A Selective Availability Anti-spoofing Module (SAASM) used by military Global Positioning System receivers to allow decryption of precision GPS observations, while the accuracy of civilian GPS receivers may be reduced by the United States military through Selective Availability (SA) and anti-spoofing (AS). However, on May 1, 2000 it was announced that SA was being discontinued, along with a United States Presidential Directive that no future GPS programs will include it. Before the advent of L2C, AS was meant to prevent access to dual-frequency observations to civilian users.
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| - Selective availability anti-spoofing module (en)
- 选择性有效反欺骗模块 (zh)
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| - A Selective Availability Anti-spoofing Module (SAASM) used by military Global Positioning System receivers to allow decryption of precision GPS observations, while the accuracy of civilian GPS receivers may be reduced by the United States military through Selective Availability (SA) and anti-spoofing (AS). However, on May 1, 2000 it was announced that SA was being discontinued, along with a United States Presidential Directive that no future GPS programs will include it. Before the advent of L2C, AS was meant to prevent access to dual-frequency observations to civilian users. (en)
- 选择性有效反欺骗模块(Selective Availability Anti-spoofing Module,SAASM),或称选择可用性反欺骗模块,是美国军用GPS接收机解码精密GPS观测(P码)所须的模块,而民用GPS接收机的精度可能被美国军方通过(SA)和(AS)降低。不过,SA政策已在2000年5月1日被宣布停止,并且美国总统指示未来的GPS计划不包括它。在L2C出现之前,AS旨在防止民用用户使用双频观测。 SAASM允许卫星认证、空中密钥更新和应急恢复。这些功能在类似但更早的PPS-SM系统中不可用。PPS-SM系统需要使用“红色密钥”来定期更新,该密钥仅能通过安全方式传输(例如将接收机物理性的带到一个安全设施,或者使用受信任的快递将含有新密钥的纸带递送给接收器,然后安全地销毁纸带。)SAASM系统可以使用一个加密的“黑色密钥”更新,它可以通过普通的信道传输。2006年9月底之后新部署的所有军用接收机必须使用SAASM。 SAASM不提供任何额外的抗干扰能力,但其较高的P(Y)码数据碎片率可以提供更高的处理增益,使其在干扰环境中提供更好的跟踪性能。在未来的GPS更新中,诸如M码将提供更强的抗干扰能力。 SAASM硬件覆盖有防篡改涂层,以阻止对其内部操作的分析。 (zh)
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| - A Selective Availability Anti-spoofing Module (SAASM) used by military Global Positioning System receivers to allow decryption of precision GPS observations, while the accuracy of civilian GPS receivers may be reduced by the United States military through Selective Availability (SA) and anti-spoofing (AS). However, on May 1, 2000 it was announced that SA was being discontinued, along with a United States Presidential Directive that no future GPS programs will include it. Before the advent of L2C, AS was meant to prevent access to dual-frequency observations to civilian users. SAASM allows satellite authentication, over-the-air rekeying, and contingency recovery. Those features are not available with the similar, but older, PPS-SM (Precise Positioning Service Security Module) system. PPS-SM systems require periodic updates with a classified "Red Key" that may only be transmitted by secure means (such as physically taking the receiver to a secure facility for rekeying or having a trusted courier deliver a paper tape with a new key to the receiver, after which that paper tape must be securely destroyed). SAASM systems can be updated with an encrypted "Black Key" that may be transmitted over unclassified channels. All military receivers newly deployed after the end of September 2006 must use SAASM. SAASM does not provide any additional anti-jam capability, however the higher data (chipping) rate of P(Y) code can provide a higher processing gain which will provide better tracking performance in a jamming environment. Future GPS upgrades, such as M-Code, will provide additional improvements to anti-jam capabilities. SAASM hardware is covered with an anti-tampering coating, to deter analysis of their internal operation. Deployment of the next generation military signal for GPS, called M-code, commenced with the launch of IIR-M and IIF satellites, beginning in 2005. A complete constellation of 18 satellites with M-code capability is planned for 2016. (en)
- 选择性有效反欺骗模块(Selective Availability Anti-spoofing Module,SAASM),或称选择可用性反欺骗模块,是美国军用GPS接收机解码精密GPS观测(P码)所须的模块,而民用GPS接收机的精度可能被美国军方通过(SA)和(AS)降低。不过,SA政策已在2000年5月1日被宣布停止,并且美国总统指示未来的GPS计划不包括它。在L2C出现之前,AS旨在防止民用用户使用双频观测。 SAASM允许卫星认证、空中密钥更新和应急恢复。这些功能在类似但更早的PPS-SM系统中不可用。PPS-SM系统需要使用“红色密钥”来定期更新,该密钥仅能通过安全方式传输(例如将接收机物理性的带到一个安全设施,或者使用受信任的快递将含有新密钥的纸带递送给接收器,然后安全地销毁纸带。)SAASM系统可以使用一个加密的“黑色密钥”更新,它可以通过普通的信道传输。2006年9月底之后新部署的所有军用接收机必须使用SAASM。 SAASM不提供任何额外的抗干扰能力,但其较高的P(Y)码数据碎片率可以提供更高的处理增益,使其在干扰环境中提供更好的跟踪性能。在未来的GPS更新中,诸如M码将提供更强的抗干扰能力。 SAASM硬件覆盖有防篡改涂层,以阻止对其内部操作的分析。 GPS下一代军用信号的部署被称为M码,已随IIR-M和IIF卫星的发射于2005年开始。计划在2016年完成18颗具有M码能力的卫星星座。 (zh)
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