Re: LF: Re: 500kHz attenuation graphs?

[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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