John B. Stephensen wrote:

Galileo transmits on 1260-1300 MHz and 1215-1300 MHz is now allocated to global positioning systems (up to 5 of them). Amateur transmissions can desense the earth-based receivers. Tests on U.S. GPS receivers showed that a 1W EIRP CW signal 10 km away would cause inteference. It would be better if 1260-1270 MHz was a downlink for amateur satellites.

73,

John KD6OZH

John,

You are neglecting real word conditions...future civilian airborne GPS/GNSS/Galileo receiver systems are going to have to incorporate anti-jam capabilities. A few do already and changes in the signal coding for the new civilian GPS downlink will have a much more robust capability when it comes to interference rejection. I also believe Galileo will too employ a more jam resistant signal waveform.

There are much greater threats to these systems than ham operators from a real-world technical perspective. However, I will concede that government agencies may eliminate amateur use of L-Band for political reasons...an easy, but meaningless way for them to show they are taking action.

However, until and if the hammer comes down, there are currently no strong technical reasons to eliminate L-Band uplinks.

Bruce