Session
Session X: The Smaller Elements
Abstract
Paramount to any satellite mission is the acquisition of accurate vehicle position and velocity information at any particular point in time. With several satellite tracking and propagation methods available, the use of the Two-Line Elements (TLEs) supplied by the North American Aerospace Defense Command (NORAD) in conjunction with the Simplified General Perturbations Satellite Orbit Model 4 (SGP4) is considered the most popular choice for many low-Earth missions. This is primarily due to the fact that the SGP4 algorithm is open-source and that the TLEs are readily available to the public. Furthermore, they are updated on a fairly consistent – albeit infrequent – basis. If a particular mission requires more stringent accuracy than the SGP4 model can provide, an on-board GPS receiver is often a natural choice. GPS receivers can provide much greater orbital position knowledge at the cost of consuming relatively large amounts of power. This paper describes a technique for increasing orbital determination accuracy through the SGP4 model using a GPS receiver for intermittent orbital information, complemented with a TLE from the most recent epoch. The goal is to increase the precision of the estimates obtained from SGP4 with an effort to minimize the duty cycle required by an onboard GPS receiver. This propagation technique is primarily geared towards nanosatellite-scaled missions with regards to stringent power and antenna pointing requirements.
Presentation Slides
Increasing the Accuracy of Orbital Position Information from NORAD SGP4 Using Intermittent GPS Readings
Paramount to any satellite mission is the acquisition of accurate vehicle position and velocity information at any particular point in time. With several satellite tracking and propagation methods available, the use of the Two-Line Elements (TLEs) supplied by the North American Aerospace Defense Command (NORAD) in conjunction with the Simplified General Perturbations Satellite Orbit Model 4 (SGP4) is considered the most popular choice for many low-Earth missions. This is primarily due to the fact that the SGP4 algorithm is open-source and that the TLEs are readily available to the public. Furthermore, they are updated on a fairly consistent – albeit infrequent – basis. If a particular mission requires more stringent accuracy than the SGP4 model can provide, an on-board GPS receiver is often a natural choice. GPS receivers can provide much greater orbital position knowledge at the cost of consuming relatively large amounts of power. This paper describes a technique for increasing orbital determination accuracy through the SGP4 model using a GPS receiver for intermittent orbital information, complemented with a TLE from the most recent epoch. The goal is to increase the precision of the estimates obtained from SGP4 with an effort to minimize the duty cycle required by an onboard GPS receiver. This propagation technique is primarily geared towards nanosatellite-scaled missions with regards to stringent power and antenna pointing requirements.
