GNSS XTRA File - Startup Infos

Hello Forum,

We use the BG600L-M3 with GNSS for a Long-Time-Tracker
The XTRA function is really very convenient!

But I wonder: As I remember for (older) A-GPS the Time AND a (rough) Location (ca. 50km?) was required.
Now, with XTRA only Time (via “AT+QGPSXTRATIME”) is OK? What happens, if the devices has moved a longer distance (e.g. 500km) between two GNSS requests but XTRA file might still be valid (Modem is sleeping/switched off between)?

(Remark: We have the chance to get a rough position, because after wake-up always the Server is contacted first (knowing the cell tower position) and synchronising the Loggers Time, then GNSS is started (only optionally to save power)).

Thanks and kind regards,
Jo (Joembedded.de)

you are right , if the gps want to hotstart , it needs to know four variables, ephemeris/almanac/ time and old position,

In fact , the Xtra file include ephemeris and almanac for next 3 days .
if the module does not move long distance ,and restart to locate in 2 hours , the GPS will do hotstart.
if the gps have move a long distance , The relocation interval is in 2~6 hours , the module will do warmstart .
if the relocation interval is greater than 6 hours , the module will do cold start.

You know , if the module has downlaod the Xtrafile in BG660L , it will try to do warmstart , instead of coldstart .

Hello Stephen,
thanks for the infos! That is very interesting to know, that <2 hours + XTRA will give hotstart.
But, do you think there will be any chance to also inject rough position, because it is easy to get via Cell-IDs? And could save a lot of power.
Best regards, Jo

(BTW: I think it might always interesting to know about end products: here it is a LowCost data logger for scientific use (Global Climate Change):
image
It has some internal sensors (T/rH, Baro, IMO), but mainly designed for external SDI-12 sensors (with open architecture (more infos on my github: JoEmbedded). And I am really happy about my decision to use Quectel (customer originally wanted to use another manufacturer). Congratulations for the excellent BG600L-M3!)

Sorry for the inconvenience , up to know , there is no AT or API for injecting location info。

In the scenario of <2 hours + XTRA , the module will do hotstart ,and use the last position saved in module .

Do I understand correctly, that after 6 hours there will be cold start even if correct XTRA data are uploaded? Will XTRA data help in this case to shorten TTFF?

Hello Andrey,
did you find a solution? I used the BG600-GNSS for a product, but for another product the current consumption is too high and Mobile Network is rare there. So the customer considered using an L86-GNSS-only module as preferred GNSS-Source (uses 5-20mA (FLP-Mode) instead of BG600 with ca. 60mA) . I saw in the docus, the L86 now supports Assisted GPS. Could be an interesting alternative. If you are interested, maybe we could cooperate for some technical details? I have a lot of drivers for Quectel (Modem and GNSS) and CPU is any module of NRF52 with BLE. I also have BLE drivers for JS and .NET (C#) (See JoEmbedded Github)…
Best regards, Jo