[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.


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
>         _______________________________________________
>         PSDR mailing list
>         PSDR at hamwan.org <mailto:PSDR at hamwan.org>
>         http://mail.hamwan.org/mailman/listinfo/psdr_hamwan.org
>     -- 
>     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>
>     ------------------------------------------------------------------------
>     _______________________________________________
>     PSDR mailing list
>     PSDR at hamwan.org
>     http://mail.hamwan.org/mailman/listinfo/psdr_hamwan.org
> _______________________________________________
> PSDR mailing list
> PSDR at hamwan.org
> http://mail.hamwan.org/mailman/listinfo/psdr_hamwan.org

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.hamwan.net/pipermail/psdr/attachments/20131005/324c6e89/attachment.html>

More information about the PSDR mailing list