Everyone,
The CCIR document that NM7M referred to is CCIR Report 252-2. It is
titled ?CCIR Interim Method for Estimating Sky-Wave Field Strength and
Transmission Loss at Frequencies Between the Approximate Limits of 2 and
30 MHz.? Whew! That?s a mouthful.
What it does is present the method that IONCAP uses for estimating the
median signal strength and the day-to-day variability (excess system
loss) of the median value. This excess system loss is presented in two
tables: one for paths less than 2500km and one for paths greater than
2500km. Each table is sub-divided by season, geomagnetic latitude, and
time of day (also included in this report are the tables for the
day-to-day variation of the MUF about the median value - which is used to
calculate the probability, called availability, that energy can get from
Point A to Point B - which has nothing to do with signal strength as NM7M
noted).
The absorption calculation (estimation is a better word) on page 92 of
this report shows absorption to be directly proportional to SSN, and
inversely proportional to frequency squared, elevation angle, and solar
zenith angle. Perhaps this is where the confusion lies - there is more
absorption at the peak of a solar cycle, and the MUFs are higher at the
peak of a solar cycle. But as NM7M pointed out they do not necessarily
track each other - they are two different processes at different rates -
one in the D region and one in the F region.
And I?m glad to see that IV3PRK took the time to take a look at recent
stratwarm data (regardless of the outcome). I would hope that others,
especially those who have contrary views, would test their observations
with objective data. I have the utmost respect for the observations of
W8UVZ and KL7Y, but observations by themselves can be misleading if not
challenged with objective data.
Carl K9LA
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