GMDSS: Element 3

1. A Device that allows an aircraft's receiver to be continuously calibrated for signal selectivity.
2. B System where a ground-based transmitter can call a selected aircraft or group of aircraft without the flight crew monitoring the ground-station frequency.
3. C Transmission that uses sequential logic algorithm encryption to prevent public eavesdropping" of crucial aircraft flight data."
4. D System where an airborne transmitter can selectively calculate the line-of-sight distance to several ground-station receivers.

Tip: press A-D to answer