Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=0.0 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, HTML_MESSAGE,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 X-Spam-DCC: EATSERVER: mailn 1166; Body=2 Fuz1=2 Fuz2=2 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by lipkowski.org (8.14.4/8.14.4/Debian-8+deb8u2) with ESMTP id v79EqqBK029779 for ; Wed, 9 Aug 2017 16:52:53 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1dfSHU-0002uE-Qf for rs_out_1@blacksheep.org; Wed, 09 Aug 2017 15:48:20 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1dfSHU-0002u5-5s for rsgb_lf_group@blacksheep.org; Wed, 09 Aug 2017 15:48:20 +0100 Received: from mout02.posteo.de ([185.67.36.66]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1dfSHQ-0007uf-0g for rsgb_lf_group@blacksheep.org; Wed, 09 Aug 2017 15:48:18 +0100 Received: from submission (posteo.de [89.146.220.130]) by mout02.posteo.de (Postfix) with ESMTPS id 5FE5920A02 for ; Wed, 9 Aug 2017 16:48:11 +0200 (CEST) Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 3xSDf30Ymrzypd for ; Wed, 9 Aug 2017 16:48:10 +0200 (CEST) Message-ID: <598B20AA.5070704@posteo.de> Date: Wed, 09 Aug 2017 16:48:10 +0200 From: DK7FC User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <597AC385.8070108@rtv5.cz> <15d88d4c847-7d6d-2b953@webprd-m86.mail.aol.com> <597B509E.8080105@posteo.de> <59858CB7.3000202@posteo.de> In-Reply-To: <59858CB7.3000202@posteo.de> X-Scan-Signature: f9f85a03ab18710b130c40acc03380f0 Subject: Re: VLF: Carrier on 3675.005 Hz / EbNaut Content-Type: multipart/alternative; boundary="------------000607010903030400000907" 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 2.75 Status: O X-Status: X-Keywords: X-UID: 12353 This is a multi-part message in MIME format. --------------000607010903030400000907 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi VLF, An attempt for a first message transfer between radio amateurs in the range 3...4 kHz for an expected distance of 226 km, or 2.77 wavelengths: *f = 3675.005000 Hz Start time: 10.August.2017 00:00:00 UTC Symbol period: 120 s Characters: 3 CRC bits: 7 Coding 16K21A Duration: 24h Antenna current: 160 mA* 73, Stefan Am 05.08.2017 11:15, schrieb DK7FC: > VLF, > > After nearly 8 days the carrier is still on the air without an > interruption, despite occasional thunderstorms :-) > It looks like the SNR is suffering by summer QRN, as expected. > > The stable carrier was good for doing local tests with my > Raspi+Octo-soundcard. The system is now completely configured > including system time setting via the GPS module. I recorded a few > days from the carrier, converted the data files into wav, reprocessed > them in SpecLab: The carrier is stable and on the expected frequency, > so the sample rate correction via vlfrx tools seems to work. > > Forthermore i corrected some bugs in the circuit of my portable RX > loop preamp for VLF (must have been late in the night when i built it > up a few months ago). Now the noise is much lower. It looks promising! > So it is time for a portable VLF experiment in the far field, just to > check the system more seriously. > > The crew of DL0AO has built up and optimised their VLF system to > receive the weak 3675.005 Hz carrier in abt 220 km distance. Looks > like there is something on their cardioidal spectrogram pointing to West, > http://df6nm.bplaced.net/dl0ao/VLFgrabber/vlfgrabber_dl0ao_test.htm > Something like 10 dB SNR in 31 uHz. That's not so bad! > > I will run it for some more time until the trace is a bit longer. Then > in some days i like to start transmitting an EbNaut message on that > frequency which can be stacked until a decode appears. Markus has > developed a tool for windows to do the stacking, maybe it works in > that experiment... It will also be a test to see if i can decode the > message from my own recording using vlfrx tools, an important step to > pass... > > So far so good. What are YOUR projects you are currently working on, > LF/MF/VLF related? > > 73, Stefan > > > Am 28.07.2017 16:56, schrieb DK7FC: >> Hi VLF, >> >> I'm back from LF for a while and built up my large VLF coil which was >> used on 2970 Hz in the beginning of the year. Actually it is under >> maintenance, one of the six stacks has to be replaced. It is already >> dismantled but the new wire is not yet wound on the 250 mm diameter >> PVC tube again. >> So now the resonance is higher! I didn't know where it is and just >> connected the coil and scanned the frequency downwards. Near 3685 Hz >> i found a maximum of the antenna. Since the Q is not extremely high, >> i decided to tune to 3675 Hz and added the usual 5 mHz offset, to >> stay away from multiples of 1 Hz. >> >> So, now *since 14:40 UTC* a carrier is running on *3675.005 Hz*. The >> antenna current is *170 mA*. I estimate the *ERP is just 3 uW*! >> >> I guess this is a first amateur radio transmission on the *82 km* >> band and that class of ERP (?). >> >> Hopefully the coil will hold the *15.5 kV* with just 5 stacks of >> windings. It's inductance is *3.9 H* in the moment! >> >> I intend to run the carrier for at least a few days, depending on the >> feedback. >> >> Good luck for the VLF experts! >> >> 73, Stefan >> >> PS: A 424 uHz RDF spectrogram is running at >> http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html >> (First pixel appears in 30 minutes) >> --------------000607010903030400000907 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit Hi VLF,

An attempt for a first message transfer between radio amateurs in the range 3...4 kHz for an expected distance of 226 km, or 2.77 wavelengths:

f = 3675.005000 Hz
Start time: 10.August.2017  00:00:00 UTC
Symbol period: 120 s
Characters: 3
CRC bits: 7
Coding 16K21A
Duration: 24h
Antenna current: 160 mA

73, Stefan



Am 05.08.2017 11:15, schrieb DK7FC:
VLF,

After nearly 8 days the carrier is still on the air without an interruption, despite occasional thunderstorms :-)
It looks like the SNR is suffering by summer QRN, as expected.

The stable carrier was good for doing local tests with my Raspi+Octo-soundcard. The system is now completely configured including system time setting via the GPS module. I recorded a few days from the carrier, converted the data files into wav, reprocessed them in SpecLab: The carrier is stable and on the expected frequency, so the sample rate correction via vlfrx tools seems to work.

Forthermore i corrected some bugs in the circuit of my portable RX loop preamp for VLF (must have been late in the night when i built it up a few months ago). Now the noise is much lower. It looks promising! So it is time for a portable VLF experiment in the far field, just to check the system more seriously.

The crew of DL0AO has built up and optimised their VLF system to receive the weak 3675.005 Hz carrier in abt 220 km distance. Looks like there is something on their cardioidal spectrogram pointing to West,
http://df6nm.bplaced.net/dl0ao/VLFgrabber/vlfgrabber_dl0ao_test.htm
Something like 10 dB SNR in 31 uHz. That's not so bad!

I will run it for some more time until the trace is a bit longer. Then in some days i like to start transmitting an EbNaut message on that frequency which can be stacked until a decode appears. Markus has developed a tool for windows to do the stacking, maybe it works in that experiment... It will also be a test to see if i can decode the message from my own recording using vlfrx tools, an important step to pass...

So far so good. What are YOUR projects you are currently working on, LF/MF/VLF related?

73, Stefan


Am 28.07.2017 16:56, schrieb DK7FC:
Hi VLF,

I'm back from LF for a while and built up my large VLF coil which was used on 2970 Hz in the beginning of the year. Actually it is under maintenance, one of the six stacks has to be replaced. It is already dismantled but the new wire is not yet wound on the 250 mm diameter PVC tube again.
So now the resonance is higher! I didn't know where it is and just connected the coil and scanned the frequency downwards. Near 3685 Hz i found a maximum of the antenna. Since the Q is not extremely high, i decided to tune to 3675 Hz and added the usual 5 mHz offset, to stay away from multiples of 1 Hz.

So, now since 14:40 UTC a carrier is running on 3675.005 Hz. The antenna current is 170 mA. I estimate the ERP is just 3 uW!

I guess this is a first amateur radio transmission on the 82 km band and that class of ERP (?).

Hopefully the coil will hold the 15.5 kV with just 5 stacks of windings. It's inductance is 3.9 H in the moment!

I intend to run the carrier for at least a few days, depending on the feedback.

Good luck for the VLF experts!

73, Stefan

PS: A 424 uHz RDF spectrogram is running at http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html (First pixel appears in 30 minutes)

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