Meteorburst radio might be a little helpful (Score 1)

May have missed it in this thread but I have not seen any reference to "meteor burst" radio.

Definitely not good for much data but for basic signals (like "keep-alive" signals) this technology has worked for years. I work for a scientific field station and we hope to use this stuff in areas for limited data communications in areas that cannot "see" the southern horizon.

Meteorcomm is one firm that does this stuff. There may be others as well...I do not know. (I do not work for MeteorComm but have visited them and they seem to be good folks.)

http://www.meteorcomm.com/technologies/tech_burst.aspx

(from their website) "meteor burst communications system (MBCS) uses ionized meteor trails as a means of radio signal propagation. These trails exist in the 80 to 120 km region of the earthâ(TM)s atmosphere, and reflect the RF energy between two stations. The height of the trails allows over-the-horizon communication at distances up to 2000 km. However, because the ionized trails exist for only short periods of time (usually from a few milliseconds to a few seconds) communication is intermittent, and high-speed digital transmission techniques must be used to convey the information. The system is particularly well suited for long-range, low data rate applications for both messaging and data acquisition."

hope this helps this thread ....