Return-Path: Received: from mtain-ma02.r1000.mx.aol.com (mtain-ma02.r1000.mx.aol.com [172.29.96.10]) by air-dc03.mail.aol.com (v129.4) with ESMTP id MAILINDC034-86a14cd871c4fe; Mon, 08 Nov 2010 16:55:16 -0500 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-ma02.r1000.mx.aol.com (Internet Inbound) with ESMTP id EA3B138002A4A; Mon, 8 Nov 2010 16:55:14 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1PFZeR-0005ts-B0 for rs_out_1@blacksheep.org; Mon, 08 Nov 2010 21:53:19 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1PFZeQ-0005tj-Gw for rsgb_lf_group@blacksheep.org; Mon, 08 Nov 2010 21:53:18 +0000 Received: from nm23-vm0.bullet.mail.sp2.yahoo.com ([98.139.91.224]) by relay1.thorcom.net with smtp (Exim 4.63) (envelope-from ) id 1PFZeO-00084n-RS for rsgb_lf_group@blacksheep.org; Mon, 08 Nov 2010 21:53:18 +0000 Received: from [98.139.91.68] by nm23.bullet.mail.sp2.yahoo.com with NNFMP; 08 Nov 2010 21:53:08 -0000 Received: from [98.139.91.15] by tm8.bullet.mail.sp2.yahoo.com with NNFMP; 08 Nov 2010 21:53:08 -0000 Received: from [127.0.0.1] by omp1015.mail.sp2.yahoo.com with NNFMP; 08 Nov 2010 21:53:08 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 588836.49904.bm@omp1015.mail.sp2.yahoo.com Received: (qmail 18545 invoked by uid 60001); 8 Nov 2010 21:53:08 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s1024; t=1289253187; bh=Xiar8LtbNIKG40Ea1OfpjmTJCxG/kQhJrSpXU7R7j64=; h=Message-ID:X-YMail-OSG:Received:X-Mailer:References:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=xWk6FpYNWzYLU5Gr44GixG2lR3bCOIs+VCyRbI3DX7ie5ZO/iyHW2KE6QjSE80RYU43/zFcJNARU+WQ6ffxjeX07xynkgsFFRp4s7SCvtlQ3NEQJcl4gI0Pop9NrGys+34pQemUd5+nSm1gLSljmC+rDUEr1+MY6+NIf/PZeFRg= DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:X-YMail-OSG:Received:X-Mailer:References:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=Ve5wzVCE6HfCLNuvtbUEoatpvbWGbE4eq3FqLWFYFF4hhNiOsIIYr/5dxtIEZnmCI1dUlWiQazfuOovMvX5HvPDLK7aoWbSU1sI8y1z8r6pkjRHtGNTt4Mu5CeOCVnAyB8EAN0uwjAXgTuSwSQZZdQ9baq18NfNpSGl3B3bZiTo=; Message-ID: <918071.9577.qm@web111903.mail.gq1.yahoo.com> X-YMail-OSG: eP94XKYVM1kTnZEz_qan4yv9DznPWfuHZ3RYN6k1Ai7q9Au 7UGZSTdDr Received: from [87.1.245.130] by web111903.mail.gq1.yahoo.com via HTTP; Mon, 08 Nov 2010 13:53:07 PST X-Mailer: YahooMailRC/504.5 YahooMailWebService/0.8.107.284920 References: <798586.46009.qm@web111901.mail.gq1.yahoo.com> <6EEAA299A2084FACB780B4F9A675C31C@JimPC> <304036.93066.qm@web111919.mail.gq1.yahoo.com> <4CD83D22.50202@iup.uni-heidelberg.de> Date: Mon, 8 Nov 2010 13:53:07 -0800 (PST) From: Daniele Tincani To: rsgb_lf_group@blacksheep.org In-Reply-To: <4CD83D22.50202@iup.uni-heidelberg.de> MIME-Version: 1.0 DomainKey-Status: good (testing) X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: Re: BBB-4-like receiver ready for first tests Content-Type: multipart/alternative; boundary="0-1031462249-1289253187=:9577" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=1.0 required=5.0 tests=FORGED_YAHOO_RCVD,HTML_20_30, HTML_MESSAGE 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-AUTHENTICATION: mail_rly_antispam_dkim-d260.2 ; domain : yahoo.com DKIM : pass x-aol-sid: 3039ac1d600a4cd871c20d1e X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --0-1031462249-1289253187=:9577 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Hello Stefan, LF, VLF, SS> So just look at 9 kHz without the generator and then increase the nois= e=20 gernerator level so that the noise increases say 20 dB. DT> OK I started with the minimum adjustable level on the Agilent 33120A= =20 (50mVpp) and got about -86dB on SpecLab at 9KHz. Then I increased the outp= ut=20 from the instrument up to 510mVpp and got about -66dB on SpecLab. This sou= nd OK=20 to me (20log(510/50) =3D 20.2dB). The response curve is still very similar= to the=20 simulated one. At 9KHz without the generator,=A0with the BBB-4 switched off and max atten= uation=20 on soundcard input (I have a potentiometer on the isolation transformer to= the=20 PC) I read about -148dB on SpecLab at 9KHz. SS> What i would worry about is the high gain arround 2 kHz, where the mai= ns hum=20 is dominant, even if the frequency response (without an input signal) woul= d be=20 flat. Maybe this could become a problem if the levels get so high that the= amp=20 stages become nonlinear and/or the soundcard input. DT> Yes, the BBB-4 was explicitly designed by McGreevy for reception=A0of= natural=20 radio emissions in locations=A0far away from power lines, buildings, trees= , etc.=20 (basically, in the middle of a desert :-)). SS> But just try what happend in reality!! In my experience it is a good= =20 indicator to see the diurnal noise levels having a minimum at arround 8...= 10=20 UTC. If the level difference is about 10...15 dB (depending on the WX of= course)=20 it is a good first step to assume a sensitive RX. =A0 DT> Good test, I will try probably next saturday. I=A0could start say at= 6.00 UTC=20 and try to collect as many hours of a broadband spectrum as allowed by res= idual=20 battery life. =A0 Cheers Daniele =A0 ________________________________ From: Stefan Sch=E4fer To: rsgb_lf_group@blacksheep.org Sent: Mon, November 8, 2010 7:10:42 PM Subject: Re: LF: Re: BBB-4-like receiver ready for first tests Hi Daniele, Jim, LF, Am 08.11.2010 16:47, schrieb Daniele Tincani:=20 > >Also consider that when I created a short circuit on the antenna input of= the rx=20 >(see Q2 in my e-mail), I got a response curve on SpecLab similar to that= I had=20 >with the Agilent, but with a peak level about 30dB lower (about -107dB ar= ound=20 >f=3D2KHz on SpecLab).This means that your generated noise level was to lo= w and you=20 >have observed the soundcards noise, at least outside the region of 2 kHz.= So=20 >just look at 9 kHz without the generator and then increase the noise gern= erator=20 >level so that the noise increases say 20 dB. ________________________________ From: James Moritz >To: rsgb_lf_group@blacksheep.org >Sent: Mon, November 8, 2010 3:22:59 PM >Subject: LF: Re: BBB-4-like receiver ready for first tests > > >The filter rolls the gain off rapidly below about 1kHz and above about 10= kHz. So=20 >this would be OK for whistlers and 9kHz reception, but would attenuate VL= F=20 >utilities at higher frequencies. > >Normally the MSKs are so strong that an attenuation of say 20 dB (compare= d to 9=20 >kHz) will probably no problem. 20 dB gain reduction would not even mean= 20 dB=20 >S/N reduction... What i would worry about is the high gain arround 2 kHz, where the mains= hum is=20 dominant, even if the frequency response (without an input signal) would= be=20 flat. Maybe this could become a problem if the levels get so high that the= amp=20 stages become nonlinear and/or the soundcard input. But just try what happend in reality!! In my experience it is a good indic= ator=20 to see the diurnal noise levels having a minimum at arround 8...10 UTC. If= the=20 level difference is about 10...15 dB (depending on the WX of course) it is= a=20 good first step to assume a sensitive RX. The rest can be seen in tests wh= ere a=20 far field signal is generated on the Dreamers Band ;-) 73, Stefan/DK7FC =20 --0-1031462249-1289253187=:9577 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
Hello Stefan, LF, VLF,
 
SS> What i would worry about is the high gain arround 2 kHz, where the= mains hum is dominant, even if the frequency response (without an input= signal) would be flat. Maybe this could become a problem if the levels ge= t so high that the amp stages become nonlinear and/or the soundcard input.=
DT> Yes, the BBB-4 was explicitly designed by McGreevy for recepti= on of natural radio emissions in locations far away from power= lines, buildings, trees, etc. (basically, in the middle of a desert :-)).=


SS> But just try what happend in reality!! In my experience it= is a good indicator to see the diurnal noise levels having a minimum at= arround 8...10 UTC. If the level difference is about 10...15 dB (dependin= g on the WX of course) it is a good first step to assume a sensitive RX.

 

DT> Good test= , I will try probably next saturday. I could start say at 6.00 UTC an= d try to collect as many hours of a broadband spectrum as allowed by resid= ual battery life.
 
Cheers
Daniele


 
=
From: Stefan Sch=E4fer <= ;schaefer@iup.uni-heidelberg.de>
Sent: Mon, November 8, 2010 7:10:42 PM
Subject: Re: LF: Re: BBB-4-like re= ceiver ready for first tests

Hi Daniele, Jim, LF,

Am= 08.11.2010 16:47, schrieb Daniele Tincani:=20
=
Also consider that when I created a short circuit on the antenna inpu= t of the rx (see Q2 in my e-mail), I got a response curve on SpecLab simil= ar to that I had with the Agilent, but with a peak level about 30dB lower= (about -107dB around f=3D2KHz on SpecLab).
This= means that your generated noise level was to low and you have observed th= e soundcards noise, at least outside the region of 2 kHz. So just look at= 9 kHz without the generator and then increase the noise gernerator level= so that the noise increases say 20 dB.
=
From: James Moritz <james.moritz@btopenworld.com>
To: rsgb_lf_group@blacksheep.org
Sent: Mon, November 8, 2010= 3:22:59 PM
Subject: LF= : Re: BBB-4-like receiver ready for first tests


The filt= er rolls the gain off rapidly below about 1kHz and above about 10kHz. So= this would be OK for whistlers and 9kHz reception, but would attenuate VL= F utilities at higher frequencies.

N= ormally the MSKs are so strong that an attenuation of say 20 dB (compared to 9 kHz) will probably no problem.= 20 dB gain reduction would not even mean 20 dB S/N reduction...

Wh= at i would worry about is the high gain arround 2 kHz, where the mains hum= is dominant, even if the frequency response (without an input signal) wou= ld be flat. Maybe this could become a problem if the levels get so high th= at the amp stages become nonlinear and/or the soundcard input.

But= just try what happend in reality!! In my experience it is a good indicato= r to see the diurnal noise levels having a minimum at arround 8...10 UTC.= If the level difference is about 10...15 dB (depending on the WX of cours= e) it is a good first step to assume a sensitive RX. The rest can be seen= in tests where a far field signal is generated on the Dreamers Band ;-)

73, Stefan/DK7FC

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