"Pascal" wrote in news:1145139514.303678.7110
@u72g2000cwu.googlegroups.com:

The frequency os AIS can change at every country?



No, it's the same. My mistake. In the USA, one of the channels was a
duplex pair used by the old marine telephone operators so its either 87a or
88a, I forget which, which designates it as a simplex frequency (one
frequency transmit and receive so AIS will work). The whole VHF bandplan
across the planet is stupidly laid out and way out of date...