On Sun, 27 Jun 2004 16:30:11 GMT, "Dave Stadt"
wrote:


"zatatime" wrote in message
.. .
On Sun, 27 Jun 2004 00:30:12 GMT, Bob Moore
wrote:

zatatime wrote
Because FM band is a "Line of Sight" communications band.

That's true, but aviation band transmissions are Amplitude
Modulation (AM). Aviation transmissions are line-of-sight
because of the frequency, not the modulation type.

Bob Moore


Can you explain? 122.6 (for example) is an FM frequency, how does ATC
transmit on the AM band?

z

Frequency and modulation type are totally unrelated. There is no such thing
as "an FM frequency." VHF aviation transceivers transmit and receive
Amplitude Modulated (AM) signals. VHF communication is typically but not
always line of sight. Signal propagation is frequency dependent not
modulation type dependent (with exceptions here and there).


Thanks. I always thought VORs/Comm were FM and NDBs were AM. Need to
learn more about the VHF band. Appreciate the post, what you say
makes sense (mostly, but because of my need to learn, not because I
think you aren't right).

z