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Re: LF: Re: 500 Khz - QSO

To: <[email protected]>
Subject: Re: LF: Re: 500 Khz - QSO
From: "Graham" <[email protected]>
Date: Sat, 3 Sep 2011 17:52:12 +0100
Importance: Normal
In-reply-to: <9443BF673E7A4E51BBF052ADEA904B4C@JimPC>
References: <001201cc6a48$c8123dd0$0401a8c0@xphd97xgq27nyf> <20110903152500.2cbf2a9e@svr1> <9443BF673E7A4E51BBF052ADEA904B4C@JimPC>
Reply-to: [email protected]
Sender: [email protected]

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" <[email protected]>
Sent: Saturday, September 03, 2011 5:33 PM
To: <[email protected]>
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






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