FM And Aero. Related Modes Question ?

[BOBRR]

Hello,

Is FM, or NFM, ever used for "any" aero. related comms ?

Or, is it always USB for HF <30 MHz, and AM above ?

Always a bit confused over modes, so if anyone could
summarize regarding the above statement, woul be appreciative.

Thanks,
Bob

 

[andy51edge]

Or, is it always USB for HF <30 MHz, and AM above ?

You're correct. Above 30 MHz, most civilian aircraft are only capable of AM. I have seen some military training aircraft use FM in the 140 MHz military band, but this is quite rare in my experience.

In the HF band, most civilian aircraft default to USB and AM can be selected. I have never seen an aircraft using AM mode though.

 

[alcahuete]

When you say "any aero related comms." yes, most definitely. Law enforcement, fire, etc., helicopters are routinely equipped with their agency radios. So aero-related...yes, there is FM, P25, etc. in use. None of that takes place on the aviation band, however. Anything you hear on the VHF aviation band is going to be AM.

 

[dlwtrunked]

You're correct. Above 30 MHz, most civilian aircraft are only capable of AM. I have seen some military training aircraft use FM in the 140 MHz military band, but this is quite rare in my experience.

In the HF band, most civilian aircraft default to USB and AM can be selected. I have never seen an aircraft using AM mode though.

Military aircraft (particularly National Guard) FM is not uncommon in the VHF low band). 138-144 MHz military active aircraft activity here is usually chit-chat between pilots doing Combat Air Patrols.

 

[vagrant]

My local air guard also use 40 MHz FM for their rotor aircraft, otherwise AM most of the time. Civilian and commercial will be USB or AM.

 

[737mech]

I find the 138-144 comms between military aircraft are still AM. You can sometimes hear it in FM on the scanner but if you can change that setting to AM you will hear the comms clearer.

 

[spacellamaman]

I find the 138-144 comms between military aircraft are still AM. You can sometimes hear it in FM on the scanner but if you can change that setting to AM you will hear the comms clearer.

I remember once monitoring some "covert" military training jump ops at my local GA airport where the air and ground were on the same and correct freq, but couldn't understand each other. A/C was in FM and ground was AM. This goes on for quite some while with me listening in on both sides. I can't recall how it was resolved but it wasn't on that frequency and no one seemed to ever figure out what the issue was. Apparently that model of aircraft when used by spec ops had a selectable modulation radio in it and they were going all across the spectrum during that time period with much of it low band FM. Tisk tisk.

And yes when I was close enough to who was transmitting, the scanner with the wrong modulation was somewhat capable of understanding what was said, but that didn't work for those actually involved. they had better radios obviously ha!