🔍 Key Concepts

• Digital Selective Calling (DSC) basics and what it is used for in GMDSS VHF/MF/HF radios • Difference between emission designators (like J3E, J2B, F1B) and error detection/coding in digital signals • How DSC calls are structured to make sure messages are received correctly

💭 Think About

• Which of the options refers to an error-detecting code versus a radio emission mode? • Think about what is needed to make sure digital distress and safety messages are received without confusion or corruption. • Ask yourself: does DSC need a specific voice mode, a specific data mode, or a specific coding method to protect the information?

✅ Before You Answer

• Identify which choices (A, B, D) are emission modes (look up what J3E, F1B, J2B mean) and which choice is not an emission mode. • Confirm what kind of modulation/emission class is actually used by DSC on VHF Channel 70 and MF/HF DSC frequencies. • Verify how DSC messages are made robust against errors (look up if they use any error-detecting code or redundancy).