NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Choice of timepiece
From: Lu Abel
Date: 2009 Nov 13, 19:30 -0800
From: Lu Abel
Date: 2009 Nov 13, 19:30 -0800
A graduate electrical engineer would note a few things:
1. The speed of light (185,000 mph, 163,000 kts, 300,000 km/h) is for a vacuum, the speed of light in air is slower -- but only a bit slower.
2. Yes, SW signals must bounce off the ionosphere to propagate around the earth. But the part of the ionosphere that short wave signals bounce off is only about 100 miles high. The zig-zag path is indeed longer -- but not that much longer.
As noted in my previous email, I misplaced the decimal point.
Anabasis75@aol.com wrote:
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1. The speed of light (185,000 mph, 163,000 kts, 300,000 km/h) is for a vacuum, the speed of light in air is slower -- but only a bit slower.
2. Yes, SW signals must bounce off the ionosphere to propagate around the earth. But the part of the ionosphere that short wave signals bounce off is only about 100 miles high. The zig-zag path is indeed longer -- but not that much longer.
As noted in my previous email, I misplaced the decimal point.
Anabasis75@aol.com wrote:
It doesn't go in a straight line, it bounces.JeremyIn a message dated 11/13/2009 8:29:57 P.M. Eastern Standard Time, jhkarl@att.net writes:
LU,
Why would it take almost a second for a radio signal to travel half
way around the earth when it travels at 163,000 nautical miles per
second?
JK
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