RE: GNSS Scheduled Downloads Interval and Enable/Disable

hk — Mon, 12 Aug 2024 11:17:02 GMT

Hi Charlie,

I have an application with periodic GNSS of 15 minutes, and before reaching 15 minutes, a gnss wake up event is generated at 10 minutes. This may have something to do with scheduled downloads?

RE: GNSS Scheduled Downloads Interval and Enable/Disable

TravdaTrav — Mon, 22 Jul 2024 15:10:57 GMT

Cool, sounds good. I appreciate the fast response.

RE: GNSS Scheduled Downloads Interval and Enable/Disable

Charlie — Mon, 22 Jul 2024 14:55:35 GMT

Hi Travis,

I think you mean nRF9160.

NCS document explains about Scheduled downloads:

A mechanism to maintain GNSS navigation data availability in periodic navigation mode.

If GNSS only runs long enough to calculate the first usable fix, it is probably never able to download for example almanacs or ionospheric correction data from the satellite broadcast. To ensure GNSS data availability and to improve accuracy in periodic navigation mode, GNSS performs scheduled downloads. When GNSS determines it needs to download ephemerides or almanacs from the broadcast, the fix interval and fix retry parameters are temporarily ignored and GNSS runs continuously for a longer period of time. GNSS performs scheduled downloads until it has downloaded the data it needs. After the downloads, normal operation is resumed. When A-GNSS is used, scheduled downloads are not necessary and you can disable them using the GNSS API. Scheduled downloads are only performed in periodic navigation mode.

So there is no way to configure the scheduled download period to be some user-defined value instead, since the GNSS satellites and device environment are not fixed.

If you disable scheduled downloads, you may get wore accurate in short time and not able to get a GNSS fix at all after a period of time, due to ephemerides and almanacs are out of date.

Best regards,

Charlie