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From: "Peter Martinez" <peter.martinez@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
References: <PAEFLMFGBDKKCONLMLBIKEOMCFAA.ganymede444@btopenworld.com> <01cd01c63d73$69bc4f80$0300a8c0@LAPTOP> <4407287F.8000306@freenet.de>
Date: Thu, 2 Mar 2006 17:57:11 -0000
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Subject: Re: LF: LORAN spurious emission levels
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Status: O

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