[HamWAN PSDR] HamWAN portable

Allen KE7IQQ at comcast.net
Sat Oct 5 18:09:57 PDT 2013

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?

  ----- Original Message ----- 
  From: Patrick Barthelow 
  To: Puget Sound Data Ring ; esarfl at gmail.com ; Patrick Barthelow ; 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> wrote:

    On Sat, Oct 5, 2013 at 9:26 AM, Jeff Francis™ <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

  Best,   Pat Barthelow 
  apolloeme at gmail.com

  Google Lunar X prize Team, SYNERGY MOON  
  pat.barthelow at synergymoon.com  


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