Subject : Re: Why is aviation COM VHF *amplitude* modulated?
(Jerry Bransford) writes:
>It still has little to do with FM capture effect. It's purely economic.
>How old is the average airplane? How old is the average car that uses land-mobile radio service? And how much $$ does an aircraft radio cost compared to one suitable for a car? And typically it's the government user that uses land-mobile radio services who can decide to spend the $$$ because it's only tax dollars they are spending, not their own personal dollars.
>Cars are replaced every few years, and end-users of land-mobile (typically government/taxi/police/fire) buying cars/trucks can make that switch to new radio technolgies with little or no economic impact. Not so with airplanes. Airplanes are NOT replaced regularily, and thus there is a huge economic cost for someone to mandate that airplanes *will* switch to the imcompatible FM mode.
