[HamWAN PSDR] HamWAN portable

Tom Hayward esarfl at gmail.com
Sat Oct 5 09:41:56 PDT 2013

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!).


More information about the PSDR mailing list