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Airplane radio reception

raccoonradio

raccoonradio

I flew Southwest recently from Manchester NH to Nashville and then back. Haven't
really flown for about 20-25 years (not really fear of flying, just prefer to drive--but I wanted to go far away and get there and back faster, etc.) So...I also brought a <a href="http://images.overstock.com/f/102/3117/8h/www.overstock.com/images/products/P406926.jpg">
portable Walkman </a> with AM/FM/TV Ch 2-13/WB. Of course I waited till they said it OK to run a "portable device".

Naturally I could only pick up certain stations, and even then they would mix
with other stations and fade away fast...I'm talking FM. AM wouldn't come in
(engine interference?), and neither would TV sound or WB.

I couldn't tell the actual flight path we took though I noticed WPXY-FM
from Rochester, NY came in well (both ways). Also WTOP-FM 107.7 //
WTOP, etc. There were stations mentioning "Roanoke" and other places that were
probably near the flightpath, etc.

Not sure which stations normally would come in up at higher altitudes and which ones would not--maybe just the most powerful of all (50,000 watt-ers and such).
Also I don't have one of those XM or Sirius receivers but would reception of
sat.-radio be possible while flying>?
 
> I flew Southwest recently from Manchester NH to Nashville
> and then back. Haven't
> really flown for about 20-25 years (not really fear of
> flying, just prefer to drive--but I wanted to go far away
> and get there and back faster, etc.) So...I also brought a
> portable Walkman with AM/FM/TV Ch 2-13/WB. Of course I
> waited till they said it OK to run a "portable device".
>

Radio's are not included in the allowable portable devices, but someone much smarter than I will have to tell you why they don't allow you to use them.
 
> Radio's are not included in the allowable portable devices,
> but someone much smarter than I will have to tell you why
> they don't allow you to use them.

The last time this came up, the thread turned into a flame war. Let's not let that happen again, please.

Airlines do not allow radios to be used during flight, because in the tuning process FM radios oscillate (transmit) at frequencies that have harmonics falling in the aviation band, just above FM. Some of those frequencies are used for navigation devices in the cockpit and you were apparently just lucky that you didn't hit any of the frequencies being used on the specific plane you were riding in.

In any event, if a flight attendant had discovered that you had a radio and not a CD/MP3/tape player, you would have been asked to turn it off.

Most people are unaware that their radios are also transmitters.
<P ID="signature">______________


</P>
 
I had a three paragraph response written, then realized it was not very clear. Your explaination was very clear, and said what I wanted to say :)
 
>
> Most people are unaware that their radios are also
> transmitters.
>

I was on a plane where a guy refuesed to stop using his Blackberry... at the arrival gate, there were TSA agents and they arrested him. Some airlines would do the same for use of an FM radio. Best to ask, before the flight. Some airlines allow radios, but most specifically prohibit them.
 
According to the Travel Tips section of southwest.com:

"While the forward-entry door is open, these devices may be turned on and operated: cellular/mobile phones, pagers/two-way pagers, AM/FM radio receivers, and television receivers...."

OK, so I can listen to radio till they close that door and start to ascend
and they do say "turn off devices". (And cell phones can't be used at all during flight.) Next:

"When indicated by Flight Attendant announcements, during the cruise phase of flight these devices may be operated: DVD, CD, and tape players, personal digital assistants (PDAs or hand-held computers), electronic calculators, hand held electronic games, electronic cameras, Global Positioning Satellite (GPS) receivers, and devices that compose e-mail or text messages without transmitting or receiving."

Hmm--didn't say "radio" though 'tape' was OK. Oops! They did make an announcement saying "personal electronic devices may now be used" but they
did NOT say "except AM-FM radios"...Yes, they probably thought I had an
Ipod or something. I think when I read the "travel tips" before flying
I saw the "tape players" part but thought it also said radio (mine is radio
only) as well. Maybe I should email them and tell the pilots or flight attendants to make it clear that AM-FM is not permitted! (I do have a couple Walkmen with both AM-FM _and_ tape, and I guess if I just stuck to a
cassette...)


I did see a kid with an Ipod, which is OK

> Airlines do not allow radios to be used during flight,
> because in the tuning process FM radios oscillate (transmit)
> at frequencies that have harmonics falling in the aviation
> band, just above FM.

Good point--I know I've been near airports and I would hear some
transmissions come through around 98 or 108 MHz on my car radio.



> Most people are unaware that their radios are also
> transmitters.

I would have thought a tiny little radio would cause no problems but better to be safe than sorry. I should have asked the flight attendant!! Thanks
 
> I had a three paragraph response written, then realized it
> was not very clear. Your explaination was very clear, and
> said what I wanted to say :)

Thank you very much for the compliment. My background in broadcast engineering (yes, I'm more than just a programmer) must be showing again. :)

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</P>
 
US Airways has never said anything to me. Last year when I flew from Hartford, CT to Philly I remember picking up 107.1 The BOX, which was a radio station on Long Island. On the TV Band I remember picking up a station that was talking about people being detained in cages at the Presidential Convention in Boston.<P ID="signature">______________
~Jay Clark~
</P>
 
> According to the Travel Tips section of southwest.com:
>
> "While the forward-entry door is open, these devices may be
> turned on and operated: cellular/mobile phones,
> pagers/two-way pagers, AM/FM radio receivers, and television
> receivers...."
>

The in-flight magazine for American specifically says radios of any kind are prohibited for in flight and on- board use.
 
many of us have heard the story of linda silver. if you haven't, she was doing overnights at WXLK (K92) Roanoke, VA in the early 80s... scott shannon was flying back from florida, and listening to radio from the plane. he heard linda, and upon landing called and offered her a job at Z100 NYC.

of course, that was 20+ years ago.

those were the good old days. i remember listening to radio from 30,000 feet back then, and you could get a LOT of stations. i remember listening to salt lake city on a cross-country flight. and coming in to atlanta i picked up Y96 in dublin, ga (this was before they increased to 50kw). we were circling for landing, so i don't know how close we actually were to dublin, of course. but i don't think the pattern puts you out that far.

i personally think it's a dumb rule. i mean how much output could a walkman actually generate? yes, i know it's the rule and we have to obey it, but an airplane is a big place, and i'd guess that your receiver would have to be pretty close to the antenna in order to cause any intereference. at that proximity you'd have to be outside (in the 'gone with the wind' smoking section).<P ID="signature">______________
</P>
 
> i personally think it's a dumb rule. i mean how much output
> could a walkman actually generate? yes, i know it's the
> rule and we have to obey it, but an airplane is a big place,
> and i'd guess that your receiver would have to be pretty
> close to the antenna in order to cause any intereference.
> at that proximity you'd have to be outside (in the 'gone
> with the wind' smoking section).
>

The 10.7 IF of any FM receiver can radiate for considerable distance, greater than the lenght of a plane. As an example, the MobileTrak ratings systems tells what each car is listening to at distances of over 150 feet by detecting the IF separations on a roadside receiver. If this can be done, low power aircraft band signals can be interfered with. Remember, the aircraft band is right above the FM band, and can be severely interferred with by an FM IF.
 
> US Airways has never said anything to me. Last year when I
> flew from Hartford, CT to Philly I remember picking up 107.1
> The BOX, which was a radio station on Long Island. On the TV
> Band I remember picking up a station that was talking about
> people being detained in cages at the Presidential
> Convention in Boston.
>

Let me know ahead of time before you fly so I know not to be anywhere near your plane. Portable Radios including walkmans generate signals in the AIRCRAFT RADIO BANDS. It's that simple! Don't use radio walkmans while flying...

They don't make the rules just for their own laughs...
 
> i personally think it's a dumb rule. i mean how much output
> could a walkman actually generate? yes, i know it's the
> rule and we have to obey it, but an airplane is a big place,
> and i'd guess that your receiver would have to be pretty
> close to the antenna in order to cause any intereference.
> at that proximity you'd have to be outside (in the 'gone
> with the wind' smoking section).

I can produce credentials as a broadcast engineer. Can you?

If not, then it doesn't matter whether or not <u>you</u> think it's a "dumb rule". Those of us who know about the subject know better.

And if you are not an engineer, your "guess" is meaningless.

{moderator mode on}

Did I, or did I not, say this thread was NOT to become a war?

{moderator mode off}
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</P>
 
If anyone wants to do some high altitude DXing, the best way is to fly with a private pilot who is fully aware of the situation, and is prepared to deal with any possible ramifications. It is interesting that they are now allowing GPS receivers. On a recent flight from Seattle to Sacramento I logged 530 MPH, and 35000 Ft. As a 2 way radio tech and HAM for over 30 years, I can say that aircraft radios work with very weak signals, and the L.O. and IF freqs of various devices could easily interFEAR with communications and nav radios. You can see the effect by trying to listen to AM radio with your computer on.
<P ID="signature">______________
Gospel Life Broadcasting</P>
 
you need to read my reply again.

"i PERSONALLY think it's a dumb rule"

that means it's my OPINION.

"how much could a walkman actually generate?"

the question mark means i'm asking, not telling.

"yes, i know it's the rule and we have to obey it"

this means i know the difference between right and wrong.

"i'd GUESS that the receiver..."

again, this means it's my OPINION.


no i can't produce credentials as a broadcast engineer. but i do have a right to an opinion, even if it's wrong. i can also disagree with the speed limit, but that doesn't make me immune to obeying it.

since i never advocated disobeying the rule just because of my opinion that it's dumb, it doesn't matter if i have broadcast engineer credentials. now, had i stated something such as "i know for a fact that this is a dumb rule because...." things would be different. my "guess" was simply that, a guess. is it meaningless because it was wrong?

by the way, my comments did not turn this into a war. i only said i disagreed with the rule, not that i would fail to obey it. i would never want to bring a plane down because of my ignorance. notice i said ignorance, not stupidity.

since you're a broadcast engineer, how far does the signal radiate from a sony walkman?

-amos








> > i personally think it's a dumb rule. i mean how much
> output
> > could a walkman actually generate? yes, i know it's the
> > rule and we have to obey it, but an airplane is a big
> place,
> > and i'd guess that your receiver would have to be pretty
> > close to the antenna in order to cause any intereference.
>
> > at that proximity you'd have to be outside (in the 'gone
> > with the wind' smoking section).
>
> I can produce credentials as a broadcast engineer. Can you?
>
>
> If not, then it doesn't matter whether or not you think it's
> a "dumb rule". Those of us who know about the subject know
> better.
>
> And if you are not an engineer, your "guess" is meaningless.
>
>
> {moderator mode on}
>
> Did I, or did I not, say this thread was NOT to become a
> war?
>
> {moderator mode off}
>
<P ID="signature">______________
</P>
 
david,

i didn't say i wouldn't or that we shouldn't obey the rule. i just find it difficult to believe that a receiver that's type accepted by the fcc could actually be received that far away. yes, i understand your example of the MobileTrak system, and i hadn't thought of that. besides, it doesn't matter if i like the law, it's a law.

to quote an above comment, my guess was dumb, and my opinion doesn't matter, anyway.

-amos

> > i personally think it's a dumb rule. i mean how much
> output
> > could a walkman actually generate? yes, i know it's the
> > rule and we have to obey it, but an airplane is a big
> place,
> > and i'd guess that your receiver would have to be pretty
> > close to the antenna in order to cause any intereference.
>
> > at that proximity you'd have to be outside (in the 'gone
> > with the wind' smoking section).
> >
>
> The 10.7 IF of any FM receiver can radiate for considerable
> distance, greater than the lenght of a plane. As an example,
> the MobileTrak ratings systems tells what each car is
> listening to at distances of over 150 feet by detecting the
> IF separations on a roadside receiver. If this can be done,
> low power aircraft band signals can be interfered with.
> Remember, the aircraft band is right above the FM band, and
> can be severely interferred with by an FM IF.
>
<P ID="signature">______________
</P>
 
>
> since you're a broadcast engineer, how far does the signal
> radiate from a sony walkman?
>

The IF offset generated by a portable device can have a range of several hundred feet. With very good equipment, reception of fractions of a watt at several miles is possible.
 
david, let me first say that i respect your opinions, and posts.

but that statement is contradictory.

if the range is several hundred feet, the reception would not be possible several miles away no matter how good the equipment.

if the reception is possible several miles the RANGE would be = several miles.

if the range is several hundred feet, the reception would be = several hundred feet.

a receiver, no matter how good, cannot pick up a signal where there is no signal.

i do realize that you made two statements: (1) IF offset range = several hundred feet, and (2) a fraction of a watt can be received several miles. the implication is that the IF offset range is a fraction of a watt, and [therefore] can be received several miles if the receiving equipment is good. to be fair, statement 2 does not directly reference statement 1, although they do appear to be related in context.

this is, in no way, meant to disagree with your post that the radio would interfere with the nav radios. it's only to point out that a receiver cannot pick up a signal where it doesn't exist. please do not interpret this as thinking you were wrong in your earlier post.

amos


> > since you're a broadcast engineer, how far does the signal
>
> > radiate from a sony walkman?
> >
>
> The IF offset generated by a portable device can have a
> range of several hundred feet. With very good equipment,
> reception of fractions of a watt at several miles is
> possible.
>
<P ID="signature">______________
</P>
 
> david, let me first say that i respect your opinions, and
> posts.
>
> but that statement is contradictory.
>
> if the range is several hundred feet, the reception would
> not be possible several miles away no matter how good the
> equipment.
>
> if the reception is possible several miles the RANGE would
> be = several miles.
>
> if the range is several hundred feet, the reception would be
> = several hundred feet.
>
> a receiver, no matter how good, cannot pick up a signal
> where there is no signal.

One statement is in regards to the average ability to receive the IF offset signal product. The other is the öccasional occurance" type of reception.

In other words, under normal circumstances, there is enough radiation from the average radio to go several hundred feet. However, under good conditions, occasionaly such power could go several miles.

Example in the DX realm. The 50 watt AM at Ramey AFB, Puerto Rico, was intended to barely cover the base, given its 50 foot high radiator and lack of a good ground system. Nonetheless, I heard it in Ohio... once.

My point is that, always, FM radios can interfere with the plane they are being operated on. And they have th epotential to interfere at greater distances on rare occasions.
 
FM radios also transmitters

Hi. Pardon a dumb question from a non-techie, but if FM radios give off those signals, couldn't those signals be used by the Arbitron ratings service to tell what stations people are really listening to (rather than those always inaccurate pain in the you know what diaries). If those signals effect aircraft radios, couldn't Aribtron put up sensors along major highways and at major street intersections (even in mobile units cruising residential areas) to measure what stations radios are tuned to? If this would work for FM, would it also work for AM? TV?

>
> Airlines do not allow radios to be used during flight,
> because in the tuning process FM radios oscillate (transmit)
> at frequencies that have harmonics falling in the aviation
> band, just above FM. Some of those frequencies are used for
> navigation devices in the cockpit and you were apparently
> just lucky that you didn't hit any of the frequencies being
> used on the specific plane you were riding in.
>
 
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