OT: AM mode
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VHF/UHF aircraft radio has always been AM, and is likely / certain
continue to be. Why? It's used world wide and discussions about changing it to FM have continued for years. The conclusion seems to be that there is simply too much usage worldwide and little reason to make the change. The cost to change to another mode would be horrendous! Of course manufacturers would -love- to see the change. There is usage of SSB on HF primarily ... but it's still "AM". (;-) 73! Ken - K0PP ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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The rational is that if two stations transmit over each other on AM they can
both be heard either as separate signals or as a beat note. Whereas, with FM due to the capture effect only the stronger station would be heard. 73 Stewart G3RXQ ex PPL On Tue, 16 Jul 2013 19:30:36 +0000, Ken G Kopp wrote: > VHF/UHF aircraft radio has always been AM, and is likely / certain > continue to be. Why? It's used world wide and discussions about > changing it to FM have continued for years. The conclusion seems > to be that there is simply too much usage worldwide and little reason > to make the change. The cost to change to another mode would be > horrendous! Of course manufacturers would -love- to see the change. > > There is usage of SSB on HF primarily ... but it's still "AM". (;-) > > 73! > > Ken - K0PP > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Ken G Kopp
* On 2013 16 Jul 14:31 -0500, Ken G Kopp wrote:
> VHF/UHF aircraft radio has always been AM, and is likely / certain > continue to be. Why? It's used world wide and discussions about > changing it to FM have continued for years. The conclusion seems > to be that there is simply too much usage worldwide and little reason > to make the change. The cost to change to another mode would be > horrendous! Of course manufacturers would -love- to see the change. From a coworker that worked in avionics years ago one reason can be summed up in two words--capture effect. As AM does not have it, an air controller can tell when two aircraft transmit at once, much like on HF SSB for us. Beyond that and I would be into speculation. 73, de Nate >> -- "The optimist proclaims that we live in the best of all possible worlds. The pessimist fears this is true." Ham radio, Linux, bikes, and more: http://www.n0nb.us ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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Re: "...capture effect. As AM does not have it, an air controller can tell when two aircraft transmit at once, much like on HF SSB for us."
Extremely important to controllers and pilots. The resulting hetrodyne is very distinctive. Mark KE6BB ________________________________ From: Nate Bargmann <[hidden email]> To: [hidden email] Sent: Tuesday, July 16, 2013 12:56 PM Subject: Re: [Elecraft] OT: AM mode * On 2013 16 Jul 14:31 -0500, Ken G Kopp wrote: > VHF/UHF aircraft radio has always been AM, and is likely / certain > continue to be. Why? It's used world wide and discussions about > changing it to FM have continued for years. The conclusion seems > to be that there is simply too much usage worldwide and little reason > to make the change. The cost to change to another mode would be > horrendous! Of course manufacturers would -love- to see the change. From a coworker that worked in avionics years ago one reason can be summed up in two words--capture effect. As AM does not have it, an air controller can tell when two aircraft transmit at once, much like on HF SSB for us. Beyond that and I would be into speculation. 73, de Nate >> -- "The optimist proclaims that we live in the best of all possible worlds. The pessimist fears this is true." Ham radio, Linux, bikes, and more: http://www.n0nb.us ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Ken G Kopp
Correct, Ken. Then there is the "capture affect" of FM. Stronger FM signals could wipe out a transmission from another aircraft causing concerns. With AM, there is a greater possibility to pick out a weak signal in the presence of a stronger signal and avoid incidents. A real plus if you are flying the aircraft with the weaker signal. ;o)
Terry W0FM -----Original Message----- From: Ken G Kopp [mailto:[hidden email]] Sent: Tuesday, July 16, 2013 2:31 PM To: [hidden email]; [hidden email] Subject: [Elecraft] OT: AM mode VHF/UHF aircraft radio has always been AM, and is likely / certain continue to be. Why? It's used world wide and discussions about changing it to FM have continued for years. The conclusion seems to be that there is simply too much usage worldwide and little reason to make the change. The cost to change to another mode would be horrendous! Of course manufacturers would -love- to see the change. There is usage of SSB on HF primarily ... but it's still "AM". (;-) 73! Ken - K0PP ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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Another benefit and maybe the reason is that all aircraft working the same
controller will hear all other aircraft - true party line! This is not possible with FM! Many times the heterodyne is so low in frequency as to not be heard. When I fly I would like to know what the other guy is doing & saying; especially at a busy airport. If we were going to change something - maybe SSB or vestigial SB would make sense if the bands get too crowded or the FCC wants to use the Aviation VHF & UHF comm. frequencies for more "Broadband". BTW the big guys already have digital communications in the cockpit at selected airports; with more coming on line. 73 George AI4VZ (Instrument Rated Private Pilot) -----Original Message----- From: Terry Schieler Sent: Wednesday, July 17, 2013 12:45 PM To: 'Ken G Kopp' ; [hidden email] ; [hidden email] Subject: Re: [Elecraft] OT: AM mode Correct, Ken. Then there is the "capture affect" of FM. Stronger FM signals could wipe out a transmission from another aircraft causing concerns. With AM, there is a greater possibility to pick out a weak signal in the presence of a stronger signal and avoid incidents. A real plus if you are flying the aircraft with the weaker signal. ;o) Terry W0FM -----Original Message----- From: Ken G Kopp [mailto:[hidden email]] Sent: Tuesday, July 16, 2013 2:31 PM To: [hidden email]; [hidden email] Subject: [Elecraft] OT: AM mode VHF/UHF aircraft radio has always been AM, and is likely / certain continue to be. Why? It's used world wide and discussions about changing it to FM have continued for years. The conclusion seems to be that there is simply too much usage worldwide and little reason to make the change. The cost to change to another mode would be horrendous! Of course manufacturers would -love- to see the change. There is usage of SSB on HF primarily ... but it's still "AM". (;-) 73! Ken - K0PP ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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