Expected Improvement in NIMA Precise Orbit and Clock Estimates Due to Adding Crosslink Ranging Data
Abstract
With the deployment of GPS Block HR and IIF satellites, crosslink data will be collected and used on-board for navigation. This motivated an effort to investigate the expected orbit and clock accuracy if crosslink data are available for post-processing on the ground. This study addresses the expected improvement in the National Imagery and Mapping Agency (NIMA) precise orbit and clock estimates with the inclusion of crosslink ranging data with the station tracking data. Simulated station data were created to reflect orbit and clock accuracy associated with NIMA production. Station tracking data were simulated for both 12- and 18-station networks covering 5 days to allow for three overlapping 3-day fit spans, with the middle day of each fit span used for analysis. Simulated crosslink ranging data, including pseudorange data, derived distance data, and derived clock data, were generated for the same 5 days and merged with the station data. Initially, a study was conducted to determine what satellite-related clock and crosslink bias parameters can be estimated with crosslink data types by themselves or in combination with station tracking data. Experiments were then conducted to investigate the characteristics and relative information content of the crosslink data types, including appropriate treatment and statistical assumptions for the crosslink biases. The sensitivity of precise orbit and clock estimates to various processing scenarios was also evaluated. Finally, the overall achievable orbit and clock accuracy through incorporating the crosslink data with station data was quantified. Analysis revealed that the inclusion of crosslink data with station data is equivalent to the inclusion of additional stations. In particular, the low noise levels associated with the derived clock observations will improve the quality of the precise clock estimates.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1999
- Accession Number
- ADA477548
Entities
People
- Everett R. Swift
- Michael J. Merrigan
Organizations
- Naval Surface Warfare Center