Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by klubnl.pl (8.14.4/8.14.4/Debian-8+deb8u2) with ESMTP id vBIMMAvi021474 for ; Mon, 18 Dec 2017 23:22:13 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1eR3i7-0003RW-5A for rs_out_1@blacksheep.org; Mon, 18 Dec 2017 22:16:35 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1eR3i6-0003RN-JI for rsgb_lf_group@blacksheep.org; Mon, 18 Dec 2017 22:16:34 +0000 Received: from omr-m001e.mx.aol.com ([204.29.186.1]) by relay1.thorcom.net with esmtps (TLSv1:DHE-RSA-AES256-SHA:256) (Exim 4.89) (envelope-from ) id 1eR3i3-0005Ic-0f for rsgb_lf_group@blacksheep.org; Mon, 18 Dec 2017 22:16:33 +0000 Received: from mtaomg-aab02.mx.aol.com (mtaomg-aab02.mx.aol.com [172.26.126.208]) by omr-m001e.mx.aol.com (Outbound Mail Relay) with ESMTP id 57FF63800086 for ; Mon, 18 Dec 2017 17:16:28 -0500 (EST) Received: from core-ace05b.mail.aol.com (core-ace05.mail.aol.com [172.27.23.5]) by mtaomg-aab02.mx.aol.com (OMAG/Core Interface) with ESMTP id 3531138000088 for ; Mon, 18 Dec 2017 17:16:27 -0500 (EST) Received: from 188.194.222.230 by webjas-vae097.srv.aolmail.net (10.96.23.100) with HTTP (WebMailUI); Mon, 18 Dec 2017 17:16:25 -0500 Date: Mon, 18 Dec 2017 17:16:27 -0500 From: Markus Vester To: rsgb_lf_group@blacksheep.org Message-Id: <1606bb3128c-170f-12ed0@webjas-vae097.srv.aolmail.net> In-Reply-To: <5A382F61.3050803@posteo.de> MIME-Version: 1.0 X-MB-Message-Source: WebUI X-MB-Message-Type: User X-Mailer: JAS STD X-Originating-IP: [188.194.222.230] x-aol-global-disposition: G DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20150623; t=1513635388; bh=D8zgzMQ7Y8c6sIgPRq5Vs/uFfY2/4kbNbCzGKl9bgCY=; h=From:To:Subject:Message-Id:Date:MIME-Version:Content-Type; b=MmFgj2GBa4m2S86YZmU61BosyQ47+/0CPV9Z/YX3zyQ6bo4sr1uDP+Hh1x+YRr7jA zaLkJYYhEzl0z3knJT5G3Ehz9Hoagm/CDteSDIYBR2oerWSQlZREzsCXxTcgCLlFCJ EuPktfc9ZQ2q54Qn9vh44K+1s+BLuuE0g9E6b/NY= x-aol-sid: 3039ac1a7ed05a383e3b6934 X-Spam-Score: 0.0 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: >> Regarding cheating ... no information must be used for getting the final decode on the RX side which is based on the known message, ... Yes I agree. Perhaps one could measure the phase of European MSK stations (HWU, JXN, ICV etc) on the other side every night, and use that as a guess to correct the phase before stacking the 17.47 kHz signal. But what is the spatial coherence of those phase changes? Old 100 kHz data suggested that Canadian Loran-C stations up to ~ 1000 km apart from each other experienced very similar nighttime phase histories on the TA path. So at lower frequency, this might be even better. [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 T_RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (markusvester[at]aol.com) 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: de74c1b05e8d69de301f516709bc3720 Subject: Re: VLF: Transatlantic success East to West Content-Type: multipart/alternative; boundary="----=_Part_99402_268601086.1513635385996" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=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 ------=_Part_99402_268601086.1513635385996 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable >> Regarding cheating ... no information must be used for getting the final= decode on the RX side which is based on the known message, ... Yes I agree. Perhaps one could measure the phase of European MSK stations (= HWU, JXN, ICV etc) on the other side every night, and use that as a guess t= o correct the phase before stacking the 17.47 kHz signal. But what is the s= patial coherence of those phase changes? Old 100 kHz data suggested that Ca= nadian Loran-C stations up to ~ 1000 km apart from each other experienced v= ery similar nighttime phase histories on the TA path. So at lower frequency= , this might be even better. Best 73, Markus -----Urspr=C3=BCngliche Mitteilung-----=20 Von: DK7FC An: rsgb_lf_group Verschickt: Mo, 18. Dez 2017 22:14 Betreff: Re: VLF: Transatlantic success East to West Hi Markus,=20 You see the phase is varying to much, at least in this experiment, in thes= e last 8 days. I could continue for several more nights and maybe we would = be there one days. But we are already in the middle of the season and time = is running. Actually i like to spend more time below 5 kHz, better on ULF, i.e. 2970 H= z and/or 970 Hz. A -6 dB carrier may be to weak to determine the phase when SNR is low. Reg= arding cheating, i think there is nothing wrong about watching the Eb/N0 bu= ilding up before a decode happens on the the RX side. But of course no info= rmation must be used for getting the final decode on the RX side which is b= ased on the known message, for example best Eb/N0 and phase of the individu= al phase. The only information known to the RX station is my message announ= cement, including the information about eventual early transmission interru= ptions. Also the individual noise levels on the RX site are known to the RX= station. Based on these informations, the decode has to be made. Then it v= alid in my opinion. 73, Stefan Am 18.12.2017 21:44, schrieb Markus Vester:=20 Hi Stefan, why give up? At -2.5 dB EbN0, Mike and Paul already had about 65% of the r= equired energy for three characters. That's about 2 out of 3, or one charac= ter's worth left to do. Now throwing that away and starting afresh, you'll = have to do twice the work.... =20 One could also send a reference carrier to enable phase alignment before s= tacking, without "cheating" by using known message content, One practical w= ay would be to unbalance the PSK by reducing the shift from +-90=C2=B0 to e= .g. +-60=C2=B0, which would spend 25% of the transmitted energy for a -6 dB= reference carrier. Best 73, Markus =20 -----Urspr=C3=BCngliche Mitteilung-----=20 Von: DK7FC An: rsgb_lf_group Verschickt: Mo, 18. Dez 2017 21:06 Betreff: Re: VLF: Transatlantic success East to West Thanks Paul for the summary.=20 Well, 8 days already and it gets worse. I think the phase changes are not = from my side, so it must be the path. I think i will give up now with this 3 character message. But even a faile= d attempt gives us a set of data showing the difficulties and phase variati= ons.=20 On the other side, a single character message is to short to let it be as = it is. So i'm trying a new message with just 2 characters before going down= to 5170 Hz. If possible, i daily feedback is apprechated. f =3D 17470.1000 Hz Start time: 18.Dec.2017 21:30:00 UTC Symbol period: 45 s Characters: 2 CRC bits: 14 Coding 16K21A Duration: 09:12 [hh:mm]=20 Antenna current: 1.2 A 73, Stefan Am 18.12.2017 18:56, schrieb Paul Nicholson:=20 Results from eight overnight transmissions of the=20 3 character message:=20 2017-12-10/11 Eb/N0 =3D -13.1 dB=20 2017-12-11/12 Eb/N0 =3D -6.3 dB, phase 125.3=20 2017-12-12/13 Eb/N0 =3D -6.8 dB, phase 143.2=20 2017-12-13/14 Eb/N0 =3D -19.6 dB (stopped 03:40 by safety limit)=20 2017-12-14/15 Eb/N0 =3D -6.0 dB, phase 68.8=20 2017-12-15/16 Eb/N0 =3D -11.0 dB=20 2017-12-16/17 Eb/N0 =3D -14.6 dB=20 2017-12-17/18 Eb/N0 =3D -9.9 dB, phase 37.0 (stopped 04:19 by snow)=20 Stacking=20 11/12 + 12/13 gives Eb/N0 =3D -3.6 dB.=20 11/12 + 12/13 + 14/15 gives Eb/N0 =3D -3.0 dB.=20 11/12 + 12/13 + 14/15 + 15/16 gives Eb/N0 =3D -2.5 dB.=20 11/12 + 12/13 + 14/15 + 17/18 gives Eb/N0 =3D -3.4 dB.=20 There's some phase changing going on here which is making=20 stacking not so effective.=20 --=20 Paul Nicholson=20 -- ------=_Part_99402_268601086.1513635385996 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
>> Regarding cheating ... no inf= ormation must be used for getting the final decode on the RX side which is = based on the known message, ...

Yes I agree. Perhaps on= e could measure the phase of European MSK stations (HWU, JXN, ICV etc) on t= he other side every night, and use that as a guess to correct the phase bef= ore stacking the 17.47 kHz signal. But what is the spatial cohere= nce of those phase changes? Old 100 kHz data suggested that Canad= ian Loran-C stations up to ~ 1000 km apart from each other experienced= very similar nighttime phase histories on the TA path. So at lower frequen= cy, this might be even better.

Best 73,
Markus


-----Urspr=C3=BCngliche Mitteilung-----
Von: DK7FC <selberdenken@posteo.de>
An: rsgb_lf_grou= p <rsgb_lf_group@blacksheep.org>
Verschickt: Mo, 18. = Dez 2017 22:14
Betreff: Re: VLF: Transatlantic success East= to West

Hi Markus,

You see the phase is varying to much, at least in this experiment, in these last 8 days. I could continue for several more nights and maybe we would be there one days. But we are already in the middle of the season and time is running.
Actually i like to spend more time below 5 kHz, better on ULF, i.e. 2970 Hz and/or 970 Hz.

A -6 dB carrier may be to weak to determine the phase when SNR is low. Regarding cheating, i think there is nothing wrong about watching the Eb/N0 building up before a decode happens on the the RX side. But of course no information must be used for getting the final decode on the RX side which is based on the known message, for example best Eb/N0 and phase of the individual phase. The only information known to the RX station is my message announcement, including the information about eventual early transmission interruptions. Also the individual noise levels on the RX site are known to the RX station. Based on these informations, the decode has to be made. Then it valid in my opinion.

73, Stefan


Am 18.12.2017 21:44, schrieb Markus Vester:
Hi Stefan,

why give up? At -2.5 dB EbN0, Mike and Paul already had about 65%= of the required energy for three characters. That's about 2 out of 3, or one character's worth left to do. Now throwing that away and starting afresh, you'll have to do twice the work....    &n= bsp;

One could also send a reference carrier to enable phase alignment before stacking, without "cheating" by using known message content, One practical way would be to unbalance the PSK by reducing the = shift from +-90=C2=B0 to e.g. +-60=C2=B0, which would spend 25% of the transmitted ene= rgy for a -6 dB reference carrier.

Best 73,
Markus
  

-----Urspr=C3=BCngliche Mitteilung-----
Von: DK7FC <selberdenken@posteo.de>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Verschickt: Mo, 18. Dez 2017 21:06
Betreff: Re: VLF: Transatlantic success East to West

Thanks Paul for the s= ummary.

Well, 8 days already and it gets worse. I think the phase changes are not from my side, so it must be the path.
I think i will give up now with this 3 character message. But even a failed attempt gives us a set of data showing the difficulties and phase variations.

On the other side, a single character message is to short to let it be as it is. So i'm trying a new message with just 2 characters before going down to 5170 Hz.
If possible, i daily feedback is apprechated.

f =3D 17470.1000 Hz
Start time: 18.Dec.2017  21:30:00 UTC
Symbol period: 45 s
Characters: 2
CRC bits: 14
Coding 16K21A
Duration: 09:12 [hh:mm]
Antenna current: 1.2 A

73, Stefan



Am 18.12.2017 18:56, schrieb Paul Nicholson:

Results from eight overnight transmissions of the
3 character message:

 2017-12-10/11  Eb/N0 =3D -13.1 dB
 2017-12-11/12  Eb/N0 =3D  -6.3 dB, phase 125.3
 2017-12-12/13  Eb/N0 =3D  -6.8 dB, phase 143.2
 2017-12-13/14  Eb/N0 =3D -19.6 dB (stopped 03:40 by safety limit= )
 2017-12-14/15  Eb/N0 =3D  -6.0 dB, phase 68.8
 2017-12-15/16  Eb/N0 =3D -11.0 dB
 2017-12-16/17  Eb/N0 =3D -14.6 dB
 2017-12-17/18  Eb/N0 =3D  -9.9 dB, phase 37.0 (stopped 04:1= 9 by snow)

Stacking

 11/12 + 12/13 gives Eb/N0 =3D -3.6 dB.
 11/12 + 12/13 + 14/15 gives Eb/N0 =3D -3.0 dB.
 11/12 + 12/13 + 14/15 + 15/16 gives Eb/N0 =3D -2.5 dB.
 11/12 + 12/13 + 14/15 + 17/18 gives Eb/N0 =3D -3.4 dB.

There's some phase changing going on here which is making
stacking not so effective.

--
Paul Nicholson
--

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