Message-ID: <238E2B3E35364E1090A6A3F982A5CF98@AGB>
From: "Graham" <g8fzk@g8fzk.fsnet.co.uk>
To: <rsgb_lf_group@blacksheep.org>
References: <4FDDE3C9.8080505@iup.uni-heidelberg.de> <15B9C0CD09D4429B83AB1E02595502AD@JimPC>
In-Reply-To: <15B9C0CD09D4429B83AB1E02595502AD@JimPC>
Date: Sun, 17 Jun 2012 23:01:10 +0100
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Subject: Re: LF: Re: Further MF impressions
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''But G4WGT and G0NBD'', //   ''is over hilly, lower conductivity ground.''
Steady on Jim , your  'not'  suggesting  Gary  and myself  are  'over the 
hill'  !!

We  did  have  on the  uk500khz  site , the  beacon  plots , that  where 
produced  by  Andy and  Gary,  using the   G3PLX  software  and  a  Tx 
timing  cct  from Andy (G4JNT)

I think  theses  are  still   saved in zip  files , or   we  may still  have 
them saved, these showed  quite  nicely  the  path  changes over  time  and 
the  noise level  variations ,

Quite a  change  to  when 'we'  first  came  on 500  with  micro erp levels 
and  no  dedicated software !

Unless you have  quite  reasonable  power levels  and  antenna systems , 
other  than  local  qso , plain  CW is  not really  a option on 500 , 
luckily with  the  recent developments, narrow  data  communications  will 
be possible for  all.

73 -G..



--------------------------------------------------
From: "James Moritz" <james.moritz@btopenworld.com>
Sent: Sunday, June 17, 2012 9:06 PM
To: <rsgb_lf_group@blacksheep.org>
Subject: LF: Re: Further MF impressions

> Dear Stefan, LF Group,
>
>> I just thought my receiver isn't working correctly. I thought the xtal 
>> does not start to oscillate due to the higher ambient temperatures in the 
>> afternoon. But later i found that the band noise on MF is significantly 
>> lower than in the evening, at least 20 dB.
>
> As well as the natural band noise being lower at MF (I estimate the noise 
> FS is about 10dB lower), there is also not the constant presence of 
> man-made noise, such as Loran and DCF39 sidebands. So the spectrum around 
> 500kHz does sound much quieter, especially during daytime.
>>
>> What do others know about the ground wave range in summer and in the 
>> afternoon? When does the band open? Similar to LF?
>
> As others have said, broadly similar to LF - sky wave is very weak until 
> darkness has arrived, so ground wave dominates daytime communication. 
> Ground wave signal levels seem to depend greatly on the type of ground at 
> distances more than 100km or so. For example I can easily hear G3KEV 
> during the daytime here,  and the path from Hatfield to Scarborough is 
> over flat, high-conductivity ground down the east of England. But G4WGT 
> and G0NBD, and stations in Wales, are extremely weak in daylight at 
> similar distances, although they are quite strong after dark The ground 
> path to these stations is over hilly, lower conductivity ground.
>
> Sky wave signals over fairly long distances show very deep fading over 
> periods of a few minutes - signal levels are usually constantly changing, 
> and I have often seen variation of over 30dB in one minute on beacon 
> signals. This can make QSOs difficult, with a signal that was R5 suddenly 
> disappearing completely and not even visible on the spectrogram. Over very 
> long distances, trans-atlantic for example, the fading seems less severe 
> although signals are usually quite weak and propagation is very variable.
>
> For contacts around Europe, I would say 136k actually gives more reliable 
> signal levels, but for many stations 500k is easier because higher ERP can 
> be achieved with a small antenna, and noise levels are often lower.
>
> Cheers, Jim Moritz
> 73 de M0BMU
>