From: Robert J. Bradbury (bradbury@www.aeiveos.com)
Date: Tue Feb 01 2000 - 14:43:31 MST
On Tue, 1 Feb 2000, KPJ wrote:
>
> NOTE: The terran atmosphere absorbs many wavelengths. Would it absorb so
> much more of the microwave radiation than of the lasered human visible
> light that the above analysis fails to give a result which matches the
> real world?
>
The terran atmosphere is pretty good for microwave (most radio in fact),
visible and some UV. Where it is terrible is in the infrared region.
(Which is why you need to go into space to do good IR astronomy).
The transmission of microwaves (including most GHz range radio),
as well as visible is impacted to a fair degree by the quantity
of water in the air. Thats why my DBS satellite disk drops data
when it rains too much in Seattle.
AT&T pulled a neat rabbit out of its hat recently with the line-of-sight
laser transmitters with very high bandwidth. Apparently these even
work in the rain, albeit with some data rate reduction. If the cost
of these gets low enough I'd pay to install one between my house and
an ISP and tell my ADSL supplying Telco where they can put their
copper rental fees...
Robert
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