Jun.-Prof. Dr. Dominik Brodowski, LL.M. (UPenn)

The SGP, SGP8 and SDP8 models for prediction of satellite position and velocity - Turbo Pascal routines

Five mathematical models for prediction of satellite position and velocity using NORAD "two-line-elements" are available: SGP, SGP4, SDP4, SGP8 and SDP8. USSPACECOM currently uses the SGP4 routines for near-earth satellites, and SDP4 for deep-space satellites.

The NORAD SGP4/SDP4 Units for Turbo Pascal by Dr TS Kelso make these currently used models available for further use (http://www.celestrak.com). Nevertheless the SGP model is of historical importance and -because of its great speed- suitable for certain applications. Additionally, Turbo Pascal units for the SGP8 and SDP8 models prepare program users for an update of USSPACECOM routines to these more advanced procedures.

Because of these reasons, I have written Turbo Pascal procedures for the SGP, SGP8 and SDP8 models. In order to use them, you aditionally need the SGP4/SDP4 Units for Tubro Pascal by Dr TS Kelso - available at http://www.celestrak.com.

A complete description of the SGP, SGP4, SDP4, SGP8 and SDP8 models can be found on http://www.celestrak.com.

Downloads

All rights reserved.

I, Dominik Brodowski, make no representations or warranties about the suitability of the turbo pascal units and programs, either express or implied, including but not limited to the fitness for a particular purbose, or non-infringement. I shall not be liable for any damages suffered in any way as a result of downloading, using, modifying or distributing these Turbo Pascal units and programs or their derivatives.

SGP

  • sgp.pas Contains the SGP core procedure (sgp0) and the SGP call procedure (sgp0call) which replaces the "sgp" procedure in the SGP4/SDP4 units by Dr TS Kelso. (4 KB)
  • sgptest.pas The test routine described in Spacetrack Report No. 3 for the SGP model. (2 KB)

SGP8 and SDP8

  • sgp8sdp8.pas Contains the SGP8 core procedure (sgp8), the SDP8 core procedures (sdp8) and the SGP call procedure (sgp8call) which replaces the "sgp" procedure in the SGP4/SDP4 unit by Dr TS Kelso. (42 KB) [update: 2005/03/20]
  • sgp8test.pas The test routine described in Spacetrack Report No. 3 for the SGP8 and the SDP8 model. (2 KB)

Bug reports, patches

Feel free to report any bugs. Patches will be included in the source code for future releases if I consider them useful. You can reach me at mail@brodo.de.

Acknowledgements

  • Spacetrack Report No. 3 - Models for Propagation of NORAD Element Sets. Felix R. Hoots, Ronald L. Roehrich, TS Kelso. December 1988. Available at http://www.celestrak.com
  • NORAD SGP4/SDP4 Units developed by Col. Dr. TS Kelso. Available at http://www.celestrak.com
  • Bugfix by Christopher Moore