Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-md05.r1000.mx.aol.com (Internet Inbound) with ESMTP id B8AC5380000A0; Sat, 12 May 2012 08:27:11 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1STBP2-0000Di-DM for rs_out_1@blacksheep.org; Sat, 12 May 2012 13:26:28 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1STBP1-0000DZ-Vf for rsgb_lf_group@blacksheep.org; Sat, 12 May 2012 13:26:27 +0100 Received: from mail-ob0-f171.google.com ([209.85.214.171]) by relay1.thorcom.net with esmtps (TLSv1:RC4-SHA:128) (Exim 4.77) (envelope-from ) id 1STBP0-0003H1-4T for rsgb_lf_group@blacksheep.org; Sat, 12 May 2012 13:26:26 +0100 Received: by obfk16 with SMTP id k16so10409532obf.16 for ; Sat, 12 May 2012 05:26:24 -0700 (PDT) X-DKIM-Result: Domain=gmail.com Result=Good and Known Domain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=JkprVh+6vubSjXGp1nZMLNmAN70/0Gl+gmmW6msRRyY=; b=bsrg9xKa270oJo1JWfZBaDQWNyG7KlH/aDpOMfPc2M8Mj2tZZlQJs4Ebiu7VXitljC iiAtjV+tEwnL29iXNrTcj135BAJWMIkfUtL6rrBHaQrGX5OkXMXYLEpRlUFDzAbAff+U psk63nwMPhGbxa7h9vntE8eScz5OXSoqezB+yE3YZGX9wEHq862OoVljqdvS8Zz8/SBI fZmekZEy4UIC50fKGM10OZo+VxMG2IeJ6gty3p/GJPVL9qcK/WTQA6sQA7Lv2JDF5LoX LPTHNa3RZuNz32YO3kankPuZdXZcGJnla/rIv3BLJar50sH4P62Mgo5c02kcgmy69aHs TjFg== MIME-Version: 1.0 Received: by 10.50.17.169 with SMTP id p9mr757000igd.60.1336825584324; Sat, 12 May 2012 05:26:24 -0700 (PDT) Received: by 10.231.60.134 with HTTP; Sat, 12 May 2012 05:26:24 -0700 (PDT) In-Reply-To: References: Date: Sat, 12 May 2012 13:26:24 +0100 Message-ID: From: Andy Talbot To: rsgb_lf_group@blacksheep.org X-Spam-Score: -0.7 (/) 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: That's exactly my findings. Most of those in the know assume the ear's effective bandwidth to be somewhere in the region of 30 - 100Hz. 7dB S/N in a signalling bandwidth is pretty typical of what any power detection software can manage blindly - it is a mathematical calculation that isn't too difficult to do. And since that value falls out of maths, its quite reasonable to expect ears to follow the laws of physics / maths too. So in a signal bandwidth, ears / eyes and signal detection software based on pure non-coherent power detection are all roughley equal. [...] Content analysis details: (-0.7 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low trust [209.85.214.171 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (andy.g4jnt[at]gmail.com) -0.0 SPF_PASS SPF: sender matches SPF record 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: 4e3b1488273adbbe9757d6bdd5adf219 Subject: Re: LF: Demonstrating audibility of weak signals - utilty to play with. Content-Type: text/plain; charset=ISO-8859-1 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: 0:2:418774976:93952408 X-AOL-SCOLL-URL_COUNT: 0 X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-m273.2 ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1d60594fae571f4f72 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none That's exactly my findings. Most of those in the know assume the ear's effective bandwidth to be somewhere in the region of 30 - 100Hz. 7dB S/N in a signalling bandwidth is pretty typical of what any power detection software can manage blindly - it is a mathematical calculation that isn't too difficult to do. And since that value falls out of maths, its quite reasonable to expect ears to follow the laws of physics / maths too. So in a signal bandwidth, ears / eyes and signal detection software based on pure non-coherent power detection are all roughley equal. Andy On 12 May 2012 12:04, Roelof Bakker wrote: > Hello Andy, > > Thank you for this little gem. > > I have been playing with it for a while. > With a signal to noise ratio of -10 dB in 2500 Hz, I can copy a 10 WPM > message with the output filter set to 2500 Hz. > Estimating my brain ear system bandwidth as 50 Hz, the effective signal to > noise ratio is 6.9 dB. > This seems a bit on the low side, so the biological filter seems to be even > narrower than 50 Hz. > > Setting the output filter to 20 Hz, results in armchair copy. > The CW tone in this case is 300 Hz. > > 73, > Roelof, pa0rdt >