Return-Path: Received: (qmail 29707 invoked from network); 23 Nov 2004 17:23:39 -0000 Received: from unknown (HELO ptb-spamcore01.plus.net) (192.168.71.1) by ptb-mailstore02.plus.net with SMTP; 23 Nov 2004 17:23:39 -0000 Received: from mailnull by ptb-spamcore01.plus.net with spamcore-l-b (Exim 4.32; FreeBSD) id 1CWegD-000BpQ-6U for dave@picks.force9.co.uk; Tue, 23 Nov 2004 17:42:19 +0000 Received: from [192.168.67.2] (helo=ptb-mxcore02.plus.net) by ptb-spamcore01.plus.net with esmtp (Exim 4.32; FreeBSD) id 1CWegC-000BpI-Vz for dave@picks.force9.co.uk; Tue, 23 Nov 2004 17:42:17 +0000 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore02.plus.net with esmtp (Exim) id 1CWeO8-000Kn2-LC for dave@picks.force9.co.uk; Tue, 23 Nov 2004 17:23:36 +0000 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1CWeMs-0000dj-EO for rs_out_1@blacksheep.org; Tue, 23 Nov 2004 17:22:18 +0000 Received: from [193.82.116.30] (helo=relay.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1CWeMs-0000da-2X for rsgb_lf_group@blacksheep.org; Tue, 23 Nov 2004 17:22:18 +0000 Received: from imo-m16.mx.aol.com ([64.12.138.206]) by relay.thorcom.net with esmtp (Exim 4.41) id 1CWeMh-0000oJ-FR for rsgb_lf_group@blacksheep.org; Tue, 23 Nov 2004 17:22:18 +0000 Received: from DL4YHF@aol.com by imo-m16.mx.aol.com (mail_out_v37_r3.8.) id l.d8.19f8abbd (4446) for ; Tue, 23 Nov 2004 12:21:59 -0500 (EST) From: DL4YHF@aol.com Message-ID: Date: Tue, 23 Nov 2004 12:21:58 EST To: rsgb_lf_group@blacksheep.org MIME-Version: 1.0 X-Mailer: 8.0 for Windows sub 6104 X-SPF-Result: relay.thorcom.net: domain of aol.com designates 64.12.138.206 as permitted sender X-Spam-Score: 0.7 (/) X-Spam-Report: autolearn=no,HTML_MESSAGE=0.001,HTML_TAG_BALANCE_HTML=0.411,NO_REAL_NAME=0.285 Subject: Re: LF: Linear amplifiers , MSK, and 500kHz Content-Type: text/html; charset=windows-1252 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Status: No, hits=0.7 required=5.0 tests=HTML_MESSAGE, HTML_TAG_BALANCE_HTML,NO_REAL_NAME autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-Spam-Filtered: by PlusNet SpamCORE (v3.00) Content-transfer-encoding: 8bit Greetings all,

I tried writing an MSK decoder, re-using parts of the PSK31/PSK08 decoder, but like Bill didn't get it working properly. Furthermore, at that time I was happy with the performance of PSK08 (and even PSK02) as implemented in Spectrum Lab - most of all because the maximum output power of my "almost-linear" PA was limited to 80 Watts so efficiency was not an issue (but this may change soon...).

To anyone trying an implementation of an MSK decoder: Forget the simple approaches using Squaring- and Costas Loops - it takes more than this. Producing an MSK signal, on the other hand, is simple if you treat it as frequency shift keying with a modulation index of 0.5 .  The bandwidth efficiency (if we had an optimum decoder) would be 1.9 (bit/sec per Hertz), almost the same as for QPSK. But, as so often, real-world problems seem to have prevented MSK being used as narrow-band amateur radio mode.

Best regards,
Wolf DL4YHF.