Sharing the 2m antenna... (APRS and AIS) IF this is the case, then... Hope suitable design and testing went on before the launch.

Even if two separate antennas are used, they might heavily interfere with each other on the same band. And if hundreds of AIS ship customers are beaconing through the sat, then the APRS system might be deafened by same band, close frequency interference. Maybe the reason why lots of RF power is required to work this sat on APRS.

Repeater builders know this...

http://www.repeater-builder.com/projects/2m-dup/dupfig13.jpg

http://www.repeater-builder.com/projects/2m-duplexer.html

One other solution might be to alternate the systems on and off. Thus no interference takes place system to system. If this is the case, then we simply do not know the APRS "on" schedule. It could be off over NA today and on again over NA tomorrow.

Where can we find better guidance ?

KC9SGV

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On Apr 12, 2019, at 10:19 AM, KC9SGV kc9sgv@gmail.com wrote:

If they use one antenna for both AIS and APRS... (APRS was added as an afterthought, completed in six days, just a box, no antenna, no battery, no power panels.) If this is the case, AIS has thousands of ships all trying to work the antenna automatically. There are only a few hams trying to work APRS through the same antenna per pass. Without proper diplexing, how would this system not be blind to APRS ? AIS is ~160 MHz for ship to shore connections. Not sure what the sat connection freq would be for AIS. Maybe it is time for AMSAT India and Exseedspace to inform us hams here ?

KC9SGV

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