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RE: LF: RE: DK7FC in Todmorden at 2970 Hz

To: <[email protected]>
Subject: RE: LF: RE: DK7FC in Todmorden at 2970 Hz
From: <[email protected]>
Date: Mon, 27 Mar 2017 15:08:45 -0400
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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)


Jim AA5BW  

-----Original Message-----
From: [email protected] 
[mailto:[email protected]] On Behalf Of Paul Nicholson
Sent: Sunday, March 26, 2017 5:15 PM
To: [email protected]
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

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