🔍 Key Concepts

• Meaning of NBDP in GMDSS communications • What TELEX is used for in maritime radio systems • Difference between simplex and duplex communications

💭 Think About

• Ask yourself: In GMDSS data systems, are we dealing more with voice (telephony) or text/message circuits? • Think about what part of the phrase the acronym NBDP (Narrow Band Direct Printing) describes: is it printing spoken words or printed text messages? • Consider which of the options correctly matches a system designed to send written messages over HF/MF radio

✅ Before You Answer

• Verify whether SITOR/NBDP is associated with telex-style text messaging rather than voice calls • Check if the system works primarily in simplex mode (one direction at a time) or full duplex (both ways at once) • Confirm that the correct wording matches the idea of a simplified telex-over-radio data service, not a voice telephone service