Return-Path: Received: from rly-me03.mx.aol.com (rly-me03.mail.aol.com [172.20.83.36]) by air-me02.mail.aol.com (v121_r4.4) with ESMTP id MAILINME023-9a64957b27b2ab; Sun, 28 Dec 2008 12:08:38 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-me03.mx.aol.com (v121_r4.4) with ESMTP id MAILRELAYINME032-9a64957b27b2ab; Sun, 28 Dec 2008 12:08:13 -0500 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1LGz7X-0002RB-3n for rs_out_1@blacksheep.org; Sun, 28 Dec 2008 17:08:07 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1LGz7W-0002R2-DE for rsgb_lf_group@blacksheep.org; Sun, 28 Dec 2008 17:08:06 +0000 Received: from smtp-out5.blueyonder.co.uk ([195.188.213.8]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1LGz7U-00029X-Hj for rsgb_lf_group@blacksheep.org; Sun, 28 Dec 2008 17:08:06 +0000 Received: from [172.23.170.142] (helo=anti-virus02-09) by smtp-out5.blueyonder.co.uk with smtp (Exim 4.52) id 1LGz7T-0008Jb-Pj for rsgb_lf_group@blacksheep.org; Sun, 28 Dec 2008 17:08:03 +0000 Received: from [92.235.33.173] (helo=p4) by asmtp-out3.blueyonder.co.uk with smtp (Exim 4.52) id 1LGz7S-0004co-IX for rsgb_lf_group@blacksheep.org; Sun, 28 Dec 2008 17:08:03 +0000 Message-ID: <15ECADEB7168445D8B1D16989B911048@p4> From: "Mark" To: References: <005a01c968ff$2a99ee10$6401a8c0@asus> <2AE02D153B264F6D83CE8993AEA5F44E@AGB> <008501c96908$4f961320$6401a8c0@asus> Date: Sun, 28 Dec 2008 17:08:02 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5512 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 X-Karma: 0: X-Spam-Score: 3.4 (+++) X-Spam-Report: autolearn=disabled,FORGED_MUA_OUTLOOK=3.36,HTML_MESSAGE=0.001 Subject: Re: LF: 500KHz QSB Content-Type: multipart/alternative; boundary="----=_NextPart_000_00F9_01C9690E.D7652B00" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.8 required=5.0 tests=FORGED_MUA_OUTLOOK,HTML_60_70, HTML_FONTCOLOR_UNKNOWN,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 X-AOL-IP: 193.82.116.20 ------=_NextPart_000_00F9_01C9690E.D7652B00 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Gents If the signals that are fading at different frequencies are from the same so= urce, then you can determine the difference in path length from the null spa= cing. (assuming you can see signals over a wide enough bandwidth from the sa= me source to see 2 nulls at the same time .. I have observed this on DRM OF= DM signals on 7MHz, they are about 10KHz wide >From null to null in the frequency domain implies that for one frequency the= path length difference between 2 paths is n lambda + 1/2 lambda, for the ne= xt frequency the path length difference must be n+1 lambda + 1/2 lambda (If=20= we assume only 2 discrete signal paths, and that one path length is fixed..=20= groundwave and that the second path is the same physical length at both freq= uencies) then we can see that difference in path length will be equal to the= wavelength of the difference frequency. This principal is often used in com= mutating line channel combiners at UHF=20 for a single carrier, it is possible to assess the rate of change in the dif= ference of the path length. this will give a measure of ionospheric movement= . if the nulls dip every 1 minute, then at 500KHz the difference in path lengt= h is changing by 1 wavelength per minute, ie 600m / minute or 10m/s Working out exactly what is happening to make the path lengths change, or pr= oving where the reflecting layer is and how it is moving takes more observ= ations and a bit more work :<) Over the years I have been capturing meteor reflections that have Doppler sh= ift. max Doppler occurs when the meteor enters vertically perpendicular to t= he path. From the Doppler you can measure the 'relative speed' of the incomi= ng rock, and its (or at least its trails' ) deceleration.. fascinating stuff= , they don't half move fast! Mark GM4ISM ----- Original Message -----=20 From: Gary - G4WGT=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Sunday, December 28, 2008 4:21 PM Subject: RE: LF: 500KHz QSB Hi Rik & Graham, =20 Thanks for the replies. =20 All understood now, the screen shot certainly shows it up. =20 I didn't relate multi path fading to what I was seeing on the display as I= am normally used to seeing/hearing single narrow signals fading differentl= y from different sources. So I hope I am correct in saying that with the thr= ee distinct signals from the NDB the additive & subtractive properties of ea= ch multi path signal even though closely related in frequency will react so=20= noticeably differently at the receiver even from the same source. =20 I missed Grahams report on the UK500KHZ group. =20 73 =20 Gary - G4WGT. =20 ----------------------------------------------------------------------------= -- From: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@black= sheep.org] On Behalf Of Graham Sent: 28 December 2008 15:30 To: rsgb_lf_group@blacksheep.org Subject: Re: LF: 500KHz QSB =20 Gary, =20 I assume its selective fading , you can see it at 100 Hz separation at > =20 > http://groups.google.com/group/uk500khz/web/propagation =20 add the shot with a few pointers ?=20 =20 G ..=20 =20 Nb .. check out the 500 band in those day's , no mal-adjusted cw signals=20 right in the middle !=20 =20 =20 =20 From: Gary - G4WGT=20 Sent: Sunday, December 28, 2008 3:15 PM To: LF -RSGB LF Group=20 Subject: LF: 500KHz QSB =20 Hi LF, =20 Just made an interesting observation regarding QSB at 508KHz. =20 For my own benefit I have started running a slow SpecLab showing 500 to 51= 0KHz & capturing for evaluation. =20 Occasionally the NDB "Z" shows up. The strange thing is that even though t= he carrier on 508KHz & the two ID offsets at 509 & 507KHz are relatively clo= se they each display at different depth of fading or an out of phase fade pa= ttern. =20 I am unsure why this should be, any comments please, see capture at link := - =20 http://myweb.tiscali.co.uk/wgtaylor/ZNDB.jpg =20 73, =20 Gary - G4WGT - IO83QP. =20 ----------------------------------------------------------------------------= -- No virus found in this incoming message. Checked by AVG - http://www.avg.com=20 Version: 8.0.176 / Virus Database: 270.10.0/1866 - Release Date: 12/27/200= 8 20:49 ----------------------------------------------------------------------------= -- No virus found in this incoming message. Checked by AVG - http://www.avg.com=20 Version: 8.0.176 / Virus Database: 270.10.0/1866 - Release Date: 12/27/200= 8 8:49 PM ------=_NextPart_000_00F9_01C9690E.D7652B00 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Gents
If the signals that are fading at different= =20 frequencies are from the same source, then you can determine the difference=20= in=20 path length from the null spacing. (assuming you can see signals over a wide= =20 enough bandwidth from the same source  to see 2 nulls at the same=20 time .. I have observed this on DRM OFDM signals on 7MHz, they are= =20 about 10KHz wide
From null to null in the frequency domain i= mplies=20 that for one frequency the path length difference between 2 paths is n lambd= a +=20 1/2 lambda, for the next frequency the path length difference must be n= +1=20 lambda + 1/2 lambda (If we assume only 2 discrete signal paths, and=20 that one path length is fixed.. groundwave and that the second pat= h is=20 the same physical length at both frequencies) then we can see that differenc= e in=20 path length will be equal to the wavelength of the difference frequency. Thi= s=20 principal is often used in commutating line channel combiners at UHF=20
for a single carrier, it is possible to ass= ess the=20 rate of change in the difference of the path length. this will give a measur= e of=20 ionospheric movement.
if the nulls dip every 1 minute, then at 50= 0KHz the=20 difference in path length is changing by 1 wavelength per minute, ie 600m /=20 minute  or  10m/s
Working out exactly what is happening to ma= ke the=20 path lengths change, or proving where the reflecting layer is  and how=20= it=20 is moving takes  more observations and a bit more work=20 :<)
 
Over the years I have been capturing meteor= =20 reflections that have Doppler shift. max Doppler occurs when the meteor ente= rs=20 vertically perpendicular to the path. From the Doppler you can measure the=20 'relative speed' of the incoming rock, and its (or at least its trails' )=20 deceleration.. fascinating stuff,  they don't half move fast!
 
Mark GM4ISM
 
 
 
 
----- Original Message -----
Gary -=20 G4WGT
Sent: Sunday, December 28, 2008 4:2= 1=20 PM
Subject: RE: LF: 500KHz QSB

Hi=20 Rik & Graham,

 

Thanks=20 for the replies.

 

All=20 understood now, the screen shot certainly shows it=20 up.

 

I=20 didn=92t relate multi path fading to what I was seeing on the display as I= am=20 normally used to seeing/hearing single narrow signals  fading differe= ntly=20 from different sources. So I hope I am correct in saying that with the thr= ee=20 distinct signals from the NDB the additive & subtractive properties of= =20 each multi path signal even though closely related in frequency will react= so=20 noticeably differently at the receiver even from the same=20 source.

 

I=20 missed Grahams report on the UK500KHZ group.<= /P>

 

73

 

Gary=20 =96 G4WGT.

 

From: owner-rsgb_lf_group@blacksheep.org=20 [mailto:owner-rsgb_lf_group@blacksheep.org= ] On Behalf Of Graham
Sent:=20= 28 December 2008 15:30
To: rsgb_lf_group@blacksheep.org
Subject: Re:=20= LF: 500KHz=20 QSB

 

Gary,

 

I assume its selective fading ,=20 you can see it at 100 Hz separation at >

 

 

add the shot with a few pointers ?=20

 

G ..=20

 

Nb ..  check out the 500 band=20 in those day's , no mal-adjusted cw signals=20

right in the middle !=20

 

 

 

From: Gary - G4WGT=20

Sent: Sunday,=20 December 28, 2008 3:15 PM

Subject:<= SPAN style=3D"FONT-SIZE: 10pt; FONT-FAMILY: Tahoma"> LF:=20 500KHz QSB

 

Hi=20 LF,

 

Just made an=20 interesting observation regarding QSB at=20 508KHz.

 

For my own=20 benefit I have started running a slow SpecLab showing 500 to 510KHz &=20 capturing for evaluation.

 

Occasionally=20 the NDB =93Z=94 shows up. The strange thing is that even though the carrie= r on=20 508KHz & the two ID offsets at 509 & 507KHz are relatively close t= hey=20 each display at different depth of fading or an out of phase fade=20 pattern.

 

I am unsure why=20 this should be, any comments please, see capture at link=20 :-

 

http://myweb.tiscali.co= .uk/wgtaylor/ZNDB.jpg

 

73,

 

Gary - G4WGT -=20 IO83QP.

 


No virus found in this incoming=20 message.
Checked by AVG - http://www.avg.com
Version: 8.0.176 / Vir= us=20 Database: 270.10.0/1866 - Release Date: 12/27/2008=20 20:49


No virus found in this incoming message.
Checked by AVG -=20 http://www.avg.com
Version: 8.0.176 / Virus Database: 270.10.0/1866 -=20 Release Date: 12/27/2008 8:49 PM
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