Military GPS receivers can use a Selective Availability Anti-Spoofing Module (SAASM) to enable decryption of precise positioning data. Selective Availability (SA) refers to a now-defunct practice by the U.S. government to degrade the civil signal to prevent full accuracy. Since May 1, 2000, Selective Availability has not been operational.
However, Anti-spoofing (AS) is still applied to the military signal to guard against fake transmissions of satellite data—by encrypting the P-code to form the Y-code. Authorized Precise Positioning Service (PPS) receivers acquire and track the Y-code by using the SAASM security architecture. Test and evaluation of PPS receiver functions requires SAASM-capable simulation equipment.
Spirent’s SimSAAS enables authorized users of the GSS9000 to test all elements of SAASM receivers, as well as the ability to change the system security clearance requirement via removable hard drive. SimSAAS has been granted Space and Missile Systems Center Security Approval for classified military applications.