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Date: Mon, 27 Mar 2017 15:08:45 -0400
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Subject: RE: LF: RE: DK7FC in Todmorden at 2970 Hz
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Hello Paul and Stefan,

I thought it would be interesting as a guide for future testing to know if path loss at 2970 Hz 100km – 1000km (a mode-sensitive combination with no validated models) is closer to the plot* that Stefan sent some months ago, or to the FDTD examples** (which show deep nulls, probably not at the exact frequencies for ionospheric and ground conditions during your tests, but indicators of the potential depths and widths of nulls at 2970 Hz, 100 km – 1000 km).

I had hoped to use the far field results (140 km, 303 km, 502 km and 881 km) to estimate path loss, but I’m not sure if Paul’s stacking process is more akin to coherent integration of the time-domain data (guessing not) or averaging in the frequency domain, or something different. Paul, is there a basic  description of your stacking process (“FFT-averaging” for example), that would enable me to convert stacked-data results to path loss? I have been calculating path loss for the results in which stacking was not used (coherently integrated data); but can’t calculate path loss for stacked-data results because I’m not sure what type of stacking is used. Can you point me in the right direction Paul?

* (based on analytic expressions using a modal approximation)
** (FDTD inherently solving for all modes)

73,

Jim AA5BW  


-----Original Message-----
From: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Paul Nicholson
Sent: Sunday, March 26, 2017 5:15 PM
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: RE: DK7FC in Todmorden at 2970 Hz


 > Does this meet the criterion that you were thinking  > of in your comments March 21st and March 22nd?

Exceeds.  About 5 sigma, exactly the right frequency, roughly the correct bearing, E and H with the expected relative phase, even the E/H ratio is about right for a distant signal (as opposed to local interference).

Now I'm trying to resolve the signal in a narrower bandwidth without stacking.

--
Paul Nicholson
--