This program allows both great-circle (polar) and
rectangular projections of the world. The great-circle
map is centered on any specified latitude and longitude
(the "home" location). The rectangular projection is
shown with the home longitude in the middle of the screen.
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The home location can be specified by either a direct
entry into a textbox or by using a pulldown list of
over 3200 sites around the world.
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Similarly, a target location can be specified
directly, by using another pulldown list or by entry
of the Maidenhead grid data into a textbox.
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The home and/or target locations may also be entered
by selecting the rectangular projection and left-clicking
on a location to instantly specify a home location, or
right-clicking on a location to instantly specify a new
target location.
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The target location may be entered on either the polar or
rectangular projection by clicking on List Calls and then
selecting a prefix.
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The current sun location along with the terminator are
(optionally) shown on both projections. An Offset input
allows correction for daylight savings or half-hour time
zone correction.
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The path from the home location to the target location is
shown on both the polar plot and the rectangular plot.
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Text data files for an antenna pattern can be overlaid onto
both the polar and the rectangular plots; pattern size is
adjustable. "Rings" showing gain referred to the azimuth
of maximum transmission and 3, 6 and 12 dB below that point
can be toggled on and off.
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The size of the plot in terms of kilometers can be stepped
by pressing the "Closer" or "Farther" buttons.
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A compass with lines at 10 degree intervals can be overlaid
on the display. This can be toggled on and off using the
"Compass" button.
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A set of rings showing distance in 1000 km intervals can
be overlaid on the display. This too can be toggled, by
using the "Distance" button.
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The resolution of the on-screen plots can be adjusted over
a wide range. This allows quick screen update even on a
slow computer, or higher-quality presentations at the expense
of an increase in plotting time. The output from the printer
is always at the highest resolution.
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The output to the printer is from a separate routine
which closely duplicates the output as seen on the screen, but
of course without pixelation. To send a plot (polar or rectangular)
to the default printer just press the "Print" button.
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If the home location is within the contiguous United
States, and if the size is set so that the map covers
mostly those states, then the map shows the state
boundaries as well.
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On exiting the program the current parameters are stored
for an easy restart.
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The plotting routines really need a fast computer. Using
a fast computer allows good screen resolution within a
reasonable time frame. Slow computers take longer to
re-plot the screen for a given resolution. Plotting
resolution is adjustable over a wide range.
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