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[213.106.115.109]) by mx.google.com with ESMTPS id 9sm64124202wid.2.2012.03.26.01.08.16 (version=TLSv1/SSLv3 cipher=OTHER); Mon, 26 Mar 2012 01:08:17 -0700 (PDT) References: <8CED1D568912879-1568-4B17@angweb-usd004.sysops.aol.com> <5BBB1EB8BEC445D6A33CE2E0CF6D7620@White> In-Reply-To: <5BBB1EB8BEC445D6A33CE2E0CF6D7620@White> Mime-Version: 1.0 (1.0) Message-Id: Cc: "" X-Mailer: iPod Mail (9A405) From: Roger Lapthorn Date: Mon, 26 Mar 2012 09:08:15 +0100 To: "rsgb_lf_group@blacksheep.org" X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Content-Transfer-Encoding: 7bit Content-Type: multipart/alternative; boundary=Apple-Mail-6921D8F8-A5B2-4405-AAD5-67A5947FFE47 Subject: Re: VLF: OK2BVG - DF6NM QSO on 8.97 kHz X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.6 required=5.0 tests=HTML_20_30, HTML_FONTCOLOR_UNKNOWN,HTML_MESSAGE,TO_ADDRESS_EQ_REAL 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-SCORE: 0:2:411785216:93952408 X-AOL-SCOLL-URL_COUNT: 0 X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-d012.2 ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1d40d94f7024232b99 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --Apple-Mail-6921D8F8-A5B2-4405-AAD5-67A5947FFE47 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii Congratulations to you both! 73s Roger G3XBM -- Via my iPod Touch 4g -- On 26 Mar 2012, at 01:33, "Markus Vester" wrote: > Today between 7:30 and 14:00, Lubos OK2BVG and I successfully completed a t= wo-way contact on 8.97 kHz. We believe that this is the first international Q= SO ever on VLF. > =20 > The distance between Breclav (JN88KS) and Nuernberg (JN59NJ 69es) is appro= ximately 424 km. The weekend before, Lubos and I had found that we could see= each other's VLF transmissions from our small home antennas in a slow spect= rogram, using about 0.45 millihertz FFT resolution ("DFCW-6000"). This long i= ntegration requires about 2000 seconds of continuous non-interrupted carrier= to reach full sensitivity.=20 > =20 > We decided to use absolute frequency encoding of characters ("MFSK-37" mod= e), which has a simple structure but is significantly more efficient than tw= o-frequency DFCW. The software signal generators in SpecLab were used to cre= ate 30 minute dashes by editing the frequency in 1 mHz steps every half hour= . This can be automated by opening a textfile which is read by the "periodic= actions" function. Between transmissions, additional half-hour gaps were in= serted to let the FFT ring down, and allow for TX-RX reconnections. > =20 > Characters are identified by reading the frequencies above 8970.000 Hz, wi= th 8970.000 to .009 assigned to the numbers, .010 idle or space, and .011 to= .036 the letters A-Z. Lubos used a Rubidium standard to lock his transmit s= amplerate, while both receivers and my TX were synchronized by military MSK= signals from GQD (22.1 kHz) and DHO (23.4 kHz). > =20 > With about 80 watts from an audio amplifier, I could get up to 0.38 A ante= nna current into my top-loaded vertical 9 m above the roof, radiating on the= order of 10 to 15 microwatts. I believe that Lubos is using similar equipme= nt, perhaps a couple of dB stronger. For receive, my soundcard was connected= straight to the loading coil and antenna, whereas Lubos has an active probe= at a quiet site remote from his TX location. > =20 > We wanted to go for a "full QSO" format with reports and confirmations, be= yond the rudimentary three-dash "micro-QSO" format which was used in June 20= 09 between DJ2LF and myself. With single-letter suffixes, we ended up procee= ding as follows: > =20 > 07:30-08:30 "NB" ;Lubos' call: df6Nm de ok2Bvg > 09:00-10:30 "BNM" ;my reply and report: Bvg Nm M =20 > 11:00-12:00 "RO" ;his confirmation and report > 12:30-14:00 "RTU" ;my confirmation and thank you > =20 > Although today the noise was not as low as it had been before, we managed= to exchange the essential information in 5.5 hours until 13 UT, after which= QRN from lightning in southeast Europe became strong enough to obliterate f= urther copy. > =20 > Attached image contains captures from Lubos' grabber at Apollons temple (t= op) and my receiver (bottom), with screenshots from the DK7FC and OE3GHB gra= bbers pasted inbetween. The original captures are at > http://df6nm.bplaced.net/VLF/ok2bvg_df6nm_120325/ > All spectrograms were stretched to the same timescale (5 min/pixel). On th= e left hand side, you can see a MFSK pre-test from Lubos, sending his call t= o hs own grabber at very low power. There was also a long dash from OE3GHB o= n 8970.030, and a carrier from DJ8WX on 8970.022 is visible at DK7FC. > =20 > The rightmost part of the captures shows the essential eight dashes from o= ur QSO. You can see that I had almost lost Lubos' "B" when my noise blanker= triggered heavily on local QRM, inducing me to give an "M" rather than "O" r= eport. But hovering the cursor to 8:15 UT does show the peak at 8970.012 Hz i= n the spectrum graph. My final "R" is just barely visible at .028, whereas t= he following "TU" at .030 and .031 ended up drowning in the increasing noise= . > =20 > During the lowest noise period (9 - 12 UT), the dashes were visible (thoug= h not decodable) in 4.5 mHz "600" spectrograms. At that time, our symbols al= so appeared on Paul Nicholson's spectrogram > http://abelian.org/vlf/fbins.shtml#p=3D1332712800&b=3D110&s=3Dsp > =20 > Thanks again to Lubos for the effort and patience! Although exchanging ha= lf-hour symbols is tedious and may sound boring to some, both of us enjoyed i= t and actually found it quite exciting. > =20 > Best 73, > Markus (DF6NM) >=20 > From: Markus Vester > Sent: Friday, March 16, 2012 11:46 PM > To: rsgb_lf_group@blacksheep.org > Subject: VLF: MFSK-37 tests above 8970 today >=20 > To explore the possibility of further two-way VLF contacts from my home an= tenna, I have conducted a test in MFSK-37 mode this morning. I was hoping to= reach 0.42 mHz ("6000") grabbers using UT-synchronized half-hour dashes. Si= milar to an earlier kite experiment, I used absolute frequency encoding of c= haracters in 1 mHz steps (0 =3D 8970.000, 1 =3D 8970.001, ... 9 =3D 8970.009= , idle =3D 8970.010, A =3D 8970.011, .. Z =3D 8970.036 Hz). > =20 > The plan was to transmit my complete callsign in 2.5 hours between 8:00 an= d 10:30. Unfortunately DHO locking failed during the first two characters, w= hich came out some 9 mHz low. Attached image shows what was actually sent ac= cording to my "monitor", which is a high harmonic of the transmitted VLF sig= nal accidentally aliased into the LF TA window. > =20 > I was pleased to find all the dashes showing up clearly as bright dots on t= he OK2BVG "6000" grabber, and even left visible traces in his "600" window. A= s I had also received Lubos' transmission last weekend with a good margin in= 0.48 mHz, a two-way QSO between us would probably be feasible within a few h= ours. > =20 > Paul Nicholson's 0.278 mHz super-sensitive spectrogram also shows the tran= smission at 120 degrees azimuth, even though the dashes were really too shor= t to reach full SNR in this bandwidth. > =20 > Results on the DK7C grabber were not quite as good, with only a single cle= ar dot on .006 Hz. This may partly have been due to the previously experienc= ed daytime minimum at our distance (180 km). Nothing distictive was visible a= t OE3GHB, who is at similar distance as OK2BVG, but seems to have suffered f= rom a bit of local QRM at the time.=20 > =20 > Again we find that a great deal is possible with very modest means... > =20 > Best 73, > Markus (DF6NM) > =20 > =20 > =20 > =20 > =20 > =20 > =20 > =20 > --Apple-Mail-6921D8F8-A5B2-4405-AAD5-67A5947FFE47 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8
Congratulations  to y= ou both!

73s
Roger G3XBM

-- Via my= iPod Touch 4g --

On 26 Mar 2012, at 01:33, "Markus Vester" &l= t;markusvester@aol.com> wrote= :

Today between 7:30 and 14:00, Lubo= s OK2BVG and=20 I successfully completed a two-way contact on 8.97 kHz. We believe that this= is=20 the first international QSO ever on VLF.
 
The distance between Breclav (JN88KS) a= nd Nuernberg=20 (JN59NJ 69es) is approximately 424 km. The weekend before, Lubos and I had f= ound=20 that we could see each other's VLF transmissions from our small home antenna= s in=20 a slow spectrogram, using about 0.45 millihertz FFT resolution ("DFCW-6000")= .=20 This long integration requires about 2000 seconds of continuous non-interrup= ted=20 carrier to reach full sensitivity. 
 
We decided to use absolute frequency en= coding of=20 characters ("MFSK-37" mode), which has a simple structure but is significant= ly=20 more efficient than two-frequency DFCW. The software signal generators in=20= SpecLab were used to create 30 minute dashes by editing the frequency in 1 m= Hz=20 steps every half hour. This can be automated by opening a textfile which=20 is read by the "periodic actions" function. Between transmissions,=20 additional half-hour gaps were inserted to let the FFT ring down, and allow f= or=20 TX-RX reconnections.
 
Characters are identified by reading th= e=20 frequencies above 8970.000 Hz, with 8970.000 to .009 assigned to the numbers= ,=20 .010 idle or space, and .011 to .036 the letters A-Z. Lubos used a Rubidium=20= standard to lock his transmit samplerate, while both receivers and my TX wer= e=20 synchronized by military MSK signals from GQD (22.1 kHz) and DHO (23.4 kHz).= =20
 
With about 80 watts from an audio ampli= fier, I=20 could get up to 0.38 A antenna current into my top-loaded vertical 9 m above= the=20 roof, radiating on the order of 10 to 15 microwatts. I believe that Lubos is= =20 using similar equipment, perhaps a couple of dB stronger. For receive, = my=20 soundcard was connected straight to the loading coil and antenna, whereas Lu= bos=20 has an active probe at a quiet site remote from his TX=20 location.
=  
We wanted to go for a "full QSO" format= with=20 reports and confirmations, beyond the rudimentary three-dash "micro-QSO" for= mat=20 which was used in June 2009 between DJ2LF and myself. With single-letter=20 suffixes, we ended up proceeding as follows:
 
07:30-08:30 "NB"    = ; ;Lubos'=20 call: df6Nm de ok2Bvg
09:00-10:30 "BNM"  ;my reply and report: Bvg N= m=20 M  
11:00-12:00 "RO"     ;his confirmation= and=20 report
12:30-14:00 "RTU"  ;my confirmation and thank you
 
Although today the noise was not as low= as it had=20 been before, we managed to exchange the essential information in 5.5 hours u= ntil=20 13 UT, after which QRN from lightning in southeast Europe became strong enou= gh=20 to obliterate further copy.
 
Attached image contains captures from L= ubos'=20 grabber at Apollons temple (top) and my receiver (bottom), with screenshots f= rom=20 the DK7FC and OE3GHB grabbers pasted inbetween. The original captures are=20= at
http://df6nm.bplaced.net/VLF/ok2bvg_df6nm_1203= 25/
All=20 spectrograms were stretched to the same timescale (5 min/pixel). On the left= =20 hand side, you can see a MFSK pre-test from Lubos, sending his call to hs ow= n=20 grabber at very low power. There was also a long dash from OE3GHB on 8970.03= 0,=20 and a carrier from DJ8WX on 8970.022 is visible at DK7FC.
 
The rightmost part of the captures show= s the=20 essential eight dashes from our QSO. You can see that I had almost lost = ;=20 Lubos' "B" when my noise blanker triggered heavily on local QRM, inducing me= to=20 give an "M" rather than "O" report. But hovering the cursor to 8:15 UT does s= how=20 the peak at 8970.012 Hz in the spectrum graph. My final "R" is just barely=20= visible at .028, whereas the following "TU" at .030 and .031 ended up drowni= ng=20 in the increasing noise.
 
During the lowest noise period (9 - 12 U= T), the=20 dashes were visible (though not decodable) in 4.5 mHz "600" spectrograms. At= =20 that time, our symbols also appeared on Paul Nicholson's spectrogram
http://abelian.org/vlf/= fbins.shtml#p=3D1332712800&b=3D110&s=3Dsp
 
Thanks again to Lubos for the effort an= d=20 patience!  Although exchanging half-hour symbols is tedious and may sou= nd=20 boring to some, both of us enjoyed it and actually found it quite exciting.=20=
 
Best 73,
Markus (DF6NM)

Sent: Friday, March 16, 2012 11:46 PM
Subject: VLF: MFSK-37 tests above 8970 today
=
To explore the possibility of further two-way VLF contacts from my= =20 home antenna, I have conducted a test in MFSK-37 mode this morning. I was ho= ping=20 to reach 0.42 mHz ("6000") grabbers using UT-synchronized half-hour dashes.=20= Similar to an earlier kite experiment, I used absolute frequency=20 encoding of characters in 1 mHz steps (0 =3D 8970.000, 1 =3D 8970.001, .= .. 9 =3D=20 8970.009, idle =3D 8970.010, A =3D 8970.011, .. Z =3D 8970.036 Hz).
 
The plan was to transmit my complete callsign in 2.5 hours between 8:00= and=20 10:30. Unfortunately DHO locking failed during the first two characters= ,=20 which came out some 9 mHz low. Attached image shows what was actually=20= sent according to my "monitor", which is a high harmonic of the transmi= tted=20 VLF signal accidentally aliased into the LF TA window.
 
I was pleased to find all the dashes showing up clearly as br= ight=20 dots on the OK2BVG "6000" grabber, and even left visible traces in= his=20 "600" window. As I had also received Lubos' transmission last week= end=20 with a good margin in 0.48 mHz, a two-way QSO between us would probably be=20= feasible within a few hours.
 
Paul Nicholson's 0.278 mHz super-sensitive spectrogram also shows = the=20 transmission at 120 degrees azimuth, even though the dashes were really too=20= short to reach full SNR in this bandwidth.
 
Results on the DK7C grabber were not quite as good, with only a single=20= clear dot on .006 Hz. This may partly have been due to the previou= sly=20 experienced daytime minimum at our distance (180 km). Nothing distictiv= e=20 was visible at OE3GHB, who is at similar distance as OK2BVG, but seems t= o=20 have suffered from a bit of local QRM at the time. 
 
Again we find that a great deal is possible with very modest means...
 
Best 73,
Markus (DF6NM)
 
 
 
 
 
 
 
 
<ok2bvg_dk7fc_oe3ghb_df= 6nm_highlighted_120325.jpg>
= --Apple-Mail-6921D8F8-A5B2-4405-AAD5-67A5947FFE47--