com

LF = 30 - 300 kHz.
MF = 300 - 3000 kHz. / 3 MHz.
HF = 3 - 30 MHz.
VHF = 30 - 300 MHz.
UHF = 300 - 3000 MHz / 3 GHz.

and so on. Most everything from 30 MHz. on down will bounce off somewhere in
the sky at some point in time, not always perfectly predictable when and where.

Jim



- This is true for the VHF frequencies used for conventional aircraft com
- communications (118-136 MHz). HF frequencies (below around 5 MHz)
-bounce
Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

"Dave" wrote in message
...

"Giganews" wrote in message
...

wrote in message
...

On 1-Jan-2004, "Dave" wrote:

In simple terms radios operate in line of sight.

This is true for the VHF frequencies used for conventional aircraft
com
communications (118-136 MHz). HF frequencies (below around 5 MHz)
bounce
off of the ionosphere and can be received well "over the horizon."
That
is
why HF is used for oceanic com.

That's why it is difficult to pick up transmissions from ground
stations,
whereas its straight forward
hearing to aircraft.

To hear ground stations you either need to be close to them on the
ground
or in the air.

Yes, picking up a distant VHF ground station while on the ground is
unlikely. Just how far away one can be and still get a usable signal
depends upon terrain and heights of antennas (at both ends).



A bigger (higher) ariel will help.

MAYBE!!!


I have for some time thought that it would be neat if the FAA (or some
other
institution), as a PR and educational initiative, put some selected
ATC
com
interchange on the web in real time streaming audio. Maybe a busy JFK
RAPCON frequency would be a good choice. ATC coms are public domain
(i.e.
they are not protected as private communications) so their
re-broadcast
on
the Web would be perfectly legal.

--
-Elliott Drucker


This already exists. Landings.com has live ATC feeds from 8 or 10
different
locations (including JFK, MIA, ORD) that you can listen to using
RealAudio.

Howard Neff

url please



http://www.landings.com/evird.acgi$pass*59815306!_h-www.landings.com/_landings/pages/live-atc.html
for live ATC transmissions.

Howard Neff