The donut hole is a problem... With two more APRS satellites to launch this year, we need -more- Omni Satgates with *lower* antennas. The vertical omni 1/4 or 3/4 wave satgate vertical antenna needs to be as low as possible (to minimize the donut hole null and to reduce lightening risk) while still seeing sky above 30 degrees.
See: http://aprs.org/aprs-satellite-igate-antennas.html
Once I deliver the last of these next two transponders, I hope to build such a satgate with a D7 HT and document its performance. I can place the HT at the base of the antenna with near zero coax, and being low, it is not vulnerable to lightening compared to surrounding structures.
Bob, WB4APR
-----Original Message----- From: AMSAT-BB [mailto:[email protected]] On Behalf Of [email protected] Sent: Sunday, June 28, 2015 10:02 AM To: [email protected] Subject: [amsat-bb] the donut effect
Is there anyway to get any APRS client to not Igate a packet with a path of ARISS in it. I run a satgate here in NJ and the donut effect is causing problems for several hams in the area that can't get a packet Igated after it is digi'd by the ISS because it's a dup. My Igate hears the first packet direct that then causes the ISS digi'd packet to be a dup. It would seem to be a simple thing to set a filter to ignore a path of ARISS, and accept everything else. I would think that this would fix the problem of people who want to run Igates, but don't because of this. I recently moved to Florida for the winter and had to shut my igate down in NJ for this reason. Also, I noticed when down there that there is a lack of satgates along the eastcoast. ISS,PSAT, and PCSAT are hearing stations fine but no satgate's available until the bird's footprint move well inland.
73 Jeff kb2m
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