Why is the airband mode AM ?

[ian]

Why does the airband use AM ?, does weak signals travel better on AM, someone told me its easier to recieve weak signals on AM, FM just gets lost in the noise, at the same signal level.

[ColinTelford]

I think it's also because two signals can be heard if they both tx at the same time

[thedeerhunter270]

Yep, AM can be heard with a lower signal level.

[RogerD]

AM Airband was around before FM was invented, and there was no reason to change. The lack of 'capture effect' is indeed an advantage.

[Minus1]

Also, if you changed it, you'd potentially have to change every aircraft in the world simultaneously…

Same reason VHF Marine still uses 25kHz bandwidth worldwide.

[Glamdring]

AM is best for it. longer range and two planes can be heard. I miss the old am police days

Just 2 planes??? I wish, would make my job a lot easier, lol.

[znww5]

Towards the end of the 8.33kHz debacle, I seem to remember mention being made of the next generation of comms being digital. Heard nothing much of the story since, so I don't know it the idea fizzled or not.

"Just 2 planes??? I wish, would make my job a lot easier, lol." Down south, that's known as Norwich

[Glamdring]

Down south, that's known as Norwich

:-)

Although to be fair to Norwich, I have previously worked Anglia radar dealing with the helis in and out of Norwich, and whilst it was fairly quiet most of the time things did get "interesting" on occasion.