Return-Path: Received: from mtain-dj10.r1000.mx.aol.com (mtain-dj10.r1000.mail.aol.com [172.19.187.146]) by air-di05.mail.aol.com (v129.4) with ESMTP id MAILINDI053-eac84cd978e713; Tue, 09 Nov 2010 11:37:59 -0500 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dj10.r1000.mx.aol.com (Internet Inbound) with ESMTP id 9159D380013CA; Tue, 9 Nov 2010 11:37:57 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1PFrBA-0000Pq-Ti for rs_out_1@blacksheep.org; Tue, 09 Nov 2010 16:36:16 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1PFrBA-0000Ph-1O for rsgb_lf_group@blacksheep.org; Tue, 09 Nov 2010 16:36:16 +0000 Received: from nm5.bullet.mail.sp2.yahoo.com ([98.139.91.75]) by relay1.thorcom.net with smtp (Exim 4.63) (envelope-from ) id 1PFrB8-0007SI-AM for rsgb_lf_group@blacksheep.org; Tue, 09 Nov 2010 16:36:16 +0000 Received: from [98.139.91.62] by nm5.bullet.mail.sp2.yahoo.com with NNFMP; 09 Nov 2010 16:36:06 -0000 Received: from [98.139.91.41] by tm2.bullet.mail.sp2.yahoo.com with NNFMP; 09 Nov 2010 16:36:06 -0000 Received: from [127.0.0.1] by omp1041.mail.sp2.yahoo.com with NNFMP; 09 Nov 2010 16:36:06 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 497435.93421.bm@omp1041.mail.sp2.yahoo.com Received: (qmail 76084 invoked by uid 60001); 9 Nov 2010 16:36:06 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s1024; t=1289320566; bh=Pl+4PJ6yxy3MCFjdmUtqFczPm6uPq5Kv5GwPzn7Ni0U=; h=Message-ID:X-YMail-OSG:Received:X-Mailer:References:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=F9XxpQ2V2H0EH16knesaY0N6bY8jeTctefHlBePTne9KF6dQs31Csp8O5rREriwdhDkiT5PDWbHDDnR4R4/rrcXulLI9sD0OWUsVtOgkY6PYoG9xVDEMqzHzW/0FJW8ZNfEPQiEYj0ENamqFdbvkXfabKjMQmqszeD/WOWm4M08= 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=MO8QCyXDDYg8OLgvrxlF1esPNpV5CY8HGOp1TS1Fxsn8DJdi/pUrh8LHdbkcMpV56vNwHrBRRuz9r7iSNvCvfduB+9cKa7l39YI3ELMer37jraqUPDNJLuE/RiTaO4bsIfx4k1eOh3dlbKKU0zhL/Zob1bvY5twQzeQYXEvyU1A=; Message-ID: <55010.75380.qm@web111919.mail.gq1.yahoo.com> X-YMail-OSG: 4096Be8VM1n0pYeUFc0opH0qDIZXGxhlaDmRz.ooAr2rHkh yCmvF5qFKgMJq3Y.UKABctjBb61eIXY5RGx3F320ifT8mqzjJruI4kNov9l2 kjIKa5D97f9hOirz.jCxwZSI81pFgkzpFe6CmRwIwxpHMjYKRL1HzpXsMiCJ SzC_H2S5OV21ZPMa1E3Ju5zc1aaH6Y.8IRbwxAD1_qkSvwnijyztP1TUs7x4 tHZMJHkjYOEAs0mzjJwLkiQPAtpxxZ_iU.9czaH422zYCNzLhdpRPhQFYIEo 401rJHQHwLnS.8EAtxrKVU1A- Received: from [151.99.187.181] by web111919.mail.gq1.yahoo.com via HTTP; Tue, 09 Nov 2010 08:36:05 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> <918071.9577.qm@web111903.mail.gq1.yahoo.com> <4CD874CE.7050003@iup.uni-heidelberg.de> <113093.88150.qm@web111908.mail.gq1.yahoo.com> <4CD95487.1000206@iup.uni-heidelberg.de> Date: Tue, 9 Nov 2010 08:36:05 -0800 (PST) From: Daniele Tincani To: rsgb_lf_group@blacksheep.org In-Reply-To: <4CD95487.1000206@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="0-1786744414-1289320565=:75380" 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-d303.2 ; domain : yahoo.com DKIM : pass x-aol-sid: 3039cdbc9d0f4cd978e516e6 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --0-1786744414-1289320565=:75380 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Hello Stefan, LF, VLF, now next questions: :-) 1) is the noise of the active antenna well below the typical band noise? 2) is the dynamic range large enough to manage=A0the strongest=A0hum level= s at my=20 listening position? Ideally I would like=A0to get some information about the MDS and the SFDR= =A0(at=20 least) of the active antenna,=A0for example at 2KHz and 9KHz, by injecting= test=20 signals at increasing levels. I'm trying to figure out what the simplest and cheapest testbench could be= for=20 this purpose. Probably I will need to build at least two good LPF's=A0at= 3KHz and=20 10KHz (to=A0get rid of harmonics=A0from the generator) and a variable atte= nuator=20 (may be a simple potentiometer in series with a high-value resistor could= do the=20 job?). Then I would place an oscilloscope on the rx input and a spectrum= =20 analyser on the rx output and try to get some (very rough!!) information= about=20 the=A0MDS and the SFDR. Does the above=A0look sensible? To capture several hours of reception (including the daily QRN minimum) at= my=20 usual listening position would be OK for attempting a direct performance= =20 comparison with my loop antenna, but I'm afraid that local hum could hide= real=20 figures. I think I should at least perform a similar data collection in a= =20 different location, far away from powerlines, in order to get an approxima= te=20 assessment of the rx sensitivity. Best regards Daniele ________________________________ From: Stefan Sch=E4fer To: rsgb_lf_group@blacksheep.org Sent: Tue, November 9, 2010 3:02:47 PM Subject: Re: LF: Re: BBB-4-like receiver ready for first tests Hi Daniele, OK now. So you have done it right. The generated noise is well above the= noise=20 of the soundcard+the noise of the antenna. And the noise of the soundcard+= the=20 noise of the antenna is well above the noise of the soundcard (you mention= ed=20 -148 dB). So, you should see the actual frequency response of the active= antenna=20 in Figure_1 :-) As far as i understand it (am not an expert i think ;-) ). And now, what do you want to do now? :-) 73, Stefan BTW: You are in a good position to my earth antenna, almost perfect! :-) Am 08.11.2010 23:34, schrieb Daniele Tincani:=20 Stefan, > >the soundcard is a M-Audio Audiophile 2496 PCI. The sample rate is 48KHz= at 24=20 >bits/sample (as configured on SpecLab, but the same is=A0reported=A0by bo= th=20 >Windows=A0and M-Audio control panels). The FFT settings are those I get= by=20 >selecting the dafault "factory" settings on SpecLab, I attach a JPEG of= the=20 >configuration panel for clarity. > >So, I have the generator at its minimum amplitude, giving -86dB (at the= output=20 >of the BBB-4) measured on SpecLab at 9KHz. Attached here as Figure_1. >Now I switch the generator OFF (power switch OFF) and leave all the rest= =20 >untouched. The result is showed in Figure_2. > >Best regards >Daniele > > ________________________________ From: Stefan Sch=E4fer >To: rsgb_lf_group@blacksheep.org >Sent: Mon, November 8, 2010 11:08:14 PM >Subject: Re: LF: Re: BBB-4-like receiver ready for first tests > >Hi Daniele, > >-148 dB is a very low noise level for a soundcard! But what is the sample= rate=20 >and FFT settings? I remember you have a good one, not just a PC internal= or=20 >cheep USB card... > >Again, what happens when you switch the noise generator OFF (after genera= ting=20 >-86 dB) and let the active antenna and PC settings as is? > >73, Stefan > >Am 08.11.2010 22:53, schrieb Daniele Tincani:=20 >Hello Stefan, LF, VLF, >> >>SS> So just look at 9 kHz without the generator and then increase the no= ise=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 ou= tput=20 >>from the instrument up to 510mVpp and got about -66dB on SpecLab. This= sound OK=20 >>to me (20log(510/50) =3D 20.2dB). The response curve is still very simil= ar to the=20 >>simulated one. >>At 9KHz without the generator,=A0with the BBB-4 switched off and max att= enuation=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= mains hum=20 >>is dominant, even if the frequency response (without an input signal) wo= uld 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=A0o= f natural=20 >>radio emissions in locations=A0far away from power lines, buildings, tre= es, 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= residual=20 >>battery life. >> >>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 tha= t I had=20 >>>with the Agilent, but with a peak level about 30dB lower (about -107dB= around=20 >>>f=3D2KHz on SpecLab).This means that your generated noise level was to= low and you=20 >>>have observed the soundcards noise, at least outside the region of 2 kH= z. So=20 >>>just look at 9 kHz without the generator and then increase the noise ge= rnerator=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= 10kHz. So=20 >>this would be OK for whistlers and 9kHz reception, but would attenuate= VLF=20 >>utilities at higher frequencies. >> >>Normally the MSKs are so strong that an attenuation of say 20 dB (compar= ed 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 --0-1786744414-1289320565=:75380 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
Hello Stefan, LF, VLF,
 
now next questions: :-)
1) is the noise of the active antenna well below the typical band noi= se?
2) is the dynamic range large enough to manage the strongest&nbs= p;hum levels at my listening position?
 
Ideally I would like to get some information about the MDS and= the SFDR (at least) of the active antenna, for example at 2KHz= and 9KHz, by injecting test signals at increasing levels.
 
I'm trying to figure out what the simplest and cheapest testbench cou= ld be for this purpose. Probably I will need to build at least two good LP= F's at 3KHz and 10KHz (to get rid of harmonics from the gen= erator) and a variable attenuator (may be a simple potentiometer in series= with a high-value resistor could do the job?). Then I would place an osci= lloscope on the rx input and a spectrum analyser on the rx output and try= to get some (very rough!!) information about the MDS and the SFDR.= Does the above look sensible?
 
To capture several hours of reception (including the daily QRN minimu= m) at my usual listening position would be OK for attempting a direct perf= ormance comparison with my loop antenna, but I'm afraid that local hum cou= ld hide real figures. I think I should at least perform a similar data col= lection in a different location, far away from powerlines, in order to get= an approximate assessment of the rx sensitivity.
 
Best regards
Daniele
=
From: Stefan Sch=E4fer <= ;Stefan.Schaefer@iup.uni-heidelberg.de>
To: rsgb_lf_group@blacksheep.org
Sent: Tue, November 9, 2010 3:02:47 PM
Subject: Re: LF: Re: BBB-4-l= ike receiver ready for first tests

Hi Daniele,
OK now. So you have done it right. The generated noise is well above the= noise of the soundcard+the noise of the antenna. And the noise of the sou= ndcard+the noise of the antenna is well above the noise of the soundcard= (you mentioned -148 dB). So, you should see the actual frequency response= of the active antenna in Figure_1 :-) As far as i understand it (am not= an expert i think ;-) ).

And now, what do you want to do now? :-)<= BR>
73, Stefan

BTW: You are in a good position to my earth anten= na, almost perfect! :-)


Am 08.11.2010 23:34, schrieb Daniele Ti= ncani:=20
Stefan,
 
the soundcard is a M-Audio Audiophile 2496 PCI. The sample rate is 48= KHz at 24 bits/sample (as configured on SpecLab, but the same is repo= rted by both Windows and M-Audio control panels). The FFT settin= gs are those I get by selecting the dafault "factory" settings on SpecLab,= I attach a JPEG of the configuration panel for clarity.
=  
= So, I have the generator at its minimum amplitude, giving -86dB (at the ou= tput of the BBB-4) measured on SpecLab at 9KHz. Attached here as Figure_1.=
= Now I switch the generator OFF (power switch OFF) and leave all the rest= untouched. The result is showed in Figure_2.
=  
= Best regards
= Daniele
From: Stefan Sch=E4fer <schaefer@iup.uni-heidelberg.de>
To: rsgb_lf_group@blacksheep.= org
Sent: Mon, Nove= mber 8, 2010 11:08:14 PM
Subject:<= /SPAN> Re: LF: Re: BBB-4-like receiver ready for first tests

Hi Daniele,

-148 dB is a very low noise level for a soundcard!= But what is the sample rate and FFT settings? I remember you have a good= one, not just a PC internal or cheep USB card...

Again, what happe= ns when you switch the noise generator OFF (after generating -86 dB) and let the active antenna and PC settings= as is?

73, Stefan

Am 08.11.2010 22:53, schrieb Daniele Tinc= ani:=20
Hello Stefan, LF, VLF,
 
SS> So just look at 9 kHz without the generator and then increase the noise= gernerator level so that the noise increases say 20 dB.
 
DT> OK I started with the minimum adjustable level on the Agilent= 33120A (50mVpp) and got about -86dB on SpecLab at 9KHz. Then I increased= the output from the instrument up to 510mVpp and got about -66dB on SpecL= ab. This sound OK to me (20log(510/50) =3D 20.2dB). The response curve is= still very similar to the simulated one.
At 9KHz without the generator, with the BBB-4 switched off and= max attenuation on soundcard input (I have a potentiometer on the isolati= on transformer to the PC) I read about -148dB on SpecLab at 9KHz.

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>
To: rsgb_lf_group@blacksheep.= org
Sent: Mon, Nove= mber 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 Tinca= ni:=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


<= br> --0-1786744414-1289320565=:75380--