Return-Path: Received: (qmail 10357 invoked from network); 31 Jul 2002 15:09:16 -0000 Content-Transfer-Encoding: 8bit Received: from marstons.services.quay.plus.net (212.159.14.223) by mailstore with SMTP; 31 Jul 2002 15:09:16 -0000 X-Priority: 3 X-MSMail-Priority: Normal Received: (qmail 19840 invoked by uid 10001); 31 Jul 2002 15:13:53 -0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from post.thorcom.com (193.82.116.70) by marstons.services.quay.plus.net with SMTP; 31 Jul 2002 15:13:53 -0000 X-SQ: A Received: from majordom by post.thorcom.com with local (Exim 3.33 #2) id 17ZwlA-0002WX-00 for rsgb_lf_group-outgoing@blacksheep.org; Wed, 31 Jul 2002 17:55:40 +0100 Received: from relay.dera.gov.uk ([192.5.29.49]) by post.thorcom.com with smtp (Exim 3.33 #2) id 17Zwl9-0002WS-00 for rsgb_lf_group@blacksheep.org; Wed, 31 Jul 2002 17:55:39 +0100 Received: (qmail 4438 invoked from network); 31 Jul 2002 16:04:11 +0100 Received: from butterfly.mod.uk (HELO warlock.dstl.gov.uk) (192.5.29.10) by relay.dera.gov.uk with SMTP; 31 Jul 2002 16:04:11 +0100 Message-ID: <7D653C9C42F5D411A27C00508BF8803DCB9B57@mail.dstl.gov.uk> From: "Talbot Andrew" To: "LF Group \(E-mail\)" Subject: LF: Droitwich carrier Date: Wed, 31 Jul 2002 16:03:53 +0100 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2653.19) Content-Type: text/plain; charset=iso-8859-1; format=flowed Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: Took a few seconds of the signal from Droitwich with speech modulation, downconverted to 0 - 6kHz and saved as a .WAV file. I already had some software that analyses a .WAV file for maximum and minimum peaks, calculates the RMS and some other analysis functions not relevant here. The Droitwich recording showed maximum positive and negative peaks (amplitude, not power) in the region of 6600 (out of 32786 maximum) and an RMS value of 2995, giving a peak to mean ratio of 6.9dB. (technically, peak to RMS, but in power terms equal to peak to mean) Bear in mind that this peak amplitude was the highest single one recorded in several seconds of audio. To compare, a sinewave has a 3dB peak to mean and this software does give exactly that figure for a .WAV test file containing a pure sinewave. A 'perfect' 100% modulated AM transmission carrying a sinewave should have 4.8 dB peak to mean, so what mechanism can account for 6.9dB ? This certainly does seem to reinforce the idea that the carrier reduces with amplitude. Andy G4JNT "This e-mail is intended for the recipient only. If you are not the intended recipient you must not use, disclose, distribute, copy, print, or rely upon this e-mail. If an addressing or transmission error has misdirected this e-mail, please notify the author by replying to this e-mail." "Recipients should note that all e-mail traffic on MOD systems is subject to monitoring and auditing."