Wrong log file time with BRD_RTC_TYPES = MAVLINK_SYSTEM_TIME

Good day!

Prerequisite:
There are lot of the information regarding time when GPS in use, but I couldn’t find anything when
BRD_RTC_TYPES = MAVLINK_SYSTEM_TIME. That’s why I’ve created this topic.

Request:
I want to make my ardupilot takes the date and time from GCS or from MAVLink message and use this data in log files.

Pain:
When I use SYSTEM_TIME from QGC or sent via mavlink,the date and time in log file is 1970-01-01 03:01:27 … and so on…

What has been done:
First of all, I set the BRD_RTC_TYPES to MAVLINK_SYSTEM_TIME only.

In first case i run flight controller and then QGC. In this way QGC sends its date and time which I can observe in MAVLink inspector under SYSTEM_TIME message.

In second case, I run QGC and then flight controller. In this way flight controller doesn’t have any chance to receive date and time from QGC and SYSTEM_TIME is 0. Then I run my python code, where from I send SYSTEM_TIME. After this, SYSTEM_TIME in MAVLink inspector shows corresponding date and time.

But. In both cases, log file contains wrong date and time as it was mentioned above.

Also, I tried to do it in SITL.
But, in SITL, in log file the date and time correct even if I disable GPS and SYSTEM_TIME is 0…

I am really struggling with it already several days…
What I have missed ?

found out that, if in SITL, specify SIM_GPS_TYPE parameter as “None”, in log file the date will be also “1970-01-01…” while SIM_GPS_DISABLE is 1, BRD_RTC_TYPES indicates as MAVLink and SYSTEM_TIME in MAVLink inspector is correct…

suppose, log datetime comes only if we have necessary number of satellites in spite of that the SYSTEM_TIME comes from MAVLink…at least for ArduPlane