As far as I can tell from the Thunderbolt documentation the location is
reported in WGS84 coordinates.
One then has to correct for the Geoid separation to get height above MSL.
My thunderbolt reports an altitude of +65m whereas google earth and my
M12+T both report a height of +43m.
Bruce
Bruce Griffiths wrote:
For more detail see:
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA407319&Location=U2&doc=GetTRDoc.pdf
<http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA407319&Location=U2&doc=GetTRDoc.pdf>
Bruce
Bruce Griffiths wrote:
More accurately (pun intended) the GPS receiver first calculates the
height above the ellipsoid that approximates the earth's surface and
then uses a geoid separation table to calculate the height above MSL.
Due to storage constraints the geoid separation table may necessarily
be inaccurate.
Bruce
John Miles wrote:
That graphics library is 95% post-consumer fiber at this point. :(
It's
good for rapid development and porting work but as you can tell it's
pretty
rough around the edges.
Every time I run a survey on a Thunderbolt here, it seems to want to
find
itself at the bottom of the lake. Bruce pointed out in an email
that what
GPS considers "altitude" isn't necessarily the same as what terrestrial
mapmakers mark as sea level, so maybe that's what's happening.
-- john
-----Original Message-----
From: Mike Naruta AA8K [mailto:[email protected]]
Sent: Wednesday, December 09, 2009 4:12 PM
To: John Miles; [email protected]
Subject: Re: [time-nuts] Lady Heather's Fat Client
Oh, I thought it was my PC.
Neat John, we like recycled code.
The KE5FX remote access is fun too, works well.
I'm surprised that your antenna receives so well,
being at -7.6 m. Doesn't it get wet?
(I know; I'm just trying to be funny)
Mike - AA8K
John Miles wrote:
Hi, Mike --
Correct, that's not a bug, and it won't change unless/until the
program is
rewritten with a new graphics library.
In fullscreen mode there's no window border, so the 1024x768
display surface
can accommodate the 1024x768 client area. When you hit F11 to
go back to
windowed mode on a machine with a 1024x768 desktop, there's no
room for the
window border and caption bar that surrounds the client area, so the
graphics system has to downsample the client area to fit.
Back when the graphics library was written, in an era when 33
MHz processors
were still common, it was much faster to downsample by factors
of two than
to incrementally shrink the image to fit. So you will always
get the tiny,
cramped display window in cases where you request a resolution in
window
mode that can't fit on the desktop.
-- john, KE5FX
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