I read in the AGPS Application Guide that a correct time is very important for EPO.
- How high must the accuracy be? How far can the time vary?
- If I manually set the time with AT+CCLK="…", then turn off GNSS and turn it on again, is my manually time pushed to the GNSS part or is there another, internal time sync?
To be sure everything is correct in my procedure:
- Turn off GNSS (with AT+QGNSSC=0)
- Wait for time sync (until “+QNTP: 0” received)
- Set Reference Position
- Enable Epo
- Turn on GNSS
Sorry for the late response.
1, The time accuracy should be less than +/- 3 seconds.
2, for the 2nd question and your flow chart, I need to confirm internally and get back to you next Monday. You could refer to the attached documentation firts.
Quectel_MC60&MC90_GNSS_Protocol_Specification_V1.2.pdf (556.2 KB) Quectel_MC60&MC90_AT_Commands_Manual_V1.3.pdf (1.6 MB)
This command, AT+CCLK="…", is used to sync time of MC60 GSM part (not the GNSS part) and it won’t change return value of command “AT+QGNSSTS?”. The precondition is that there should be an extra RTC to provide exact time. You can use that command to replace time synchronization part of the whole operation process.
BTW, attached the correct documantation.
Quectel_MC60&MC90_GNSS_AGPS_Application_Note_V1.2.pdf (607.1 KB)