[Milsurplus] FM vs AM in aircraft

[Ray Fantini]

Strongly doubt Dopler for aircraft in high speed is an issue. operated enough mode J satellite with VHF FM up and UHF FM down and they travel along at around twelve thousand miles an hour. total Dopler from AOS to LOS is only around 10 kHz and working the packet /APRS node on ISS on VHF FM has maybe 5 kHz total and regular FM radios have no big issue dealing with that.

Ray F/KA3EKH

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From: milsurplus-bounces at mailman.qth.net <milsurplus-bounces at mailman.qth.net> on behalf of Jack Antonio <scr287 at att.net>
Sent: Wednesday, July 30, 2025 12:18 PM
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Subject: [Milsurplus] FM vs AM in aircraft

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I have heard that one of the issues with FM in military aircraft is
the unpredictable nature of phase shifts due to doppler, at high speeds
or in manuevering.

The question is:

Is there any documentation anywhere discussing this?

My searches just return discussions of capture effect.
It seems to me that somewhere, someone would have researched
this.

Thanks

Jack Antonio
WA7DIA
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