Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-da01.r1000.mx.aol.com (Internet Inbound) with ESMTP id 30D0D380000BA; Fri, 2 Dec 2011 12:03:20 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1RWWV3-00021s-9B for rs_out_1@blacksheep.org; Fri, 02 Dec 2011 17:02:13 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1RWWV2-00021j-Rf for rsgb_lf_group@blacksheep.org; Fri, 02 Dec 2011 17:02:12 +0000 Received: from nm1.bt.bullet.mail.ird.yahoo.com ([212.82.108.232]) by relay1.thorcom.net with smtp (Exim 4.63) (envelope-from ) id 1RWWV1-0005wi-0Y for rsgb_lf_group@blacksheep.org; Fri, 02 Dec 2011 17:02:12 +0000 Received: from [212.82.108.229] by nm1.bt.bullet.mail.ird.yahoo.com with NNFMP; 02 Dec 2011 17:02:05 -0000 Received: from [212.82.108.224] by tm2.bt.bullet.mail.ird.yahoo.com with NNFMP; 02 Dec 2011 17:02:05 -0000 Received: from [127.0.0.1] by omp1001.bt.mail.ird.yahoo.com with NNFMP; 02 Dec 2011 17:02:05 -0000 X-Yahoo-Newman-Id: 160737.69030.bm@omp1001.bt.mail.ird.yahoo.com Received: (qmail 23106 invoked from network); 2 Dec 2011 17:02:05 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=btopenworld.com; h=DKIM-Signature:X-Yahoo-Newman-Property:X-YMail-OSG:X-Yahoo-SMTP:Received:Message-ID:From:To:References:In-Reply-To:Subject:Date:MIME-Version:Content-Type:Content-Transfer-Encoding:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE; b=cMevtlARqsJQrlkk0Jnkl0Lhvbcpt5V4u3ImT3daYwjmVpFzuzAwe/tJwV1PdFdaOXvQT36bG4z/KQUbRcxCVk1NKfHSGV7GODSnjj01IBA29a3p835rsFp0+znCtwqbPzrUdCqCAQdzMNl0sCisCCjeQDHdiELQLMEXsjaI4/I= ; DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=btopenworld.com; s=s1024; t=1322845325; bh=Y6JLGkGN1kB6yrJSoHD3ca3iV2l6NA7tGkPli+bPjZI=; h=X-Yahoo-Newman-Property:X-YMail-OSG:X-Yahoo-SMTP:Received:Message-ID:From:To:References:In-Reply-To:Subject:Date:MIME-Version:Content-Type:Content-Transfer-Encoding:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE; b=TaaJOi8TP4xGbZj2DCWo/QmKCfEzXtGLQAeYwdzb/sChPQh4GpWIekzymsZ0WJPgbfGtOU4MXIO0jNjKoRNf8j7J/HhELgHxCC6IWzvO/wb69hT9d/bRPdKJ14vapanlqIAFSck2j8JHFJM5vdtVTCZ1bBDFaOU0cpuHUEaVNgc= X-Yahoo-Newman-Property: ymail-3 X-YMail-OSG: AcmQEmgVM1mYH2WDVzM4ziYobrGB1vYjulPBiW9QMt98jdq .ippkRedvlmtDiRN7R7CsggQUJjykNzKtXAha42mYNyOXe8PvfE70HYP8pEG 42TtjWd7I6eVeZBuE7e6KdjVEZA0OnRiFp3VRNAd5Qw203rji5WyzhpQ4PI2 anjaDXokCzAq7i0AgYbit4QL2HFBDIS1wJNBHZE8cnyGzbRCVPeIOPdMN5kv NcM41hLT1XQuCisRk4SrQlyhSJykxsyCa0z76Tc05B7YdeUutmqTTGgRjyy2 UNQZuD6bpa77Q9WQlJrJJHQgodeWyDqgt7lymqrsst2sMOmURAW3tgLsbErq eiRlRLD65XBHY67gBlXv0XeUqGYTrats5_9Gn9bwed_ETjZTpw8Ib2vbuXGn lJp85o3lQ8Lupticr6w-- X-Yahoo-SMTP: Cxhli3eswBD1ozmtAojhjrja86kWx0Qm9tycD5QR1DKWrOLgjJcXkw-- Received: from JimPC (james.moritz@86.161.94.127 with login) by smtp825.mail.ird.yahoo.com with SMTP; 02 Dec 2011 09:02:04 -0800 PST Message-ID: <80A163C9035C44FBA23C7501118A6FDF@JimPC> From: "James Moritz" To: References: In-Reply-To: Date: Fri, 2 Dec 2011 17:02:17 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Windows Mail 6.0.6002.18197 X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6002.18463 DomainKey-Status: good (testing) X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,UNPARSEABLE_RELAY=0.001 Subject: Re: LF: 16 bit vs 24 bit ADC? Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original 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=0.1 required=5.0 tests=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 x-aol-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:457582688:93952408 X-AOL-SCOLL-URL_COUNT: 0 X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-d250.1 ; domain : btopenworld.com DKIM : pass x-aol-sid: 3039ac1d40494ed904d83703 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none Dear Bill, Andy, LF Group, It seems to me it should be quite easy to subject this to practical testing. First, using SpecLab etc., measure the SNR of a weak signal in the presence of noise, with the FFT parameters chosen so that the signal is near the quantisation noise level.. Then attenuate the signal and noise at the ADC input by, say, 24dB. This would effectively reduce the resolution/accuracy of the A-D conversion by 4 bits ( I guess you would want to chose the signal, noise and attenuation levels so that the external noise was well above the sound card or other ADC noise floor, with and without the attenuation). Then see if the SNR in the FFT output has changed. Cheers, Jim Moritz 73 de M0BMU