Message-ID: <20100121213644.sbqj435ce8k8w0cs@webmail6.kuleuven.be>
Date: Thu, 21 Jan 2010 21:36:44 +0100
From: Rik Strobbe <Rik.Strobbe@fys.kuleuven.be>
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>,
        Roger
	Lapthorn <rogerlapthorn@gmail.com>
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	<20100121104239.E3CDE31E702@smtps01.kuleuven.be>
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Subject: Re: LF: about guns, water pistols and dripping tabs
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Hello Roger,

path lengths (earth surface):
G3XBM: 337km
G3ZJO: 411km
G4JNT: 420km
But I assume that at night time it is ionospheric propagation, where =20
the path loss is mainly determined by attenuation and reflection loss =20
in the ionosphere.

When using daytime (groundwave) signals one would indeed need to take =20
the distance (and terrain) into account.

For ionospheric propagation the take-off angle of the antenna is also =20
important. A low take-off angle will give better signals at long =20
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 =20
some dB's (although far less than 100dB).

It would be interesting to do the same exercise for other RX stations, =20
the "raw data" are available at wsprnet.org ...

73, Rik  ON7YD - OR7T

Quoting Roger Lapthorn <rogerlapthorn@gmail.com>:

> Hi Rik,
>
> This is most interesting. I notice that M0BMU was running with 50mW  =20
> ERP last night, so it might be worth plugging in his reports as well =20
>  for last night. My ERP was based on (a) field strength measurements =20
>  done some time ago by M0BMU and (b) calculations based on my  =20
> estimate of effective height and antenna current. I estimated it as  =20
> being in the region of 500uW to 2mW but Jim seemed to believe the  =20
> 1mW ERP was a fair estimate with quite large error margins. It would =20
>  be interesting to know if M0BMU still believes the 1mW ERP is a  =20
> correct figure. I have not made any further improvements since Jim's =20
>  last estimates some 6-8 weeks ago.
>
> What is the path length difference between us all over to you? That  =20
> will also have some effect on the relative levels.
>
> BTW, Dom Baines M1KTA quoted something interesting to me today:  =20
> "Terman's Radio Engineering Handbook (1948)
> stated the maximum working distance for 1 kW 500kHz over salt water  =20
> was 1,500 miles!". So, I need to up my power then!
>
> 73s
> Roger G3XBM
>
>
>
>
> 2010/1/21 Rik Strobbe  =20
> <rik.strobbe@fys.kuleuven.be<mailto:rik.strobbe@fys.kuleuven.be>>
> Eddie, Andy, Roger, all,
>
> the nice thing about WSPR and the www.wspr.org<http://www.wspr.org/> =20
>  web site is that a lot af data is available.
> I copied the my spots (past 7 days) of G4JNT, G3XBM and G3ZJO from  =20
> the web site and threw them in the mill to check how often I copied  =20
>  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  =20
> is 1 hop ionospheric and small differences in distance are less  =20
> important.
>
> * G3XBM - G3ZJO: 6 'hits', average difference =3D 8dB (in favor of Roger=
)
> 6 data sets is a bit low to to proper statistics, but the difference =20
>  of 8dB between Roger and Eddie fits well into the claimed ERP's =20
> (1mW  and 200uW =3D 7dB)
>
> * G4JNT - G3XBM : 60 'hits', average difference =3D 15dB (in favor of An=
dy)
> 15dB difference would mean that if Roger's 1mW ERP is correct that  =20
> Andy would run "only" 30mW ERP ?
> But the standard dev. is 6dB, so it could be (a more realistic)  =20
> 120mW as well ...
>
> * G4JNT - G3ZJO: 6 'hits', average difference =3D 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, =20
>  my QRPp 200uW ERP is on..
>
> 73
>
> Eddie G3ZJO
>
> -----Original Message-----
> From:  =20
> owner-rsgb_lf_group@blacksheep.org<mailto:owner-rsgb_lf_group@blacksheep=
.org> [ mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Andy  =20
> Talbot
> Sent: 20 January 2010 22:01
> To: rsgb_lf_group@blacksheep.org<mailto:rsgb_lf_group@blacksheep.org>
> 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 <bvgbob@hotmail.com<mailto:bvgbob@hotmail.com>>
> 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
> ________________________________
> Windows 7: Kter=FD po=E8=EDta=E8 je pro v=E1s ten prav=FD? Dal=B9=ED  =
=20
> informace.<http://windows.microsoft.com/shop>
>
>
> No virus found in this incoming message.
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>
>
> --
>
> http://g3xbm-qrp.blogspot.com/
> http://www.g3xbm.co.uk
> http://www.youtube.com/user/G3XBM
> G3XBM    GQRP 1678      ISWL G11088
>