That's right; that's good DR'ing - ded reckoning; gives you Probable
Position (PP); add a sun line to it and you get a Most Probable Position
(MP - a little better than just DR), but still not a Fix (known position).
Cross a sun line with a bearing from another object of known location (star
or earth-bound object) and one can get a Fix (know position). Course, in an
earth-bound vehicle, one can usually look out the window at a known
object/address and get a Fix - sometimes not possible if ya don't recognize
what you're seeing. ;<)
Wilton
----- Original Message -----
From: "Tim Crone" <bb...@crone.us>
To: "Mercedes Discussion List" <mercedes@okiebenz.com>
Sent: Monday, July 01, 2013 10:52 AM
Subject: Re: [MBZ] I think I need this
On Sun, Jun 30, 2013 at 11:19 AM, Mitch Haley <m...@voyager.net> wrote:
WILTON wrote:
OK, I saw the key two words the second time I read it - "in part." Sun
can give you only ONE "line of positions" (LOP) - a huge circle on the
earth; ya gotta know about where ya are for this info to be any good, i.
e.
- dead reckoning (RD), for example - projecting info from last known
position to reckon/guess present position. Using old info plus sun LOP,
you can reckon/guess a "most probable position" MPP - lot better than
nothing and is "neat," anyway - handheld astrotracker. Now, if it could
track stars --. ;<)
Well, if you know the time, date, and position of the sun...
I can imagine the car knowing the time and date to some fraction of a
second, but would it know the angle of the sun well enough to locate
itself
within 200 miles or so?
When you lose your GPS signal, you:
- know where you are "right now", including time, trajectory, and speed
- know where the sun is, including which direction it is
- know what time it is and where the sun is headed relative to your exact
location
Seems like it would be trivial to calculate, from light monitoring, which
direction the car is turning; you still know speed and time, so it seems
like it would be fairly simple to calculate a reasonably accurate course.
That said I've never lost GPS when I was in a place where the sun was
visible.
Best,
Tim
no LORAN in cars?
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