Return-Path: Received: (qmail 1933 invoked from network); 30 Jul 2002 23:45:55 -0000 Received: from warrior.services.quay.plus.net (212.159.14.227) by mailstore with SMTP; 30 Jul 2002 23:45:55 -0000 X-Priority: 3 X-MSMail-Priority: Normal Received: (qmail 26615 invoked from network); 30 Jul 2002 23:45:57 -0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from post.thorcom.com (193.82.116.70) by warrior.services.quay.plus.net with SMTP; 30 Jul 2002 23:45:57 -0000 X-SQ: A Received: from majordom by post.thorcom.com with local (Exim 3.33 #2) id 17ZiNQ-0000uS-00 for rsgb_lf_group-outgoing@blacksheep.org; Wed, 31 Jul 2002 02:34:12 +0100 Received: from imo-d09.mx.aol.com ([205.188.157.41]) by post.thorcom.com with esmtp (Exim 3.33 #2) id 17ZiNP-0000uN-00 for rsgb_lf_group@blacksheep.org; Wed, 31 Jul 2002 02:34:11 +0100 Received: from RaySoifer@cs.com by imo-d09.mx.aol.com (mail_out_v32.21.) id l.86.1e10d725 (3980) for ; Tue, 30 Jul 2002 19:42:06 -0400 (EDT) From: RaySoifer@cs.com Message-ID: <86.1e10d725.2a787e4e@cs.com> Date: Tue, 30 Jul 2002 19:42:06 EDT Subject: Re: LF: Droitwich Carrier To: rsgb_lf_group@blacksheep.org MIME-Version: 1.0 Content-Type: text/html; charset=windows-1252 X-Mailer: CompuServe 2000 6.0 for Windows US sub 10511 Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: Content-transfer-encoding: 8bit Hi,

I have no AM broadcast experience, having only been chief engineer of an FM (but not AM) BC station in the 1960s, but from my amateur experience, any form of controlled-carrier transmission I've ever seen reduced the carrier when the audio was at low level, not when it was high.  This "downward modulation" that has been measured by several observers would almost certainly imply a degree of overmodulation on audio peaks.  That could result from a number of causes: insufficient grid drive on the RF stages, too much audio relative to the carrier, or if compression is being used, an incorrect setting of the maximum audio level.

I was in England last week, and Droitwich sounded fine on my LF BC receiver, but that doesn't prove anything re overmodulation.

73,

Ray, W2RS