单项选择题
A.10 meters B.20 meters C.50 meters D.100 meters
What does not contribute to the commercial GPS receiver...
单项选择题What does not contribute to the commercial GPS receiver position error（）.
A.Satellite clock B.Ship's speed C.Atmospheric/ionospheric propagation D.Receiver
To obtain accuracy in fixing by DF，（）and three stations...
单项选择题To obtain accuracy in fixing by DF，（）and three stations should be used.
A.Parallel bearings B.Long-range bearings C.Short-range bearings D.Cross bearings
The use of pulse groups and extremely precise timing at...
单项选择题The use of pulse groups and extremely precise timing at each Loran-C station makes possible the use of（）.
A.High frequency pulses B.Combinations of high and low frequency pulses C.The same frequency for all stations in a chain D.Varied long and short pulses
