Improved Low Power Time Source (LPTS) on EMAGR Enables Direct Y Acquisitions

Brent Disselkoen, Britt Snodgrass

Abstract:	Military airborne receivers need the capability for direct Y code (Direct-Y) acquisition after being powered down for up to 24 hours. During military operations, an aircraft will typically sit on the runway overnight and be powered up the next day where performing a Direct-Y acquisition will eliminate the C/A code vulnerability. Previously, Direct-Y acquisitions after long term power outages could be accomplished by either accurate time initialization from an external source, or by maintaining accurate time using a relatively high power frequency standard. A Low Power Time Source (LPTS) was employed to maintain accurate time when the power outage time was limited to a few minutes. Using new LPTS technology developed by Rockwell Collins, it is possible to withstand power outages of many hours (even days) over a wide temperature range, with the quality of a normal frequency standard. The EMAGR (Enhanced Miniaturized Airborne GPS Receiver) was used as a demonstration platform for this new technology. Although the LPTS itself was significantly modified, the interfaces to the receiver software and hardware remained the same. A variety of live satellite tests were conducted using the EMAGR and the new LPTS. These test results show unparalleled performance in the maintenance of GPS time over long term power outages, even when the receiver undergoes significant temperature variation. This capability can be incorporated into all Rockwell military receivers to provide significant advantage for military applications by reducing the need for C/A code acquisition.
Published in:	Proceedings of the 1998 National Technical Meeting of The Institute of Navigation January 21 - 23, 1998 Westin Long Beach Hotel Long Beach, CA
Pages:	59 - 65
Cite this article:	Disselkoen, Brent, Snodgrass, Britt, "Improved Low Power Time Source (LPTS) on EMAGR Enables Direct Y Acquisitions," Proceedings of the 1998 National Technical Meeting of The Institute of Navigation, Long Beach, CA, January 1998, pp. 59-65.
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