Hello Roger,
path lengths (earth surface):
G3XBM: 337km
G3ZJO: 411km
G4JNT: 420km
But I assume that at night time it is ionospheric propagation, where
the path loss is mainly determined by attenuation and reflection loss
in the ionosphere.
When using daytime (groundwave) signals one would indeed need to take
the distance (and terrain) into account.
For ionospheric propagation the take-off angle of the antenna is also
important. A low take-off angle will give better signals at long
distance and might give the impression of low ERP at short distance.
So, as said in my previous mail: all figures given are give or take
some dB's (although far less than 100dB).
It would be interesting to do the same exercise for other RX stations,
the "raw data" are available at wsprnet.org ...
73, Rik ON7YD - OR7T
Quoting Roger Lapthorn <[email protected]>:
Hi Rik,
This is most interesting. I notice that M0BMU was running with 50mW
ERP last night, so it might be worth plugging in his reports as well
for last night. My ERP was based on (a) field strength measurements
done some time ago by M0BMU and (b) calculations based on my
estimate of effective height and antenna current. I estimated it as
being in the region of 500uW to 2mW but Jim seemed to believe the
1mW ERP was a fair estimate with quite large error margins. It would
be interesting to know if M0BMU still believes the 1mW ERP is a
correct figure. I have not made any further improvements since Jim's
last estimates some 6-8 weeks ago.
What is the path length difference between us all over to you? That
will also have some effect on the relative levels.
BTW, Dom Baines M1KTA quoted something interesting to me today:
"Terman's Radio Engineering Handbook (1948)
stated the maximum working distance for 1 kW 500kHz over salt water
was 1,500 miles!". So, I need to up my power then!
73s
Roger G3XBM
2010/1/21 Rik Strobbe
<[email protected]<mailto:[email protected]>>
Eddie, Andy, Roger, all,
the nice thing about WSPR and the www.wspr.org<http://www.wspr.org/>
web site is that a lot af data is available.
I copied the my spots (past 7 days) of G4JNT, G3XBM and G3ZJO from
the web site and threw them in the mill to check how often I copied
at least 2 of the 3 calls in the same time slot:
I took only the night time spots as I assume that propagation then
is 1 hop ionospheric and small differences in distance are less
important.
* G3XBM - G3ZJO: 6 'hits', average difference = 8dB (in favor of Roger)
6 data sets is a bit low to to proper statistics, but the difference
of 8dB between Roger and Eddie fits well into the claimed ERP's
(1mW and 200uW = 7dB)
* G4JNT - G3XBM : 60 'hits', average difference = 15dB (in favor of Andy)
15dB difference would mean that if Roger's 1mW ERP is correct that
Andy would run "only" 30mW ERP ?
But the standard dev. is 6dB, so it could be (a more realistic)
120mW as well ...
* G4JNT - G3ZJO: 6 'hits', average difference = 23dB (in favor of Andy)
Nice, this is the sum of the previous values (as iit should be ;-) )
All values are give or take some dB, but they seem to make sense.
73, Rik ON7YD - OR7T
At 23:14 20/01/2010, you wrote:
Yeh ! Congratulations Roger.
Lubos you have the Water Pistol, can you now RX a tiny Dripping Tap,
my QRPp 200uW ERP is on..
73
Eddie G3ZJO
-----Original Message-----
From:
[email protected]<mailto:[email protected]> [ mailto:[email protected]] On Behalf Of Andy
Talbot
Sent: 20 January 2010 22:01
To: [email protected]<mailto:[email protected]>
Subject: Re: LF: G3XBM
Congratulations, "water pistol"
1200km - a very comfortable margin too.
Andy
www.g4jnt.com<http://www.g4jnt.com>
2010/1/20 Lubos OK2BVG <[email protected]<mailto:[email protected]>>
Hello Roger, LF!
This moment is just now:
2136 -7 0.2 0.503874 0 G4JNT IO90 23
2142 -29 -0.5 0.503910 1 G3XBM JO02 0
Congratulation!
Lubos, OK2BVG, JN88KS
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