A Domestic Flight but ‘International’

railiner said:

jis said:

Seaboard92 said:

I've never thought about bringing a GPS along. I might have to do that next time.

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First make sure that the airline that you are flying, allows them. Not all airlines allow them.

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I am somewhat surprised that they are allowed...I had thought that all devices that contained any sort of 'radio' within were banned in flight.

Of course, that becomes hard to define or enforce...what about bluetooth earpieces? Or wireless mouses...or radio set, wristwatches? The latter example cannot even be 'turned off'....

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GPS actually will not interfere with flight electronics, because it is receive only, unlike cellular.

EDIT: Sorry, just saw that jis beat me to it.

But radio's and television's are also banned in flight because even though they only 'receive', they do have superheterodyne circuit's that generate RF signal's that allegedly can interfere with air navigation.

I have always wanted to use my scanner in flight, to monitor ATC, but those are banned. The only way to get around that, would be to find an antique crystal radio set, and have it tuned to the ATC frequency. Those do not generate any RF signal, but even if you found one, good luck trying to convince the flight crew of that....

I was carrying my Garmin GPS on flights 12 or 13 years ago and never a problem. The one on my Smart Phone is much better now....and the IFE one is better than that with the constant read-out of additional flight info.

Airlines that approve or disapprove of inflight GPS (a bit outdated)

http://www.gpsinformation.net/airgps/airgps.htm

Do GPS receivers use Superhet? I suspect that the pure digital receivers do not. All that they do is convert the received signal to digital form and then do all the demodulation etc. in DSPs. But I am a bit rusty in this area, so I may be wrong.

Coming to think of it, any digital receiver as in a software defined radio would not suffer from the stray transmission that is inherent in superhet I suppose. No?

jis said:

Do GPS receivers use Superhet? I suspect that the pure digital receivers do not. All that they do is convert the received signal to digital form and then do all the demodulation etc. in DSPs. But I am a bit rusty in this area, so I may be wrong.

Coming to think of it, any digital receiver as in a software defined radio would not suffer from the stray transmission that is inherent in superhet I suppose. No?

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I don't know...sounds like you know more about it than I do....but if they don't generate any RF, why do some airlines ban them anyway? Or is it more of a "security", than radio interference issue?

railiner said:

jis said:

Do GPS receivers use Superhet? I suspect that the pure digital receivers do not. All that they do is convert the received signal to digital form and then do all the demodulation etc. in DSPs. But I am a bit rusty in this area, so I may be wrong.

Coming to think of it, any digital receiver as in a software defined radio would not suffer from the stray transmission that is inherent in superhet I suppose. No?

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I don't know...sounds like you know more about it than I do....but if they don't generate any RF, why do some airlines ban them anyway? Or is it more of a "security", than radio interference issue?

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Residual analism?

One can build a modern crystal radio, no problems. Tuning it to ATC would be a major problem, as there is little selectivity or rejection of adjacent channel signals. Hanging a wire antenna out of the plane window might be problematic too!

I note that aircraft ATC still use AM transmissions, I wonder why that is, most modern systems would be FM or digital?

I love to see the scenery from a plane, amazed at the dry ground under flights from Doha, etc to the UK... The main thing is I need an aisle seat for my legroom in economy, so not often I see the ground!

Ed.

caravanman said:

I note that aircraft ATC still use AM transmissions, I wonder why that is, most modern systems would be FM or digital?

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It would require a worldwide ground-up reboot of the civil ATC comm system, which hasn't happened since the 1930s. Frequency allocations have been expanded and channels have been added and narrowed, but a change to entirely new technology would be a massive undertaking...and expense.

Was just on this route Monday. Of course, the CRJ900 didn't have the "shoulder room" of the A330, but at least Row 1 had plenty of leg room.

The Fall Colors are nearly at their peak in the Annapolis Valley right now. Makes for a very beautiful drive going down 101... Which, unfortunately, we're doing daily visiting the hospital in Kentville.

Heading back to California on Thanksgiving. (That'd be this next Monday, for the non-Canadians in the room.)

One of the most interesting airplane window views that I have had was on a Delta Buenos Aires-Atlanta flight. Being awakened when the interior lights began to brighten, I looked at the in-flight map (which I always keep on, if it is available), and I saw we were just East of Orlando. Raising the shade, the very large metro area of Orlando was alight! Never realized how much territory metro Orlando covered!

ehbowen said:

caravanman said:

I note that aircraft ATC still use AM transmissions, I wonder why that is, most modern systems would be FM or digital?

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It would require a worldwide ground-up reboot of the civil ATC comm system, which hasn't happened since the 1930s. Frequency allocations have been expanded and channels have been added and narrowed, but a change to entirely new technology would be a massive undertaking...and expense.

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There are some more explanation's (or opinion's) over here... https://www.airliners.net/forum/viewtopic.php?t=1357995

and here https://www.pilotsofamerica.com/community/threads/why-are-aircraft-radios-am.13841/