Return-Path: <owner-rsgb_lf_group@blacksheep.org> Received: (qmail 99871 invoked from network); 13 Apr 2005 12:58:14 -0000 Received: from unknown (HELO ptb-spamcore01.plus.net) (192.168.71.1) by ptb-mailstore02.plus.net with SMTP; 13 Apr 2005 12:58:14 -0000 Received: from mailnull by ptb-spamcore01.plus.net with spamcore-l-b (Exim 4.32; FreeBSD) id 1DLhTi-0004GM-UR for dave@picks.force9.co.uk; Wed, 13 Apr 2005 14:00:23 +0100 Received: from [192.168.101.73] (helo=pih-mxcore07.plus.net) by ptb-spamcore01.plus.net with esmtp (Exim 4.32; FreeBSD) id 1DLhTi-0004GB-JX for dave@picks.force9.co.uk; Wed, 13 Apr 2005 14:00:22 +0100 Received: from post.thorcom.com ([193.82.116.20]) by pih-mxcore07.plus.net with esmtp (PlusNet MXCore v1.0) id 1DLhRd-0000cD-An for dave@picks.force9.co.uk; Wed, 13 Apr 2005 13:58:13 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1DLhR9-0006VJ-CY for rs_out_1@blacksheep.org; Wed, 13 Apr 2005 13:57:43 +0100 Received: from [193.82.116.30] (helo=relay.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1DLhR8-0006VA-Vg for rsgb_lf_group@blacksheep.org; Wed, 13 Apr 2005 13:57:42 +0100 Received: from imo-m23.mx.aol.com ([64.12.137.4]) by relay.thorcom.net with esmtp (Exim 4.43) id 1DLhR5-0000fU-EZ for rsgb_lf_group@blacksheep.org; Wed, 13 Apr 2005 13:57:42 +0100 Received: from G0MRF@aol.com by imo-m23.mx.aol.com (mail_out_v38.7.) id l.e8.112bca7a (3940) for <rsgb_lf_group@blacksheep.org>; Wed, 13 Apr 2005 08:57:25 -0400 (EDT) From: G0MRF@aol.com Message-ID: <e8.112bca7a.2f8e7135@aol.com> Date: Wed, 13 Apr 2005 08:57:25 EDT To: rsgb_lf_group@blacksheep.org MIME-Version: 1.0 X-Mailer: 9.0 SE for Windows sub 5003 X-SPF-Result: relay.thorcom.net: domain of aol.com designates 64.12.137.4 as permitted sender X-Spam-Score: 0.2 (/) X-Spam-Report: autolearn=no,HTML_30_40=0.056,HTML_MESSAGE=0.001,NO_REAL_NAME=0.178 Subject: Re: LF: Re: How to easily cross the Pond ? (was : G3AQC in ZL) 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=0.8 required=5.0 tests=HTML_20_30,HTML_MESSAGE, 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 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=Content-Type content="text/html; charset=US-ASCII"> <META content="MSHTML 6.00.2800.1491" name=GENERATOR></HEAD> <BODY id=role_body style="FONT-SIZE: 10pt; COLOR: #000000; FONT-FAMILY: Arial" bottomMargin=7 leftMargin=7 topMargin=7 rightMargin=7><FONT id=role_document face=Arial color=#000000 size=2> <DIV> <DIV>In a message dated 13/04/2005 11:09:18 GMT Standard Time, dibene@usa.net writes:</DIV> <BLOCKQUOTE style="PADDING-LEFT: 0px; MARGIN-LEFT: 0px"><FONT style="BACKGROUND-COLOR: transparent" face=Arial color=#000000 size=2>Rik,<BR><BR> probably your idea would work, but I think that if you can achieve <BR>phase coherence then the<BR>best technique would be to compute the two correlations between the <BR>received signal and<BR>what the signal should be in case either of a "1" or of a "0", then <BR>select the symbol that<BR>gives the highest correlation value. And. if you have CPU cycles to <BR>spare, which probably is<BR>the case for low signaling rates, then you could even correct for small <BR>phase errors by<BR>computing several correlation sums, each shifted by a few degrees, <BR>finding then the peak.<BR>And adding a convolutional FEC coding with a soft-decision Viterbi <BR>decoder would certainly<BR>be of no harm...<BR><BR>73 Alberto I2PHD</FONT></BLOCKQUOTE></DIV> <DIV> </DIV> <DIV>I wonder if the new narrow version of JT65 would give us something to play with. Not the complete transmission bandwidth, but just the couple of characters that occur in close vicinity to the sync tone. I believe this uses a similar decoding algorithm and needs to be locked to within a second of the receiving station. I must read the help files again.</DIV> <DIV>There is also a narrowband version designed for laser communication. However, even this narrowband system is still 10Hz wide for the full character set.</DIV> <DIV> </DIV> <DIV>Both can use class C D E etc.</DIV> <DIV> </DIV> <DIV>73</DIV> <DIV> </DIV> <DIV>David</DIV></FONT></BODY></HTML>