The Downlink Adjacent Interference for Low Earth Orbiting (LEO) Search and Rescue Satellites
DOI: 10.4236/ijcns.2010.32016   PDF    HTML     6,172 Downloads   11,649 Views   Citations


NOAA (National Oceanic and Atmospheric Administration) - LEO environmental satellites provide continuous coverage of Earth, supplying high-resolution global meteorological, oceanic and space observation data. In addition, these satellites are part of the international COSPAS – SARSAT program, which aides search and rescue teams worldwide. The USA segment, referred to as SARSAT (Search and Rescue Satellite Aided Tracking) system, is designed to provide distress alert and location data to assist on search and rescue operations. SARSAT locates distress beacons (406MHz) activated at distress locations. The system calculates a location of the distress event using Doppler processing techniques. Processed data is continuously retransmitted through the SARSAT downlink to Local User Terminals (LUT) when satellites are in view. The downlink adjacent interference is expected when two satellites operate in close proximity and share the same frequency. The downlinks of all SARSAT LEO satellites use the same 1544.5 MHz frequency. In cases where the satellites are within the main lobe of the local user terminal antenna, transmissions from adjacent satellites act as interference to one-another, effectively decreasing the signal-to-noise ratio of the desired downlink. This can result in missed distress beacon bursts or no stored solutions received at the LUT, consequently no data is provided about a distress location. Analysis on interference prediction, impacts on system operation and recommendations for mitigating interference periods where the duration may be significant, are presented in this paper.

Share and Cite:

S. CAKAJ, M. FITZMAURICE, J. REICH and E. FOSTER, "The Downlink Adjacent Interference for Low Earth Orbiting (LEO) Search and Rescue Satellites," International Journal of Communications, Network and System Sciences, Vol. 3 No. 2, 2010, pp. 107-115. doi: 10.4236/ijcns.2010.32016.

Conflicts of Interest

The authors declare no conflicts of interest.


[3] D. Ludwig, R. Wallace, and Y. Kaminsky, “Proposed new concept for an advanced search and rescue satellite system,” IAF, International Astronautical Congress, 36th, Stockholm, Sweden, pp. 18, October 1985.
[4] I. W. Taylor and M. O. Vigneault, “A neural network application to search and rescue satellite aided tracking (SARSAT),” in Proceedings of the Symposium/ Workshop on Applications of Experts Systems in DND, pp. 189–201, Royal Military College of Canada, 1992.
[5] S. Cakaj and K. Malaric, “Rigorous analysis on performance of LEO satellite ground station in urban environment,” International Journal of Satellite Communications and Networking, UK, Vol. 25, No. 6, pp. 619–643, November/December 2007.
[6] F. Vataralo, G. Emanuele, C. Caini and C. Ferrarelli, “Analysis of LEO, MEO and GEO global mobile satellite systems in the presence of interference and fading,” IEEE Journal on Selected Areas in Communications, Vol. 13, No. 2, pp. 291–299, February 1995.
[7] J. S. Landis and J. E. Mulldolland, “Low cost satellite ground control facility design,” IEEE, Aerospace & Electronic Systems, Vol. 2, No. 6, pp. 35–49, 1993.
[8] L. Losik, “Final report for a low–cost autonomous, unmanned ground station operations concept and network design for EUVE and other NASA Earth orbiting satellites,” Technology Innovation Series, Publication 666, Center for EUVE Astrophysics, University of California, Berkeley, California, July 1995.
[9] “Specification for COSPAS” – SARSAT406MHz Distress Beacons, C/T T.001, No. 3 – Revision 9, October 2008.
[10] COSPAS –SARSAT System Monitoring and Reporting, C/S A.003, No. 1, Revision 15, October 2008.
[11] COSPAS – SARSAT 406MHz Frequency Management Plan, C/T T.012, No. 1 – Revision 5, Probability of Successful Doppler Processing and LEOSAR System Capacity, October 2008.
[12] G. Maral and M. Bousquet, “Satellite communication systems,” John Willey & Sons, Ltd, Chichester, England, 2002.
[13] D. Roddy, “Satellite communications” McGraw Hill, New York, 2006.
[14] M. Richharia, “Satellite communication systems” Mc- Graw Hill, New York, 1999.
[15] Sh. Cakaj, M. Fischer, and A. L. Schotlz, “Sun synchronization of Low Earth Orbits (LEO) through inclination angle,” in Proceedings of 28th IASTED International Conference on Modelling, Identification and Control, MIC 2009, Innsbruck, Austria, pp. 155–161, Feruary16– 18, 2009.
[16] J. D. Kanellopoulos, T. D. Kritikos, and A. D. Panagopoulos, “Adjacent satellite interference effects on the outage performance of a dual polarized triple site diversity scheme”, IEEE Transaction on Antennas, Vol. 55, Issue 7, pp. 2043–2055, July 2007.
[17] S. Cakaj, “Practical horizon plane and communication duration for Low Earth Orbiting (LEO) satellite ground stations”, WSEAS Journal Transactions on Communications, Vol. 8, No. 4, pp. 373–383, April 2009.
[18] S. Cakaj, K. Malaric, and A. L. Schotlz, “Modelling of interference caused by uplink signal for Low Earth Orbiting satellite ground stations,” in Proceedings of 17th IASTED International Conference on Applied Simulation and Modelling, ASM 2008, Corfu, Greece, pp. 187–191, June 23–25, 2008.

Copyright © 2024 by authors and Scientific Research Publishing Inc.

Creative Commons License

This work and the related PDF file are licensed under a Creative Commons Attribution 4.0 International License.