BG95: XTRA feature questions

Hello,

I’m trying to reduce the time to first fix on the BG95 by using the XTRA feature. Although it basically works as described in the GNSS application note I’ve got several questions regarding QGPSXTRATIME that, I think, are not answered in the application note or in the forum explicitly.

Firmware Version: “BG95M3LAR02A04_01.002.01.002”

  1. I observed that even when AT+CCLK returns a valid and (as far as i can tell) correct timestamp, the XTRA time still is unset. So is the RTC not used as “automatic time source” for XTRA (with PSM enabled)?

  2. I observed that right after a power cycle or when the BG95 was shut down QGPSXTRATIME always contains a (as far as i can tell) correct XTRA time. Could the reason be that during startup the XTRA time is updated from network? In contrast to this, when waking up from PSM QGPSXTRATIME is always unset. This is rather unfortunate, as we use PSM a lot. Is there an issue with QGPSXTRATIME when PSM is used?

  3. When PSM is used and QGPSXTRATIME is unset initially (as described in 3.) QGPSXTRATIME seems to be updated automatically right, when a RMC sentence that contains a timestamp is output on the GNSS UART. Is this just by accident or is the GNSS time used as “automatic time source” for XTRA?

  4. Are there any additional “automatic time sources” for XTRA?

If you need more information or something is unclear im happy to provide further information.

Best regards,
Sebastian

Is there something not clear with the question? I’d be happy to provide further information if necessary.

@Isaac.Wang-Q maybe you got some information?