[EXS82] Engine GNSS, How ephemeris and almanac retrieving work | Telit Cinterion IoT Developer Community
August 24, 2021 - 2:56pm, 2581 views
I use the EXS82 Module and I don't understand how ephemeris and almanac retrieving work.
I make fix cycles in Startmode "0".
- Start module.
- Send "engine 3" to start GNSS.
- After 35s I receive "Engine OK". What happens during that time ? is this the treatment for Almanac/Ephemeris ?
- After few time I received a position.
- I send "Engine 0" to stop GNSS.
- Finally, switch off module with "AT+SMSO" command.
When device is switched on again (without losing power supply, just switched off), Almanac and ephemeris are retained and used for next fix ?
I've seen, if SIM is inserted time taken to receive "Engine OK" is variable ( < 35s).
Thanks for your help.
I think that this time to get OK may depend on the settings - "Engine/StartMode" - if GpsOneXTRA assistance data is used - in that case the startup procedure includes connection to NTP server and then to XTRA server and downloading of the assistance data if necessary. So data connection is used here before the GNSS engine is started.
After it starts the receiver should be able to use Almanac and Ephemeris data if still valid - Ephemeris data is valid for up to 4 hours and it takes 30 seconds to download it from the satellite; Almanac data is valid much longer but it takes 12.5 seconds to download it.
I use the setting "Engine/startmode : 0", there is no GpsOneXtraAssistance. That's why I don't understand why the SIM has an impact.
Do you think a switch off of the module will delete the ephemeris/Almanac in the memory ?
If I switch on the GNSS engine it returns OK quite fast - I can't observe the problem that you describe.
The module should keep Almanac and Ephemeris data.
Could you also paste the ATI1, AT^SGPSC? and AT^SCFG? commands replies?
Below, the start procedure used from Switched off to Start engine :
The text editor changed "Mo-de" by "****".
Gemalto is switched off between two fix.
Please provide AT^SGPSC? and AT^SCFG? replies without '=' sign to show the current configuration. With '=' sign you just list the possible values which does not bring anything.
As for the ATI1 value the firmware seems to be already quite old. It would be also good to update to the latest version to exclude any potential problems which might already have been fixed in the later releases. Please contact your local technical sales for the firmware.
Sorry for the mistake.
Thank you for the outputs. I have the same settings for some of the relevant parameters and do not observe such behavior. I noticed that you disabled all NMEA outputs and left only the URC. But even with such settings I get the OK reply in 2 seconds.
This module does not allow for concurrent LTE and GNSS operations - but you have "MEopMode/RscMgmt/Rrc" set for 'GNSS preferred' which is OK. What you could try to check is if the module is registered to 4G and compare if it is the same if you force 2G (with SXRAT command).
And please try the latest firmware.