Troposcatter & ducting
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A random observation...
There is troposcatter and then there is tropospheric ducting, which is what most VHF+ ops from east of the continental divide (and some west coasters) are familiar with, when 2M and above 'opens' over paths exceeding 3-400 miles.
While troposcatter is a useable propagating mode most anywhere and accountable for a good majority of those 300 mile Q's on 10M and above, tropo ducting is another animal altogether and rarely appears in areas of drastically variable terrain like central and western Colorado. The temperature inversions that often (always ??) cause ducting to occur are usually at low enough elevations that they are blocked by high terrain. Plus, inversions go hand in hand with atmospheric moisture content, something hard to come by in the dry southwest. My current humidity here in DM58 is 15%, which actually is high for this time of year.
On Fri, Sep 13, 2019, 3:08 PM James Duffey <JamesDuffey@...> wrote:
I was referring to the Olathe-Amarillo path. Tropo losses rise steeply beyond 300 miles. Six and two are not too different with respect to the plot below. Meteor scatter starts to overcome tropo at about 350 miles, depending on station capability. WSJT-X helps, but at those distances MSK144 is probably better than FT8 or FT4 for that path. Typical modest station capability on 2M is about 200dB, less on 6M roughly by the difference in antenna gains.