Re: LF: Re: 500kHz attenuation graphs?

[PETER CLEALL <peter.cleall@virgin.net>]

below are my rather vague memories, I am sure I have it archived on CD somewhere, but will not have access for several weeks. The information may still be on the web but  had a quick look and could not see it. Maybe contacting Geri direct will help.

Geri DK8KW used to have some useful charts from the time when he was trying to justify an increase in power for the German allocation. The basic curve on the chart was the equivalent of the CCIR information.Then he had the strengths of numerous European signals

regards

peter G8AFN

2009/10/31 Roger Lapthorn <rogerlapthorn@gmail.com>

Thanks Alan.

I have downloaded the GRNDWAV3 programme and am playing with it - looks useful.

Really looking for some normalised curves so I could do very quick estimates of expected losses versus distance. I've seen these years ago in a CCIR paperback and was hoping to find these on the net somewhere.

Now back to 500kHz WSPRing....

73s
Roger G3XBM

2009/10/31 Alan Melia <alan.melia@btinternet.com>

Hi Roger you will find that the late Reg Edwards programs GRNDWAV3 (I think)
gives a very good idea of ground wave strengths. I do have an article here
(somewhere) from Jack Belrose with I believe some skywave strength formula
in it. (I am "between two PCs" at the moment :-)) and it is undoubtedly on
the other one ) Generally at LF the skywave starts to equal or exceed the
groundwave strength at ranges exceeding 700km. It may be a little less that
that at 500k. It also depends a little on the receive-system senitivity to a
given mode, which is why very low power stations sometimes experience a
"quiet zone" at least to audible reception.

Alan G3NYK





----- Original Message -----
From: "Roger Lapthorn" <rogerlapthorn@gmail.com>
To: <rsgb_lf_group@blacksheep.org>
Sent: Saturday, October 31, 2009 12:28 PM
Subject: LF: 500kHz attenuation graphs?


> Can someone please point me to any CCIR or similar graphs (preferably on
the
> internet) showing the attenuation with distance expected on groundwave and
> skywave at 500kHz?
>
> 73s
> Roger G3XBM
>
> --
> -------------------------------------------------------------
> http://g3xbm-qrp.blogspot.com/
> http://www.g3xbm.co.uk
> G3XBM    GQRP 1678      ISWL G11088
>

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