On Thu, 14 Dec 2006 19:41:33 -0500, "C. J. Clegg"
wrote:


I thought I understood about critical frequencies and MUFs and such, but
an event this evening has me puzzled.

I was on a military net on a frequency somewhat above the 75-meter band.
According to the "Near Real Time F2-Layer Critical Frequency Map" at
http://solar.spacew.com/www/fof2.html, the critical frequency in this area
at that time was below 3 MHz, which would have put it WELL below our
frequency of operation. Yet, I was able to communicate with another
station about 70 miles away, with weak-but-clear (Q5 copy) both ways. And
I'm only running 5 watts (he was running 100 watts I believe).

70 miles seems a bit far for groundwave, and the critical frequency seemed
much too low for NVIS, so how was I able to communicate reliably with this
other station?


Do you know what f0F2 was at the path midpoint, or are you depending
on interpolation?

In this neck of the woods, there is abundant sporadic E, and of such
intensity that ionsondes are showing two, three and four
"reflections". How do they measure f0F2 in the presense of long
running high intensity Es that prevent rays passing through to the F2
layer?

Owen
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