";
if ($fof2x>-1)
{
$fof2=$fof2x;
$timeF=$time;
}
if ($hmf2x>-1)
{
$hmf2=$hmf2x;
$timeH=$time;
}
if ($fof2<1) $fof2=1;
if ($hmf2<1) $hmf2=1;
$freq=6.925;
if ($freq<$fof2)
{
$skipZone=0;
// print "skip zone is zero
";
}
else
{
$skipZone=2.0*$hmf2*sqrt(($freq*$freq/$fof2/$fof2)-1);
}
$skipZoneMiles = floor($skipZone/1.609344);
//print "$time Skip Zone: $skipZoneMiles mi
";
}
if ($fof2<1) $fof2=1;
if ($hmf2<1) $hmf2=1;
//print "fof2: '$timeF' '$fof2'
";
//print "hmf2: '$timeH' '$hmf2'
";
$freq=6.925;
if ($freq<$fof2)
{
$skipZone=0;
// print "skip zone is zero
";
}
else
{
$skipZone=2.0*$hmf2*sqrt(($freq*$freq/$fof2/$fof2)-1);
}
$skipZoneMiles = $skipZone/1.609344;
//print "$freq MHz Skip Zone: $skipZone km, $skipZoneMiles mi
";
$freq=6.300;
if ($freq<$fof2)
{
$skipZone=0;
}
else
{
$skipZone=2.0*$hmf2*sqrt(($freq*$freq/$fof2/$fof2)-1);
}
$skipZoneMiles = $skipZone/1.609344;
//print "$freq MHz Skip Zone: $skipZone km, $skipZoneMiles mi
";
$freq=7.850;
if ($freq<$fof2)
{
$skipZone=0;
}
else
{
$skipZone=2.0*$hmf2*sqrt(($freq*$freq/$fof2/$fof2)-1);
}
$skipZoneMiles = $skipZone/1.609344;
//print "$freq MHz Skip Zone: $skipZone km, $skipZoneMiles mi
";
//2012 01 31 2145 7.9 -1 3.33 3000 210 96 7.2 295 8.6 -1.0 1.9 105 2.1 -1.0 17.3
//2012 01 31 1700 9.6 235 3.30 3000 212 -1 8.8 310 10.2 4.3 3.0 95 4.1 -1.0 -1.0
?>
Predicted 6925 kHz Skip Zone For Boulder, CO
This is a graph of the predicted skip zone for 6925 kHz, based off ionosonde data from Boulder, CO
available here: http://legacy-www.swpc.noaa.gov/ftpdir/lists/iono_day/Boulder_iono.txt
Predicted 6925 kHz Skip Zone For Wallops Island, VA
This is a graph of the predicted skip zone for 6925 kHz, based off ionosonde data from Wallops Island, VA
available here: http://legacy-www.swpc.noaa.gov/ftpdir/lists/iono_day/Wallops_iono.txt
The skip zone is the area around a transmitter site where radio waves are not reflected by the ionosphere back to Earth.
listeners inside the skip zone cannot receive the signals (or they are extremely weak).
The diameter of the skip zone can be estimated based on the strength and height of the ionosphere.
For detailed information regarding how this is calculated, see NVIS Near Vertical Incident Sky Wave.
Charts are available for:
Boulder, CO
Wallops Island, VA
";
?>