Selective Availability


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Selective Availability

A function in the GPS navigation system that deliberately introduced random errors for civilian GPS receivers. It was implemented to prevent enemy troops on foreign soil from using the GPS system to their advantage, while allowing friendly troops to obtain the true signals in GPS receivers that supported military encryption. Selective Availability (SA) was temporarily disabled in the Gulf War, because so many U.S. troops were using consumer-grade GPS receivers, and SA was disabled permanently in 2000.

Because of the lack of accuracy for the consumer market, ground-based augmentation systems were created to correct the discrepancies. See GPS augmentation system.
References in periodicals archive ?
6 in March 1996, and culminated with the elimination of selective availability in May 2000.
Research was conducted with and without selective availability.
Under the contract, Trimble will incorporate Selective Availability Anti-Spoofing Module (SAASM) capability into its TASMAN(TM) ARINC-12 (TA-12) Global Positioning System (GPS) navigation receiver and maintain Federal Aviation Administration (FAA) approval to Technical Standard Order (TSO) C-129a.
This so-called Selective Availability (SA) could be filtered from the signal for authorized users to provide full accuracy.
In addition, the impact of setting Selective Availability (SA) to zero within the next 10 years is addressed from the perspective of its impact on both L5 and DGPS.
Manufacturers of GPS-based navigational aids, however, maintain that so-called Selective Availability civil devices cannot be adapted to guide weapons.
After several brief experimental periods, the Defense Department activated its data-degrading system, called selective availability (SA), on a full-time basis in March.
The Trimble M7 GPS-S is a Selective Availability Anti-Spoofing Module (SAASM) compliant GPS system with Global Navigation Satellite System (GNSS) capability.
But the Polaris devices do not have the military encryption known as the Selective Availability Anti-Spoofing Module.
Selective Availability Anti-Spoofing Module technology allows the DAGR to function much more effectively in an electronic warfare environment than its predecessor, the Precision Lightweight GPS Receiver, and much better than current commercial GPS receivers.
Both missiles were equipped with the Interstate Electronics (L-3 Communications subsidiary) Selective Availability Anti-Spoofing Module (Sassm)-based GPS TruTrak receiver, which provides precise measurement to the onboard computer, even in a hostile jamming environment.

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