[SADXA] July SADXA Presentation Abstract on Tucson/Heard Island Gray-Lilne Propagation Study

[W7EXG (Bill)]

To: SADXA Members
FROM: Bill W7EXG
RE: Tucson/Heard-Island Gray-line study Presentation - Part 1

Over the past 3 Months, I have studied extensively Gray-line Propagation,
and especially as it relates to the Tucson / Heard Island Observations. 

Unfortunately, this is NOT a LOW BAND Gray-line discussion, since I am
unaware of any Tucson-Heard 160m or 80m signal data to study. Perhaps the
mire absence of low band data may be of value. However, I am convinced that
many of the lessons learned on the observed 40m, 30m, 20m, and 17m Gray-line
signals, can be applied to the low band cases. 

I plan to present part 1 of this study in our July Meeting. 

PRESENTATION REPORT: 
Gray-line Propagation: Lessons Learned from the Tucson / Heard-Island
Experience -- PART 1 of 2 Parts

WHEN: July 21, 2016
WHERE: SADXA Meeting
DURATION: ~ 45 min / 15 min Q&A

WHO: Bill Davis -- Licensed as W7EXG in 1956
Bill is an Electrical Engineer, having retired from Motorola - after working
30 years, as an Analog IC Design Engineer / Manager. Bill was a Senior
Member of the Motorola's Technical Staff.  

ABSTRACT - PART 1

	This study was motivated by Gray-line Observations of signals
between Tucson and the Heard-Island DXpedition, by several SADXA members.
These Observations appeared to challenge or modify both past and current
definitions and descriptions of Gray-Line Propagation. 
	After a brief review of such definitions and descriptions, an
observed 40m Long Signal Path is shown as an interesting example of oddity.
Starting at night 2500 mi from the Sunset Terminator, this signal traveled
3600 mi in DARK, then about 10,200 miles in daylight, 1700 mi and 2.5 hours
from the Sunrise Terminator. This signal path defied some Gray-line
definitions such as "Near or Along the Edge of Terminator", or "requires
Simultaneous Sunrise and Sunset"...etc.  
	Twenty Signal Observations were gathered by 6 members of the SADXA
group, and were compiled as AM / PM, Long Path / Short Path, Band, and Date.
Six example Timelines are shown for both AM and PM Observations. The Impact
of the Kp Solar Indices is discussed, during these observations. 
Eleven questions were raised regarding these observations, such as WHY:  ALL
propagation was AFTER Sunrise/Sunset?; NO AM Short Path or 40m Short Path
propagation?; 40m Long Path observed before 30m long path? Or, how does a
40m signal travel over 10,000 mi in the DAY regions, 1700 mi from sunrise
terminator? 
	A Review of Day/Night Ionospheric Layers is discussed, including
Day/Night Band Use and Limitations. The concepts and importance of EMUF and
MUF on Gray-line propagation are also discussed. 
A review of electron charge distribution for each layer is shown over
Day/Night Period, including Sunrise and Sunset.  
The important of the EMUF at Sunrise / Sunset is shown to be a critical
factor in defining Gray-line geographic widths, using a mid band signal as
example. 
	EMUF is defined in terms of the Critical E Frequency (foE).
Ionsosndes (Vertical Soundings) foE Data is shown at Sunrise, from a Mid
Latitude ionosonses Observatory. This foE data supports and explains the 40m
Long Path propagation cited above. The E-Layer electron density and
Rise/Decay time of foE is considered critical in defining Low/Mid band
Gary-line geographic width and propagation. The foE data also demonstrates
ionization in Twilight region, prior to Sunrise.
	MUF is defined in terms of the Critical F Frequency (foF2). Using
foF2 Data, World Color (MUF) Maps are shown for specific Tucson-Heard
Propagation dates, and times. Long or Short Signal Paths are superimposed on
these MUF maps as a function of time,  which explains the observed timeline
delays and durations, as well as the viability of Long or Short Paths for AM
and PM propagation. 
	Finally, the 11 questions raised by the Tucson-Heard Observation
data are reviewed and answered based on the preceding discussion. 

Part 2 presentation is planned, during September SADXA meeting. There is
actually much more to say, such as ionization in the DARK region at Sunrise,
effects of E and D-Absorption, Solar Indices effects, Band dependant
Propagation Corridors, and Daily, Seasonal and Annual Angular World
Coverage... etc.  

Best 73s, 

Bill W7EXG