SUPL Data Validity Period

[Thomas]

Hi,

I was wondering if you could give me information on the validity period of the GPS assistance data?

In other words, how often do you need to download the data? I can't seem to find any documentation on this?

Kind regards,

Thomas

[Martin]

I did some experiments with the SUPL library yesterday and have the same question.
I also could almost not detect a difference in speed to get to a position solution with or without AGPS data.

I am testing here in Brasil and the two networks with LTE-M do not seem to accept PSM and eDRX.
Testing protocol:
1. Let GPS get a position fix without LTE and SUPL (wait for 60 GPS fixes)
2. Sending every thrity second a UDP request and receive a reply
3. In the remaining time try to get a GPS fix
4. If SUPL is allowed it will get pulled during the first cycle 

Without SUPL and the a low 30s cycle GPS is normally lost after about 5 cycles.
With SUPL and a low 30s cycle GPS is normally only lost after 25 cycles.

That means that under these circumstances I need to switch off LTE for a time to recover the GPS signal ...

Best regards
- Martin

[Heidi-Irene Harvey Sollie]

Hi!

The use of A-GPS doesn't change the amount of time the data is valid, just the time it takes to acquire it. The ephemeris is valid for four hours and the almanac is valid for up to two weeks.

However, the modem should request this data when it needs it, so this process should be automatic and independent of your application.

Best regards,

Heidi