🔍 Key Concepts

• DSC (Digital Selective Calling) functions versus normal voice communications on VHF • What a self-test or built‑in test normally does on radio/safety equipment • Regulatory limits and restrictions on unnecessary transmissions on Ch-70 and Ch-16

💭 Think About

• Ask yourself: would a proper self-test feature be allowed to send any real signal on a distress/safety channel during normal testing? Why or why not? • Consider what the purpose of a self-test is: is it mainly to radiate a test signal over the air, or to check internal circuits and functions? • Look at each choice and decide which one best matches how modern marine electronics are designed to avoid interfering with other stations.

✅ Before You Answer

• Verify whether DSC Ch-70 may be used for test transmissions in normal operation, and under what conditions. • Think about whether a routine self-test should depend on another radio receiver picking up its signal, or if it should work even when no antenna is connected. • Check which option best describes an internal diagnostic of the radio’s DSC functions without causing external interference.