[LoBlo]

I've always wondered about it as well. I remember reading somewhere (a while back so I don't know where) that subs can link to satellites with "directional" transmission (sorta like direct TV I'm assuming, unless someone corrects me) so that they can point their signal to the satellite receiver they want to make it harder for their transmission to give away position.

That being said... I'm sure its still possible for a fairly techno-capable enemy to somehow detect the transmission... either by backscatter of the noise of transmission or by its own spysats picking up some of the radiowave scatter off the atmosphere that will probably, at least roughtly, give the sea/ocean where the transmission is coming from if not greater.

These are all just assumptions of course given what is capable with modern technology seems reasonable.

I've always wondered if some sorta of ultra-refined "Laser Communication" exist where a sub can litteraly point a very fine laser at one and only one satellite that no one else can pick up (an example of how it would work would be a laser pen light, you can't see where the laser came from, only the reflection of where it hit). Intuitively hat would be a secure way to communicate, but would probably be very heavily dependent on atmospheric conditions.