Return-Path: X-Spam-DCC: paranoid 1233; Body=2 Fuz1=2 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-1.7 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, HTML_40_50,HTML_MESSAGE,HTML_TITLE_EMPTY autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id t5RCKBbZ001785 for ; Sat, 27 Jun 2015 14:20:11 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Z8oyW-0002j9-HQ for rs_out_1@blacksheep.org; Sat, 27 Jun 2015 13:12:48 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Z8oyW-0002j0-25 for rsgb_lf_group@blacksheep.org; Sat, 27 Jun 2015 13:12:48 +0100 Received: from omr-m04.mx.aol.com ([64.12.143.78]) by relay1.thorcom.net with esmtps (TLSv1:DHE-RSA-AES256-SHA:256) (Exim 4.85) (envelope-from ) id 1Z8oyT-0001nQ-3H for rsgb_lf_group@blacksheep.org; Sat, 27 Jun 2015 13:12:46 +0100 Received: from mtaout-mcd02.mx.aol.com (mtaout-mcd02.mx.aol.com [172.26.223.206]) by omr-m04.mx.aol.com (Outbound Mail Relay) with ESMTP id CAE0D7000009B for ; Sat, 27 Jun 2015 08:12:42 -0400 (EDT) Received: from White (ipb21bee4a.dynamic.kabel-deutschland.de [178.27.238.74]) by mtaout-mcd02.mx.aol.com (MUA/Third Party Client Interface) with ESMTPA id D450438000083 for ; Sat, 27 Jun 2015 08:12:39 -0400 (EDT) Message-ID: From: "Markus Vester" To: References: <8D27C7D3E7D6748-14A8-F71B3@webmail-vm149.sysops.aol.com> <558D8FEC.2090102@posteo.de> <7D39EA36066C485998744D9E994DAC52@White> <558DC2A1.2040608@posteo.de> Date: Sat, 27 Jun 2015 14:12:38 +0200 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 12.0.1606 X-MimeOLE: Produced By Microsoft MimeOLE V12.0.1606 x-aol-global-disposition: G DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20150623; t=1435407162; bh=24eRlupVdI7+l94Szpwoul/WBQCIRsrZTxSuvLu/CTo=; h=From:To:Subject:Message-ID:Date:MIME-Version:Content-Type; b=EOREoTqPPAh8O/PqwkRjfCqdL9b9Up4KvVwvjAeAve9je5C0hIbb1YsR3rXTVpDsf zZoNyIwNkYaKH8ZywBxaw0I3PAH4sXpXy+gq95W0I5cj5ZBsnpdsHgyRF1v8vFRWqz o6yd0abrSP2F9heMbm4zNRajaMUhak16ipzlp000= x-aol-sid: 3039ac1adfce558e93374814 X-AOL-IP: 178.27.238.74 X-Scan-Signature: 68701e491b3279fd2ee04d15cfa5e3e8 Subject: Re: LF: Heidelberg remote MF receiver Content-Type: multipart/alternative; boundary="----=_NextPart_000_0008_01D0B0E3.52A2F360" 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-Scanned-By: MIMEDefang 2.56 on 10.1.3.10 Status: O X-Status: X-Keywords: X-UID: 3539 Dies ist eine mehrteilige Nachricht im MIME-Format. ------=_NextPart_000_0008_01D0B0E3.52A2F360 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi Stefan, since last night your two receivers have been operating without = interruption, allowing to compare results from your two grabbers. - WSPR: Last night, 21 of my low-power WSPR transmissions were decoded = simultaneously by DK7FC/p and DK7FC. On average, the /p receiver had a = 5.67 dB SNR advantage. For my direction, the receive loop and the T = antenna seem to have performed similarly.=20 Today between 11.08 and 11:24 I sent some more SNR sequences with higher = power (0.1 W EMRP), expecting a higher SNR difference in the lower = daytime background noise. However half of the transmissions were not = decoded on either grabber, and those that were picked up by both showed = only a small advantage. This is probably due to the strong QRN from = flashes from a nearby thunderstorm, which for some reason are heavily = affecting WSPR decodes. It might help to use effective noise blanking in = the SpecLab instance which is feeding WSPR. Anyway if the statics happen = to ease off I will attempt another daytime comparison later today.=20 - DFCW: Between the thunderstorms this morning, my 2 mW DFCW-60 = transmission was definitely picked up more clearly on the /p receiver. = However this one suffers from a large frequency drift (10 Hz upwards), = which appears to be strongly correlated with RasPi core temperature and = solar chargerate plots - so presumably just crystal temperature. In = addition, some of the dashes appeared slightly disrupted, either by = audio glitches or by fast and small LO frequency jitter. During the = storms, my impression was that noise blanking in the narrow spectrograms = could also be optimized a bit. There are a couple of QRM lines which are always commonly visible on = both receivers (472.36 and 477.74 kHz). I am wondering whether you could = perhaps use them as references for a SpecLab frequency drift correction? BTW. I have taken a number of screenshots from your grabbers which I = have copied to our private dropbox folder. All the best, Markus (DF6NM) =20 From: Markus Vester=20 Sent: Saturday, June 27, 2015 12:39 AM To: rsgb_lf_group@blacksheep.org=20 Subject: LF: Heidelberg remote MF receiver Hi Stefan, it looks like signals are consistently better on your remote receiver, = perhaps around 6 dB or something in that ballpark. So it seems that all = your work is finally paying off! I'm looking forward to see a daytime = comparison tomorrow. My guess is that the main contributor to frequency variation would be = the 461 kHz LO crystal rather than the soundcard samplerate. Anyway = exchanging the 12 MHz crystal may possibly have no effect at all, = because the samplerate of USB soundcards is usually derived from the bus = master clock (ie the RasPi) and not from the internal crystal on the = dongle.=20 Best 73, Markus (DF6NM) From: DK7FC=20 Sent: Friday, June 26, 2015 11:22 PM To: rsgb_lf_group@blacksheep.org=20 Subject: Re: LF: 476.181 kHz from indoor loop Hi Markus,=20 Really? Wonderful! :-) And the stream is still running. I'll watch it = some days now to see if all Raspi problems are gone, then the next = part-project is the RX. Meanwhilethe sky wave is present and i can see you quite strong in = DFCW-30 with your 3 mW ERP from the loop. I missed watching you on the = remote grabber in daytime. What was the SNR ralative to the city = location? Same or better? I switched back to the T antenna in the = afternoon. It would be interesting so see you on my loop. On 21:19 i = switched to the loop! Ah and now you can see the drift of my RX which is quite visible, but = still uncritical for QRSS-30 or WSPR. I thought about changing the 12 MHz xtal of the soundcard. It is the = cheap SMD xtal which has 100 ppm/K but there are other versions with 30 = ppm/K. Maybe an idea, they are no expensive and still compact... 73, Stefan Am 26.06.2015 21:04, schrieb Markus Vester:=20 Hi Stefan, good to see the remote station working nicely now. >> but don't see you ...yes you do ;-) There is a slight frequency offset in the remote = grabber which had put me out of your QRSS-30 band. I now switched to my = "heritage" QRG 136172.5 ahem 476172.5 Hz, and voila there it is, loud = and clear. Currently still on the low Marconi, also about 2 mW EMRP. The = relatively strong coupling to the LF grabber E-field antenna produced = some aliases and noise there, which have been mitigated by a 475 kHz = Saugkreis (trap) - same as in old AM radios ;-)=20 73, Markus From: DK7FC=20 Sent: Friday, June 26, 2015 7:46 PM To: rsgb_lf_group@blacksheep.org=20 Subject: Re: LF: 476.181 kHz from indoor loop Hi Markus,=20 Thanks for your DFCW-30 transmission. I can see you clearly in daytime = on my RX in the city! However i can't see you on my RX is the garden! = The remote system seems to run stable now, at least for a longer time = then in the last 3 days :-)=20 = http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_remote_Grabber.html I switched between a T antenna and a loop beaming 300/120 deg but = don't see you. It appears that the hill between us is (my garden is on = the hill side, the city antenna is more distant to the hill) actually = reducing the SNR. So it also reduces QRN from the east and favours the = west. But i would prefer an omnidirectional pattern :-/ 73, Stefan Am 24.06.2015 12:11, schrieb Markus Vester:=20 I am currently running a DFCW-60 beacon on 476.181 kHz, using the = same 10m^2 indoor transmit loop as previously on LF. With 35 Watts of RF = input, estimated radiated power is around 2 mW, with lobes pointing west = and east. The daytime groundwave signal is visible in the bottom panel of the = DK7FC MF grabber. Going by the CCIR plots for 3 mS/m conductivity, the = groundwave attenuation for this distance would be about 23 dB in excess = off lossless 1/r propagation, resulting in approximately 0.2 uV/m in = Heidelberg.=20 Best 73, Markus (DF6NM) ------=_NextPart_000_0008_01D0B0E3.52A2F360 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hi Stefan,
 
since last night your two receivers = have been=20 operating without interruption, allowing to compare results from = your two=20 grabbers.
 
- WSPR: Last night, 21 of my = low-power=20 WSPR transmissions were decoded simultaneously by DK7FC/p and DK7FC. On=20 average, the /p receiver had a 5.67 dB SNR advantage. For my=20 direction, the receive loop and the T antenna seem to have = performed=20 similarly.
 
Today between 11.08=20 and 11:24 I sent some more SNR sequences with higher = power=20 (0.1 W EMRP), expecting a higher SNR difference in the lower daytime = background=20 noise. However half of the transmissions were not decoded on either = grabber, and those that were picked up by both showed only a small = advantage.=20 This is probably due to the strong QRN from flashes from a nearby = thunderstorm,=20 which for some reason are heavily affecting WSPR decodes. It might = help=20 to use effective noise blanking in the SpecLab instance which is = feeding=20 WSPR. Anyway if the = statics happen to ease=20 off I will attempt another daytime comparison later today. =
 
- DFCW: Between the thunderstorms this=20 morning, my 2 mW DFCW-60 transmission was definitely picked up more = clearly=20 on the /p receiver. However this one suffers from a large frequency = drift=20 (10 Hz upwards), which appears to be strongly correlated with RasPi core = temperature and solar chargerate plots - so presumably just crystal = temperature. In addition, some of the dashes appeared slightly = disrupted, either by audio glitches or by fast and small LO = frequency=20 jitter. During the storms, my impression was that noise blanking in = the=20 narrow spectrograms could also be optimized a bit.
 
There are a couple of QRM lines which = are always=20 commonly visible on both receivers (472.36 and 477.74 kHz). I am = wondering=20 whether you could perhaps use them as references for a SpecLab = frequency=20 drift correction?
 
BTW. I have taken a number of = screenshots=20 from your grabbers which I have copied to our private dropbox=20 folder.
 
All the best,
Markus (DF6NM)

 
From: Markus Vester
Sent: Saturday, June 27, 2015 12:39 AM
Subject: LF: Heidelberg remote MF receiver

Hi Stefan,
 
it looks like signals are = consistently better=20 on your remote receiver, perhaps around 6 dB or something in that = ballpark.=20 So it seems that all your work is finally paying off! I'm = looking=20 forward to see a daytime comparison tomorrow.
 
My guess is that the main contributor = to frequency=20 variation would be the 461 kHz LO crystal rather than the soundcard = samplerate.=20 Anyway exchanging the 12 MHz crystal may possibly have no effect at all, = because=20 the samplerate of USB soundcards is usually derived = from the bus=20 master clock (ie the RasPi) and not from the internal crystal on the=20 dongle. 
 
Best 73,
Markus (DF6NM)
 

From: DK7FC
Sent: Friday, June 26, 2015 11:22 PM
Subject: Re: LF: 476.181 kHz from indoor = loop

Hi = Markus,=20

Really? Wonderful! :-) And the stream is still running. I'll = watch it=20 some days now to see if all Raspi problems are gone, then the next = part-project=20 is the RX.
Meanwhilethe sky wave is present and i can see you quite = strong in=20 DFCW-30 with your 3 mW ERP from the loop. I missed watching you on the = remote=20 grabber in daytime. What was the SNR ralative to the city location? Same = or=20 better? I switched back to the T antenna in the afternoon. It would be=20 interesting so see you on my loop. On 21:19 i switched to the = loop!
Ah and=20 now you can see the drift of my RX which is quite visible, but still = uncritical=20 for QRSS-30 or WSPR.

I thought about changing the 12 MHz xtal of = the=20 soundcard. It is the cheap SMD xtal which has 100 ppm/K but there are = other=20 versions with 30 ppm/K. Maybe an idea, they are no expensive and still=20 compact...

73, Stefan

Am 26.06.2015 21:04, schrieb Markus = Vester:=20
Hi Stefan,
 
good to = see the remote=20 station working nicely now.
 
>> but don't see = you
 
...yes you do ;-) There is = a slight=20 frequency offset in the remote grabber which had put me out = of your=20 QRSS-30 band. I now switched to my = "heritage" QRG 136172.5 ahem=20 476172.5 Hz, and voila there it is, loud and clear.
 
Currently still on the low = Marconi, also=20 about 2 mW EMRP.  The relatively strong coupling to = the LF=20 grabber E-field antenna produced some aliases and noise there, = which have=20 been mitigated by a 475 kHz Saugkreis (trap) - same as in old AM = radios=20 ;-)
 
 73, Markus
 

From: DK7FC
Sent: Friday, June 26, 2015 7:46 PM
Subject: Re: LF: 476.181 kHz from indoor = loop

Hi Markus,=20

Thanks for your DFCW-30 transmission. I can see you clearly in = daytime=20 on my RX in the city! However i can't see you on my RX is the garden! = The=20 remote system seems to run stable now, at least for a longer time then = in the=20 last 3 days :-)
http://www.iup.uni-heidelberg.de/schaefer_vlf/DK= 7FC_remote_Grabber.html
I=20 switched between a T antenna and a loop beaming 300/120 deg but don't = see you.=20 It appears that the hill between us is (my garden is on the hill side, = the=20 city antenna is more distant to the hill) actually reducing the SNR. = So it=20 also reduces QRN from the east and favours the west. But i would = prefer an=20 omnidirectional pattern :-/

73, Stefan

Am 24.06.2015 = 12:11,=20 schrieb Markus Vester:=20
I am currently running a DFCW-60 beacon on 476.181 kHz, = using=20 the same 10m^2 indoor transmit loop as previously on LF. With = 35 Watts=20 of RF input, estimated radiated power is around 2=20 mW, with lobes pointing west and east.
 
The daytime groundwave signal is visible in the bottom panel of = the=20 DK7FC MF grabber. Going by the CCIR plots for 3 mS/m = conductivity, the=20 groundwave attenuation for this distance would be about 23 dB in = excess off=20 lossless 1/r propagation, resulting in approximately 0.2 uV/m in=20 Heidelberg. 
 
Best 73,
Markus (DF6NM)

 
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