Gamma ISP: Reference Manual

ORB_prop_SLC

NAME
ORB_prop_SLC -Calculate additional state vectors using orbit propagation and interpolation

SYNOPSIS
ORB_prop_SLC <SLC_par> [nstate] [interval] [extra] <mode>

<SLC_par>	ISP image parameter file
[nstate]	number of state vectors to calculate (enter - for a value determined from the duration of the existing state vectors)
[interval]	time interval between state vectors (default: input state vector time interval)
[extra]	extra time for state vector coverage at start and end of image (default= 30.0 s.)
<mode>	orbit propagation mode: 0: polynomial interpolation (default, if 3 or more state vectors available) 1: integration of the equations of motion (default, if less than 3 state vectors available) 2: polynomial interpolation between state vectors, minimum of 3 state vectors; integration of the equations of motion outside of the time span of the existing state vectors

EXAMPLE
ORB_prop_SLC 05263.slc.par - 10. 30. 2

obtain state vectors at 10 second intervals, extending 30 seconds before and after the existing state vectors using the combined propagation method. The number of state vectors is determined by the program based on the image duration.

DESCRIPTION
ORB_prop_SLC calculates additional state vectors given at least one state vector in the ISP image parameter file. This program is useful in generating state vectors that extend outside of the image bounds that are required for geocoding applications. New state vectors are calculated by polynomial interpolation if there are more than 1 existing state vector. If there is only one state vector, then the new state vectors are generated by iintegration of Newton's equation of motion.

The mode parameter has several options including interpolation only (mode 0), integration of the equations of motion only (mode 1), or a combined mode (mode 2). In the combined mode, interpolation is used between the existing state vectors and propagation outside the existing interval. This method is recommended if the new set of state vectors extends more than a few seconds ouside of the input state vector data because the polynomial interpolation function diverges strongly from the orbital track outside the region constrained by the state vectors.