"Paul Keinanen" wrote in message
news
On Fri, 30 Jan 2004 02:05:19 -0000, (gudmundur)
wrote:

Is the 100khz Loran C signal useable while submerged? Do to it's
long wave nature, does it penetrate the surface to any depth beyond
a few feet?

Losses are about 10 dB/m at 100 kHz.

Paul


The U.S. uses VLH to "communicate with submerged submarines on at
frequencies of 3-30 kHz" (http://www.fas.org/nuke/guide/usa/c3i/vlf.htm).
The data rate is 50 baud but it must work - there are Trident ballistic
missile subs waiting for launch orders on the receiving end.
The depth and receiver characteristics are likely classified.