Can you make ship to shore communications using a duplex channel?

In maritime communications, a duplex channel allows simultaneous transmission and reception of signals, which is vital for effective communication. However, for ship to shore communications using a duplex channel to be successful, both the ship and the shore station must be equipped with compatible duplex equipment. This means that if a ship transmits on one frequency, the shore station must be able to receive on another designated frequency that corresponds to the ship’s transmitting frequency.

Having a sister duplex channel ashore is critical because it ensures that both ends of the communication can operate simultaneously without interference. If the shore station does not have a matching duplex channel, it would not be able to receive the communication while the ship is transmitting, leading to a failure in establishing effective communication.

Therefore, without the appropriate equipment or channel agreement on both sides, ship to shore communication through a duplex channel is not feasible. This is why the option highlighting the necessity of having a sister duplex channel at the ashore radio is the most accurate explanation of the scenario.