Return-Path: Received: from mtain-dl03.r1000.mx.aol.com (mtain-dl03.r1000.mx.aol.com [172.29.74.209]) by air-de05.mail.aol.com (v129.4) with ESMTP id MAILINDE053-5eb44d7c155dff; Sat, 12 Mar 2011 19:52:45 -0500 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dl03.r1000.mx.aol.com (Internet Inbound) with ESMTP id 5254138000096; Sat, 12 Mar 2011 19:52:44 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1PyZX7-0001XQ-U9 for rs_out_1@blacksheep.org; Sun, 13 Mar 2011 00:51:45 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1PyZX7-0001XH-4z for rsgb_lf_group@blacksheep.org; Sun, 13 Mar 2011 00:51:45 +0000 Received: from imr-ma04.mx.aol.com ([64.12.206.42]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1PyZX4-0001dg-8E for rsgb_lf_group@blacksheep.org; Sun, 13 Mar 2011 00:51:45 +0000 Received: from mtaout-ma03.r1000.mx.aol.com (mtaout-ma03.r1000.mx.aol.com [172.29.41.3]) by imr-ma04.mx.aol.com (8.14.1/8.14.1) with ESMTP id p2D0pVYs027152 for ; Sat, 12 Mar 2011 19:51:31 -0500 Received: from White (nrbg-4d07457a.pool.mediaWays.net [77.7.69.122]) by mtaout-ma03.r1000.mx.aol.com (MUA/Third Party Client Interface) with ESMTPA id 2CBB8E0001AA for ; Sat, 12 Mar 2011 19:51:27 -0500 (EST) Message-ID: <47AA7A077A074BAE875A773483289D66@White> From: "Markus Vester" To: References: <006301cbe00d$762f0220$0401a8c0@xphd97xgq27nyf> <4D7BF0D8.6030704@iup.uni-heidelberg.de> <4D7C05EB.7090704@talktalk.net> Date: Sun, 13 Mar 2011 01:51:25 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 12.0.1606 X-MimeOLE: Produced By Microsoft MimeOLE V12.0.1606 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: VLF traces Content-Type: multipart/alternative; boundary="----=_NextPart_000_0004_01CBE121.293C0200" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: ** X-Spam-Status: No, hits=2.2 required=5.0 tests=CELL_PHONE_BOOST,HTML_20_30, HTML_MESSAGE,MISSING_OUTLOOK_NAME 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-sid: 3039ac1d4ad14d7c155b3472 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none ------=_NextPart_000_0004_01CBE121.293C0200 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable perhaps related to http://en.wikipedia.org/wiki/Boffin ?? 73, Markus From: qrss@talktalk.net=20 Sent: Sunday, March 13, 2011 12:46 AM To: rsgb_lf_group@blacksheep.org=20 Subject: Re: LF: VLF traces A can of worms. Some would say G9*** is a research and development licence and no G9's= are Amateur calls. "G9 Plus two or three letters have been issued to research organisatio= ns" However "I used a G9 plus two callsign for research activities" "About 5 years ago, I obtained GW9T for Wrexham ARS." Quotes are from MW1LCR So there is a bit of background on G9 calls. What I think Andy was doi= ng was telling the story without using a normal Amateur callsign which= may have been issued ie not an actual person, for the illustration. Or does Andy use G9BOF at work, I don't know. Eddie On 12/03/2011 22:42, Andy Talbot wrote:=20 err...=20 mmmm... perhaps someone else may care to explain some of our special reserve= d callsigns :-) 'JNT =20 2011/3/12 Stefan Sch=E4fer Andy,=20 I agree 100% but who is G9BOF? 73, Stefan Am 11.03.2011 23:28, schrieb Andy Talbot:=20 Can I point out that a carier that appears at a known time and= on a known frequency IS modulated. It is on off keyed. (Well...off= /on anyway :-) The only way that a carrier can be unmodulated is if= it has been there since the beginning of (RF)time and is never switc= hed off, ever, never, before the end of (RF)time. Its appearance or= disappearance is information; what that info means depends on how it= has been coded. Any switching, at all, introduces modulation and widens the band= width, and therefore counts as a means of identification if the meanin= g of the on/off is pre-arranged. =20 In comms-theory-speak If G9BOF makes the announcement "I'll be= transmitting on Sunday at 1300z on 8910.0004Hz" he has now generated= a codebook. The appearance of the carrier at that point in time ind= icates a single bit of information, which by reference to the code boo= ok means G9BOF is sending a '1'. No carrier detected,he is sending a= '0', or there has been a bit error. In other words, no error correc= tion.or detection has been performed. If G9BOF now makes another ann= ouncement that "I'll switch it off at 2358z" he has added another entr= y to the code book. If the carrier really does go off then, the two= bits of information together make a dual-redundant pair, the minimum= needed for error detection. =20 If G9BOF also makes the statement that "my signal is stable and= accurate to 1mHz" and another signal appears in the passband that is= 2mHz away, or wobbles by 1.5mHz, then is is not G9BOF, and error dete= ction will flag it as not valid. If a receiving station cannot detec= t this error, and incorrectly assesses the carrier then the Rx has use= d the wrong codebook, and therefore cannot be deemed to be listening= to G9BOF at all. =20 All a rather extreme and somewhat petty example of coding theor= y and error detection, but its exactly the same as simple Hamming cod= es all the way thorough to reed Solomon. And... I'm not sure how G9B= OF getting his frequency or time wrong would fit into the coding theor= y. So, conclusion, a carrier as stable and on the exact frequency= as stated, at the right time is going to be valid. If you have no= way of proving it really is as stable as quoted, or in the right plac= e, you've no right to question its validity. And anyway, how many spurious signals can even give any pretence= to being stable in these terms - if you think they are, get a better= receiver. We are talking about 0.1ppm over the duration of a signal= ling element as a minimum frequency stability requirement for most ser= ious VLF through LF signalling - which means a quite good TCXO, an ave= rage to middling OCXO or ideally a locked source. If you can't manag= e this, do not cry 'foul' when others do. Andy www.g4jnt.com=20 =20 On 11 March 2011 21:30, Markus Vester wro= te: Dear Mal, with all due respect, I very much disagree here. Whenever I see a clear trace appear at the right time and with= in a milliHz of a confirmed and correctly calibrated frequency, I have hard= ly a doubt about the validity of the reception. Even more so if the trans= mission can be verified by comparison to a calibrated grabber in another loca= tion. It seems that the G3KEV antenna does have excellent sensitivit= y at VLF. It would be fantastic if you could augment that with a stable, pr= operly calibrated, and narrowband reception system. SpecLab has made= that so easy now - throw out the wildly drifting "receiver", connect your= antenna directly to the soundcard instead, lock to one of your MSK nei= ghbours (GBZ or GQD), and your in the game. Best regards, Markus (DF6NM) From: mal hamilton Sent: Friday, March 11, 2011 5:57 PM To: rsgb Subject: LF: VLF traces I can see a couple of vy weak traces around 8970 but this is= no guarantee who it might be because there is no ID. Frequency alone is not= a VALID report- it could be anything. G3KEV ------=_NextPart_000_0004_01CBE121.293C0200 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
 
73, Markus
 

Sent: Sunday, March 13, 2011 12:46 AM
Subject: Re: LF: VLF traces

A=20 can of worms.
Some would say G9*** is a research and development li= cence and=20 no G9's are Amateur calls.
"G9 Plus two or three letters have= been=20 issued to research organisations"
However
"= I used a=20 G9 plus two callsign for research activities"
"About= 5 years=20 ago, I obtained GW9T for Wrexham ARS."
Quotes are from=20 MW1LCR

So there is a bit of background on G9 calls. What I thin= k Andy was=20 doing was telling the story without using a normal Amateur callsign wh= ich may=20 have been issued ie not an actual person, for the illustration.
Or does=20 Andy use G9BOF at work, I don't know.

Eddie

On 12/03/201= 1 22:42,=20 Andy Talbot wrote:=20
err...
mmmm...
 
perhaps someone else may care to explain some of our special re= served=20 callsigns :-)
 
'JNT


 
2011/3/12 Stefan Sch=E4fer = <schaefer@iup.uni-heidelberg.de>
Andy,

I agree 10= 0% but who is=20 G9BOF?

73, Stefan

Am 11.03.2011 23:28, schrieb Andy= Talbot:=20
Can I point out that a carier that appears at a known time= and on a=20 known frequency IS modulated.   It is on off keyed.&nb= sp;=20 (Well...off/on anyway :-)    The only way that a= carrier=20 can be unmodulated is if it has been there since the beginning= of =20 (RF)time and is never switched off, ever, never, before the end= of=20 (RF)time.   Its appearance or disappearance is=20 information;  what that info means depends on how it has be= en=20 coded.
 
Any switching, at all, introduces modulation and widens&nbs= p;the=20 bandwidth, and therefore counts as a means of identification if= the=20 meaning of the on/off is pre-arranged.  
 
In comms-theory-speak  If G9BOF makes the announcement= "I'll be=20 transmitting on Sunday at 1300z on 8910.0004Hz" he has now gener= ated a=20 codebook.   The appearance of the carrier at that poin= t in time=20 indicates a single bit of information, which by reference to the= code=20 boook means G9BOF is sending a '1'.  No carrier detected,he= is=20 sending a '0', or there has been a bit error.   In oth= er words,=20 no error correction.or detection has been performed.  = If G9BOF=20 now makes another announcement that "I'll switch it off at 2358z= " he has=20 added another entry to the code book.  If the carrier reall= y does go=20 off then,  the two bits of information  together make= a=20 dual-redundant pair, the minimum needed for error=20 detection.  
 
If G9BOF also makes the statement that "my signal is= stable and=20 accurate  to 1mHz" and another signal appears in the passba= nd that is=20 2mHz away, or wobbles by 1.5mHz, then is is not G9BOF, and error= detection=20 will flag it as not valid.   If a receiving station ca= nnot=20 detect this error, and incorrectly assesses the carrier the= n the Rx=20 has used the wrong codebook, and therefore cannot be deemed to= be=20 listening to G9BOF at all.  
 
All a rather extreme and somewhat petty  example of co= ding=20 theory and error detection,  but its exactly the same= as simple=20 Hamming codes all the way thorough to reed Solomon.  And...= =20  I'm not sure how G9BOF getting his frequency or time= wrong=20 would fit into the coding theory.
 
So, conclusion, a carrier as stable and on the exact=20 frequency as stated, at the right time is going to be=20 valid.   If you have no way of proving it really is as= stable as=20 quoted, or in the right place, you've no right to qu= estion its=20 validity.
 
And anyway, how many spurious signals can even give any pre= tence to=20 being stable in these terms - if you think they are, get a bette= r=20 receiver.   We are talking about 0.1ppm over the durat= ion of a=20 signalling element as a minimum frequency stability requirement= for most=20 serious VLF through LF signalling - which means a quit= e good=20 TCXO, an average to middling OCXO or ideally a locked= =20 source.   If you can't manage this, do not cry 'foul'= when=20 others do.
 
Andy
 
 
 

 
On 11 March 2011 21:30, Markus Vester= <markusvester@aol.com= > wrote:
Dear=20 Mal,

with all due respect, I very much disagree=20 here.

Whenever I see a clear trace appear at the right= time and=20 within a milliHz
of a confirmed and correctly calibrated fr= equency, I=20 have hardly a doubt
about the validity of the reception. Ev= en more so=20 if the transmission can be
verified by comparison to a cali= brated=20 grabber in another location.

It seems that the G3KEV an= tenna does=20 have excellent sensitivity at VLF. It
would be fantastic if= you could=20 augment that with a stable, properly
calibrated, and narrow= band=20 reception system. SpecLab has made that so easy
now - throw= out the=20 wildly drifting "receiver", connect your antenna
directly= to the=20 soundcard instead, lock to one of your MSK neighbours (GBZ
= or GQD),=20 and your in the game.

Best regards,
Markus=20 (DF6NM)


From: mal hamilton
Sent: Friday, March= 11, 2011=20 5:57 PM
To: rsgb
Subject: LF: VLF traces


I ca= n see a=20 couple of vy weak traces around 8970 but this is no guarantee<= BR>who it=20 might be because there is no ID. Frequency alone is not a=20 VALID
report- it could be=20 anything.
G3KEV






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