15 the us government does not directly monitor or

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Unformatted text preview: tions and Constraints ≤ 6 meters RMS SIS SPS URE • Average of the constellation’s individual satellite across the entire constellation SPS SIS RMS URE values over any 24-hour interval, for any point within the service volume The U.S. Government does not intend to impose range rate or range acceleration errors on the SPS signal. The U.S. Government’s commitments for maintaining PDOP (Table 3-2) and constellation SPS SIS URE (Table 3-5) result in support for position and time transfer accuracy standards as presented in Table 3-6. These accuracy standards were established based on the worst two of 24 satellites being removed from the constellation and a 6-meter constellation RMS SIS URE. Page 14 October, 2001 GPS SPS Performance Standard Table 3-6. Positioning and Timing Accuracy Standard Accuracy Standard Conditions and Constraints Global Average Positioning Domain • Defined for position solution meeting the Accuracy representative user conditions • Standard based on a measurement interval of 24 • ≤ 13 meters 95% All-in-View hours averaged over all points within the service Horizontal Error (SIS Only) volume • ≤ 22 meters 95% All-in-View Vertical Error (SIS Only) Worst Site Positioning Domain • Defined for position solution meeting the Accuracy representative user conditions • Standard based on a measurement interval of 24 • ≤ 36 meters 95% All-in-View hours for any point within the service volume Horizontal Error (SIS Only) • ≤ 77 meters 95% All-in-View Vertical Error (SIS Only) Time Transfer Accuracy • Defined for time transfer solution meeting the representative user conditions • ≤ 40 nanoseconds time transfer • Standard based on a measurement interval of 24 error 95% of time (SIS Only) hours averaged over all points within the service volume 3.5 GPS Status and Problem Reporting Standard The U.S. Government provides notification of changes in constellation operational status that affect the service being provided to GPS users, or if the U.S. Government anticipates a problem in supporting performance standards established in this document. The current mechanism for accomplishing this notification is through the Notice: Advisory to Navigation Users (NANU). NANUs are a primary input in the generation of GPS-related Notice to Airmen (NOTAM) and U.S. Coast Guard Local Notice to Mariners (LNM). Most outages affect both PPS and SPS users. However, since the GPS Control Segment currently monitors PPS, not SPS, in near real-time, notification of SPS unique service disruptions may be delayed. Since NANUs are currently tailored to PPS outages, notification of SPS unique outages may require the use of the general “free text” NANU vice a tailored template. In the case of a scheduled event affecting service provided to GPS users, the U.S. Government will issue an appropriate NANU at least 48 hours prior to the event. In the case of an unscheduled outage or problem, notification will be provided as soon as possible after the...
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This document was uploaded on 09/26/2013.

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