Return-Path: Received: from mtain-mg02.r1000.mx.aol.com (mtain-mg02.r1000.mx.aol.com [172.29.96.202]) by air-mf08.mail.aol.com (v128.3) with ESMTP id MAILINMF081-8bf54bd62f5727f; Mon, 26 Apr 2010 20:27:03 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-mg02.r1000.mx.aol.com (Internet Inbound) with ESMTP id E6C2B3800026F; Mon, 26 Apr 2010 20:27:00 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1O6Ycl-00048r-ID for rs_out_1@blacksheep.org; Tue, 27 Apr 2010 01:26:03 +0100 Received: from [193.82.59.130] (helo=relay2.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1O6Yci-000475-N0 for rsgb_lf_group@blacksheep.org; Tue, 27 Apr 2010 01:26:00 +0100 Received: from smtp-out05a.alice.it ([85.33.3.5]) by relay2.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1O6Ycd-0002AS-38 for rsgb_lf_group@blacksheep.org; Tue, 27 Apr 2010 01:26:00 +0100 Received: from FBCMMO03.fbc.local ([192.168.68.197]) by smtp-OUT05A.alice.it with Microsoft SMTPSVC(6.0.3790.3959); Tue, 27 Apr 2010 02:25:48 +0200 Received: from FBCMCL01B03.fbc.local ([192.168.69.84]) by FBCMMO03.fbc.local with Microsoft SMTPSVC(6.0.3790.3959); Tue, 27 Apr 2010 02:25:48 +0200 Received: from PCCasa ([87.3.195.233]) by FBCMCL01B03.fbc.local with Microsoft SMTPSVC(6.0.3790.3959); Tue, 27 Apr 2010 02:25:47 +0200 Message-ID: <2B460BBAF166453C9B99F67A38457609@PCCasa> From: "Daniele Tincani" To: References: <4EB4F8217FCC42CAB07AE666A6AB07B8@AGB> <4BD5F358.8040508@freenet.de> <4BD6147C.7080201@usa.net> <4BD62289.6040703@usa.net> In-Reply-To: <4BD62289.6040703@usa.net> Date: Tue, 27 Apr 2010 02:25:08 +0200 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Windows Mail 6.0.6002.18005 X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6002.18005 X-OriginalArrivalTime: 27 Apr 2010 00:25:47.0598 (UTC) FILETIME=[2EC9B6E0:01CAE5A0] X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: Probably not a new question... Content-Type: multipart/alternative; boundary="----=_NextPart_000_012B_01CAE5B0.DB466930" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.1 required=5.0 tests=HTML_20_30,HTML_MESSAGE, HTML_TITLE_EMPTY,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-sid: 3039ac1d60ca4bd62f547118 X-AOL-IP: 193.82.116.20 ------=_NextPart_000_012B_01CAE5B0.DB466930 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi Alberto, I'm quite familiar with digital signal processing (I work in the embed= ded SW area for a big manufacturer of telecommunications equipments an= d digital streams of several Gbit/s are common on our boards), neverth= eless I know that analog conditioning of signals (before they become= "numbers") is at least as important as the digital treatment, unless= you accept to sample meaningless information (noise) at the ADC :-)= Anyway I'm sure this is dealt with perfectly in SDR's so I think we= can stop here this discussion. Thank you for clarifications. Cheers D, ----- Original Message -----=20 From: Alberto di Bene=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Tuesday, April 27, 2010 1:32 AM Subject: Re: LF: Probably not a new question... On 4/27/2010 12:50 AM, Daniele Tincani wrote:=20 Hi Alberto, thank you very much for clarification. I was misled by the softroc= k example :-) Anyway, a doubt persists...I read on the frontpanel of the R&S SDR= that it is a "digital wideband receiver"...Well, in my "prejudice",= "wideband" does not match with "high-quality", unless the radio conta= in several different "narrow band" receivers. Is this (apparent) confl= ict solved at the digital signal processing level? Regards D HI Daniele, yes, it is a prejudice, as a matter of facts.... why "wideband" sh= ould be not compatible with "high quality" ? This stems probably from= the old analog world, where you had to face conflicting requirements...= in a SDR, "wideband" can mean e.g. that an ADC does directly sample= the=20 incoming RF spectrum at a rate of 150 MHz (there are ADCs capable of= this), thus providing information up to the Nyquist frequency of 75= MHz. Then you have just numbers, and with numbers you can perform miracle= s, if correctly handled (ask to an accountant, if you don't believe me= ... :-) When you have the digitized stream of numbers that represents the 75= MHz chunk of spectrum, you can, if you need to, analyze those 75 MHz with a resolution of 0.001 Hz, yes, one millihertz... changin= g on-the-fly where that millihertz is placed on the spectrum, or even= its bandwidth... try that with an old, analog "high quality" radio....= :-) Of course, you need both the mathematical background in digital sign= al processing and coding ability to do that, and these are skills not= very=20 familiar to analog RF engineers that hence look suspiciously to the= new world of SDRs. But this does not mean that it can't be done.... 73 Alberto I2PHD =20 ----------------------------------------------------------------------= -------- Nessun virus nel messaggio in arrivo. Controllato da AVG - www.avg.com=20 Versione: 9.0.814 / Database dei virus: 271.1.1/2835 - Data di rila= scio: 04/25/10 20:31:00 ------=_NextPart_000_012B_01CAE5B0.DB466930 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hi Alberto,
 
I'm quite familiar wi= th digital=20 signal processing (I work in the embedded SW=20 area for a big manufacturer of telecommunications= equipments=20 and digital streams of several Gbit/s are common on our boards), never= theless I=20 know that analog conditioning of signals (before they become "numbers"= ) is at=20 least as important as the digital treatment, unless you accept to samp= le=20 meaningless information (noise) at the ADC :-) Anyway I'm sure this is= dealt=20 with perfectly in SDR's so I think we can stop here this=20 discussion.
Thank you for=20 clarifications.
Cheers
D,
 
----- Original Message -----
From:=20 Alberto di= Bene=20
Sent: Tuesday, April 27, 2010= 1:32=20 AM
Subject: Re: LF: Probably not= a new=20 question...

On 4/27/2010 12:50 AM, Daniele Tincani wrote:=20
Hi Alberto,
 
thank you very mu= ch for=20 clarification. I was misled by the softrock example :-)
Anyway, a doubt= persists...I read=20 on the frontpanel of the R&S SDR that it is a "digital wideban= d=20 receiver"...Well, in my "prejudice", "wideband" does not match wit= h=20 "high-quality", unless the radio contain several different "narrow= band"=20 receivers. Is= this (apparent)=20 conflict solved at the digital signal processing level?
Regards
D
HI Daniele,

  yes, it is a= prejudice, as a matter of=20 facts.... why "wideband" should be not compatible with "high quality= " ? This=20 stems probably from the
old analog world, where you had to face= conflicting=20 requirements... in a SDR, "wideband" can mean e.g. that an ADC does= directly=20 sample the
incoming RF spectrum at a rate of 150 MHz (there are= ADCs=20 capable of this), thus providing information up to the Nyquist frequ= ency of 75=20 MHz.
Then you have just numbers, and with numbers you can perform= miracles,=20 if correctly handled (ask to an accountant, if you don't believe me.= ..=20 :-)

When you have the digitized stream of numbers that repres= ents the=20 75 MHz chunk of spectrum, you can, if you need to, analyze those
= 75 MHz=20 with a resolution of 0.001 Hz, yes, one millihertz... changing on-th= e-fly=20 where that millihertz is placed on the spectrum, or even its
band= width...=20 try that with an old, analog "high quality" radio.... :-)

Of= course,=20 you need both the mathematical background in digital signal processi= ng and=20 coding ability to do that, and these are skills not very
familia= r to=20 analog RF engineers that hence look suspiciously to the new world of= SDRs. But=20 this does not mean that it can't be done....

73  Alberto=  =20 I2PHD
 


Nessun virus nel messaggio in arrivo.
Controllato da= AVG -=20 www.avg.com
Versione: 9.0.814 / Database dei virus: 271.1.1/2835= - =20 Data di rilascio: 04/25/10 20:31:00
------=_NextPart_000_012B_01CAE5B0.DB466930--