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From: "Graham" <g8fzk@g8fzk.fsnet.co.uk>
To: <rsgb_lf_group@blacksheep.org>
References: <001201cc6a48$c8123dd0$0401a8c0@xphd97xgq27nyf> <20110903152500.2cbf2a9e@svr1> <9443BF673E7A4E51BBF052ADEA904B4C@JimPC>
In-Reply-To: <9443BF673E7A4E51BBF052ADEA904B4C@JimPC>
Date: Sat, 3 Sep 2011 17:52:12 +0100
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Subject: Re: LF: Re: 500 Khz - QSO
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Yes  that's the  problem  Jim,  from this  side,  Mal's  over the  hill ...

I can  acquire   mf-2  lock  with  round  35/50 watts  carrier  power 
during
the  day to  John, but  need  round  150/180   for the  path  to Delft

Unfortunately , I think , due  to  Ae  modifications this  qth ,  my Rx
noise  level  is  very  high  to  the  point of  reducing Rx  s/n
considerably . so  any  comparisons  are  marred  at the  moment

Last  night  it  was  not  till  nearly  midnight , I decoded John's  wspr
tx  beacon ..

2011-09-02 23:42   GM4SLV   0.503859   -26   0   IP90gg   0.5   G0NBD 
IO83lk   766   188
 2011-09-02 23:32   GM4SLV   0.503869   -24   0   IP90gg   0.5   G0NBD 
IO83lk   766   188

Yes  nothing  during  these  decodes  , 25  miles  to  my  east , unless 
there  is fringing
at play ?

2011-09-02 22:46   GM4SLV   0.503852   -8   0   IP90gg   0.5   G4WGT 
IO83qo   745   186
 2011-09-02 22:34   GM4SLV   0.503852   -16   0   IP90gg   0.5   G4WGT 
IO83qo   745   186


--------------------------------------------------
From: "James Moritz" <james.moritz@btopenworld.com>
Sent: Saturday, September 03, 2011 5:33 PM
To: <rsgb_lf_group@blacksheep.org>
Subject: LF: Re: 500 Khz - QSO

>
> Dear John, LF Group,
>
>> Good signals in daytime - steady with little QSB, but some QRN just
>> starting to build. The sea-path down the East Coast must help
>> enormously!
>
> Looking at the map, the path Shetland - Scarborough is almost entirely 
> over the sea, while Shetland - Lancashire/Cheshire is about 50% over the 
> rocky ground of Scotland and NW England. Looking at the ITU ground loss 
> curves for 500kHz, and applying the "Millington Method" for the 
> appropriate distances and ground conductivities comes up with something 
> like 30dB less signal at G0NBD/G4WGT compared with G3KEV, even though the 
> distance is similar. This is easily enough to make the difference between 
> an audible signal and one that would require long integration periods on a 
> spectrogram to detect. It might be interesting one day for you to try 
> transmitting slow QRSS signals during daytime ground-wave conditions, and 
> see if your signals are detectable at inland and western UK locations to 
> make a comparison with east-coast locations.
>
> Cheers, Jim Moritz
> 73 de M0BMU
>
>