View Full Version : radio vs radar
air_cowboy
19th Jul 2007, 10:47
what is the difference between radio altimeter and radar altimeter?? is it just the frequencies they use...?
topper74
19th Jul 2007, 10:56
I have a book which contains all theese aviation terms... and it says its the same thing..... i just looked it up.
Well, it's radar, but it uses continuous wave, rather than pulses, hence the confusion.
Phil
air_cowboy
19th Jul 2007, 22:47
so which one uses pulse technique?
"Normal" radar uses pulse technique - radar/radio altimeters use continuous wave:
"A continuous wave FM radio beam in the SHF band is directed towards the ground in a 30° cone, and the signal is reflected back to the aircraft. Continuous wave (as opposed to pulse) eliminates minimum target reception range, since the time delay for a pulsed signal would be too small to measure properly (as well, the antennae cannot switch between transmit and receive that quickly). As the potential time interval is very small, you need separate transmitter and receiver aerials."
phil