🔍 Key Concepts

• Old radiotelegraph distress procedures and how the auto-alarm was used to wake up unattended receivers • Relationship between the auto-alarm signal and the timing of the actual distress call on 500 kHz • Why a short pause was needed: to give operators time to man watches and clear the frequency

💭 Think About

• Think about why the auto-alarm signal was sent first: what did it need to accomplish before the distress call could start? • How much time would be reasonable for radio operators on different ships to reach their sets and prepare to copy the message? Too short, reasonable, or excessively long? • Which of these times best balances speed in an emergency with giving enough time for ships to respond and listen carefully?

✅ Before You Answer

• Verify what the international auto-alarm signal was used for in traditional MF distress (500 kHz) systems • Consider which option is long enough for operators to react but not so long that it needlessly delays the distress call • Eliminate any time intervals that would clearly be impractical in a real emergency (either too short or much too long)