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Topband: Spot Light Effects...

To: "Tom Rauch" <w8ji@contesting.com>, <Topband@contesting.com>,<160m@mailman.qth.net>
Subject: Topband: Spot Light Effects...
From: "Ford Peterson" <ford@cmgate.com>
Date: Mon, 3 Jan 2005 10:01:02 -0600
List-post: <mailto:topband@contesting.com>
>From Tom-W8JI's comment on the beacon thread:

...SNIP...

> I wonder is a lot of the "search light" effect is really
> just normal small or modest level increases. I wish I could
> record absolute signal levels over a long period of time,
> but I can't.
> 
> 73 Tom

Tom, and others...

I have been following the 'beacon' thread for some weeks now.  It's interesting 
to observe (it would be more interesting to participate) but the distances to 
MN are a waste of time at such low levels.  In my view, the close-in path of 
very low level signals is not very interesting.  I have NO problem working 
anyone within 1000 miles of here, even at QRP levels.  So the scientific nature 
of these close-in paths is not extremely interesting to this op.

What is of interest is the so-called spot light effects on longer paths, of 
which I am a firm believer, but fail to understand the physics.  There are 
loads of speculations but little 'proof' and even considerable numbers of 
people that believe these effects to be nothing short of fairy tale--pure 
randomness.  I have worked enough 160M contests to know that NFL/WCF/FL in 
general is a difficult path to MN for some reason.  I can also demonstrate from 
numerous logs on different weekends that the MN/SC, MN/FL, MN/AL, MN/MS, MN/LA 
(and others) can be a similar difficult path.  Nothing in the log and then 
suddenly 3 or 4 stations (or more) from a single section will appear 
consecutively with good signal strength--never to be heard from again the 
entire night.  Weird and too coincidental to simply dismiss as a fairy tale.

For the last couple of weeks, I have been investigating an experiment to 
attempt to document what is happening in hopes of solidifying the nature of the 
physics.  While contest logs are somewhat interesting, they only document 
completed QSOs.  My 'experiment' involves a beacon running all night.  Special 
software would be utilized to allow receiving stations to set and forget the 
project rest of the night.  The software would listen and document the S-Meter 
reading on the radio throughout the evening--posting an average reading to a 
data file every few seconds perhaps?  A file transfer the next day via email 
would permit a cumulative database of these 'reports.'

The point Tom makes about variations in antenna patterns, and equipment 
sensitivity, makes the results only relative from station-to-station.  Absolute 
levels are not necessarily comparable at all.  But with enough reports, I 
believe a series of maps could be developed that performs some average 
results--perhaps by using grid squares--over the course of an entire 
evening--for the entire continent.  By orchestrating different beacon locations 
on different nights, and coordinating the reporting efforts from a central 
clearing house, I believe the maps could serve to illustrate the effectiveness 
of that path through the entire period of darkness.

Power level would be set at the beacon to facilitate a reliable path but remain 
well within the AGC range of most distant radios  (100W maybe? 50W? 25W? 10W?)  
I don't know yet.  Perhaps the software can track many beacons all at once?  
E.g. a beacon in CT, SC, GA, SFL, TX, MO, MN, AZ, CO, WA, CA all on the same 
night but a different frequency for each.  The software at each receiving 
station would be programmed to QSY to each frequency in sequence, document the 
SMeter reading and QSY to the next.  Tens of Thousands of data points 
throughout the evening from hundreds of reporting stations would document the 
various paths over time and in unison.  The resulting database would be large, 
but easily managed using any beefy computer.  A summary of paths could then be 
placed on a grid map to document the path condition to each beacon--perhaps 
using color to identify relative intensity of the signals.  Correlating these 
results to propagation conditions throughout the evening.  Documenting 6M or 
10M conditions simultaneously may prove interesting as well, but increases the 
complexity of the project substantially.

I have contacted Alex-VE3NEA (the DX Atlas guy) and discussed the project and 
am waiting for his educated advice on the matter.  I've worked with Alex before 
on software projects--he's a magician with software.  He may be too consumed 
with his other projects (like Peter I) to take this on.  But perhaps others 
would like to give it a shot?  I think it would be a worthwhile effort as long 
as whoever acts as the clearing house of the data is willing to also share the 
resulting data collected.  If I am the clearing house, I can assure all that 
the data would be available to all who participate--and only those that 
participate (an incentive to participate).

Ford-N0FP
ford@cmgate.com



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