I have no trouble receiving FM radio broadcasts on a small am/fm radio
I sometimes listen to while onboard commercial jet airliners (flying
at cruise altitude), but I never seem to be able to pick up AM radio
stations. It's just static across the AM band.

Any explanation for this?

Any explanation for this?

FM radio generally operates at longer range than AM radio, however it's
limited to line-of-sight. However, when you're 40,000 feet up you can "see"
a lot of transmitters hence the FM signals.

Cheers,
Geoff Glave
Vancouver, Canada

In message HxHud.9448$eb3.8331@clgrps13, Geoff Glave
writes
Any explanation for this?

FM radio generally operates at longer range than AM radio, however it's
limited to line-of-sight. However, when you're 40,000 feet up you can "see"
a lot of transmitters hence the FM signals.

Cheers,
Geoff Glave
Vancouver, Canada



The window holes are much too small to let the much longer wavelengths
of the 'AM' signals through. The body of the plane is a very effective
screen. The 'FM' signals can squeeze in, but it helps if you have a
window seat. I've also listened to SW in the middle of the Atlantic.

Flying from the UK to Florida, on the other side of the Atlantic the
first FM stations you hear are usually speaking French (from Quebec)
It's quite alarming!
Ian.
--

"Ian Jackson" wrote in
message ...
In message HxHud.9448$eb3.8331@clgrps13, Geoff Glave
writes
Any explanation for this?

FM radio generally operates at longer range than AM radio, however
it's
limited to line-of-sight. However, when you're 40,000 feet up you
can "see"
a lot of transmitters hence the FM signals.

Cheers,
Geoff Glave
Vancouver, Canada



The window holes are much too small to let the much longer wavelengths
of the 'AM' signals through. The body of the plane is a very effective
screen. The 'FM' signals can squeeze in, but it helps if you have a
window seat. I've also listened to SW in the middle of the Atlantic.

Flying from the UK to Florida, on the other side of the Atlantic the
first FM stations you hear are usually speaking French (from Quebec)
It's quite alarming!
Ian.
--

If you stretch a string on a globe from London to Florida, it will show
the 'great circle' route that's the shortest, and that should be your
plane's path, barring storme, hurricanes, etc. You'll see that it comes
really close to the eastern Canadian provinces.

If you stretch a string on a globe from London to Florida, it will show
the 'great circle' route that's the shortest, and that should be your
plane's path, barring storme, hurricanes, etc. You'll see that it comes
really close to the eastern Canadian provinces.

In fact the Avalon Peninsuala in the most eastern part of the island portion
of the province of Newfoundland and Labrador, Canada, is a 'Way Point' for
many transatlantic flights headed to/from Europe.
Clear days Transatlantic flight con-trails, at 30,000 feet etc. can be seen
almost continuously.
That is why so many of the flights that were prevented from entering US air
space 9/11 had to land in eastern Canada.
Many US/Canada friendships were founded between grounded travellers that day
and eastern and western Canadians who voluntarily accommodated them during
the delay.
Cape Spear near St John's is the most easterly point in North America.
Marconi received the first transatlantic wireless telegraph signal near St
John's in Dec. 1901.
French is one of the 'Official Languages' in Canada. A significant
percentage of the population, mainly in Quebec, New Brunswick, but also
elsewhere in Canada, is French speaking. Many/most are bilingual.
Same way Spanish is significant in the USA?
The word 'Cajun' in southern US comes from the French word "Acadian";
originally inhabitants of Acadia or what is now the eastern Canadian
Province of Nova Scotia.
Terry.
PS. Staff at the National Historic Park at Signal Hill, St. John's, which
incorporates the memorial and events which celebrate Marconi's first
wireless telegraph reception say that visitors unaware of the approximately
1800 miles across the Atlantic, (4.3 hours by jet to London-Heathrow) will
sometimes ask "Can you see across to England/Ireland etc.". The answer is;
"No, but sometimes you can see "Whales"! :-)
And sometimes icebergs as well.

"Geoff Glave" wrote in message
news:HxHud.9448$eb3.8331@clgrps13...
Any explanation for this?

FM radio generally operates at longer range than AM radio, however it's
limited to line-of-sight. However, when you're 40,000 feet up you can "see"
a lot of transmitters hence the FM signals.

Cheers,
Geoff Glave
Vancouver, Canada



I reckon you just answered the wrong question !!

The reason A.M. radio can not be received in a plane is that it is a Faraday
cage to the (lower frequency) A.M
frequencies, whereas the VHF frequencies can just about get through the
windows.

There may be a bit of frequency / range issue as well but top band and 80 mtrs
gets across the pond so
I don't think this is the issue here...

Nick

No one has mentioned that in many cases you need the pilot's permission to
operate a radio or other electronic device for that matter on a commercial
airliner. That includes AM/FM radios.

Radio emissions may screw up the plane's avionics.

See URL:
http://www.fordyce.org/scanning/scan.../scan_fly.html

It sez:
"The FAA does not allow inflight use of walkie-talkies, radio controlled
toys, AM/FM radios, portable telephones, or portable television sets, all of
which may affect aircraft radio and navigation equipment"

Also cruise ships may deny use of two way (FRS) or ham radios -- always
check with the communications officer.

For Hams always check with the person in charge on any commercial
transportation, busses, taxi's, ships planes etc.

Yeah yeah I know you did it without getting permission, but read the URL as
to what airlines have published.

And I know from personal experience that some cruise lines do not allow FRS
or ham radios transmissions.

--
RF Gotta Go SomeWhere



"nick smith" wrote in message
...

"Geoff Glave" wrote in message
news:HxHud.9448$eb3.8331@clgrps13...
Any explanation for this?

FM radio generally operates at longer range than AM radio, however it's
limited to line-of-sight. However, when you're 40,000 feet up you can
"see"
a lot of transmitters hence the FM signals.

Cheers,
Geoff Glave
Vancouver, Canada



I reckon you just answered the wrong question !!

The reason A.M. radio can not be received in a plane is that it is a
Faraday
cage to the (lower frequency) A.M
frequencies, whereas the VHF frequencies can just about get through the
windows.

There may be a bit of frequency / range issue as well but top band and 80
mtrs
gets across the pond so
I don't think this is the issue here...

Nick

Reception of radiosignals inside a Faradaycage is limited to frequencies
that are smaller then the holes in the cage.
"Geoff Glave" schreef in bericht
news:HxHud.9448$eb3.8331@clgrps13...
Any explanation for this?

FM radio generally operates at longer range than AM radio, however it's
limited to line-of-sight. However, when you're 40,000 feet up you can
"see"
a lot of transmitters hence the FM signals.

Cheers,
Geoff Glave
Vancouver, Canada

"Geoff Glave" wrote in message
news:HxHud.9448$eb3.8331@clgrps13...
Any explanation for this?

FM radio generally operates at longer range than AM radio,

Nonsense! AM radio stations can be heard for thousands of miles, FM for
'line of sight', which is usually less than a hundred miles.

however it's
limited to line-of-sight. However, when you're 40,000 feet up you can
"see" a lot of transmitters hence the FM signals.

Nonsense! The passenger is sitting in a Faraday Cage, a fuslage made of
alumninum. The FM wavelength is short enough to go thru the windows,
but mot the AM signals.


Cheers,
Geoff Glave
Vancouver, Canada

Some Guy wrote:
I have no trouble receiving FM radio broadcasts on a small am/fm radio
I sometimes listen to while onboard commercial jet airliners (flying
at cruise altitude), but I never seem to be able to pick up AM radio
stations. It's just static across the AM band.

Any explanation for this?

Yes, there is. The AM cops have figured you out, since what you are
doing is illegal on commercial airliners. The FM cops are a little
slower, but they will pull the plug on you also, eventually.

Seriously, though, you are inside a metal cigar tube you call an
airplane, and you are being shielded by the body of the aircraft.
Although windows (portholes, not Gates), and the metal itself, don't
block out signals completely, you will see an effect from this (look up
"Faraday Cage" on google). AM broadcast is a very long wavelength
(hundreds of meters long) whereas FM broadcast is a smaller wavelength
(around 3 meters). If you were trying to throw a bunch of marbles
through an upstairs window, you would probably be able to do it. But if
you were trying to throw a bunch of beachballs through an upstairs
window, it wouldn't be as easy, right?

The aperture is the important issue. Although the airplane is not a
completely shielded RF-proof "screen room", it acts somewhat like one.
That is why avionics antennas are on the outside of the plane, not
inside. That is also why there is a teeny mesh grid in the door of your
microwave oven - they have to be that small to block the microwaves.

Using my example befo if you are throwing beachballs (AM broadcast),
or marbles (FM broadcast) or a handful of sand (microwaves), how small
would you want the window to be in order to block it?

OK, getting back to my first paragraph, if you are ever on a plane with
me, please let me know, so I can take the next flight. The local
oscillator of FM receivers is often on the same frequency as the VOR
stations that airplanes use to naviagate with, and can cause
interference. There are failsafe solutions that the pilot has, to deal
with loss of VOR coverage, but I don't want to depend on them because
you are listening to gangster rap at 32,000 feet. Get an iPod or something.

All the best,
Dave