Return-Path: Received: from mtain-ma09.r1000.mx.aol.com (mtain-ma09.r1000.mx.aol.com [172.29.96.17]) by air-da06.mail.aol.com (v127_r1.1) with ESMTP id MAILINDA063-863e4b9f6bc62ab; Tue, 16 Mar 2010 07:30:14 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-ma09.r1000.mx.aol.com (Internet Inbound) with ESMTP id 2B5FE38000141; Tue, 16 Mar 2010 07:30:12 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NrUxi-0003o0-NB for rs_out_1@blacksheep.org; Tue, 16 Mar 2010 11:29:26 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NrUxh-0003nr-U2 for rsgb_lf_group@blacksheep.org; Tue, 16 Mar 2010 11:29:25 +0000 Received: from mail-bw0-f210.google.com ([209.85.218.210]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1NrUxc-0002Ri-UA for rsgb_lf_group@blacksheep.org; Tue, 16 Mar 2010 11:29:25 +0000 Received: by bwz2 with SMTP id 2so3887231bwz.30 for ; Tue, 16 Mar 2010 04:29:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:content-type; bh=Q/qfoUfdhvp4oBschcFl88LwE9J7/wjSNU951hXwAK4=; b=dZAMEkqYRgmFCsLSHFM29quVAPXeDLRN4LAgtUmMPBahrjNSyruvQWp8OOHeCsBa/J TVjohMiLxm2R8ahmOtJkk7LWlTIbyWHbLmyxhfkeDz51SyPvk5MV2/6lH6s+QHWrDLOX MsiuXFfKiQa7au+kvUv4SSqcM0eggjhabtEDc= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=CAbWOPNDMnyU0ZvUv3WmcQm8AMdsHiKV8GJWu0kZP7s5DPSf9/ybcAai5i3nUrLGEm Jf93TPQeUt7COi9z4V1cyLjOeshaWiUd+zmXvwkXvrSNiSQwzXoHbA10PBK8GtmmnzQi NtFqM2TfZXC55OUH2BLpm1YVHhmZqYOQoDiFM= MIME-Version: 1.0 Received: by 10.204.34.197 with SMTP id m5mr5629974bkd.20.1268738954567; Tue, 16 Mar 2010 04:29:14 -0700 (PDT) In-Reply-To: <4B9F62B8.40701@abelian.org> References: <000001cac47a$f4ba1350$0202a8c0@laptopcore2> <38A51B74B884D74083D7950AD0DD85E82A1B57@File-Server-HST.hst.e-technik.tu-darmstadt.de> <9afca2641003152340y38ac70f6pef79d498f1e37a47@mail.gmail.com> <4B9F62B8.40701@abelian.org> Date: Tue, 16 Mar 2010 11:29:14 +0000 Message-ID: <9afca2641003160429u27717c95y248d7cdf4875b90e@mail.gmail.com> From: Roger Lapthorn To: rsgb_lf_group@blacksheep.org DomainKey-Status: good (testing) X-Spam-Score: 0.3 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,MAILTO_TO_SPAM_ADDR=0.276 Subject: Re: LF: DK7FC's 2nd VLF TX test... Content-Type: multipart/alternative; boundary=00032555772eb3205f0481e94ee6 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.2 required=5.0 tests=HTML_FONTCOLOR_UNSAFE, 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 x-aol-global-disposition: G X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-d292.2 ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1d60114b9f6bc46895 X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) --00032555772eb3205f0481e94ee6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable A very good summary and analysis Paul - thank you. Further tests, with an ID, will be good, but the signal clearly got there and 858.7kms is a very long way for an amateur signal on 8.97kHz. Who's next then? HI 73s Roger G3XBM On 16 March 2010 10:51, Paul Nicholson wrote: > Here is my reception report... > > Transmitter: Amateur radio station DK7FC transmitting from > 49.77647N 8.699525E, (near Frankfurt) on 8970 Hz, ERP estimated > at up to 1.7mW, vertically polarised CW. > > Receiver: Todmorden, UK, 53.703N 2.072W. Orthogonal loops, > 20 square metres each, LT1028 front-end, system sensitivity > 0.03fT in 5mHz bandwidth. Frequency locked to MSF at 60kHz. > > The distance to the transmitter is 858.7 km, bearing 116.2 deg. > > Test date: 2010-03-15. All times UT. > Flux density error: +/- 50%. > > Transmitter website http://www.qrz.com/db/DK7FC > Receiver website http://abelian.org/vlf/nb.shtml > > Observations > ------------ > The signal appeared faintly in the 0.005Hz/200 second > spectrogram between 14:30 and 16:00. The spectrogram was > produced from the loop signal oriented to null the > prevailing background noise which averaged 1.56 fT in 5mHz > on mean bearing 162/342 deg. The signal was not visible in > a omni-directional spectrogram. > > After orienting the loops to null the average background, > the remaining noise averaged 0.73 fT in 5mHz. All further > analysis refers to the oriented signal. > > A graph of the (non-coherent) average flux density over the > 90 minute period is shown here, > > http://abelian.org/vlf/ss100315/p1.png > > The standard deviation is 0.085fT and the peak at 8970.01 Hz > is 1.34fT, which is 7.2 sigma away from the mean background. > > The signal is spread somewhat across three frequency bins, > due either to tx modulation or propagation. If the signal > energy represented by the three bins is combined, the > resulting average signal amplitude is 2.2fT. > > The averaged bearing is 135 degrees, which agrees very well > with a signal-amplitude weighted average of the transmitter > on 116 degrees and the noise on 162 degrees. > > Only in one 200 second integration period did the signal show > clearly above noise. This was 14:38:37 to 14:41:57, in which > we have significant energy concentrated into a single bin at > 8970.01 Hz, amplitude 3.1fT with a bearing of 117/297 deg. > > http://abelian.org/vlf/ss100315/p2.png > > The noise in this spectrum has mean 0.70fT and standard > deviation 0.365fT which puts the peak at about 6.6 sigma > above the mean. > > To estimate the significance of this peak, a 7 hour period of > data was scanned to look for peaks of height > 6 sigma relative > to each 200 second integration frame. The period chosen was > 09:00 to 16:00 during which the background noise had similar > amplitude to that present during the test. In 126 frames and > 50400 bin samples, no other peaks were found with higher sigma. > The nearest was one at 15:35:23 on 8969.9297 Hz with a peak > of 3.2 fT, bearing 108 deg and a sigma of 5.5. This peak > is 80mHz below the transmit frequency. > > A spectrogram of the band is at > > http://abelian.org/vlf/ss100315/sg1.png > > The signal is visible faintly before the noise starts to rise > at 16:00. Markus Vester (DF6NM) has made a visual alignment > of this spectrogram with the signal he received at N=FCrnberg > at a range of about 180km, > > http://abelian.org/vlf/ss100315/8k97_100315_14-18UT.jpg > > Notes/Comments > -------------- > Here is the daily chart for DHO on 23.4kHz, > > http://abelian.org/vlf/live/100315.DHO.png > > The ionosphere begins to be disturbed from 15:00 onwards. > (The small 'SID' shortly before 10:00 is actually a 62.7 > second outage of DHO.) Fluctuation of bearing and phase angle > (between the two loops) indicates multiple signal paths arriving > on different bearings. > > The test would have been better performed earlier in the day. > During the morning the noise was very low and bearing about > 25 deg which left the beam of the antenna pointing directly > at Frankfurt! > > Rapid keying, such as QRSS 120, is too fast for this frequency > resolution. A long CW transmission would be more useful > scientifically. At times, path length fluctuation will spread > the signal outside of a 5mHz filter. In this situation there > is no benefit to using even narrower bandwidth. With further > CW tests it should be possible to estimate a minimum usable > daytime bandwidth. > > The signal detection here is quite satisfactory when regarded > as a physical measurement. However, for amateur radio record > purposes it is appropriate to require a message or at least > a callsign to be decoded. At this S/N ratio and bandwidth it > would probably require QRSS 300 or greater and take a few hours > to send a callsign. This might be reduced if a synchronous > FSK mode was used. > > It is not clear what to make of the peak at 15:35:23 on > 8969.9297 Hz which is quite a significant peak 80mHz below > the transmit frequency. Doppler shift due to path length > changes are to be expected, but this amount of shift requires > a sustained rate of increase of path length of 2.6km/sec. > In the same integration frame, the signal at 8970.01 Hz was > about 2.1fT. > > The average signal strength was 1.34fT during the 90 > minutes analysed. For part of that time, the transmitter > was off, and the signal energy is spread across about 15mHz. > Considering this, the signal amplitude was probably around > 3fT which is rather higher than an estimate of 0.9fT derived > from 1.7mW ERP. > > On the spectrogram is visible another intermittent narrow > band signal at about 8970.1Hz, rather fainter than DK7FC. > This signal is too weak to analyse. > > During the test, no lightning was present in Europe. Only > weak, distant sferics were present and the sferic blanker > was removing about 3% of the signal. > > Conclusion > ---------- > This signal detection at 857km is very encouraging and we > await further tests. Undoubtedly before too long the first > amateur radio message will be sent across more than 100km > at 9kHz and this test suggests that much higher range may > be possible. Daytime, mid-morning to early afternoon probably > offers the best propagation and background noise. The DHO > chart indicates that the D layer is stable during this time, > and the background noise is at its lowest. For amateur radio > purposes it is important to modulate the signal. For scientific > analysis of propagation, a continuous signal is more useful. > Hopefully future tests can accommodate both requirements. > -- > Paul Nicholson > -- > > --=20 http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/G3XBM G3XBM GQRP 1678 ISWL G11088 --00032555772eb3205f0481e94ee6 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable A very good summary and analysis Paul - thank you.

Further tests,= with an ID, will be good, but the signal clearly got there and 858.7kms= is a very long way for an amateur signal on 8.97kHz.

Who's nex= t then? HI

73s
Roger G3XBM
=A0

On 16 Marc= h 2010 10:51, Paul Nicholson <vlf0308@abelian.org> wrote:
Here is my reception report...

Transmitter: Amateur radio station DK7FC transmitting from
49.77647N 8.699525E, (near Frankfurt) on 8970 Hz, ERP estimated
at up to 1.7mW, vertically polarised CW.

Receiver: Todmorden, UK, 53.703N 2.072W. Orthogonal loops,
20 square metres each, LT1028 front-end, system sensitivity
0.03fT in 5mHz bandwidth. =A0Frequency locked to MSF at 60kHz.

The distance to the transmitter is 858.7 km, bearing 116.2 deg.

Test date: 2010-03-15. =A0All times UT.
Flux density error: +/- 50%.

Transmitter website http://www.qrz.com/db/DK7FC
Receiver website http://abelian.org/vlf/nb.shtml

Observations
------------
The signal appeared faintly in the 0.005Hz/200 second
spectrogram between 14:30 and 16:00. The spectrogram was
produced from the loop signal oriented to null the
prevailing background noise which averaged 1.56 fT in 5mHz
on mean bearing 162/342 deg. =A0The signal was not visible in
a omni-directional spectrogram.

After orienting the loops to null the average background,
the remaining noise averaged 0.73 fT in 5mHz. =A0All further
analysis refers to the oriented signal.

A graph of the (non-coherent) average flux density over the
90 minute period is shown here,

=A0ht= tp://abelian.org/vlf/ss100315/p1.png

The standard deviation is 0.085fT and the peak at 8970.01 Hz
is 1.34fT, which is 7.2 sigma away from the mean background.

The signal is spread somewhat across three frequency bins,
due either to tx modulation or propagation. If the signal
energy represented by the three bins is combined, the
resulting average signal amplitude is 2.2fT.

The averaged bearing is 135 degrees, which agrees very well
with a signal-amplitude weighted average of the transmitter
on 116 degrees and the noise on 162 degrees.

Only in one 200 second integration period did the signal show
clearly above noise. =A0This was 14:38:37 to 14:41:57, in which
we have significant energy concentrated into a single bin at
8970.01 Hz, amplitude 3.1fT with a bearing of 117/297 deg.

=A0ht= tp://abelian.org/vlf/ss100315/p2.png

The noise in this spectrum has mean 0.70fT and standard
deviation 0.365fT which puts the peak at about 6.6 sigma
above the mean.

To estimate the significance of this peak, a 7 hour period of
data was scanned to look for peaks of height > 6 sigma relative
to each 200 second integration frame. =A0The period chosen was
09:00 to 16:00 during which the background noise had similar
amplitude to that present during the test. =A0In 126 frames and
50400 bin samples, no other peaks were found with higher sigma.
The nearest was one at 15:35:23 on 8969.9297 Hz with a peak
of 3.2 fT, bearing 108 deg and a sigma of 5.5. =A0This peak
is 80mHz below the transmit frequency.

A spectrogram of the band is at

=A0h= ttp://abelian.org/vlf/ss100315/sg1.png

The signal is visible faintly before the noise starts to rise
at 16:00. =A0 Markus Vester (DF6NM) has made a visual alignment
of this spectrogram with the signal he received at N=FCrnberg
at a range of about 180km,

=A0http://abelian.org/vlf/ss100315/8k97_100315_14-18UT.jpg=

Notes/Comments
--------------
Here is the daily chart for DHO on 23.4kHz,

=A0http://abelian.org/vlf/live/100315.DHO.png

The ionosphere begins to be disturbed from 15:00 onwards.
(The small 'SID' shortly before 10:00 is actually a 62.7
second outage of DHO.) =A0Fluctuation of bearing and phase angle
(between the two loops) indicates multiple signal paths arriving
on different bearings.

The test would have been better performed earlier in the day.
During the morning the noise was very low and bearing about
25 deg which left the beam of the antenna pointing directly
at Frankfurt!

Rapid keying, such as QRSS 120, is too fast for this frequency
resolution. =A0A long CW transmission would be more useful
scientifically. =A0At times, path length fluctuation will spread
the signal outside of a 5mHz filter. =A0In this situation there
is no benefit to using even narrower bandwidth. =A0With further
CW tests it should be possible to estimate a minimum usable
daytime bandwidth.

The signal detection here is quite satisfactory when regarded
as a physical measurement. =A0However, for amateur radio record
purposes it is appropriate to require a message or at least
a callsign to be decoded. =A0At this S/N ratio and bandwidth it
would probably require QRSS 300 or greater and take a few hours
to send a callsign. =A0This might be reduced if a synchronous
FSK mode was used.

It is not clear what to make of the peak at 15:35:23 on
8969.9297 Hz which is quite a significant peak 80mHz below
the transmit frequency. =A0Doppler shift due to path length
changes are to be expected, but this amount of shift requires
a sustained rate of increase of path length of 2.6km/sec.
In the same integration frame, the signal at 8970.01 Hz was
about 2.1fT.

The average signal strength was 1.34fT during the 90
minutes analysed. =A0For part of that time, the transmitter
was off, and the signal energy is spread across about 15mHz.
Considering this, the signal amplitude was probably around
3fT which is rather higher than an estimate of 0.9fT derived
from 1.7mW ERP.

On the spectrogram is visible another intermittent narrow
band signal at about 8970.1Hz, rather fainter than DK7FC.
This signal is too weak to analyse.

During the test, no lightning was present in Europe. =A0Only
weak, distant sferics were present and the sferic blanker
was removing about 3% of the signal.

Conclusion
----------
This signal detection at 857km is very encouraging and we
await further tests. =A0Undoubtedly before too long the first
amateur radio message will be sent across more than 100km
at 9kHz and this test suggests that much higher range may
be possible. =A0Daytime, mid-morning to early afternoon probably
offers the best propagation and background noise. =A0The DHO
chart indicates that the D layer is stable during this time,
and the background noise is at its lowest. =A0 For amateur radio
purposes it is important to modulate the signal. =A0For scientific
analysis of propagation, a continuous signal is more useful.
Hopefully future tests can accommodate both requirements.
--
Paul Nicholson
--




--

http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/G3XBM G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL G11088
--00032555772eb3205f0481e94ee6--