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From: "Alan Melia" <alan.melia@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
References: <PAEFLMFGBDKKCONLMLBIKEOMCFAA.ganymede444@btopenworld.com> <01cd01c63d73$69bc4f80$0300a8c0@LAPTOP> <4407287F.8000306@freenet.de> <029801c63e22$bb20b190$0300a8c0@LAPTOP>
Date: Thu, 2 Mar 2006 19:53:41 -0000
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Subject: Re: LF: LORAN spurious emission levels
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Peter have you looked at the "megapulse" web site for power levels. ERPs may
be calculatable if we know the mast heights....these may be available
elsewhere.
http://www.megapulse.com/chaininfo.html

Lessay and Sylt are quoted as 250kW, there are even powers for the western
Chayka system ! Exact locations are also given.

Also at a lot of locations you will receive signals from more than one
station maybe from different chains....will this affect you calculations? or
the sensitivity idea. I suppose there will generally be one main site, the
nearest, which will predominate ?
----- Original Message -----
From: Peter Martinez <peter.martinez@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
Sent: 02 March 2006 17:57
Subject: Re: LF: LORAN spurious emission levels


> Wolf:
>
> That would be another way to get a calibration, so long as we also knew
the
> emrp of DCF39. If you are close enough to receive surface wave from DCF39
> and surface wave from Sylt, then a ratio of the DCF39 carrier level to the
> level of a typical Sylt LORAN line (at midday) could be used to give the
> emrp of the LORAN line. WE can estimate the path loss from the distance
> within a few dB so long as the both paths are over similar type of ground.
>
> But Dave G0MRF also sent me a nice spreadsheet of some measurements which
> were made at Rugby when the LORAN transmitter was installed. This is a
> record of the classic USCG measurement to confirm that only 1% of the
energy
> is outside 90-110kHz. This spreadsheet seems to be a chart of the readings
> of a spectrum analyser which is changed in 2kHz steps between 70 and
130kHz,
> measuring the levels in a narrow bandwidth (<2kHz?) from an
antenna-current
> monitoring point. From this I can apply an F-squared factor to calculate
the
> power spectral density. I have to guess the shape of the curve from 130kHz
> to 136kHz.
>
> This tells me (if I did it right) that the spectral density at 136kHz is
> about 47.5dB down on the spectral density at 100kHz. The problem now is
that
> I don't know how to convert this to the mean level of a single spectral
> line - I need to know the relationship between the published power of the
> transmitter (presumably the peak pulse emrp) and the spectral density
(mean
> power/kHz) at 100kHz.
>
> Anyone have any ideas?  Maybe this can be measured off-air, or we can
figure
> it out from published info.
>
> 73
> Peter G3PLX
>
>