Block IIR UHF Crosslink Enhancements Study

Henry E. Sonntag

Abstract:	The current application of the Global Positioning System (GPS) Block IIR UHF Crosslink provides for transfer of Nuclear Detonation Detection System (NDS) data between Block II, Block IIA and Block IIR GPS Space Vehicles (SVs) within RF view of each other. The Block IIR Crosslink also provides for the transfer of Autonomous Navigation (AUTONAV) and ranging data between Block IIR SVs as well as a limited commanding capability. This paper describes enhancements to the Block IIR Mission Data Unit (MDU) Processor software that provides further capability for the Block IIR SVs through enhanced crosslink communications. The enhancements include a new data protocol that provides more general commanding and acknowledgment functions without impairing the NDS or AUTONAV missions. This protocol gives the Crosslink the capability of remote commanding the Block IIR SVs. SVs are selectively addressed. For many years the GPS constellation will consist of a mix of Block IIR and Block II/IIA SVs. The critical problem of synchronizing the time reference of a mixed constellation of Block IIR (using AUTONAV) and Block II/HA (using ground- navigation) SVs using the Crosslink is described. Future enhancements that can be provided by the Crosslink through the reprogrammable feature of the Block IIR SVs are also discussed.
Published in:	Proceedings of the 1997 National Technical Meeting of The Institute of Navigation January 14 - 16, 1997 Loews Santa Monica Hotel Santa Monica, CA
Pages:	819 - 828
Cite this article:	Sonntag, Henry E., "Block IIR UHF Crosslink Enhancements Study," Proceedings of the 1997 National Technical Meeting of The Institute of Navigation, Santa Monica, CA, January 1997, pp. 819-828.
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