Which frequency/mode is authorized for use...

🔍 Key Concepts

• Maritime Safety Information (MSI) broadcasts and which GMDSS systems/frequencies are reserved for them • Difference between FEC (Forward Error Correction) and ARQ (Automatic Repeat reQuest) modes in narrow-band direct printing (NBDP) / radiotelex • Distinction between distress and calling frequencies versus information broadcast frequencies in the MF band (around 4 MHz)

💭 Think About

• First decide: For international MSI broadcasts (like NAVTEX or HF MSI), is the transmission typically one-way to all ships, or a two-way, acknowledged link? How does that affect whether FEC or ARQ is appropriate? • Look at the specific frequencies: which one (4125 kHz or 4209.5 kHz) is normally associated with distress/voice versus data/telex services in the MF/HF maritime bands? • Ask yourself: If all ships worldwide must be able to receive MSI simultaneously without setting up an individual connection, which mode and type of frequency best fits that requirement?

✅ Before You Answer

• Verify which ITU HF MSI frequency around 4 MHz is assigned for NBDP safety broadcasts (not voice distress) • Confirm whether ARQ is used primarily for individual ship–coast links that require acknowledgments, or for general broadcast to all ships • Check if 4125.0 kHz is designated internationally as a distress and calling frequency for radiotelephony (voice), not primarily for MSI telex broadcasts

Which frequency/mode is authorized for use internationally for Maritime Safety Information transmissions?

4209.5 kHz using FEC mode

4209.5 kHz using ARQ mode

4125.0 kHz using simplex mode

4125.0 kHz using FEC mode

🔍 Key Concepts

💭 Think About

✅ Before You Answer