Return-Path: Received: (qmail 29750 invoked from network); 1 Apr 1999 11:43:08 +0100 Received: from magnus.plus.net.uk (HELO magnus.force9.net) (195.166.128.27) by guiness.force9.net with SMTP; 1 Apr 1999 11:43:08 +0100 Received: (qmail 22945 invoked from network); 1 Apr 1999 10:43:39 -0000 Received: from post.thorcom.com (194.75.130.70) by magnus.plus.net.uk with SMTP; 1 Apr 1999 10:43:39 -0000 Received: from troy.blacksheep.org ([194.75.183.50] ident=root) by post.thorcom.com with esmtp (Exim 2.04 #3) id 10SetX-0003mk-00; Thu, 1 Apr 1999 11:40:19 +0100 Received: (from root@localhost) by troy.blacksheep.org (8.6.12/8.6.12) id MAA01071 for rsgb_lf_group-outgoing; Thu, 1 Apr 1999 12:32:05 GMT X-Priority: 3 X-MSMail-Priority: Normal 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 MAA01067 for ; Thu, 1 Apr 1999 12:32:03 GMT Received: from bw85zhb.bluewin.ch ([195.186.1.75]) by post.thorcom.com with esmtp (Exim 2.04 #3) id 10SesI-0003jP-00 for rsgb_lf_group@blacksheep.org; Thu, 1 Apr 1999 11:39:02 +0100 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from phonakcom.ch ([195.186.13.166]) by bw85zhb.bluewin.ch ( with ESMTP id AAA3B31 for ; Thu, 1 Apr 1999 12:38:55 +0200 Message-ID: <37033EDB.63B6BC32@phonakcom.ch> Date: Thu, 01 Apr 1999 11:39:39 +0200 From: "Toni Bdrtschi" Organization: Phonak Communications AG X-Mailer: Mozilla 4.03 [de] (Win95; I) MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org Subject: LF: AF-filters and CW versus SlowCW Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 8bit Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org >From HB9ASB, JN36pt 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): 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) 3. Slow CW with the Spectrogram (3sec dots) gives an advantage of about 10dB above aural CW with narrow audio filtering. 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). These findings differ from theoretical values but it proves how good our ear-brain detector works. 73 de Toni