Re: Got one - distance calculator

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From: Ronald C. McConnell (rcmcc@earthlink.net)
Date: Wed Aug 22 2001 - 10:02:17 CDT


Hi, Phil,

I'm catching up on qrp-l reading.

  http://www.indo.com/distance

that you found is the best web great
circle calculator of which I am aware.
There are other good ones like Ed Williams's

   http://www.best.com/~williams/gccalc.htm

For the best introduction to great circle
navigation with worked out examples, see Ed's

   http://www.best.com/~williams/avform.htm

If you want to "roll your own" with logging on,
my freeware great circle, lat&long/grid, MUF,
miles/Watt, etc.,
DOS command line program GCGC

   http://home.adelphia.net/~nj2dx/hoarc/gcgc9900.zip

may do what you want. It works in a DOS window,
and on HP 95 and Poquet PC DOS palmtops.
It has the US NGS forward and inverse
ellipsoidal earth model routines built in.
My main addition is a more usable interface.
(The filename is "9900," but is actually
the 2001/01 0r "0101" version.)

Unzip it into a new directory.
Skim file "read1st.txt" and "d2gread.txt."

Then a DOS command (in a DOS window) in a format like

  g lat1 long1 lat2 long2

or with real #s (degrees and minutes here for example)

  g 40 46.9 n 74 41.4 w 53.5 n 0 e

will calculate between my house and (near) London.
The lat/long/grid input format is pretty forgiving.

   40 46 54 n 74 41 24 w
   w 74.6900 n 40.7817
   n 40.7817 w 74 41 24
   fn20ps
      etc. all work

If you store your lat/long as the first
(or only) line of ASCII text file "home.dat"
using Notepad or other text editor, then

  g + Cyprus p 3.2

will work between your house and Levkosia
and calculate miles/Watt for 3.2 Watts.

For forward calculations a DOS input line like

   g b 127.3 d 675.4

will calculate the lat/long from your coordinates
in home.dat for a point at a true bearing
of 127.3 degrees and 675.4 miles.

   g 675.4 k 127.3 d

also works. (Use "k" instead of "d" for km)

GCGC also calculates magnetic bearings using
the World Magnetic Model with 2000-2005 parameters.

I have plans for a Linux version of GCGC.
The source compiles. I just need to translate
the "g.bat" command into bash syntax
when I can get access to a Linux machine again.

Have fun.

Cheers, 73,

Ron McConnell
w2iol@arrl.net


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