On Thursday, September 3, 2020 at 2:32:50 PM UTC-4, Dan Daly wrote:
On Thursday, September 3, 2020 at 12:11:57 PM UTC-4, wrote:
On Wednesday, September 2, 2020 at 8:48:37 PM UTC-4, wrote:
Not to hijack the thread, but I was seriously disappointed in the quality of radio communication when I left hang gliders for sailplanes. With 2M amateur band radios and the repeater system in use worldwide, like MANY savvy and dedicated hang glider pilots, I enjoyed crystal clear comms with fellow pilots and hundreds of discrete simplex and duplex frequencies. I often "dialed up" the freqs used in Telluride while flying in New Mexico just to talk to my buddies who were in the air in Colorado.

Once I got into sailplanes, I was forced to accept the low quality RX/TX, minimal frequency choices and lack of a repeater network. I almost felt like smoke signals would be about as good.

So I carry a tiny 2M radio just in case. (Along with cell phone, InReach, spare battery, etc.)

Besides the lack of repeaters for aviation frequencies, the low quality reception is due to the use of AM, while other VHF users, including ham radio, use FM. The reason for sticking with AM, beside the historical inertia since the 1940's, is that reflections of the radio waves off a rotating propeller would add a frequency wobble (due to Doppler effect) that would cause audible noise in an FM receiver. Or so I'm told. Anybody tried ham radio - or broadcast FM - reception in a powered plane?

I wonder why they don't make aviation radios that you can switch between AM (talking to ATC) and FM (while talking with compatible buddies in gliders)? The same bandwidth around the same frequency should be legal?

On Maritime Patrol aircraft we had VHF-AM (ATC) and VHF-FM (Maritime radio) among others (UHF/HF/Satcom). P3's have 4 very large propellers. There was no frequency wobble or audible noise on VHF-FM. I think you might have been led astray.

So it's just historical inertia, over about 70 years? Wow. They didn't hesitate to make our old ELTs and transponders obsolete. Nor the older comm radios (with 100 KHz spacing, 50 KHz spacing, and now in Europe even the models with 25 KHz spacing). On each forced change in radios, the switch to FM could have been made? With some issues during the transition period, of course.