelp/v4.44/en/NMEA-0183messages_GSV.html

 

We see that there's not many that has >30 dB/Hz signal strength, which is around the number you want to see to be able to track a satellite successfully.

 I've just got nrf9160dk

Which version of the nRF9160DK do you have? Older versions, prior to v0.14.0, has a recommendation of using an external antenna.

With v0.14.0 and newer, you can safely use the on-board GPS antenna.

 

2. After got fix, device keep lost-fix and re-fix.

Is this normal or not? Please help me figure out

Do you mean that it successfully gets a fix, then after a while starts searching again? This is normal if the GPS loses track of a satellite (ie. it goes out of "line of sight"), and a new one comes into range.

 

Kind regards,

Håkon

[taitk]

Thanks Håkon,

That's clear for me. My board said PCA10090 1.0.0 2021.11.
As my thought, "using 4" means device chose 4 best, doesn't it?
Is there any way to improve signal strength? It's outside the window, and this is my best scene.
As my monitor, GPS soon get 3 satellites in used, but long after to get the 4th.
The situation when gps loses tracking should appear frequently, how could I improve for it to get  track back fast from that?

Regards,
Taitk