SPS Performance 2001

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Unformatted text preview: llites 25-32, Special Messages, Satellite Configuration Flags, and Ionospheric and UTC Data Frame Pages 1-25 Almanac and Health Data for Satellites 1-24 and Almanac Reference Pages 1-25 Time and Week Number Figure 2-1. Navigation Message Content and Format Overview 2.2 Usage Assumptions for SPS Performance Standards Operational SPS performance standards do not take into consideration any error source that is not under direct control of GPS constellation operations, such as: • Ionosphere single-frequency model error • Troposphere model error • Signal reception interference, to include scintillation • Receiver thermal noise • Multipath Since not all SPS receiver designs are within the purview of the U.S. Government, this document makes certain minimum assumptions concerning receiver characteristics and usage. These assumptions establish a frame of reference for deriving SPS operational performance standards. Two generic types of SPS users are discussed in this section: navigation users and time transfer users. Whenever a receiver is discussed without mentioning one type of user or the other, the statement applies to representative receivers for both types of users. This document assumes the use of a representative SPS receiver that: • is designed in accordance with ICD-GPS-200C. • is tracking all satellites in view above a 5° mask angle with respect to the local horizon (no local obscura are considered). It is assumed the receiver is operating in a nominal noise environment that does not interrupt receiver acquisition and tracking capabilities. Page 8 October, 2001 GPS SPS Performance Standard • accomplishes satellite position and geometric range computations in the most current realization of the World Geodetic System 1984 (WGS 84) Earth-Centered, Earth-Fixed (ECEF) coordinate system. • generates a position and time solution from data broadcast by all satellites in view. • compensates for dynamic Doppler shift effects on nominal SPS ranging signal carrier phase and C/A code measurements. • reads the health field and status bits in the navigation message and excludes unhealthy satellites from the position solution. • ensures the use of up-to-date and internally consistent ephemeris and clock data for all satellites it is using in its position solution. • loses track in the event a GPS satellite stops transmitting C/A code. • is operating at a surveyed location (for a time transfer receiver). Page 9 October, 2001 GPS SPS Performance Standard (INTENTIONALLY BLANK) Page 10 October 2001 GPS SPS Performance Standard SECTION 3 GPS SPS Performance Standards This section establishes SPS performance standards for GPS operations. The U.S. Government is committed to operating GPS in accordance with these standards, in a manner consistent with system capabilities and subject to budgetary constraints. The U.S. Government reserves the right to adjust GPS constellation management practices as necessary to support military and civil en...
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This document was uploaded on 09/26/2013.

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