I seem to remember that the aircraft radios we used during the 60-80s in P-3s/C-130s etc (ARC-94/102 aka 618T) had a selection called AME (AM equivalent). It was explained to us (pilots) by the techs that it wasn't a high level AM, but USB with carrier. It sounded OK, but then again, it was designed for communications and not "easy listening"! All the airways communication now days is SSB, so the AME position rarely gets selected.
Perhaps someone is familiar with that mode and can expand on it. 73 Tom/W4OKW ------------------------------------------------------------------------ ------ Message: 2 Date: Thu, 7 Feb 2008 17:22:14 -0600 From: "D. Chester" <[EMAIL PROTECTED]> Subject: [AMRadio] Re: Carrier with one sideband To: <[email protected]> Message-ID: <[EMAIL PROTECTED]> Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original > From: Peter Markavage <[EMAIL PROTECTED]> > A number of the early phasing type transmitters/exciters and SSB adapters > allowed you to operate on "AM" with just one sideband. So, only operating > DSB AM would really be an issue. >> From: "Bob Macklin" <[EMAIL PROTECTED]> > Any of the Heath SSB rigs (SB-100/101, SB-400/401, HW-100/101) could be > modified to Vestigial SB. SSB with carrier reinserted. > > Bob Macklin > K5MYJ SSB with the carrier re-inserted is not the same thing as what we know as AM. It is nothing more than SSB with poor carrier suppression. Reception with an envelope detector inherently generates severe distortion at modulation levels beyond about 20%. This mode is useful only with a receiver with BFO that locks onto the "pilot carrier" to eliminate frequency error in SSB reception, a technique that has in fact long been used in commercial services, with the carrier level reduced to about 20 dB below p.e.p. At modulation levels low enough to avert this distortion, known as "quadrature distortion" it is very wasteful of power since the sideband power becomes a very small percentage of total radiated power. Those amateur SSB rigs that transmit "AM" with carrier and one sideband sound like CRAP. Unless the receiving station is equipped with a proper receiver with PLL carrier reinsertion, which includes very few amateur receivers, it is a totally useless mode beyond simply getting someone's attention when they are receiving in AM mode, in order that they may switch the receiver over to SSB to receive the signal in normal SSB fashion. This problem is inherent to the principles of modulation, and has nothing to do with the quality of the equipment used. Transmitting AM with one sideband is NOT a solution to the problem nor is it even a satisfactory option. 73, Don k4kyv ______________________________________________________________ Our Main Website: http://www.amfone.net AMRadio mailing list List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:[email protected] To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
