What is meant by the term " radio silence "?
A. Stations remaining off the air to safeguard proprietary information.
B. Two three-minute silent periods, at the top and bottom of every hour, that provide a transmitting " window " for distressed vessels to transmit distress alerts.
C. Stations not directly involved with the on-going distress communications may not transmit on the distress frequency or channel.
D. Communications on a distress frequency or channel is banned for 24 hours following the cessation of the distress traffic.
What frequency is required in survival craft portable radiotelephony equipment?
A. 121.5 MHz.
B. 156, 3 MHz.
C. 156. 650 MHz.
D. 156. 8 MHz.
微信支付 
支付宝支付