Electronic Navigation Systems Flashcards
1
Q
How do you know if your ECDIS is up to date?
A
2
Q
How do you know if your ECDIS is type Approved?
A
3
Q
GPS
How does it work?
A
When a GPS set on board receives a satellite signal, it can calculate the range from the known satellite position by the time difference between signal transmission and receipt.
A satellite transmits a signal, which carries a particular code. The receiver generates this same code internally, starting at precisely the same time.
When it receives the code from the satellite, it can measure the difference between them.
Since radio waves travel at the speed of light, which is known, the range can be determined.
A clock inaccuracy of just one-millionth of a second would give a ranging error of about 400m.
