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time setting command line options

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time setting command line options

Postby mhab » Mon Mar 16, 2015 10:34 pm

Hello

As I recently tried to understand time settings in FG I came across what seems to me to be a documentation BUG.

In Wiki it says about time options:

Code: Select all
  --time-match-real            Synchronize time with real-world time
  --time-match-local           Synchronize time with local real-world time

Whatever the difference between "real-world time" and "local real-world time" is :roll:

In manual it says (a bit more eloquent):

--time-match-local, --time-match-real
--time-match-real, is default: Simulator time is read from the system clock,
and is used as is. When your virtual flight is in the same timezone as where
your computer is located, this may be desirable, because the clocks are synchronized.
However, when you fly in a different part of the world, it may
not be the case, because there is a number of hours difference, between the
position of your computer and the position of your virtual flight.

The option --time-match-local takes care of this by computing the timezone
difference between your real world time zone and the position of your virtual
flight, and local clocks are synchronized.

Good explanation, but simply put: It is just the other way round ...

Here is what I experience in FG 3.4

My system clock is set to middle Europe (GMT+1) 23.00h
I choose Grand Canyon (USA South West) as airport
I choose default time setting option: --time-match-real

and what I get is: Simulation time after startup is 16:00, which matches the time of the airport, and is the real time at the airport of choice

If I startup FG with --time-match-local the time in sim matches my local system time, NOT the local time at the airport of choice.

Can somebody confirm what I describe ? I hope so.

Mike-DE
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Re: time setting command line options

Postby wkitty42 » Tue Mar 17, 2015 1:06 am

i use time-match-local and so far everything has been right except that now zulu time is off by an hour... i think i can agree with your statement that they are backwards but it gets confusing at times... yeah, i've written time code in the past and it was confusing then, too... especially when it came to choosing the proper timezone nomenclature as one format puts you on one side of zulu and the other puts you on the opposite side...
"You get more air close to the ground," said Angalo. "I read that in a book. You get lots of air low down, and not much when you go up."
"Why not?" said Gurder.
"Dunno. It's frightened of heights, I guess."
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Re: time setting command line options

Postby mhab » Tue Mar 17, 2015 6:55 pm

Hello

I changed the Wiki http://wiki.flightgear.org/Command_line_options#Time_Options to:

Code: Select all
   --time-match-real            Synchronize time with current time at chosen airport
   --time-match-local           Synchronize time with system time of computer


Mike-DE
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