Return-Path: Received: (qmail 76320 invoked from network); 23 Feb 2005 19:02:09 -0000 Received: from unknown (HELO ptb-spamcore02.plus.net) (192.168.71.3) by ptb-mailstore02.plus.net with SMTP; 23 Feb 2005 19:02:09 -0000 Received: from mailnull by ptb-spamcore02.plus.net with spamcore-l-b (Exim 4.32; FreeBSD) id 1D41mm-0000qW-9i for dave@picks.force9.co.uk; Wed, 23 Feb 2005 19:03:03 +0000 Received: from [192.168.67.1] (helo=ptb-mxcore01.plus.net) by ptb-spamcore02.plus.net with esmtp (Exim 4.32; FreeBSD) id 1D41ml-0000qB-LG for dave@picks.force9.co.uk; Wed, 23 Feb 2005 19:02:59 +0000 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore01.plus.net with esmtp (Exim) id 1D41ni-00076P-R3 for dave@picks.force9.co.uk; Wed, 23 Feb 2005 19:03:58 +0000 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1D41km-0005yi-Pi for rs_out_1@blacksheep.org; Wed, 23 Feb 2005 19:00:56 +0000 Received: from [193.82.116.30] (helo=relay.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1D41km-0005yZ-E7 for rsgb_lf_group@blacksheep.org; Wed, 23 Feb 2005 19:00:56 +0000 Received: from relay.sotline.ru ([80.89.139.226]) by relay.thorcom.net with esmtp (Exim 4.43) id 1D41kj-0002ZI-OQ for rsgb_lf_group@blacksheep.org; Wed, 23 Feb 2005 19:00:56 +0000 Received: from astral.omskcity.com (mxs.sotline.ru [80.89.139.227]) by relay.sotline.ru (8.x.x) with ESMTP id j1NJ0q5r091083 for ; Thu, 24 Feb 2005 01:00:52 +0600 (OMST) (envelope-from fitec@omskcity.com) Received: from noname.nodomain.nowhere (host198.m02.dial.sotline.ru [81.176.51.198]) by astral.omskcity.com (8.x.x) with ESMTP id j1NJ0nLG024758 for ; Thu, 24 Feb 2005 01:00:50 +0600 (OS) Received: from localhost (fitec@localhost) by noname.nodomain.nowhere (8.8.5/8.8.5) with SMTP id BAA00241 for ; Thu, 24 Feb 2005 01:18:46 GMT X-Authentication-Warning: noname.nodomain.nowhere: fitec owned process doing -bs Date: Thu, 24 Feb 2005 01:18:46 +0000 (GMT) From: "Alexander S. Yurkov" To: rsgb_lf_group@blacksheep.org In-Reply-To: <421C92DB.20300@usa.net> Message-ID: MIME-Version: 1.0 X-SPF-Result: relay.thorcom.net: domain of omskcity.com designates 80.89.139.226 as permitted sender X-Spam-Score: 1.3 (+) X-Spam-Report: autolearn=no,DATE_IN_FUTURE_06_12=1.202,FORGED_RCVD_HELO=0.05 Subject: Re: LF: Re: Off Topic Ft101zd Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.9 required=5.0 tests=DATE_IN_FUTURE_06_12 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-Spam-Filtered: by PlusNet SpamCORE (v3.00) Content-transfer-encoding: 8bit Dear Alberto, On Wed, 23 Feb 2005, Alberto di Bene wrote: > > > Do really exist A/D converters capable of 24-bit resolution at 30 MHz > bandwidth ? Why one need 24-bit? Though 16 bit is adequate for most SW,MW,LW recievers. 16 bit yelds abt 90 dB dynamic range (every bit exept sign bit yelds 6dB). But this is dynamic range if there is no filtering. When you make banwidth narrow by DSP then dynamic range will be improved because noise decreases. If frontend sampling rate is, say 100 MHz (there is such an ADC) and bandwidth of DSP filter is about, say 10 kHz this yelds 40 dB of noise decreasing. Thus RX dynamic range to be about 90+40=130 dB! Realy DD is not 130 dB of cose. But it much less due to analog (!) effects in ADC absolutely similary as in conventional analog RX. This is not digital effect! Because 3G celular systems require such chips (ADC, DDC having sampling rate abt 100 - 200 MHz) this chips are avaliabale now. Seems radioingeneer speciality now change to programer speciality. To build say RX now you need very few standard chips (ADC,DDC and CPU) connected in standard way and lot of programing! Nothing more, forgot about soldering iron, learn C++. Present days are days of digital radio. Analog radio died. 73 de RA9MB/Alex http://www.qsl.net/ra9mb