[extropy-chat] Worldwide SOS system

[Dan Clemmensen]

Emlyn proposed a system with the following characteristics:

"transmitter" fits in a one-gallon container and has a very long shelf life.
Receivers are in orbit.
Rugged, robust, dead simple.

I think we need to add: satellites must be cheap and offer coverage in a 
short time,
preferably less than two hours.

Sorry, Emlyn, but radio can do all of this for a lot less money than
satellite imagery.

Use a highly simplified radio that is designed to broadcast at a low bit 
rate in
a narrow bandwidth. This yields a high Eb/No (energy per bit) even with low
power. The assumption is that there are only a few transmitters at any 
given time. in
any particular part of the world,

You can get arbitrarily long shelf life for a simple battery. For 
example. use a
lead-acid battery, but keep the acid in a separate sealed container 
until you need to
use the radio. You can get a lot of energy in a half-gallon container. 
The radio would
be detectable from simple satellites for at least two days after you 
pull the tab. The
satellite would notify the emergency response team, which would fly over 
the area
to localize the transmitter. No need for GPS, cell phone, or even 
primitive AM radio,
I think the emergency transmitter including container, battery, and 
acid, could cost
less than $20.00,  Add GPS, FM receiver, AM receiver for less than an 
additional $30.00,
and a transponder system (to speed up localization after the response 
team gets to the
area) for an additional $10,

Fifty satellites at $100,000 each would give great coverage and would be 
cheaper than
a one satellite that is capable of the imagery your system requires.