Return-Path: Received: (qmail 18769 invoked from network); 1 Aug 2002 09:46:31 -0000 Received: from warrior.services.quay.plus.net (212.159.14.227) by mailstore with SMTP; 1 Aug 2002 09:46:31 -0000 Received: (qmail 13544 invoked from network); 1 Aug 2002 09:46:21 -0000 X-Priority: 3 X-MSMail-Priority: Normal Received: from post.thorcom.com (193.82.116.70) by warrior.services.quay.plus.net with SMTP; 1 Aug 2002 09:46:21 -0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-SQ: A Received: from majordom by post.thorcom.com with local (Exim 3.33 #2) id 17aEAj-0004Zb-00 for rsgb_lf_group-outgoing@blacksheep.org; Thu, 01 Aug 2002 12:31:13 +0100 Received: from d12lmsgate-2.de.ibm.com ([195.212.91.200]) by post.thorcom.com with esmtp (Exim 3.33 #2) id 17aEAi-0004ZV-00 for rsgb_lf_group@blacksheep.org; Thu, 01 Aug 2002 12:31:13 +0100 Received: from d12relay02.de.ibm.com (d12relay02.de.ibm.com [9.165.215.23]) by d12lmsgate-2.de.ibm.com (8.12.3/8.12.3) with ESMTP id g719d8PV034548 for ; Thu, 1 Aug 2002 11:39:14 +0200 Received: from usa.net (ss2.bld.socks.ibm.com [9.14.4.67]) by d12relay02.de.ibm.com (8.12.3/NCO/VER6.3) with ESMTP id g719d0a9034414 for ; Thu, 1 Aug 2002 11:39:06 +0200 Message-ID: <3D49015E.E2800231@usa.net> Date: Thu, 01 Aug 2002 11:37:34 +0200 From: "Alberto di Bene" X-Mailer: Mozilla 4.79 [en] (Windows NT 5.0; U) X-Accept-Language: en MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org Subject: LF: Re: Droitwich carrier References: <200208010356.g713ujZ12610@block.iamanidiot.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: David Willmore wrote: > This is different from what I would expect to happen. > To start with, one takes a carrier or some power, then > one modulates its amplitude. This process spreads some > of the energy into the symetrical side bands--taking > power out of the carrier, thus causing 'downward > modulation' of the carrier, right? I beg to differ. A properly modulated AM signal will have a carrier of constant amplitude, unaffected by the modulation. That's why SSB was born, to eliminate altogether a spectral component that didn't carry any information content. FM is another case... Its spectrum can be computed with the Bessel functions and shows a carrier of amplitude changing with the modulation index, going down to zero for certain values of it, as Jim Moritz pointed out in a past message. 73 Alberto I2PHD