Selective Availability (Sa) - Leica GR10 Operational Manual

Operational Manual (Online Help)

Selective Availability (SA)

The policy and procedure of denying to most nonmilitary GPS users the full accuracy of the system. SA is achieved by dithering
the satellite clock (delta-process) and degrading the navigation message ephemeris (epsilon-process). Currently SA primarily
uses the delta-process. The effects can be removed with encryption keys or through DGPS techniques.
442