Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-db02.r1000.mx.aol.com (Internet Inbound) with ESMTP id 82EA33800008E; Fri, 10 Feb 2012 03:44:19 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Rvm3r-00046c-E9 for rs_out_1@blacksheep.org; Fri, 10 Feb 2012 08:42:31 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Rvm3q-00046T-Ls for rsgb_lf_group@blacksheep.org; Fri, 10 Feb 2012 08:42:30 +0000 Received: from out1.ip09ir2.opaltelecom.net ([62.24.128.245]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Rvm3o-0006ps-Ai for rsgb_lf_group@blacksheep.org; Fri, 10 Feb 2012 08:42:30 +0000 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: ApMBAP7XNE9cGSeI/2dsb2JhbAAMN7JlAQEBAQM4QBELCQ8JFg8JAwIBAgFFEwYCAQEawGWLMQQaARIBAxYBBQQDBAQHDgYBAwgBBCKDZHuDHQSNZJou X-IronPort-AV: E=Sophos;i="4.73,395,1325462400"; d="scan'208";a="505284931" Received: from host-92-25-39-136.as13285.net (HELO [192.168.2.5]) ([92.25.39.136]) by out1.ip09ir2.opaltelecom.net with ESMTP; 10 Feb 2012 08:42:22 +0000 Message-ID: <4F34D86D.1010405@talktalk.net> Date: Fri, 10 Feb 2012 08:42:21 +0000 From: qrss User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:10.0) Gecko/20120129 Thunderbird/10.0 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <4F341AE5.1050704@talktalk.net> <4F342525.1050200@talktalk.net> <4F34313C.1080005@talktalk.net> <1659D80990BC4B5482FF78B6249AACAF@JimPC> In-Reply-To: X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,RATWARE_GECKO_BUILD=1.426 Subject: Re: LF: Cats among pigeons Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit 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-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:491741696:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d40564f34d8e36bac X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none Hello Andy We do need to refer back to my original posts here. > Yes OP8 decodes but almost always either equal S/N or worse. After that Graham asked for what I meant by worse. I have been keen to run some tests because I have never been monitoring and seen the expected 3dB advantage of OP8 over OP4 on 500kHz. Seeing repeated OP4 then OP8 results when OP8 does not decode but OP4 does, put me in doubt of my PIC timing. Regularly seeing OP4 produce between 3dB and 7dB stronger reports than OP8 when both were de-coding at low signal levels I considered made all OP8 reports invalid, and confused the theory.. (On 500kHz on the paths tried) Surely this is QSB, visible on some transmissions, hence the shorter OP modes win over on 500kHz. Eddie On 09/02/2012 21:20, Andy Talbot wrote: > The reported S/N (normalised to 2500Hz) for each mode should be the > same; the decoding threshold is different in proportion to teh speed. > > If the reported value is consistently and systematically out, either > there's a big mistake in the software decoding, or there are other > factors coming into play. > > 'jnt > > > > On 9 February 2012 21:11, James Moritz wrote: >> Dear Eddie, LF Group, >> >> So what you are saying is that the actual SNR at the decode/no decode >> threshold is the same for Op8 and Op4, but that the SNR indicated by Op8 at >> this level is 3dB lower than that indicated by Op4? >> >> Cheers, Jim Moritz >> 73 de M0BMU >> >