Received-SPF: neutral (google.com: 193.82.116.20 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org)
From: G0MRF@aol.com
Message-ID: <cf5.113d9e9c.33db0c88@aol.com>
Date: Fri, 27 Jul 2007 04:53:28 EDT
To: rsgb_lf_group@blacksheep.org
CC: Alan.Melia@btinternet.com, g3yxm@wireless.org.uk
MIME-Version: 1.0
Subject: LF: 500  G0MRF 3 mode beacon beacon
Content-Type: multipart/alternative; boundary="-----------------------------1185526408"
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org
Status: O


-------------------------------1185526408
Content-Type: text/plain; charset="US-ASCII"
Content-Transfer-Encoding: 7bit

 
Dear all.
 
Thank you for the various reports sent direct and in messages via the  
reflector. Harmut's report from 763km is quite astounding.
 
 
The DDS driving the beacon is set to 503.700 and a quick check with a  
frequency counter confirms the frequency as 503.701 to 503.702. I've not  checked 
against an off-air standard. 
503.700 is just too high to appear on the G3YXM grabber as it's off the  edge 
of the filters. A quick retune from here shows it makes the distance most  of 
the time.
 
The beacon sends CW QRS3 and PSK31 messages.  Two local stations Dave  G3WCB 
and Derek G3HEJ have decoded the PSK and kindly sent Argo screen captures  
showing a small time period where the transmitter is generating 'artefacts' at  
harmonics of the 15.625Hz  PSK data rate.
 
Looking at the captures shows the offending period to be caused by the  
transmission of the continuous period of phase reversals just before the PSK31  
data.  These phase reversals are used to lock the receivers decoder prior  to 
sending the PSK31 message. The transmitted spectrum appears to be double  
sideband supressed carrier. - i.e. all the energy is transmitted in the  sidebands. 
Hence the 'interesting' Argo pics.  The beacon has  been sending 9 seconds of 
phase reversals followed by 14 seconds of PSK31  data.   It's currently off-air 
so I can reprogram the  microcontroller and reduce this to about 1.5 seconds, 
this will minimise the  generation of sidebands. (I'm also adding a key 
input!)
 
Output ERP is apx 2.5mW.
 
I've tried to send a URL for the beacon on a few occasions, but it seems to  
be blocked by AOL or blacksheep.  Anyway, if you know my website it's  listed 
on the index page. If you don't then it is g0mrf freeserve co uk   followed by 
500k beacon htm (a few spaces need to be removed and dots added  !)
 
 
73
 
David


-------------------------------1185526408
Content-Type: text/html; charset="US-ASCII"
Content-Transfer-Encoding: quoted-printable

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=3DContent-Type content=3D"text/html; charset=3DUS-ASCII">
<META content=3D"MSHTML 6.00.2800.1491" name=3DGENERATOR></HEAD>
<BODY id=3Drole_body style=3D"FONT-SIZE: 10pt; COLOR: #000000; FONT-FAMILY:=20=
Arial"=20
bottomMargin=3D7 leftMargin=3D7 topMargin=3D7 rightMargin=3D7><FONT id=3Drol=
e_document=20
face=3DArial color=3D#000000 size=3D2>
<DIV>&nbsp;=20
<DIV>Dear all.</DIV>
<DIV>&nbsp;</DIV>
<DIV>Thank you for the various reports sent direct and in messages via the=20
reflector. Harmut's report from 763km is quite astounding.</DIV>
<DIV>&nbsp;</DIV>
<DIV>&nbsp;</DIV>
<DIV>The&nbsp;DDS driving the beacon is set to 503.700 and a quick check wit=
h a=20
frequency counter&nbsp;confirms the frequency as 503.701 to 503.702. I've no=
t=20
checked against an off-air standard. </DIV>
<DIV>503.700 is just too high to appear on the G3YXM grabber as it's off the=
=20
edge of the filters. A quick retune from here shows it makes the distance mo=
st=20
of the time.</DIV>
<DIV>&nbsp;</DIV>
<DIV>The beacon sends CW QRS3 and PSK31 messages.&nbsp; Two local stations D=
ave=20
G3WCB and Derek G3HEJ have decoded the PSK and kindly sent Argo screen captu=
res=20
showing a small time period where the transmitter is generating 'artefacts'=20=
at=20
harmonics of the 15.625Hz &nbsp;PSK data rate.</DIV>
<DIV>&nbsp;</DIV>
<DIV>Looking at the captures shows the offending period to be caused by the=20
transmission of the continuous period of phase reversals just before the PSK=
31=20
data.&nbsp; These phase reversals are used to lock the receivers decoder pri=
or=20
to sending the PSK31 message. The transmitted spectrum appears to be double=20
sideband supressed carrier. - i.e. all the energy is transmitted in the=20
sidebands.&nbsp;Hence the 'interesting' Argo pics.&nbsp;&nbsp;The beacon has=
=20
been sending 9 seconds of phase reversals followed by 14 seconds of PSK31=20
data.&nbsp;&nbsp; It's currently off-air so I&nbsp;can reprogram the=20
microcontroller and reduce this to about 1.5 seconds, this will minimise the=
=20
generation of sidebands. (I'm also adding a key input!)</DIV>
<DIV>&nbsp;</DIV>
<DIV>Output&nbsp;ERP is apx 2.5mW.</DIV>
<DIV>&nbsp;</DIV>
<DIV>I've tried to send a URL for the beacon on a few occasions, but it seem=
s to=20
be blocked by AOL or blacksheep.&nbsp; Anyway, if you know my website it's=20
listed on the index page. If you don't then it is g0mrf freeserve co uk&nbsp=
;=20
followed by 500k beacon htm (a few spaces need to be removed and dots added=20
!)</DIV>
<DIV>&nbsp;</DIV>
<DIV>&nbsp;</DIV>
<DIV>73</DIV>
<DIV>&nbsp;</DIV>
<DIV>David</DIV></DIV></FONT>   </BODY></HTML>

-------------------------------1185526408--