Return-Path: Received: (qmail 20086 invoked from network); 1 Apr 1999 13:22:04 +0100 Received: from magnus.plus.net.uk (HELO magnus.force9.net) (195.166.128.27) by guiness.force9.net with SMTP; 1 Apr 1999 13:22:04 +0100 Received: (qmail 4438 invoked from network); 1 Apr 1999 12:22:35 -0000 Received: from post.thorcom.com (194.75.130.70) by magnus.plus.net.uk with SMTP; 1 Apr 1999 12:22:35 -0000 Received: from troy.blacksheep.org ([194.75.183.50] ident=root) by post.thorcom.com with esmtp (Exim 2.04 #3) id 10SgQf-0004kT-01; Thu, 1 Apr 1999 13:18:37 +0100 Received: (from root@localhost) by troy.blacksheep.org (8.6.12/8.6.12) id OAA01940 for rsgb_lf_group-outgoing; Thu, 1 Apr 1999 14:11:34 GMT Received: from post.thorcom.com (root@post.unica.co.uk [194.75.183.70]) by troy.blacksheep.org (8.6.12/8.6.12) with ESMTP id OAA01936 for ; Thu, 1 Apr 1999 14:11:32 GMT X-Priority: 3 X-MSMail-Priority: Normal Received: from nms.rz.uni-kiel.de ([134.245.1.2]) by post.thorcom.com with smtp (Exim 2.04 #3) id 10SgQV-0004kO-00 for rsgb_lf_group@blacksheep.org; Thu, 1 Apr 1999 13:18:27 +0100 Received: from mail.uni-kiel.d400.de (actually srv1.mail.uni-kiel.de) by nms.rz.uni-kiel.de with Local-SMTP (PP); Thu, 1 Apr 1999 14:17:47 +0200 Received: from nephro.uni-kiel.de by mail.uni-kiel.d400.de (SMI-8.6/SMI-SVR4) id OAA10112; Thu, 1 Apr 1999 14:17:45 +0200 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Message-ID: <37036390.D7B84D15@nephro.uni-kiel.de> Date: Thu, 01 Apr 1999 14:16:16 +0200 From: "P. W. Schnoor" Organization: Clinic of Nephrology, University of Kiel X-Mailer: Mozilla 4.5 [en] (X11; I; Linux 2.0.36 i586) X-Accept-Language: de, en To: rsgb_lf_group@blacksheep.org Subject: Re: LF: AF-filters and CW versus SlowCW References: <37033EDB.63B6BC32@phonakcom.ch> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org Hello Gang, Hi Toni, "Toni Brtschi" wrote: > Today I've made some comparisons of different Audio-filter settings and > CW against Slow CW. All test were made blind and under real band-noise > conditions with the main receiving antenna (low noise, no QRN) and a > QRP-TX with a separate antenna. Here the main results (RX Harris RF590): Very interesting experiments! I do not understand "blind" in *this* case? > 1. Good audio filters with BW from 10 to 50Hz may give a 6dB advantage > above the receiver without Audio-filter (250Hz IF). A 150Hz passive > LC-filter was somewhere in between. > > 2. There is no big difference between different BW in the range from 10 > to 50Hz. Although I got the impression that 10Hz was already to small > and 20Hz the optimum in my case (Timewave DSP599zx) Our ear-brain system is able to decode better if a small amount of noise is present, probably since it's working at the edge to quantum mechanics with specific selfmade "noises" (the pathologic case is known as "Tinnitus aurium"). There are some scientific articles dealing with hearing CW in noise. One of the better ones will be found there: http://www.nitehawk.com/rasmit/br_cpy.html. Furthermore Peter, SM7CMY got his MD about this stuff; I have a copy. > 3. [...] > 4. I can confirm the optimal settings of Spectrogram found by Marco, > IK1ODO > > 5. There is no clear advantage of using longer dot-periods (e.g. 10s). I cannot confirm this. But I have to fight against pulsatile and Lux-Effect noise and I'm not using Spectrogram. 3 sec. dot length often is too short here. > These findings differ from theoretical values but it proves how good our > ear-brain detector works. They differ from practical experiences working under *different* conditions. 54°16'N / 10°04'E, JO54ag 73 es gl de Peter, DF3LP