The third number

[Kream926]

FN FAL

what you say is sounding alot like free flight. whats the deal with that i can never find any good articles on it?

 

[Stepclimb]

More on AM vs FM

I thought that too. I mean, FM radio is VHF, as is the aviation frequency range, no? Of course, I too know nothing about the mechanics of radio waves...

Within any frequency band, one can modulate a carrier signal in many ways; AM, FM, SSB (upper, lower) etc.
True, the US VHF commercial broadcast spectrum is modulated in FM from 97-108 MHz, but the aviation band above 108 MHz is AM. UHF (military aviation band) is also AM.
Back in the infancy of aviation radio, AM was simpler and therefore lighter. So it became the standard since it was around before FM. I don't think Frequency modulation even became popular until much later in the last century.
So now at this day in age, changing every radio in every aircraft and every ATC facility would not be cost-effective. Besides, AM has some advantages for aircraft use: namely signal quality vs. distance for a given transmitter power.

Also, with AM, one can cram more 'channels' into an existing spectrum with out worrying about 'bleed over', provided the transmitter can transmit narrowly and the receiver can filter accurately. (see my first post)
There are some other advantages to AM vs FM in aircraft use, but I can't remember them all. I'm sure there are some interesting articles on the subject floating around the web.
-Stepclimb

 

[FN FAL]

FN FAL

what you say is sounding alot like free flight. whats the deal with that i can never find any good articles on it?

With Slant/G, we are almost living in an age of "free flight", as long as we're in radar contact.

What I'm talking about, is secure digital data up-link. No more talking on static filled radios...we'll have digital signals relaying clearances, through push buttons. Heck, we got that here, right now, as we're talking amongst ourselves...why can't we have it with ATC?

Talking is going to consume too much time on radios and we don't have the bandwith to expand. The cops want more bandwidth, the fire and rescue guys want more bandwidth...ATC has, what they have (and what about those days when you hear Memphis Approach on Chicago Center and vice a versa?).

Frequency wars are just begining and 911 (not 9/11) is in a war with cell phones as we speak. Cops and Fire Fighters are in a situation now in some places, where their radios don't work because of cell phone towers.

Improved digital communications, will mean that a lot more signals can be sent over the same airwaves.

I'm all for ATC being digitized...to the point where clearances are push button...from aircrew to ATC and back.

For our communications, we need to acknowledge simple requests and ask for simple changes to clearances...but yet we have to talk about it. All of us know of the day when it took 12 conversations to get a sqawk code and an IFR clearance.

I'd like to push a button and get things going...without getting stepped on and without all the chatter.

 

[Kream926]

sounds like a great idea and im sure they are in the works. i would hate to see it eat jobs in the towers and centers tho. my plan B is airtraffic control. kinda like how top gun opened peoples minds to aviation, Pushing Tin did it for me for atc. as far the emergency services needing more nambwidth, i read somewhere that there's a bill that going up for vote to chrage people a dolla for 911 (not 9-11) cell phone calls. the reason in for better technology so they can pin point your location using cell phone. even tho i think they allready can do this.

sorry if this isnt flowing. im running on minimal sleep, finals.

 

[FL000]

Thanks for the AM/FM info y'all. I had no idea.