Re: Annual Blips
Between 4 and 1000 spikes detected by Aricebo are persistent. If they are alien transmissions they would likely have orbital ephemerides for our planet, are currently tracking us, perhaps even directly imaging Earth. They are far more advanced than us, or at least much older. The remaining 2.5 billion spikes might be periodic, meaning they do not have ephemerides for Earth, and may be in the early stages of their own SETI programs.
http://setiathome.ssl.berkeley.edu/process_page/