Return-Path: Received: (qmail 9050 invoked from network); 1 Aug 2002 12:34:29 -0000 Received: from murphys.services.quay.plus.net (212.159.14.225) by mailstore with SMTP; 1 Aug 2002 12:34:29 -0000 Received: (qmail 13519 invoked from network); 1 Aug 2002 12:34:19 -0000 Received: from post.thorcom.com (193.82.116.70) by murphys.services.quay.plus.net with SMTP; 1 Aug 2002 12:34:19 -0000 X-SQ: A Received: from majordom by post.thorcom.com with local (Exim 3.33 #2) id 17aGpn-0004uA-00 for rsgb_lf_group-outgoing@blacksheep.org; Thu, 01 Aug 2002 15:21:47 +0100 Received: from ns2.etecsa.net ([206.49.67.1] helo=mxb.etecsa.net) by post.thorcom.com with esmtp (Exim 3.33 #2) id 17aGpl-0004u5-00 for rsgb_lf_group@blacksheep.org; Thu, 01 Aug 2002 15:21:46 +0100 Received: (from daemon@localhost) by mxb.etecsa.net (8.10.2+Sun/8.10.2) id g71CU8r23742 for rsgb_lf_group@blacksheep.org; Thu, 1 Aug 2002 08:30:08 -0400 (EDT) Received: from ppp-098ved.pppi.etecsa.cu(65.169.247.98), claiming to be "user" via SMTP by mail, id smtpdAAABJa4uU; Thu Aug 1 08:30:05 2002 Message-ID: <009c01c2394e$e6d44ae0$62f7a941@user> From: "Prof. Arnaldo Coro Antich" To: rsgb_lf_group@blacksheep.org References: <5.1.0.14.0.20020801100707.00a17630@POP3.freeler.nl> Subject: LF: Re: "Downward modulation" Date: Thu, 1 Aug 2002 08:30:47 -0300 MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: You are certainly talking about DAM... Dynamic Amplitude Modulation.... a process that is used with very high power transmitters to save energy..... When there is no modulation, the carrier level is moved UP, in order to keep the signal to noise ratio on the channel at a better level for the listener ( i.e. no background noise or co-channel stations... you require 26 dB signal to noise ratio on an AM system that has between 4 and 5 kiloHertz bandwidth in order to provide full quieting ...) AND YES.... there are many high power AM transmitters nowadays that are facing very poor operation !!! 73 and DX Arnie Coro CO2KK