"FAA Primary En Route Long Range Radar Restructuring Program
The FAA currently uses and supports 126 primary en route radar
facilities. The FAA is chartered to provide Primary radar services to
all federal agencies requiring this data to meet their operational
missions."
http://www.faa.gov/asd/ia-or/longrangeradar.htm

With whom does the FAA share radar? I would understand the military,
but that's about it. My impression is that weather radar works with
different frequencies and uses doppler. So with whom does the FAA
share radar information?

-Charles Talleyrand