What are Radio telephony Procedures as per GMDSS?

Duplex and simplex mode of R/T operation.

• Simplex operation is used for :-
  1. All stations broad cast, distress urgency, safety and    routine call and reply.
  2. Ship to ship communication.

Note :-

In simplex mode one frequency is used for transmission and reception. ex :- CH – 16 2182 kHz.

• Duplex operation used for :-
  • Ship to coast station. (CRS)
  • Public correspondence using paired frequency.

Note :-

In Duplex mode transmission and reception are simultaneous using two different frequency so that it is just like normal telephonic conversation.

Points to remember:-

Radio telephone calls, may also be made on semi – simplex/ duplex mode where one end uses simplex and other end uses duplex.