🔍 Key Concepts

• International distress frequencies used historically for radiotelegraph (Morse) versus radiotelephone (voice) • Difference between kHz (kilohertz) and MHz (megahertz) bands in maritime communications • Role of the medium frequency (MF) band in traditional maritime distress signaling

💭 Think About

• Think about which frequency was famously associated with early 20th‑century SOS traffic and classic Morse distress calls at sea. • Among the listed options, which one falls in the traditional MF maritime distress band long used before satellite GMDSS systems? • Recall whether the historic maritime distress frequency was closer to the middle or the edges of the 300–600 kHz range given in the choices.

✅ Before You Answer

• Confirm that you are thinking about radiotelegraph (Morse), not radiotelephone (voice) or VHF DSC. • Verify which of the given values was internationally recognized as the primary MF distress and calling frequency for shipboard Morse sets. • Double‑check that the frequency you choose matches what is often mentioned in classic sea stories and historical accounts of SOS signals.