Delivered-To: daveyxm@virginmedia.com Received: by 10.50.96.198 with SMTP id du6csp48613igb; Sat, 19 Oct 2013 14:29:23 -0700 (PDT) X-Received: by 10.180.39.34 with SMTP id m2mr4238163wik.26.1382218163228; Sat, 19 Oct 2013 14:29:23 -0700 (PDT) Return-Path: Received: from post.thorcom.com (post.thorcom.com. [195.171.43.25]) by mx.google.com with ESMTP id lf4si2429866wjb.170.2013.10.19.14.29.22 for ; Sat, 19 Oct 2013 14:29:23 -0700 (PDT) Received-SPF: neutral (google.com: 195.171.43.25 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) client-ip=195.171.43.25; Authentication-Results: mx.google.com; spf=neutral (google.com: 195.171.43.25 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) smtp.mail=owner-rsgb_lf_group@blacksheep.org; dkim=pass header.i=@mx.aol.com Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1VXdge-0000it-2o for rs_out_1@blacksheep.org; Sat, 19 Oct 2013 22:03:52 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1VXdgd-0000ik-Go for rsgb_lf_group@blacksheep.org; Sat, 19 Oct 2013 22:03:51 +0100 Received: from omr-d03.mx.aol.com ([205.188.109.200]) by relay1.thorcom.net with esmtps (TLSv1:AES256-SHA:256) (Exim 4.77) (envelope-from ) id 1VXdgb-0006Lr-Gd for rsgb_lf_group@blacksheep.org; Sat, 19 Oct 2013 22:03:50 +0100 Received: from mtaout-ma04.r1000.mx.aol.com (mtaout-ma04.r1000.mx.aol.com [172.29.41.4]) by omr-d03.mx.aol.com (Outbound Mail Relay) with ESMTP id 30ECA70141917 for ; Sat, 19 Oct 2013 17:03:46 -0400 (EDT) Received: from White (95-91-237-85-dynip.superkabel.de [95.91.237.85]) by mtaout-ma04.r1000.mx.aol.com (MUA/Third Party Client Interface) with ESMTPA id 42A2FE0000A1 for ; Sat, 19 Oct 2013 17:03:43 -0400 (EDT) Message-ID: <6C820DF06C284FE197C3B0463A7E936F@White> From: "Markus Vester" To: References: <000701cecb29$d06ee7f0$6401a8c0@JAYDELL> <525FCC72.3080506@iup.uni-heidelberg.de> <002001cecb35$90568ea0$6d01a8c0@DELL4> <525FFA57.1020001@iup.uni-heidelberg.de> <525FFAD3.2000406@iup.uni-heidelberg.de> <005401cecb51$fb859bf0$6d01a8c0@DELL4> <52608759.1070509@iup.uni-heidelberg.de> <526090AA.20402@iup.uni-heidelberg.de> <003101cecbab$78a2e2b0$6401a8c0@JAYDELL> <52611614.7090703@charter.net> <52612B46.4020701@iup.uni-heidelberg.de> <5261B880.5090903@iup.uni-heidelberg.de> <001d01cecc56$bb771380$6401a8c0@JAYDELL> <003b01cecc5a$562ce9b0$6401a8c0@JAYDELL> <9EBF60108805460E920141D8F0B47E04@White> <000b01cecc5f$0e3421a0$6401a8c0@JAYDELL> <0E38A9ECFD4D42FC98B7C1A320D49BC9@White> <5262D9D7.2040302@charter.net> <5262D976.5030109@iup.uni-heidelberg.de> <9B05FD086F7D43BCB2856D8AD6BF2485@White> <5262EA97.6010908@iup.uni-heidelberg.de> Date: Sat, 19 Oct 2013 23:03:40 +0200 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 12.0.1606 X-MimeOLE: Produced By Microsoft MimeOLE V12.0.1606 x-aol-global-disposition: G DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20121107; t=1382216626; bh=VzMI7LcmjbQbv3prWbiuAR0aI1Kacp9uyYjFDeUhroo=; h=From:To:Subject:Message-ID:Date:MIME-Version:Content-Type; b=Pp9A+b6G5MmyCX92WWJri1bl26nVNqDaukOMrrtBhwBLQOLYXWP5AaIwXgEdsd6aL a5tg+FAh9fLF6N9Fg8EMFYuLwrFrxQ0AK0zb2s/RYRvqV0tU4SjE9HwTmAbOiCbwTw XMOipyxnppu14p+RJr2r+sGokUueEbpm9Ze2eo3E= x-aol-sid: 3039ac1d29045262f3af3336 X-AOL-IP: 95.91.237.85 X-Spam-Score: -0.4 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: With a much longer list, you would still get the same sensitivity in the first place, but a higher probability of false positives. To avoid these, you would then want to raise the threshold (eg. from 15 to 16 dB), thus decreasing sensitivity indirectly. At constant false alarm rate, the required threshold fortunately scales only weakly (less than logarithmic) with the number of entries. [...] Content analysis details: (-0.4 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [205.188.109.200 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (markusvester[at]aol.com) -0.0 SPF_PASS SPF: sender matches SPF record -0.4 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: c40596c1cc3306f1877076595a921c57 Subject: Re: LF: T/A OPDS Content-Type: multipart/alternative; boundary="----=_NextPart_000_0004_01CECD1F.73C91000" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.9 required=5.0 tests=HTML_30_40,HTML_MESSAGE, MISSING_OUTLOOK_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 Status: O X-Status: X-Keywords: X-UID: 3024 Dies ist eine mehrteilige Nachricht im MIME-Format. ------=_NextPart_000_0004_01CECD1F.73C91000 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable With a much longer list, you would still get the same sensitivity in the = first place, but a higher probability of false positives. To avoid = these, you would then want to raise the threshold (eg. from 15 to 16 = dB), thus decreasing sensitivity indirectly. At constant false alarm = rate, the required threshold fortunately scales only weakly (less than = logarithmic) with the number of entries. But processing time will be proportional to the length of the list. For = a "true decode" of the 28 bit compressed callsign, one would need to go = through 268 million templates ;-)=20 73, Markus From: Stefan Sch=E4fer=20 Sent: Saturday, October 19, 2013 10:24 PM To: rsgb_lf_group@blacksheep.org=20 Subject: Re: LF: T/A OPDS Hello Markus,=20 Am 19.10.2013 21:36, schrieb Markus Vester:=20 BTW In my other posting I hadn't explained the last dB number in the = opds result line. This describes the quality of the match to the = callsign template, ie how many dBs the highest peak in the = cross-correlation function exceeds its average power, which comes from = noise and autocorrelation sidelobes. The range is from about 22 dB for a = perfect signal, down to a chosen threshold of 15 dB where false = positives start to appear occasionally. OK, understood. Another question for a better OPDS understanding: Is the decode = performance of the program also a function of the number of call signs = in the list? Example: If i go to add any valid amateur radio callsign in = the list, will decodes (close to the limit) become more unlikely? 73, Stefan/DK7FC ------=_NextPart_000_0004_01CECD1F.73C91000 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
With a much longer list, you would = still get the=20 same sensitivity in the first place, but a higher probability of = false=20 positives. To avoid these, you would then want to raise the = threshold=20 (eg. from 15 to 16 dB), thus decreasing sensitivity = indirectly. At=20 constant false alarm rate, the required threshold fortunately = scales only=20 weakly (less than logarithmic) with the number of entries.
 
But processing time will be = proportional to=20 the length of the list. For a "true decode" of the 28 bit = compressed=20 callsign, one would need to go through 268 million=20 templates ;-) 
 
73, Markus

From: Stefan = Sch=E4fer
Sent: Saturday, October 19, 2013 10:24 PM
Subject: Re: LF: T/A OPDS

Hello = Markus,

Am=20 19.10.2013 21:36, schrieb Markus Vester:=20
BTW In my other posting I hadn't = explained=20 the last dB number in the opds result line. This describes the = quality of=20 the match to the callsign template, ie how many dBs the highest peak = in the=20 cross-correlation function = exceeds its average power,=20 which comes from noise and autocorrelation sidelobes. The range=20 is from about 22 dB for a perfect signal, down to a chosen = threshold=20 of 15 dB where false positives start to appear=20 occasionally.
OK,=20 understood.

Another question for a better OPDS understanding: Is = the=20 decode performance of the program also a function of the number of call = signs in=20 the list? Example: If i go to add any valid amateur radio callsign in = the list,=20 will decodes (close to the limit) become more unlikely?

73,=20 Stefan/DK7FC
------=_NextPart_000_0004_01CECD1F.73C91000--