Exporting Two Line Element Sets
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In addition to providing the capability to import TLE files, FreeFlyer allows the user to export SGP4 states from the TwoLineElement, TLECatalog, Spacecraft, and Formation objects.
TwoLineElement and TLECatalog
The SGP4StateEstimator owns a TwoLineElement object called TLEHandler. Once the SGP4 state is generated from the SGP4StateEstimator, the user is able to modify certain properties of the TLEHandler in order to write out the data in the TLE format. For example, assuming that an SGP4StateEstimator object has a valid SGP4 state, the following syntax generates a TLE file containing a single SGP4 state of the ISS:
In addition to writing to a file, the SGP4 state can be written to a pair of String objects (one for each line in the two-line element set):
The TLECatalog object allows the user to export a collection of TwoLineElement objects to a file via the TLECatalog.WriteToFile method:
Spacecraft and Formation
The TwoLineElement and TLECatalog objects can also be used to write the state of a Spacecraft or Formation object to a TLE file. Once the user has initialized the TwoLineElement or TLECatalog from a Spacecraft or Formation, the WriteToFile method is used to export the TLE.
To write a Spacecraft state to a TLE file using a TwoLineElement object, the following syntax can be used:
A similar technique can be used with a Formation object and the TLECatalog obejct:
•TwoLineElement Properties and Methods
•TLECatalog Properties and Methods
•SGP4StateEstimator Properties and Methods