Hey Jeff:
Those stations you hear that are reading out random sounding letters and
numbers have been labelled as "spy stations" or stations that are
transmitting coded information to in the field operatives, from embassies
located in different parts of the world.
They have been tracked to US, british, Canadian and other western countries
embassies located around the world.
I know, this sounds kind of Tom Clansy conspiracy theory stuff, but it
actually seems legitimate.
If you look up the Kornette project on the internet, you may find out more
information then what i have given.
Apparently, the numbers and letters, though random sounding, are used to
decode portions of common novels that can be bought anywhere in the world.
The operatives have a pre designed cypher in their heads, which is used in
conjunction with the letters and numbers they receive via short wave, and
the novel.

Apparently, this is done so that if they are ever identified or caught, all
they will have is a short wave radio and a book to read and no vital data or
saved images from a satelite feed.
I would have thought in this day and age of incripted satelite
communications and so on that this sort of short wave activity would have
gone out with the cold war...but apparently, it is still one of the most
secure methods of getting information to operatives in foreign countries.
73
Colin, V A6BKX