RETRAN ESTIMATION OF ORBITAL PARAMETERS AND TRACKING SYSTEM BIASES.
Abstract
RETRAN (Refined Trajectory Analysis) is a computer program for determining optimum minimum variance estimates of spacecraft orbital parameters in use at the Real Time Computer Facility at ETR. This program is an adaptation of the GLAD (Glotrac Adjustment) program developed at the Technical Laboratory and is programmed primarily in FORTRAN (a few subroutines in COMPASS) for use on a CDC 3600, large scale, general-purpose computer. RETRAN is a multi-station orbit estimation program and can accept data from radar (A, E, R) and Azusa (l, m, R) systems, to a maximum of 30 origins. Using a Cowell trajectory generator, computer data are produced for times at which observed data occur. The computer data are corrected for the effects of refraction and signal travel time, and additive, multiplicative, rate and time biases. The Cowell trajectory generator produces a computer trajectory by integrating the equations of motion using Runga-Kutta-Gill or Adams-Moulton numerical integration techniques. The equations of motion consist of accelerations due to the earth's gravity field and drag. The non-spherical earth gravity field can be simulated with zonal and tesseral harmonics through the fifteenth degree and order. Drag perturbations are computed based on density and speed of sound profiles obtained from a static reference atmosphere. Residuals are calculated by substracting the computed from the observed data. These residuals are then entered into a minimum variance adjustment with numerically computed partial derivaties and either input or computed standard deviations of measurements.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1967
- Accession Number
- AD0814383
Entities
People
- James A. Ward Jr.