Message-ID: <000c01bed375$edbbe120$c996b38f@w8k3f0>
From: "Dick Rollema" <d.w.rollema@gironet.nl>
To: "LF-Group" <rsgb_lf_group@blacksheep.org>
Subject: LF: Re: A help with rx sensitivity ??
Date: Wed, 21 Jul 1999 14:37:44 +0200
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Alan, G3NYK wrote:

>Mike G3XDV, mentioned using DCF39 as a standard signal for comparing aerial
>performance, in a previous exchange which culminated in the fascinating
>article and results reported by Dick PA0SE. This has just surfaced again
for
>me as I have had another packet contact with F5MLP. As you may remember he
>has erected a 300m wire in anticipation of getting a permit for 136. He is
>disappointed in its performance, and has sent a bull round the packet
>network asking for other stations reading of the strength of DCF39.
>
>It occurs to me that this is a fairly meaningless quest unless the stations
>replying are really 'switched-on' to LF aerial tuning and performance. It
>also occurs to me that a definitive list of measurements on the station
from
>different locations might form a useful guide to newcommer's to the band
> as well as lazy old ones like me!)
>I don't want to clog the reflector with what many might regard as junk, so
I
>am suggesting that I am willing to collect and collate (via e-mail to my
>personal address below) any reports that you would like to send to me
>direct.
>As a guide may I suggest :-
>Call    Locator  Aerial  Receiver  (S-meter )   DCF39   DCF39      noise
>level
>                                              Calibration)    (day)
(after
>dark) (quiet day)
>There is a lot of room for discussion on what is important and what is not,
>but maybe this could serve as a basis to collect some guidance data.
>I know we think that there is not much difference in the day and night
>signal from the station, but does everybody find it so? As for the s-meter
>calibration I am thinking of something like 'S-9 = 50uV' or something
>similar. If the formula that Dick refers to does work we should be able to
>work out the field strength at any location in the reception area of DCF39.
>Qualifying comments accepted, if you care to add them.
>
>When I have collected a reasonable number of reports I will post the
results
>as a digest to the reflector for all to see.
>I hope you will see this as a worthwhile exercise and deluge me with
>reports!
>73 de Alan G3NYK
>Alan.Melia@btinternet.com


I don't think this is a reliable method.  I have measured the field strength
of DCF39 at my location as reported  in my e-mail of 15-7-99  15.28.

The power of DCF39, as deduced from the field strength was unlikely high.

In a telephone call Gamal Soegiono pointed out that the signal I received
from DCF39 was not only by ground wave but also by skywave. I had not
expected this because the day to day variation of the signal, as measured by
my selective level meter, is very small, less than 1 dB. At least during
daytime; after dark the variations become much larger.

Gamal Soegiono's remark is supported by Vaino, OH2LX. He has professionally
measured the signal of DCF39 for more than 10 years, 24 hrs a day,  at a
location 1545 km from DCF39. The graphs Vaino has sent me show large
variations from day tot day and also over the 24 hrs of a day.
I will be happy to send the graphs to anyone interested with a direct e-mail
as the reflector does not accept messages with attachments of large size.

So near DCF39, where the skywave is very weak as compared o the ground wave,
the DCF39 signal could probably be used as a kind of yardstick. But al large
distances, and I suppose that applies to the UK, one should be careful in
interpreting the results.

I   am  also compiling the interesting info Vaino has given me into a single
e-mail without attachments. You will receive that via the reflector one of
the coming days.

73, Dick, PA0SE
JO22GD
D.W. Rollema
V.d. Marckstraat 5
2352 RA Leiderdorp
Tel. +31 71 589 27 34
E-mail: d.w.rollema@gironet.nl