State vector and TLE - Averaging the State vector for Precise Orbital Elements

[goodvettri]

I have a set of State vectors (x,y,z , vx,vy,vz).
With Single Epoch value , i have written a program to convert the state vector to TLE (with algorithm given in Vallado book).
The same matches to some extend with STK orbital para generated with Single Epoch values.
Stk also generates the orbital parameters with multiple values .

Please let me know how to use all the state vector sets to compute more accurate orbital elements .

Also please let me know , how to generate the Bstar Drag Term in the first line of the TLE

 

[boogabooga]

I am not sure that I understand the question, but I will refer you here:
https://celestrak.com/columns/v04n05/index.asp#FAQ05
http://www.orbiter-forum.com/showthread.php?p=506757&postcount=27

The elements given in the TLE are mean elements meant to be used with a specific model, not instantaneous elements. I assume that is why STK or whatever is using multiple epochs to generate "TLEs". You would have to go into details of the SGP4/SDP4 model to see how to handle it. You can find that here: https://celestrak.com/NORAD/documentation/spacetrk.pdf

For the Bstar drag term, you need to know the coefficient of drag, which is a property of the satellite itself and not any instantaneous state vector. I assume that this can be found by watching the satellite for some period of time and noticing how much its orbit decays. But you have to assume no maneuvers, constant attitude, etc.

 

[goodvettri]

Dear boogabooga,

Thank you so much for the immediate reply...I have referred those links sent by you...
I have used the SGP4 model to calculate sat position from TLE ..
Also i have written program to calculate instantaneous elements from single observation (pos,vel) and its output is validated.
But now i want to calculate the mean elements with the set of observations...Can you tell the logic behind how to compute it and how to code the same please...