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 vB3FJPDt016925 for ; Sun, 3 Dec 2017 16:19:28 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1eLVy3-000328-0X for rs_out_1@blacksheep.org; Sun, 03 Dec 2017 15:14:07 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1eLVy2-00031z-BF for rsgb_lf_group@blacksheep.org; Sun, 03 Dec 2017 15:14:06 +0000 Received: from omr-m008e.mx.aol.com ([204.29.186.7]) by relay1.thorcom.net with esmtps (TLSv1:DHE-RSA-AES256-SHA:256) (Exim 4.89) (envelope-from ) id 1eLVxz-000630-35 for rsgb_lf_group@blacksheep.org; Sun, 03 Dec 2017 15:14:05 +0000 Received: from mtaomg-mad02.mx.aol.com (mtaomg-mad02.mx.aol.com [172.26.221.208]) by omr-m008e.mx.aol.com (Outbound Mail Relay) with ESMTP id F39CE38000A5 for ; Sun, 3 Dec 2017 10:13:59 -0500 (EST) Received: from core-acc05a.mail.aol.com (core-acc05.mail.aol.com [172.26.125.15]) by mtaomg-mad02.mx.aol.com (OMAG/Core Interface) with ESMTP id F2F1C38000085 for ; Sun, 3 Dec 2017 10:13:58 -0500 (EST) Received: from 188.194.222.230 by webjas-vad003.srv.aolmail.net (10.96.35.6) with HTTP (WebMailUI); Sun, 03 Dec 2017 10:13:56 -0500 Date: Sun, 3 Dec 2017 10:13:58 -0500 From: Markus Vester To: rsgb_lf_group@blacksheep.org Message-Id: <1601cf0e0da-1d7d-57a6@webjas-vad003.srv.aolmail.net> In-Reply-To: <27d67172-8512-8661-ffa5-b304b8f64452@abelian.org> 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=1512314039; bh=S8txlC1KqP9iJaAg3kX0cH4+LK5/Y8q8DCYFw/Y05nw=; h=From:To:Subject:Message-Id:Date:MIME-Version:Content-Type; b=HvDajTkTGGMwP7Ony0BWEhqKiWAOi2R8dcDfK1uj9mFtv3aXWw56gluqHh82nHsJH qZ13ekyguXQyHcAVev+Wq+7XTFo1AcwrKypgs0kgWabQFHUqqyKDBTvwvGcXtgjAtb VSm3vidQ0FjfWMsiMen07KkFWvh5ud7TmZYtxFT0= x-aol-sid: 3039ac1addd05a2414b60936 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: Thanks very much Paul for these explanations - enlightening indeed. I felt tempted to your the new spectrogram with a third signal from the opposite direction, and started a carrier on 8270.0025 at 14:12 UT. Unfortunately it is snowing on the antenna and I can't get above 180 mA, about 6 dB down to my normal ~ 10 uW EMRP. If all stays healthy I'll run until about 16 UT. [...] 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: fce77e88417377663dedf94f027ec622 Subject: Re: LF: W4DEX at 8270 Hz - and VO1NA Content-Type: multipart/alternative; boundary="----=_Part_27689_1921121164.1512314036442" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.1 required=5.0 tests=HTML_MESSAGE, MAILTO_TO_SPAM_ADDR 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_27689_1921121164.1512314036442 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Thanks very much Paul for these explanations - enlightening indeed. I felt tempted to your the new spectrogram with a third signal from the opp= osite direction, and started a carrier on 8270.0025 at 14:12 UT. Unfortunat= ely it is snowing on the antenna and I can't get above 180 mA, about 6 dB d= own to my normal ~ 10 uW EMRP. If all stays healthy I'll run until about 16= UT. Best 73, Markus -----Urspr=C3=BCngliche Mitteilung-----=20 Von: Paul Nicholson An: rsgb_lf_group Verschickt: So, 3. Dez 2017 15:36 Betreff: Re: LF: W4DEX at 8270 Hz - and VO1NA Two T/A signals at the same time, and on almost the same bearing: VO1NA 280.1 deg at 3575.4 km W4DEX 284.6 deg at 6194.2 km This couldn't have happened any better if we'd planned it. Perfect timing by Dex to come on to 8270 when he did. Markus wrote: > The directional lobe seems rather sharp The bearing of each Fourier bin is calculated (mod 360) and any bins which have bearing outside a +/- 20 degree band around the chosen azimuth, are suppressed by setting their magnitude to a small value. This is the 'filtered bearings' part of it. That gives the impression of sharpness as you swing the compass. The bins which survive the filtering then have their magnitudes re-calculated by synthesizing a cardioid aimed on the bin's bearing. Thus we obtain some extra gain in the forward direction and a null in the opposite direction. It is possible to run without the bearing filter stage, then you just get the cardioid response. This may be better in some situations. I've got a slicker version of the spectrogram in the pipeline and that will have the option to filter bearings or not. But I won't try to finish that until I've upgraded the H receiver. > What is the latency between the end of a one-hour buffer and > the time the latest spectrogram comes online? About an hour. > are you still using three separate stereo soundcards with > individual timing corrections, Still three M-Audio 192 PCI cards 24 bit 192k/sec. Each has VLF signal into one channel and a shaped PPS into the other. Three instances of vtcard and vttime, and a vtjoin to align them by timestamp. The result is a 3-channel stream. Various things T-off that. A vtresample to 48k/sec and a vtwrite records /raw continuously and the spectrogram dips into /raw with vtread to grab one hour segments. > Could downconvert-and-decimate be used to speed up FFT > calculations for the narrow spectrogram? The one hour segments of 3-axis stream are passed through a vtfilter which applies the phase EQ for each channel, then through the sferic blanker, then mixed down and resampled to 240 samples/sec before the bank of Goertzel filters. I don't think it would be any quicker to replace the Goertzel bank with a fast Fourier transform. I'm very keen to eliminate the three PCI sound cards and replace them with one capture device but so far I haven't found one good enough. -- Paul Nicholson -- ------=_Part_27689_1921121164.1512314036442 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
Thanks very much Paul for these explanation= s - enlightening indeed.

I felt tempted to your the new spectro= gram with a third signal from the opposite direction, and started a carrier= on 8270.0025 at 14:12 UT. Unfortunately it is snowing on the antenna and I= can't get above 180 mA, about 6 dB down to my normal ~ 10 uW EMRP. If= all stays healthy I'll run until about 16 UT.

Best 73,
Mar= kus


-----Urspr=C3=BCnglic= he Mitteilung-----
Von: Paul Nicholson <vlf0403@abelian= .org>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org= >
Verschickt: So, 3. Dez 2017 15:36
Betr= eff: Re: LF: W4DEX at 8270 Hz - and VO1NA

=

Two T/A signals at the same time, and on almost the = same
bearing:

VO1NA 280.= 1 deg at 3575.4 km

W4DEX 284.6 deg at 61= 94.2 km

This couldn't have happened any be= tter if we'd planned it.
Perfect timing by Dex to come on t= o 8270 when he did.

Markus wrote:

> The directional lobe seems rather sharp
The bearing of each Fourier bin is calculate= d (mod 360) and
any bins which have bearing outside a +/- 2= 0 degree band around
the chosen azimuth, are suppressed by = setting their magnitude
to a small value. This is the 'fi= ltered bearings' part of it.

That gives th= e impression of sharpness as you swing the compass.

The bins which survive the filtering then have their magnitudesre-calculated by synthesizing a cardioid aimed on the bin's<= br abp=3D"2744">bearing. Thus we obtain some extra gain in the forward dir= ection
and a null in the opposite direction.

It is possible to run without the bearing filter stage, = then you
just get the cardioid response. This may be bette= r in some
situations. I've got a slicker version of the sp= ectrogram
in the pipeline and that will have the option to = filter bearings
or not. But I won't try to finish that u= ntil I've upgraded
the H receiver.

> What is the latency between the end of a one-hour buffer an= d
> the time the latest spectrogram comes online?

About an hour.

> are you still using three separate stereo soundcards with
> individual timing corrections,

Still three M-Audio 192 PCI cards 24 bit 192k/sec. Each has
VLF signal into one channel and a shaped PPS into the other.
Three instances of vtcard and vttime, and a vtjoin to align
them by timestamp. The result is a 3-channel stream.
=
Various things T-off that. A vtresample to 48k/sec anda vtwrite records /raw continuously and the spectrogram
dips into /raw with vtread to grab one hour segments.

> Could downconvert-and-decimate be used to spe= ed up FFT
> calculations for the narrow spectrogram?
The one hour segments of 3-axis stream are p= assed through a
vtfilter which applies the phase EQ for eac= h channel, then
through the sferic blanker, then mixed down= and resampled
to 240 samples/sec before the bank of Goertz= el filters.
I don't think it would be any quicker to replac= e the Goertzel
bank with a fast Fourier transform.

I'm very keen to eliminate the three PCI sound c= ards and replace
them with one capture device but so far I = haven't found one
good enough.

--
Paul Nicholson
--
<= br abp=3D"2789">
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