Re: Troposcatter & ducting

James Duffey
 

Yes, tropoducting is almost unheard of in the Southwest. Of course, we don’t get the tropical storms either.

James Duffey KK6MC
Cedar Crest NM

On Sep 13, 2019, at 15:35, Steve London <n2ic@...> wrote:

Last week, there were several -days- of 2 meter propagation between Mississippi and Ontario/Western NY, to the west of Dorian. Eat your heart out.

73,
Steve, N2IC

On 09/13/2019 03:29 PM, Keith Morehouse wrote:
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.
-W9RM
Keith Morehouse
via MotoG
On Fri, Sep 13, 2019, 3:08 PM James Duffey <JamesDuffey@... <mailto: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.
The difference in large part is due to the height of the scattering media;
for troposatter it is about 35,000 ft or below, for meteor scatter is it 60
miles or so. - Duffey
James Duffey KK6MC
Cedar Crest NM
> On Sep 13, 2019, at 13:42, Steve London <n2ic@...
<mailto:n2ic@...>> wrote:
>
> Albuquerque-to-Amarillo: 269 miles. Once you get over the Sandia's, it's
a mostly downhill-to-flat path.
>
> Olathe-to-Amarillo: 410 miles.
>
> For reference, My QTH in DM52XT to Santa Fe is 240 miles. Can work W7QQ
on 6 and 2.
>
> 73,
> Steve, N2IC
>
>> On 09/13/2019 10:29 AM, Arne N7KA wrote:
>> I am hearing him and decoding.
>> Arne N7KA
>>> On September 13, 2019 at 10:20 AM Ed <n5jeh@...
<mailto:n5jeh@...>> wrote:
>>>
>>> MSK 144 would work better for that distance with no other propagation
to help. Just MHO
>>>
>>> Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for
Windows 10
>>>
>>> *ED N5JEH DM65RD *
>>>
>>> *From: *Arne N7KA <mailto:N7KA@... <mailto:N7KA@...>>
>>> *Sent: *Friday, September 13, 2019 8:52 AM
>>> *To: *NMVHF <mailto:nmvhf@groups.io <mailto:nmvhf@groups.io>>
>>> *Subject: *[nmvhf] DM95
>>>
>>> I copied N5KS on 6M FT8 yesterday with good sigs -8 to -14. I am
trying to work him for new 6M grid and sent him an email about looking this
way and into Olathe during the contest this weeked. He is in Amarillo. N5EPA might have a good chance, possibly W7QQ.
>>>
>>> Arne N7KA
>>>
>
>
>

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