NRF9160 GPS Reboot

RE: NRF9160 GPS Reboot

Thomas — Tue, 11 Aug 2020 01:01:45 GMT

Hi Didirk,

40 seconds is reasonable for a cold fix however when I turn the GPS on and off without rebooting the system it gets a hot fix within 5 or so seconds, so I would have thought that if it saves the ephermeris to flash that a reboot of the system would provide a hot fix after providing the position and time?

I'll do a modem trace later this week (bad weather here for the next few days).

Kind regards,

Thomas

RE: NRF9160 GPS Reboot

Didrik Rokhaug — Mon, 10 Aug 2020 15:15:25 GMT

I have looked a bit more through our internal information and talked to some of my colleagues.

The last good fix should be stored to flash when you send AT+CFUN=0 and should help with finding satellites faster.

[quote user="Thomas2197"]It took around 40 seconds for both fixes using the DK 0.9.0's onboard antenna.[/quote]

That doesn't sound very unreasonable to me. The onboard GPS antenna isn't very good on the 0.9.0 or older DKs.

You should be able to see an improvement if you use the external antenna that came with the DK. Remember to change SW2 to "CON".

[quote user="Thomas2197"]The time was from the GPS fix + RTC.[/quote]

By "RTC", do you mean Real Time Clock or Counter?

Anyway, if there are any further performance gains to be had (outside A-GPS or better antenna), I suspect it is the time estimate that is the problem.

Could you take a modem trace?

That will let me see what you are sending to the modem, and how the modem is using it.

RE: NRF9160 GPS Reboot

Thomas — Mon, 10 Aug 2020 01:20:29 GMT

Hi Didrik,

It took around 40 seconds for both fixes using the DK 0.9.0's onboard antenna. The test was performed in a park with a clear view of the sky.

The time was from the GPS fix + RTC.

Kind regards,

Thomas

RE: NRF9160 GPS Reboot

Didrik Rokhaug — Fri, 07 Aug 2020 15:35:10 GMT

Hi.

How long does it take to get the first fix, and how long does it take after the reset?

What antenna and DK version did you use?

Where was the device placed? Did it have a clear view of the sky?

How did you get the current time?

I will look more into this from my end on Monday, and will hopefully have some information to you by then (Norway time).

Best regards,

Didrik