Chris,
How does the USCG know it was your vessel sending the DSC? Not trying to be a smart guy. Obviously I don't know how this system is supposed to work. I did find some info on DSC (see link below) and I'm a little smarter now. But still not clear as to how they would know it was your vessel and not your next door neighbor's. I’m assuming the signal is generic with some kind of encryption (registration) code unique to your radio?
Digital Selective Calling - USCG Navigation Center
Thanks,
Wayne