单项选择题
Reliable delivery of messages is ensured by（）techniques.
A.forward error correction
B.aftward error correction
C.DGPS
D.error-free and low error reception
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相关考题
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单项选择题
How long must the GMDSS radio log be retained on board（）.
A.At least two years after the last entry
B.At least one year after the last entry
C.At least 90 days after the last entry
D.At least 30 days after the last entry -
单项选择题
Each satellite broadcasts（）traffic on a designated channel.
A.LES
B.ESA
C.NCS
D.EGC -
单项选择题
At sea，all required GMDSS equipment（other than survival craft equipment）must be proven operational by（）.
A.daily testing
B.either A or C
C.operational use of the equipment
D.testing at least every 48 hours
