AGPS and PSM

[Tron]

Hi

Looking at the AGPS sample code, it seems GPS/LTE is turned on and off using AT commands (AT+CFUN=x, x in {20, 21, 31}). 

Do you recommend NOT using PSM when using AGPS?

Tron

[Didrik Rokhaug]

Hi.

The gps sample was originally created with only GPS in mind. It was later expanded when we added A-GPS support.

That is why the sample only uses GPS, and not LTE (more than necessary for A-GPS). Another consideration to factor in is that the sample is not guaranteed to be granted PSM, and can therefore not rely on PSM to get enough run-time for the GPS.

That is no longer necessary, with the improvements to the modem, but the sample is still meant to be as basic as possible.

 

Do you recommend NOT using PSM when using AGPS?

I would probably enable PSM after downloading the A-GPS data, but there should not be a problem using PSM with A-GPS.

However, we have found that the SUPL library is more stable if the GPS is turned off before the SUPL session is started.

This would make the following order of events: Start GPS -> Get A-GPS data request -> Stop GPS (using socket interface) -> Start SUPL session -> SUPL session ends -> Enable PSM -> Start GPS

But, things could be done in other orders as well.

Best regards,

Didrik

[Tron]

Thank you, precise and to the point.