Vdop for local vertical pdop for all three

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Unformatted text preview: GEC is equal to Ωk when the argument of latitude (Φ) is zero. Mean Down Time (MDT): A measure of time required to restore function after any downing event. Mean Time Between Downing Events (MTBDE): A measure of time between any downing events. Page B-1 October 2001 GPS SPS Performance Standard Mean Time Between Failures (MTBF): A measure of time between unscheduled downing events. Mean Time to Restore (MTTR): A measure of time required to restore function after an unscheduled downing event. Navigation Message: Data contained in each satellite's ranging signal and consisting of the ranging signal time-of-transmission, the transmitting satellite's orbital elements, an almanac containing abbreviated orbital element information to support satellite selection, ranging measurement correction information, and status flags. The message structure is described in Section 2.1.2 of the SPS Performance Standard. Operational Satellite: A GPS satellite which is capable of, but is not necessarily transmitting a usable ranging signal. PDOP Availability: Defined to be the percentage of time over any 24-hour interval that the PDOP value is less than or equal to its threshold for any point within the service volume. Positioning Accuracy: Defined to be the statistical difference, at a 95% probability, between position measurements and a surveyed benchmark for any point within the service volume over any 24-hour interval. • Horizontal Positioning Accuracy: Defined to be the statistical difference, at a 95% probability, between horizontal position measurements and a surveyed benchmark for any point within the service volume over any 24-hour interval. • Vertical Positioning Accuracy: Defined to be the statistical difference, at a 95% probability, between vertical position measurements and a surveyed benchmark for any point within the service volume over any 24-hour interval. Position Solution: An estimate of a user’s location derived from ranging signal measurements and navigation data from GPS. Position Solution Geometry: The set of direction cosines that define the instantaneous relationship of each satellite's ranging signal vector to each of the position solution coordinate axes. See DILUTION OF PRECISION. Pseudo Random Noise (PRN): A binary sequence that appears to be random over a specified time interval unless the shift register configuration and initial conditions for generating the sequence are known. Each satellite generates a unique PRN sequence that is effectively uncorrelated (orthogonal) to any other satellite’s code over the integration time constant of a receiver’s code tracking loop. Representative SPS Receiver: The minimum signal reception and processing assumptions employed by the U.S. Government to characterize SPS performance in accordance with performance standards defined in Section 3 of the SPS Performance Standard. Representative SPS receiver capability assumptions are identified in Section 2.2 of the SPS Performance Standard. Right Ascension of Ascend...
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