Return-Path: Received: from rly-md09.mx.aol.com (rly-md09.mail.aol.com [172.20.29.147]) by air-md09.mail.aol.com (v121_r4.4) with ESMTP id MAILINMD092-92249739ba22b0; Sun, 18 Jan 2009 16:14:20 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-md09.mx.aol.com (v121_r4.4) with ESMTP id MAILRELAYINMD092-92249739ba22b0; Sun, 18 Jan 2009 16:14:12 -0500 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1LOexx-0000Mc-Gd for rs_out_1@blacksheep.org; Sun, 18 Jan 2009 21:13:57 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1LOexx-0000MT-3W for rsgb_lf_group@blacksheep.org; Sun, 18 Jan 2009 21:13:57 +0000 Received: from smtp-out-1.talktalk.net ([62.24.128.231] helo=smtp.talktalk.net) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1LOexw-0006NI-Fz for rsgb_lf_group@blacksheep.org; Sun, 18 Jan 2009 21:13:57 +0000 X-Path: TTSMTP X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AqgEAGcqc0lZ8PRx/2dsb2JhbACEVspihXM Received: from unknown (HELO mal769a60aa920) ([89.240.244.113]) by smtp.talktalk.net with SMTP; 18 Jan 2009 21:13:50 +0000 Message-ID: <01b201c979b1$a8e2add0$0301a8c0@mal769a60aa920> From: "mal hamilton" To: References: <062295BFBDD5429597FB842D9F5B24B7@DennisPC> <00fc01c9798d$9a308330$0301a8c0@mal769a60aa920> <200901181845260601.12CD2642@smtp.wanadoo.fr> <49739359.7080706@freenet.de> Date: Sun, 18 Jan 2009 21:13:50 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Karma: unknown: X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: Re: LF: PSK CONTACT G4JNT - M0BMU Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 8bit X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=none 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-AOL-IP: 193.82.116.20 That Indian curry has certainly stimulated the mind now into the Megacycles range. Don't get convulsions !!!!!! ----- Original Message ----- From: "Andy Talbot" To: Sent: Sunday, January 18, 2009 9:04 PM Subject: Re: LF: PSK CONTACT G4JNT - M0BMU Amateur bands are typically 2 to 10% of their centre frequency, so lets take a figure of 5%, giving a useable band 95uHz wide. Allow a waveform that criutically fits inside this bandwidth - OFDM or MFSK fit the bill nicely as they both have 'brick wall' frequency spectra, so with really good coding we ought to be able to fit in about 100 - 200 u Bits/s, or one bit per 500 - 10000s. Say one bit per hour. We will use a codebook based approach to coding callsigns and reports so as to compress a message into the smallest space possible: say a maximum of 256 stations on the band in the world, means 8 bits need to be allocated to callsign, and four possible reports (poor/marginal/OK/strong) gives 10 bits per QSO. Add two more bits for QSO formatting and we end up with 12 bits of data per frame . We will need good error correction, so make it a convolutional rate half code - 24 bits in total. A QSO needs a minimum of two overs each for full acknowledgement each way so at least 96 bits need to be exchanged. If no further overhead is used, the QSO could therefore be completed in four days. Andy G4JNT www.g4jnt.com 2009/1/18 Wolfgang Büscher : > John wrote: >> >> 1.9mhz - now what sort of signalling rate can you get on 160Gm? >> >> John F5VLF >> >> > > ;o) > Need a pretty decent antenna length for that, right ? > And just consider the 1/f noise in the milliHertz receiver - use liquid > helium cooling for the frontend ;-) > > > -------------------------------------------------------------------------------- No virus found in this incoming message. Checked by AVG - http://www.avg.com Version: 8.0.176 / Virus Database: 270.10.8/1899 - Release Date: 1/17/2009 5:50 PM