[HamWAN PSDR] HamWAN portable
Bart Kus
me at bartk.us
Sat Oct 5 19:41:14 PDT 2013
We don't have good data on trees. We should certainly develop some.
How much attenuation does a trunk of X diameter present? Is there a
variation between trees? How does it scale with diameter? What about
branches/needles? I can tell you that I shoot through trees about a
mile away, but the fresnel zone helps me out there. I can also tell you
that rain affects me, but not because of the rain itself! On a clear
shot with rain, there's hardly any signal degradation. It's the fact
that the rain coats the trees in a film of water, and that seems to be
the killer of signal. In my case, I think I lose about 8dB, but we
don't have good data on this either. It's gonna take a while to build
it since we don't control the weather...yet. :)
Where are you located? We can do a path analysis and see if we can help
you do a site survey.
--Bart
On 10/5/2013 6:09 PM, Allen wrote:
> So looking at that profile I see a small rise close by that is
> probably less than my tower. But I have a lot of fir and ceder all
> around me that are higher than the tower. How well will 5ghz pass
> through the fir and cedar?
> 73,
> Allen
>
> ----- Original Message -----
> *From:* Patrick Barthelow <mailto:apolloeme at gmail.com>
> *To:* Puget Sound Data Ring <mailto:psdr at hamwan.org> ;
> esarfl at gmail.com <mailto:esarfl at gmail.com> ; Patrick Barthelow
> <mailto:apolloeme at gmail.com> ; jeff at gritch.org
> <mailto:jeff at gritch.org>
> *Sent:* Saturday, October 05, 2013 10:38 AM
> *Subject:* Re: [HamWAN PSDR] HamWAN portable
>
> Hello Guys,
>
> I have been following the threads from the eaves here, with
> interest, because I do/have done this intervisibility/path loss
> kind of stuff a lot. I recently discovered a very powerful
> program that can assist in this pursuit. Check out:
> http://www.heywhatsthat.com . This program will construct, file
> and store a skyline horizon from any location on the planet,
> looking in any direction. And it will identify nearby
> intervening terrain peaks. It will answer questions such as
> range, and elevations, intervisibility profile plots, bearings,
> distances, fresnel zones, path loss, etc.. Make your viewshed
> maps, and file them, in a library of such, on-line, or send them
> to your colleagues.
> . Try it out. Enjoy..
>
> Best, 73, Pat
>
>
>
> On Sat, Oct 5, 2013 at 9:41 AM, Tom Hayward <esarfl at gmail.com
> <mailto:esarfl at gmail.com>> wrote:
>
> On Sat, Oct 5, 2013 at 9:26 AM, Jeff Francis^(TM)
> <jeff at gritch.org <mailto:jeff at gritch.org>> wrote:
> > http://plane.gritch.org/plane/tn/2013-09-08%2014.18.42.jpg.html
> >
> > If you look in the back of the truck, you can see
> precisely the same
> > antenna setup that Tom is using laying on top of the spare
> tire (next to the
> > stool). From the park, I was close enough I just propped
> the antenna up and
> > did it that way. No need for the tripod (and the strange
> looks from other
> > park-goers).
>
> From that photo, I can tell you that it won't work. You're
> aimed at
> the sky. The beamwidth of these dishes is very narrow and they
> must be
> aimed precisely in both azimuth and elevation.
>
> Here's my algorithm for aiming:
> - First, I calculate the bearing from my current location to a
> HamWAN
> site (your APRS client should be able to do this for you with the
> HamWAN* objects).
> - Then I sight that bearing with my compass.
> - With the Poynting on the tripod mast, I sight down the
> feedhorn of
> the Poynting and line it up with the same landmark I spotted
> with the
> compass, being sure to keep the feedhorn level in the
> elevation axis.
> - At this point the signal LEDs on the modem have usually
> registered
> something (I'm connected) and I can pan and tilt slightly in each
> directly to maximize signal.
>
> This works really well for me because I have a sighting compass
> accurate to 1 degree and I know how to use it. Another
> technique is to
> plot the path on Google Earth and look for landmarks along the
> path.
> I've done this and sighted "between the two water towers." This
> technique requires more patience and panning.
>
> This is microwave. It's a lot harder to get a signal than VHF, but
> it's really satisfying when you do (and faster than 1200 baud!).
>
> Tom KD7LXL
>
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>
>
>
>
> --
> Best, Pat Barthelow
> apolloeme at gmail.com <mailto:apolloeme at gmail.com>
>
> Google Lunar X prize Team, SYNERGY MOON
> wwww.synergymoon.com <http://wwww.synergymoon.com>
> pat.barthelow at synergymoon.com <mailto:pat.barthelow at synergymoon.com>
>
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