Aircraft transmissions are AM to allow detection a weaker signal that may come from a distressed aircraft. A carrier 30 dB lower will still produce a whistle allowing the controller to ask the other aircraft to stand by to copy the weaker signal.
Art, KC6UQH
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Nate Duehr Sent: Monday, March 16, 2009 5:27 PM To: 'amsat' Subject: [amsat-bb] Re: Tranzit-B telemetry system on ISS
How are the "American aircraft signals" which are all AM, being rebroadcast in any intelligible way by an FM receiver?
The only aircraft that MIGHT transmit with FM, are military aircraft. And rarely in the clear or without frequency-hopping spread spectrum technology involved. (And that's not really FM, so to speak -- nor copyable through the repeater you're describing.)
I smell something wrong here with your information, or there's more to the story.
Nate WY0X
-----Original Message-----
Sometimes you can hear VHF-1 while ISS is passing over the USA. When the repeater mode is active you can hear American aircraft signals being re-transmitted over the ISS commercial repeater.
_______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
__________ Information from ESET NOD32 Antivirus, version of virus signature database 3937 (20090314) __________
The message was checked by ESET NOD32 Antivirus.
__________ Information from ESET NOD32 Antivirus, version of virus signature database 3941 (20090317) __________
The message was checked by ESET NOD32 Antivirus.