🔍 Key Concepts

• Duplex vs. simplex operation in marine VHF communications • Role of the International Telecommunication Union (ITU) in assigning marine radio channels • Difference between frequency pairings and specific channel number ranges

💭 Think About

• Think about what makes a channel "duplex" rather than "simplex" in terms of transmit and receive frequencies. • Ask yourself: Does "ITU channel" describe a specific list of numbered channels, or a way those channels are organized and standardized? • Consider whether duplex ITU channels are mainly intended for ship-to-ship, ship-to-shore, or a more general/common use.

✅ Before You Answer

• Verify what duplex means: same frequency both ways, or one frequency to transmit and another to receive? • Confirm that ITU deals with international standards and frequency allocations, not just one nation’s channel numbering scheme. • Check if a duplex ITU channel is defined by a pair of frequencies and whether its primary purpose is only ship-ship or broader/common use.